1
DEPARTMENT OF HEALTH AND HUMAN
SERVICES
FOOD AND DRUG
ADMINISTRATION
CENTER FOR BIOLOGICS EVALUATION
AND RESEARCH
BLOOD PRODUCTS ADVISORY COMMITTEE
This
transcript has not been edited or corrected, but appears as received from the
commercial transcribing service:
Accordingly the Food and Drug Administration makes no representation as
to its accuracy.
Friday, July 23, 2004
8:00 a.m.
Gaithersburg Holiday
Inn
2 Montgomery Village
Avenue
Gaithersburg, Maryland
20877
2
PARTICIPANTS
Kenrad E. Nelson, M.D., Chair
Linda A. Smallwood, Ph.D., Executive
Secretary
Pearline K. Muckelvene, Scientific
Advisors
& Consultants Staff
MEMBERS:
James R. Allen, M.D., M.P.H.
Kenneth Davis, Jr., M.D.
Donna M. DiMichele, M.D.
Samuel H. Doppelt, M.D.
Jonathan C. Goldsmith, M.D.
Harvey G. Klein, M.D.
Suman Laal, Ph.D.
Katherine E. Knowles,
Acting Consumer Representative
D. Michael Strong,
Non-Voting Industry Representative
TEMPORARY VOTING MEMBERS:
Liana Harvath, Ph.D.
F. Blaine Hollinger, M.D.
Katharine E. Knowles
Matthew J. Kuehnert, M.D.
Susan F. Leitman, M.D.
Keith C. Quirolo, M.D.
George B. Schreiber, Sc.D.
Donna S. Whittaker, Ph.D.
3
C O N T E N T S
PAGE
Update on West Nile Virus, Hira Nakhasi,
Ph.D. 6
IV. Hepatitis B Virus Nucleic Acid
Testing (NAT)
for Donors of Whole
Blood:
A. Introduction and
Background,
Gerardo Kaplan, Ph.D.,
Laboratory
of Hepatitis and Related
Emerging
Viruses, DETTD, OBRR, FDA 28
B. Serological Course of
Hepatitis B,
F. Blaine Hollinger, M.D.,
Baylor College of
Medicine 32
C. Preclinical and Clinical
Data for
HBV MP NAT, Steven Herman, Ph.D.,
Roche Molecular
Systems 51
Allan Frank M.D., M.S.,
Roche Molecular
Systems 65
Open Public Hearing:
Michael Busch, Blood Centers
of the Pacific 103
William Andrew Heaton,
Chiron 121
Sherrol McDonough,
Gen-Probe 129
Richard Smith, NGI 136
Harvey Alter, AABB 144
IV. Hepatitis B Virus Nucleic Acid
Testing (NAT)
for Donors of Whole
Blood:
E. Committee Discussion and
Recommendations 154
V. Current Trends in Plasma Product
Manufacturing
A. Introduction and
Background,
Mark Weinstein, Ph.D.,
Associate
Deputy Director, OBRR, FDA 223
B. Presentation, Jan M.
Bult, CEO,
Plasma Protein
Therapeutics
Association 225
Open Public Hearing:
Patrick Schmidt, CEO, FFF
Enterprises 258
4
1 P R O C E E D I N G S
2 DR. SMALLWOOD:
May I ask all advisory
3
committee members to, please, take your seats?
4
Welcome to the second day of the Blood Products
5
Advisory Committee meeting.
Yesterday I read the
6
conflict of interest statement that applies to this
7
meeting, however, we have a new process now and we
8
will read a conflict of interest statement for each
9
day.
10 So, if you will indulge me, I will read
11
that at this point. This brief
announcement is in
12
addition to the conflict of interest statement read
13
at the beginning of the meeting yesterday, and is
14
part of the public record for the Blood Products
15
Advisory Committee meeting on July 23, 2004. This
16
announcement addresses conflicts of interest for
17
topic V.
18 Drs. Liana Harvath, Blaine Hollinger,
19
Matthew Kuehnert, Susan Leitman, Keith Quirolo,
20
George Schreiber, Donna Whittaker and Ms. Katherine
21
Knowles have been appointed as temporary voting
22
members for this meeting
5
1
Dr. Michael Strong is participating in this meeting
2
as the non-voting industry representative, acting
3
on behalf of regulated industry.
The Food and Drug
4
Administration has prepared general matters waivers
5
for the special government employees participating
6
in this meeting who required a waiver under Title
7
XVIII, United States Code 208.
8 In addition, there are regulated industry
9
and other outside organization speakers making
10
presentations. These speakers
have financial
11
interests associated with their employers and with
12
other regulated firms. They were
not screened for
13
these conflicts of interest. I
would just like to
14
remind everyone participating to, please, make
15
known, if you have not already done so, any
16
affiliation you may have and your status with that
17
affiliation prior to speaking.
18 Our committee chairman, Dr. Kenrad Nelson
19
has joined us this morning, and we also have Dr.
20
Blaine Hollinger who will also be part of the
21
committee this morning.
22 I just wanted to announce to those who
6
1
were not here yesterday that the next date, which
2
is tentative however pretty much firm, for the next
3
Blood Products Advisory Committee meeting will be
4
October 21st and 22nd, 2004.
5 At this time I will turn over the
6
proceedings of the meeting to the chairman, Dr.
7
Kenrad Nelson.
8 Update on West Nile Virus
9 DR. NELSON:
Thank you, Dr. Smallwood. I
10
will try to keep awake after the 24-hour airplane
11
ride. I came in last night but I
feel really
12
pretty good and I am very interested in the topic
13
today so I think that will help.
14 The first topic is an update on West Nile
15
virus by Hira Nakhasi.
16 DR. NAKHASI:
Good morning. I just want
17
to give you an update, as Dr. Kenrad Nelson
18
mentioned, on the West Nile epidemic and donor
19
testing which is happening now, in 2004. First I
20
will try to wrap up last year's things and then
21
come up to 2004.
22 Next slide, please.
The topics which I
7
1
will update you on are, as I said, last year's
2
epidemiology and the investigational West Nile
3
testing outcome of that, and some of the
4
transfusion-transmitted cases, and then the trigger
5
for the ID-NAT testing. Then I
will update you on
6
the West Nile donor and product management
7
recommendations with the recent revelations we have
8
got. Then I will update you on
the 2004 epidemic
9
and investigational West Nile testing, and also our
10
efforts in-house on the panel development and other
11
scientific issues--you know, the variation among
12
the strains of viruses infectivity of these
13
studies.
14 Next slide, please.
If you summarize in
15
one slide the last year's epidemic, it really
16
basically sums up that we had approximately 1000
17
[sic] cases or, to be precise, 9862 cases, human
18
cases, and 264 deaths. And, the
proportion of the
19
West Nile meningitis/encephalitis was 29 percent,
20
whereas, the fever was 69 percent in the human
21
cases.
22 Forty-six states, including
Washington,
8
1
D.C., were endemic, and donor testing started, as
2
all of you know, in July of 2003, using two
3
investigational NAT testing. In
some cases, a
4
small proportion started in the middle of June.
5
Despite this testing, I think these two
6
investigational NAT testing--these are minipool and
7
the two tests were the Gen-Probe test and the Roche
8
test, and Roche tested, as you know, in pools of 6
9
and the Gen-Probe test involves a pool of 16.
10 Despite testing, there were some
11
transfusion-transmitted cases and CDC had
12
investigated a total of 23 cases.
They were
13 confirmed by NAT and IgM reactivity and also by
14
follow-up of both the donor and the recipient. Out
15
of the 23, 6 were confirmed cases.
Only 4/6, you
16
may recall, had very low viremia, around 0.1
17
pfu/ml. Eleven cases did not confirm;
3 were
18
inconclusive because of the follow-up situation;
19
and 3 were open investigations.
20 Next slide, please.
As I said, since it
21
started on July 1 of last year, screening using
22
minipool NAT and IND, all geographic regions of the
9
1
U.S. were screening at that time.
With that, what
2
happened 1000 units of West Nile infected blood
3
donors were interdicted after screening
4
approximately 8 million donations.
So, I think it
5
was a very, very vast improvement over the year
6
before when there was no testing.
The last
7
positive donation was reported in the middle of
8
December in 2003.
9
Despite this testing, as you
see, the
10
majority of cases were interdicted, more than 75
11
percent, but there was a small percentage which
12
went through because, as you know, this was done in
13
minipool NAT.
14 Next slide, please.
This slide is Mike
15
Busch's slide where he showed why we were missing
16
some of these cases, and we knew that minipool NAT
17
sensitivity was such. The areas,
you know, where
18
the wrap-up takes place when--you know, he calls it
19
stage I, II, III, IV and V, and in stage I and II
20
they are ID-NAT positive but minipool NAT negative,
21
IgM negative. So, it could be
plus/minus. So,
22
during that stage they become IgM positive but they
10
1
become minipool negative and they are still ID-NAT
2
positive. So, this region and
this region were the
3
ones where they went through.
But, you know, these
4
were IgM negative and these were IgM positive so
5
the question is what is the infection of these
6
types of samples.
7 Next slide, please.
So there was a
8
potential for transmission of West Nile through
9
minipool NAT negative blood of low viremia in some
10
patients. Therefore, what
happened at that time is
11
that limited prospective ID-NAT testing started in
12
high incidence areas. If you
remember last year,
13
Colorado, Kansas and certain other areas, and
14
Nebraska were hot spots and ID-NAT was triggered at
15
that time, and the trigger was based on if the
16
preceding the rate of 1/200 minipool NAT positive
17
rate of 1/250, then they would start testing with
18
ID-NAT testing. Also, what happened
at that time
19
is that there was voluntary withdrawal of the
20
frozen transfusables in the high incidence areas
21
before the ID-NAT was initiated by some blood
22
establishments.
11
1 Next slide, please.
There was also
2
another initiative started at that time. The
3
initiative was to go back to do the retrospective
4
study on the minipool NAT negative samples and test
5
them by ID-NAT to find out how many we missed. It
6
would also let us know what was the low level of
7
viremic high incidence samples in high incidence
8
areas where minipool NAT did not pick them up.
9 The other purpose of the study was also to
10
identify samples which are like minipool NAT low
11
titer, minipool NAT negative but ID-NAT positive
12
for infectivity studies. I told
you that we do not
13
know whether those samples are still infectious at
14
low levels, and what is the level of infectivity.
15
So, these samples would be tested in various animal
16
models including non-human primates.
Also, the
17
purpose of these samples is to really find out the
18
relative clinical sensitivity of various West Nile
19
investigational testing. I will
report in a minute
20
what is happening with the infectivity state.
21 Next slide, please.
Based on the
22
observation that we had minipool testing and we
12
1
missed some of the samples because the viremia was
2
low, and also in the ID-NAT testing in the high
3
incidence areas--based on those studies and based
4
on the logistics issues, the question was what
5
should be the trigger for ID-NAT, and also logistic
6
issues such the availability of adequate resources,
7
recruitment, reagents and trained technologists.
8 So, the discussion about the trigger for
9
ID-NAT was held in collaboration with the AABB task
10
force. By the way, we are very
indebted to the
11
AABB task force for the biweekly meetings almost
12
throughout the year, and weekly meetings with the
13
task force during the epidemic to update us and
14
jointly discuss the strategies for how to go
15
forward with the testing performance, as well as
16
the epidemic.
17 So, based on that discussion, which was
18
held in February, the recommendations were the
19
following for the ID-NAT trigger:
It was discussed
20
that we should monitor reactive rates by zones
21
daily, enrolled 7 days when the epidemic was
22
starting, which was usually, you know, around the
13
1
beginning of July and early June even and this year
2
even May some cases were found.
The trigger was
3
that if you have 2-4 cases in any geographic
4
area--that is the blood collection, and the
5
frequency of 1/1000. This was
based on the fact
6
that every 1/4 would be missed by minipool NAT and
7
require ID-NAT. This was the
study done by ARC and
8
BSL and they found out that that would be the
9
trigger. And, you go back to
minipool NAT only
10
when you see ID-NAT reactivity and you don't find
11
zero cases in a consecutive 3-4 day period or the
12
rate is less than 1/1000. So,
that was the trigger
13
because, you know, we wanted to be prepared this
14
year because last year it was on an ad hoc basis to
15
start ID-NAT testing in those hot areas. So, we
16
wanted to be prepared this year if these areas
17
become hot so that we get the logistics present
18
there so we can start without interruption of the
19
ID-NAT testing.
20 Next slide, please.
Now we come to 2004,
21
where are we now? As of July 20,
which is a couple
22
of days back--as you see, every week the numbers
14
1
keep changing. Last week there
were 108. This
2
week it is 182 human cases out of which there were
3 4
deaths. There are 2 from Arizona, 1
from Texas
4
and 1 from Iowa. Out of total
infections, 74
5
percent of cases are neuroinvasive West Nile
6
illness and 26 percent cases are West Nile fever.
7
At the moment there are 35 states endemic for West
8
Nile. This slide has been kindly
provided by Jen
9
Brown, from CDC, and other slides which I will
10
mention later.
11 The total number of presumptive West Nile
12
viremic donors reported to the CDC ArboNet--that is
13
why I highlighted this, is 23.
There are more
14
cases than that but, as you know, there is a delay
15
in reporting to the ArboNet from the health
16
departments. So, using minipool
NAT as well as
17
ID-NAT in select areas, starting on May 4. Out of
18
these 23 presumptive West Nile viremic donors, 21
19
are from Arizona. The majority
are from the
20
Maricopa county near Phoenix, in Arizona; 1 from
21
New Mexico and 1 from Iowa. But
this is the tip of
22
the iceberg.
15
1
Next slide, please. This slide, again, is
2
provided by Jen. You can see the
distribution of
3
the West Nile, both the animal, avian and mosquito
4
infection, which is in this color, and the blue
5
color shows you the human cases.
You can see it is
6
very high in Arizona and California.
I am telling
7
Mike Strong that it is creeping up in Washington
8
soon. So, he has been telling me
we don't see
9
anything and I said, well, wait and watch! As you
10
remember, in 1999, how this started and how it is
11
spreading and, you know, it just keeps on going. I
12
hope it will end up in the ocean sometime.
13 Next slide, please.
This is just to give
14
you how early the human cases can be detected. As
15
you see from the slide, the earliest one was in
16
April. So, you know, there is an
expansion of this
17
epidemic, it looks like. We were
told in the
18
textbooks it is mostly in August and September or
19
late July but you can see it as early as April now,
20
and last year we saw it as late as December, in the
21
middle of December. So, you
know, it is almost a
22
year-round activity now.
16
1 Next slide, please.
Thanks to all the
2
blood establishments and testing establishments, I
3
got these data from several folks and I will
4
acknowledge them as I speak. The
total number,
5
according to my calculations but this may not be
6
right, is 61 presumptive viremic donors reported,
7
starting in May, 2004. As I
said, some of them are
8
reported to ArboNet and some of them are not. So,
9
it is not in addition to that; it is inclusive of
10
the ArboNet reports. ARC has
told me--Sue Stramer
11
gave the data from June 16 to July 20, 7 hard
12
cases. Again, this is also in
the Arizona area.
13
But she says no region has their ID-NAT trigger.
14 Mike Strong gave me this data from Roche.
15
There are 2 positive confirmed by ID-NAT--around
16
300,000 donations screened.
17 BSL, Sally Caglioti and Mike Busch told me
18
that there are 23 confirmed, out of which 16 came
19
from minipool NAT and 7 came from ID-NAT, confirmed
20
positives. There are 14 pending
and he was saying
21
that some of them are ID-NAT and would have been
22
missed by minipool NAT. Also,
some of them are low
17
1
viremic and also there are some which are IgM
2
positive. The denominator is
around 400,000.
3 Gen-Probe, Leanne Kiviharju, gave the
4
data. These are non-ARC data but
I am not sure--I
5
sent an email to Leanne--whether this is also
6
non-BSL but I am not sure; maybe we can find out
7
from here, but 21 confirmed positive and 7 are
8
pending. I am glad that you guys
sent me several
9
slides. I was basically trying
to summarize what
10
the presumptive donors are and, you know, I really
11
appreciate your sending extra slides.
12 The Department of Defense, Ron Hagey sent
13
me the data which has 8 confirmed out of 62,774
14
since January of 2004.
15 So, you know, this is the majority of the
16
screening going on at this time and there may be a
17
few cases which have not been reported yet, but
18
this is where we stand as of today.
19 Next slide, please.
I just wanted to sort
20
of briefly remind you that FDA is still continuing
21
to work closely with the test kit manufacturers and
22
we would like to facilitate implementation of these
18
1
tests and expediter test licensure.
I just want to
2
remind you that we issued two guidances in October,
3
2002 and May, 2003. There are 3
INDs for West Nile
4
minipool-NAT. One is from Roche,
one from
5
Gen-Probe and one from ARC. This
is public
6
information. FDA is continuing
to work with the
7
AABB task force. I think that
has been a
8
wonderful, wonderful collaboration with the AABB
9
task force and the people on the task force are
10
really helpful in doing this project together, and
11
with the CDC, NIH help, and to monitor the epidemic
12
and monitor the testing.
13 Next slide, please.
Both ARC and BSL did
14 a
study, which is unpublished observation.
We had
15 a
small discussion at the task force on what they
16
found out in some of the viremic donors when they
17
followed up. They wanted to find
out what is the
18
rate of the disappearance of RNA when they convert
19
IgM and IgG. As you remember, in
the last years
20
before the testing started the literature was that
21
it can go as long as 28 days of viremia. But from
22
their studies, and I don't want to go into detail
19
1
here because these are unpublished and, you know, I
2
don't want to divulge information--the gist of that
3
was that what they found out in both cases is that
4
the viremia may last up to 49 days in one case and
5 39
days in the ARC study, and in the BSL 49 days,
6
and West Nile RNA may go coexist with IgM.
7
Therefore, this sort of started us thinking. In
8
the guidance document we put 28-day donor deferral
9
and so we may have to rethink the deferral for
10
that.
11 Next slide, please.
We have not discussed
12
it with the AABB task force but we will be
13
discussing with the task force that, you know, the
14
integration of West Nile testing information. We
15 are thinking about maybe 56-day deferral for
West
16
Nile diagnosis of symptoms, including headache and
17
fever, or 14 days after symptom resolution if it is
18
more than 56 days. Potential
reinstatement of
19
donor deferral for West Nile symptoms only
20
following 30 days without symptoms, and negative by
21
West Nile IgM or ID-NAT. Again,
this is current
22
thinking. We have nothing in the
works yet but we
20
1
have internal discussions, and we will discuss it
2
at our next regular AABB task force before we come
3
up with a recommendation. Dr.
Alan Williams is
4
spearheading this initiative.
5 Next slide, please.
With regard to our
6
activities in-house, as I mentioned last year also,
7
we are still working on the panel development. The
8
purpose is to monitor sensitivity of assays to
9
detect viral nucleic acid antibodies, and also
10
trying to isolate and characterize West Nile
11
strains from human samples during 2003 and 2002
12
epidemics. The purpose of this study, which is done
13
by Dr. Maria Rios in our group--and all these
14
studies actually really are done by Dr. Maria Rios'
15
group--is the genetic variation of viral strains;
16
detection by currently available West Nile assays.
17
The purpose is to really see if there is any
18
genetic variation and also infectivity studies
19
using animal models. Currently,
the samples have
20
been identified which could be used for infectivity
21
studies. However, there are
logistic issues about
22
the animals, baboons, which are being worked out
21
1
with the Southeast Medical Center.
I guess the
2
task force is working on that.
Hopefully, we will
3
get some information by fall and we will be set to
4
do those studies.
5 Next slide, please.
Briefly, they have
6
two isolates, NY99 in 2002, which have been
7
characterized by genetic sequencing which I can
8
show you in a minute. The viral
infectivity is
9
determined by in vitro studies using cell lines and
10
primary human blood cell cultures.
Final panel
11
specifications are being established through the
12
collaborative studies, and the range of
13
concentration ranges between 1000-5 copies/ml.
14 Next slide, please.
Just a piece of
15
information here that Maria was kind enough to
16
provide to me. You know, she did
the comparison of
17
the human 2002 strain and the NY99 flamingo isolate
18
and then passed through the Vero cells.
She found
19
there were 20 nucleotide mutations and one
20
insertion. The mutations are
distributed all
21
across the region which result in 5 amino acid
22
substitutions. She is
characterizing more isolates
22
1
and she already has 6 from 2002, 11 from 2003 and 6
2
from 2004. So, the purpose is to
really compare
3
and to see what the differences are and how those
4
differences impact on our tests.
5 Next slide please.
The outcome of the
6
panel testing--six laboratories participated in
7
that. She tells me there were no
false-positive
8
results reported. More
variability in detection
9
was found towards the lower end of the viral
10
concentration, i.e., 80 percent of the time
11
detected 100 copies/ml member but all laboratories
12
detected 100 percent of the time the panel members
13
of 500-1000 copies/ml. Further
testing is going to
14
define the consensus copy number.
15 Next slide, please.
This is the important
16
slide. I would like to thank all
the people who
17
really helped to make this talk possible. Jennifer
18
Brown, whom I have always been bugging to provide
19
the slides. Thank you,
Jennifer. Dr. Sue Stramer,
20
Dr. Mike Busch and Sally Caglioti, Dr. Mike Strong,
21
Leanne Kiviharju, Roland, Maria and all these
22
people--whoever I send an email they are kind
23
1
enough to respond quickly. Also
my colleagues at
2
the FDA, Maria Rios, Alan Williams, Dr. Epstein,
3
Martin Ruta, Indira Hewlett--always helping in this
4
whole project and, last but not the least, the AABB
5
task force. I am really, really
grateful to them
6
for providing all the information and helpful
7
discussion. Thank you very much.
8 DR. NELSON:
Thank you. Any questions or
9
comments? Yes?
10 DR. GOLDSMITH:
Do you have additional
11 data on the level of viremia in these samples that
12
you have been studying? What is
the maximum level
13
of viremia?
14 DR. NAKHASI:
Which samples are you
15
talking about?
16 DR. GOLDSMITH:
The ones that you
17
recovered from the viremic donors.
18 DR. NAKHASI:
From the viremic donors, I
19
don't know. Maria, do you know
what the levels
20
are?
21 DR. RIOS:
Between 10
5 and 106 is the high
22
level of viremia that we have found.
Are you
24
1
asking for the range of viremia or the high level
2
of viremia?
3 DR. GOLDSMITH:
I was just curious about
4
the high but it is fine to give the range.
5 DR. RIOS: It
varies. It varies. The
6
assays, in general, that use lower volumes do not
7
detect them. Assays that have higher
volume and
8
high throughput detect, but do not give accurate
9
quantitation, to 10
6 copies/ml.
10 DR. NELSON:
One of your slides had 23
11
positives with 16 by minipool and 7 by ID. Were
12
those 7 not detectable by minipool or was it just
13
that ID screening was triggered and they weren't
14
tested by minipool?
15 DR. NAKHASI: I
think they came for the
16
ID-NAT testing. Is that
true? Yes. You know, in
17
BSL they had already started ID-NAT testing in
18
Maricopa County. The trigger had
started earlier.
19 DR. NELSON:
So, they were negative by
20
minipool?
21 DR. STRONG:
No, the trigger was activated
22
and they started doing ID screening so they haven't
25
1
gone back yet, I think, to see if those would have
2
been picked up by minipool.
3
DR. BUSCH: Actually, 7/12 that were
4
picked up in the region that had been converted to
5
ID-NAT, 7 of them had been fully worked up and 5 of
6
those 7 are negative at 1:16 dilutions so they
7
would have been missed by minipool.
Of those 5, 1
8
of them is antibody negative and 4 have IgM and
9
IgG.
10 DR. NELSON:
Has anybody looked at the
11
characteristics of the donors that have low levels?
12
Are there host factors that might influence whether
13
somebody has high level or low level?
I know one
14
feature may be antibody but in those that are
15
antibody negative, I wonder if there are any donor
16
characteristics that influence the level of
17
viremia.
18 DR. BUSCH: Sue
has looked at that I think
19
more formally and there wasn't any correlation.
20
These are representative donors of the donor pool
21
in terms of the viremics, non-viremics and low
22
viremics. I think it is just by
chance. This
26
1
phase of early viremia is completely asymptomatic.
2 DR. RIOS: It
may have some inherited
3
characteristics that limit the viral replication.
4
The reason why we think that is because we have
5
performed some in vitro studies with human primary
6
macrophages and there is a great variability not
7
only in the day of the viral peak, but some
8
individuals can have a very steady and low titer
9
that doesn't progress to peak.
So, that indicates
10
that some inheritance variability may interfere
11
with replication.
12 DR. NELSON:
That is interesting. Other
13
questions?
14 DR. LAAL:
Unless I misunderstood, I
15
noticed that in 2003 we had a majority of your
16
isolates from people who had fever, and about
17
one-quarter were from neuroinvasive cases. In 2004
18
it is reversed.
19 DR. NAKHASI:
Yes, that is an important
20
point. I discussed it with the
CDC folks and they
21
said, you know, don't pay attention to that because
22
the fever cases were--you know, this year they are
27
1
paying more attention so some of the fever cases
2
were not real fever cases. You
are right, you saw
3
the switch.
4 DR. LAAL: But
then in the isolates that
5
you are picking up now for the genetic studies, are
6
you carefully making sure that you look at both
7
types?
8 DR. NAKHASI:
Maybe Maria can say; I don't
9
know.
10 DR. RIOS: The
isolates that have been
11
studied so far don't come from patients. Actually,
12
that is the effort we are going to move towards
13
now. They are identified through
the blood
14
screening. So, in order to
evaluate if there is
15
any isolate that may not be picked up by the blood
16
screening we need to acquire samples from cases
17
that are non-blood donors to investigate this
18
possibility.
19 DR. NELSON:
Yes, Mike?
20 DR. STRONG:
Just a quick comment on the
21
donors. In the studies that were
done last year,
22
many of the donors that were interviewed, in fact,
28
1
were symptomatic either shortly before or shortly
2
after their donations but the screening questions
3
just didn't pick them up.
4
IV. Hepatitis B Virus Nucleic Acid Testing (NAT)
5 for Donors of Whole Blood
6 DR. NELSON:
Thanks. The next topic is
7
hepatitis B virus nucleic acid testing for donors
8
of whole blood. Dr. Gerardo
Kaplan will introduce
9
this and give us background.
10 A. Introduction and Background
11 DR. KAPLAN:
Good morning.
12 [Slide]
13 I am Gerardo Kaplan, Chief of the Lab of
14
Hepatitis and Related Virus Emerging Agents. I am
15
with the Office of Blood, and I will introduce for
16
you the hepatitis B virus n nucleic acid testing
17
for donors of whole blood.
18 [Slide]
19 The general agenda for this meeting is
20
that after the introduction and background, Dr.
21
Blaine Hollinger will give us an update on the
22
serology of hepatitis G. This
will be followed by
29
1
two presentations from the Roche Molecular Systems
2
and their preclinical and clinical data in support
3
of their application. Finally, I
will come back to
4
give you the FDA perspective on hepatitis B MP-NAT
5
and present the questions for the committee. I
6
understand that there will be a break and then a
7
public hearing.
8 [Slide]
9 So, the issue is that the FDA is seeking
10
the opinion of the committee on the performance of
11
the Roche COBAS AmpliScreen HBV test in minipools
12
of 24 samples to screen blood for transfusion by
13
nucleic acid testing, and its proposed intended use
14
as an alternative to hepatitis B surface antigen
15
testing in conjunction with testing for antibodies
16
to hepatitis B core antigen.
17 [Slide]
18 In support of their claims, Roche
19
Molecular Systems performed a clinical trial. The
20
study objectives of the clinical trial were to
21
determine whether the COBAS AmpliScreen test, which
22
is a minipool of 24 samples of plasma from
30
1
volunteer blood donors, can detect hepatitis by DNA
2
in hepatitis B surface antigen-anti-core negative
3
window period cases. This is the
primary objective
4
of the study. In hepatitis B
surface
5
antigen-positive donors, who are acutely infected
6
or chronic carries, and in persons previously
7 exposed
to hepatitis B as the secondary objective.
8 [Slide]
9 During the clinical trial, Roche Molecular
10
Systems identified two window period cases in about
11
600,000 volunteer whole because donations screened
12
by hepatitis B NAT using their minipools of 24
13
samples.
14 RMS, Roche Molecular Systems, claims that
15
the use of the COBAS AmpliScreen HBV test in
16
conjunction with the anti-core test would reduced
17
the residual risk of transfusion-transmitted
18
hepatitis B, and also that this test, the COBAS
19
AmpliScreen, could be used as an alternative to the
20
commonly used hepatitis B surface antigen donor
21
screening test. I would like to
point out that
22
blood in the U.S. is currently being tested by
31
1
surface antigen and core antibodies.
2 [Slide]
3 So, we would like to request comment of
4 the
committee on three questions.
Basically, the
5
firs would be do the sensitivity and specificity of
6
the Roche COBAS AmpliScreen hepatitis B test in
7
minipools of 24 samples support licensing of the
8
assay as a donor screen?
9 [Slide]
10 If so, assuming continued use of screening
11
tests for anti-hepatitis B-core, do the data
12
support use of the Roche COBAS AmpliScreen
13
hepatitis B test in minipools of 24 samples to
14
screen blood for transfusion as an equivalent
15
alternative to the surface test?
If not, which
16
studies would be required to validated such a new
17
test?
18 The third question is do the data support
19
use of the Roche COBAS AmpliScreen hepatitis B test
20
on minipools of 24 samples to screen blood for
21
transfusion as an added test in conjunction with
22
licensed donor screening tests for hepatitis B
32
1
surface and anti-core?
2 Now I would like to introduce Dr. Blaine
3
Hollinger. He will give us an
update on hepatitis
4 B
serology.
5 B. Serological Course of Hepatitis B
6 DR. HOLLINGER:
Thank you, Gerardo. It is
7
always a pleasure to come to these meetings and I
8
always tend to learn more than I think anyone here
9
because there is always so much information.
10 [Slide]
11 The talk today is about serology, and
12
serology can be confusing. It is
confusing to our
13
GI residents and fellows in trying to determine
14
what happens after hepatitis B infection. The
15
clinical and serologic changes that occur following
16
infection represent a complex interaction between
17
the host, the virus and specific antigens. If you
18
have an understanding of these items, I think it
19
becomes very easy to understand what happens.
20 There are certain changes that occur after
21
infection with all viruses that seem to be very
22
similar. Viruses are either
enveloped or
33
1
non-enveloped. Hepatitis B virus
happens outcome
2
have a lipoprotein envelope that contains hepatitis
3 B
surface antigen as the envelope protein.
There
4
are also some other particles in this serum which
5
are seen in excess of the infectious virion, and
6
these are the small particles here, and these
7
tubular forms which actually come off, in many
8
cases, from the hepatitis B virion.
9 The inside, or the nucleocapsid of the
10
virion is comprised of the hepatitis B core
11
antigen, and this encloses a relaxed, circular,
12
partially double-stranded DNA molecule.
Another
13
antigen which is seen also is the hepatitis B
14
antigen, but this is not part of the virion in any
15
way. It is a secretory protein,
about 16-17 kd in
16
size, that is secreted during active infection, and
17
is representative usually of high concentrations of
18
virus in the bloodstream. We
don't really know
19
what is the reason for this particular antigen.
20 [Slide]
21 This is the HBe genome. It has four open
22
reading frames. One of them is
responsible for the
34
1
hepatitis B-surface antigen and is comprised of a
2
small, a medium and a large protein.
A second one
3
is the core gene which expresses the core-antigen,
4
the hepatitis B core-antigen and also the e-antigen
5
as well. There is a DNA
polymerase that is
6
important for the replication of this virus, and
7 there is an x-gene here
which is very important for
8
initiation and probably maintenance of the
9
infection. It is probably also
weakly oncogenic as
10
well. Now, once one understands
these things, you
11
can then start to see what happens after an
12
infection.
13 Next slide, please.
This slide shows what
14
happens in the typical course--now, I am going to
15
talk about typical things here.
Certainly all of
16
us know about the exceptions and we have all seen
17
them at one time or another, but I think it is
18
important to deal right now with the typical
19
changes that can occur. Again
what happens, you
20
have a hepatocyte that is infected.
There is a
21
very short eclipse phase in which we would not see
22
virus in the hepatocyte. Then
viruses start to be
35
1
produced and are transported out of the cell.
2
Then, one sees initially HBV DNA in the
3
bloodstream. It precedes the
expression of
4
hepatitis B-surface antigen which then starts to
5
occur here very early in the course of the disease
6
and peaks usually during the acute phase of a
7
clinical illness.
8
What happens then in this
non-cytolytic
9
infection is that there are usually some holes that
10
are punched in the plasma membrane of a hepatocyte.
11
ALT, which is in the cytosol, aminotransferase
12
enzyme which is in the cytosol of hepatocytes, are
13
released into the bloodstream.
So, the ALT is
14
elevated in these patients and then follows the
15
clinical symptoms of anorexia, fatigue, jaundice,
16
etc.
17 Usually about the time the ALT begins to
18
appear, HBeAg and IgM anti-HBc are found. IgM anti
19
HBc appears in high titer or high concentration in
20
individuals as a response to the synthesis of
21
nucleocapsids and, therefore, represents active
22
viral replication. The IgM rises
during the early
36
1
courses of infection and then starts to disappear.
2
Usually by 4-6 months or so, or 6-9 months, the IgM
3
anti-HBc disappears, although it may be present for
4
up to 2 years in individuals, if you use very
5
sophisticated research tools.
6 Usually the HBV DNA disappears in the
7
acute infection at the time that a hepatitis
8
B-surface antigen disappears.
So, you have a
9
pattern here. HBV DNA first; HB
surface antigen,
10
and the HBsAg disappears and usually about that
11
time HBV DNA is gone, or at least is
12
non-detectable.
13 Again, another pattern appears. When
14
HBsAg disappears it is replaced by its antibody,
15
anti-HBs. Now, we know that
probably anti-HBs is
16
produced very early in the course of the infection,
17
even probably back in this area here, which results
18
in serum sickness, vasculitis or other things, but
19
you don't detect it because there is so much
20
hepatitis B surface antigen available so it is
21
non-detectable. But eventually
the surface antigen
22
goes; anti-HBs then is detected.
When HBeAg
37
1
disappears in the active infection, then anti-HBe
2
replaces it. Anti-HBe lasts in
most patients for a
3
long period of time but in about a third of the
4
patients disappears after about 6 months of
5
follow-up.
6 Of course, the IgM anti-HBc--there is a
7
switch-over between the IgM anti-HBc and IgG
8
anti-HBc. What is important to
recognize is that
9
the assay, the total anti-HBc assay, detects not
10
only IgM but IgG antibodies. It
is not an IgG
11
test; it detects both IgG and IgM.
So, whenever
12
IgM is present you ought to see the total anti-HBc
13
test positive.
14 Next slide, please.
This is an older
15 slide
I have but I think it helps us a little bit
16
understand the relationship of all these assays
17
that we are looking at. The EIA
assay and those
18
that are being developed can detect down to about a
19
tenth of a nanogram of HBsAg.
HBsAg circulates up
20
to 200 mcg or more per ml of blood.
These tests
21
really have an upper level of sensitivity of about
22 1
mcg/ml. So, usually they are at their
upper
38
1
limits of detection for most infections.
2 The second test that came along them were
3
the hybridization assays, the liquid phase and the
4
filter hybridization assays.
These could detect
5
down to a tenth to 1 pg of genomic equivalence in
6
the blood. At least, at 24 hours
if you have the
7
autoradiographs stay for maybe up to 5 days, you
8
can detect anywhere from 2- to 10-fold more virus
9
in the blood. So, they are
detecting about this
10
level here, somewhere between here and here, and 1
11
pg is equivalent to about 300,000 copies/ml. You
12
will see 280,000, 330,000 but let's just talk about
13
300,000 copies/ml. So, 1 pg is
here, 300,000,
14
30,000, 3,000 and 300 down at the femptogram
15
levels.
16 The PCR assays, which are somewhere
17
between 700-7,000 times more sensitive than
18
hybridization assays, can detect down to 50 copies
19
or less per ml. So, they are
down in this range,
20
here. As I said, this is
300,000, 3,000 and 300
21
copies/ml. This would be 30
copies/ml. These are
22
usually with nested PCRs or other assays, nucleic
39
1
acid--the tests that are available today.
2 So, you see the differences between these
3
assays. One might ask why is it
then that the EIA
4
tests are detecting HBsAg very closely to the HBV
5
DNA. Part of the reason for that
is that there are
6
anywhere from 1,000 to 10,000 times more--at least
7
10,000 times more hepatitis B surface antigen
8
particles per infectious virion, and there may be
9
even more naked HBV particles.
So, you have a lot
10
more HBsAg produced initially than you do
11
infectious virions. That is the
reason I think
12
that there is not a great deal of difference, at
13
least initially, in the detection of these
14
particles.
15 Next slide, please.
So, during the course
16
of infection HBV DNA is detected from 2-5 weeks
17
after infection and up to 40 days before the HBsAg
18
is detected. However, there is a
wide coefficient
19
here of variation but the mean of that is around
20
6-15 days, and there are some exceptions to this.
21
It rises slowly during the course of infection at a
22
relatively low level, say 10
2 to 104
copies/ml
40
1
during the seronegative period, that is, before the
2
HBsAg appears.
3 Next slide, please.
HBsAg, on the other
4
hand, appears 1-3 weeks before the ALT becomes
5
abnormal or 3-5 weeks before the onset of symptoms
6
or jaundice. It reaches a peak
during the acute
7
stage of the disease and then it declines to
8
undetectable levels within 4-6 months.
9 Next slide.
IgM anti-HBc is indicative,
10 as I said, of ongoing viral replication and appears
11
at the onset of ALT abnormality at high
12
concentration. It is present but
undetectable in
13
some chronic infections and may reappear,
14
therefore, during reactivation of HBV during
15
chronic infection.
16 Now, one of the questions that often
17
arises is when you have acute hepatitis how do you
18
determine that this is not a reactivation of
19
chronic disease compared to an acute disease? That
20
has always been an issue. For
all practical
21
purposes, the IgM anti-HBc test can be utilized to
22
determine that. It is at high
concentrations.
41
1
Whereas, patients who have reactivation of their
2
hepatitis B virus infection from chronic disease
3
often have a relatively low concentration of IgM
4
anti-HBc in their test. We use a
sample to cut-off
5
ratio and it is usually somewhere between 1-3 in
6
those cases, whereas in acute disease it is at its
7
maximum.
8 In addition, the other way, if you have
9
the means to do this, is that the IgM has a 19S
10
sedimentation coefficient during acute infection.
11
It has a 7S sedimentation coefficient during
12
chronic infection. That is
another way that one
13
could use to determine acute from chronic.
14 Next slide, please.
The anti-HBs is a
15
neutralizing antibody occurring during recovery and
16
after infection, and in most cases indicates
17
protection against reinfection.
However, it may
18
become undetectable in up to 20 percent of patients
19
after several years.
20 Next slide.
This slide sort of shows what
21
happens in a patient who gets acute disease and
22
gets over it. The anti-core is a
very strong
42
1
antibody, high concentration of antibody compared
2
to anti-HBs. Over time, as I
said, in about 20
3
percent of patients this antibody will disappear.
4
Then you are left with a person who has only an
5
anti-HBc response.
6 Next slide.
One of the ways that one can
7
tell that that is present is you can do an HBsAg
8
vaccine challenge. You can give
them a vaccine.
9
About 2-4 weeks later you have them come back in
10
for a quantitative anti-HBs test and if the
11
response is greater than 10 milli-international
12
units/ml, that is indicative that this person
13
probably had a prior infection and was immune. It
14
is unusual for a susceptible person or a person
15
with a low-level infection to respond to the
16
hepatitis B surface antigen by 2-4 weeks. Probably
17
less than 3 percent in 2 weeks will respond to the
18
vaccine at this particular level.
19 Next slide. I
have talked a little bit
20
about chronic infection. The
difference is that
21
arbitrarily, say, if the HBsAg is still positive
22
after 6 months or the person has ALT abnormalities
43
1
for a period of time, then they probably have
2
chronic infection. In addition,
the HBsAg is at
3
very high concentrations through that period of
4
time. It doesn't start to
decline. So, if you
5
could dilute these samples as a patient is being
6
followed along, you will find that the HBsAg
7
concentration is declining. Just
remember that the
8
upper level of their reference is about 1 mcg/ml so
9
you do have to do some dilutions in order to see
10
this happening. The IgM does
disappear but remains
11
usually positive at very low levels.
With research
12
tools you can detect it in most patients. It just
13
isn't positive in the way the test is done, which
14
is to dilute the sample about 1:1000 or 1:2000.
15
That is why you don't see it in these individuals.
16
That is how the test is configured.
Part of that
17
is because of prozone effects and other things
18
which could make a positive test negative if you
19
did not dilute.
20 E antigen is usually present initially,
21
but over time about 5-10 percent of patients will
22
seroconvert from HBeAg positivity to anti-HBe
44
1
positive. During that period of
time they usually
2
show reactivation of their disease.
Often it is
3
just an elevation of the liver enzymes but they may
4
become jaundiced and they may develop symptoms that
5
look just like acute disease.
Until we understood
6
this, this was one of the reasons we used to think
7
that 10 percent of patients who had acute disease
8
would become chronically infected.
Now that we
9
know that many of these patients were chronically
10
infected to start with, we now feel that probably
11
less than 3 percent of the immunocompetent patients
12
who develop acute disease will actually become
13
chronically infected. Of course,
the anti-core and
14
HBsAg remain positive in most patients.
15 Next slide, please.
Let me just go
16
through, finally, some of the findings that we just
17
talked about. This is HBVd and a
surface antigen,
18
anti-HBc and anti-HBs. You can
see in the
19
pre-seroconversion window period--we have a couple
20
of windows here because we used to talk about a
21
window period between the end of the HBsAg phase
22
and the development of anti-HBs in which the IgM
45
1
anti-core is present during acute disease. But
2
here I am talking about the pre-seroconversion of
3
antibodies or the seronegative, if you will, window
4
period.
5 Then, in the early acute infection both
6
the HBVd and a and HBsAg are positive.
The
7
anti-core and the anti-HBs are negative. The
8
presence of HBsAg is indicative of a hepatitis B
9
infection, either acute or chronic.
Just the HBsAg
10
alone--you can't tell. But the
presence of all
11
three of these together in the absence of anti-HBs
12
indicates an HBV infection, either acute or
13
chronic. Eventually you will
lose these markers
14
and you are left with anti-HBc and anti-HBs, which
15
means a previous infection with immunity.
16 Next slide.
The other findings are in
17
individuals who have a solitary anti-HBc test
18
present. They have no anti-HBs
and no HBsAg. Some
19
of them may contain HBV DNA and these represent
20
low-level carriers which do not have enough surface
21
antigen present in the blood to be detectable by
22
the current assays.
46
1 The other thing is that if this is
2
negative, this could also indicate an early
3
convalescent period in which this anti-HBc will be
4
IgM. It could represent an HBV
infection in the
5
remote past, as we talked about, in which the
6
anti-HBs has disappeared and you could do a vaccine
7
challenge, or it could be in many cases a
8
false-positive reaction. Most of
these reactions
9
show anti-core at a very low level, again, a sample
10
to cut-off ratio somewhere between 1-3.
The
11
anti-HBe is usually absent in these individuals as
12
well, and they don't respond to the vaccine
13
challenge.
14 Then you have a group that have no
15
markers. This usually excludes
an HBV infection in
16
this case. Then you have
individuals with anti-HBs
17
only. This represents a vaccine
type response. It
18
is really unusual to see something else happening,
19
or you shouldn't see anything other than anti-HBs
20
in a patient who gets the vaccine because it only
21
contains HBsAg.
22 Next slide.
This is my final slide. It
47
1
looks at discordant or unusual hepatitis B
2
serologic profiles requiring further evaluation. I
3
have probably seen all of these at some time or
4
another in my career. For
example, I have a
5
patient right now who has HBsAg positive only, who
6
is anti-core negative, with 900 million copies or
7
IU of virus per ml of blood. He
has been like that
8
most of his life. It happens in
some young
9
children who get hepatitis B and become chronically
10
infected. It is seen in other
adults, particularly
11
in Asians. But it is a really
unusual phenomenon.
12
So, that is a possibility but really rare.
13 Finding of all these three markers in one
14
patient does occur in about 5-10 percent of
15
patients. It is mostly in drug
users or people who
16
have been exposed to different genotypes of the
17
virus. It could be found in
people who have been
18 vaccinated and have made antibodies to a
different
19
genotype, and it usually is in patients who have
20
more serious liver disease.
21 Anti-HBs or anti-HBc positive only--we
22
have talked about those phenomena.
The are not so
48
1
uncommon. HBsAg negative
individuals who are HBeAg
2
positive--you shouldn't really see that but I have
3
seen at least two cases that have been HBeAg
4
positive, HBV DNA negative but do not have the
5
presence of surface antigen present.
6 You could have patients who are positive
7
for both e antigen and anti-e at the same time.
8
That has to do with the nuances of the test and
9 probably nothing else. And, you can find patients
10
who are anti-core negative--I mean, you should not
11
find a patient who is anti-HBc negative but IgM
12
anti-HBc positive.
13 Well, I hope now you are a little bit more
14 familiar with the serology of this disease.
15
Antigens are followed by antibodies.
HBV DNA
16
precedes the development of antigens very early in
17
the course and usually remains throughout the
18
disease entity itself. Thank you
very much.
19 DR. NELSON:
Thanks, Blaine. Are there
20
any questions? Harvey?
21 DR. KLEIN:
Blaine, there have been a
22
number of reports of people who have low levels of
49
1
HBV DNA and have anti-HBs. Do
you know if any of
2
those are infectious? Have you
ever seen one?
3 DR. HOLLINGER:
Well, it is not whether we
4
have ever seen one. The issue I
guess is that we
5 have
this question all the time about occult
6
infection in HBV DNA even though there are no
7
markers, usually in people who are very sick and
8
would not be donors, for example, liver cancer
9
patients and immunocompromised individuals. So,
10
you wouldn't find these as donors anyway. It is my
11
belief that most of these issues of finding nucleic
12
acid in the presence of antibodies probably means
13
it is neutralized and it is not infectious. You
14
see that with RNA found very late in the course of
15
the disease. In the presence of
antibody it
16
doesn't appear to be infectious biologically,
17
clinically or in trials.
18 So, I think that finding anti-HBs at a
19
reasonable concentration and HBV DNA would probably
20
not indicate somebody is infectious.
But you just
21
have to do these studies, and no one has really,
22
say, taken a chimpanzee and looked at these. I
50
1
think Prince did so a few years ago and the data
2
was that they were not infectious.
3 DR. NELSON:
You didn't mention the
4
genetic variations in the surface antigen. Could
5
those lead to a false-negative surface antigen test
6
in people who were actually infectious?
7 DR. HOLLINGER:
Yes, Kenrad, it is a good
8
question. There are about six or
seven genotypes
9
of this disease, from a to h, but because they all
10
have a group a antigen present, they all seem to be
11
detectable by the usual tests which are available
12
today. Now, could it
happen? Sure, I think it is
13
possible but I think it would be unusual.
14 DR. NELSON:
One other comment too, we
15
have studied hepatitis B in injection drug users
16
and it is extremely common for them to have
17
hepatitis B core antibody only, without surface, at
18
very high levels. They are
actually truly infected
19
and it is up to 20 percent of injection drug users.
20
It is possible that co-infection with hepatitis C
21
may play a part in that because they are all
22
infected with hepatitis C as well.
It is a very
51
1
complex interaction. But seeing
hepatitis B core
2
antibody only in somebody who actually is a drug
3
user and comparing drug users with others without a
4
history, it is like 20 percent of the drug users,
5
maybe 1 or 2 percent in gay men who have had
6
hepatitis B infection.
7 DR. HOLLINGER:
Yes, you see it not only
8
in drug users but you see it in volunteer donors
9
who are found to be anti-HCV positive and then you
10
go do some other tests and they are found to be
11
anti-HBc positive only. They
don't respond well to
12
the vaccine. And, we know that
HCV interferes with
13
the replication of hepatitis B virus so that is a
14
possibility.
15
DR. NELSON: Other comments?
16 [No response]
17 Thanks. Dr.
Herman, from Roche?
18
C. Preclinical and Clinical Data for HBV MP NAT
19 DR. HERMAN:
Thank you very much. It is a
20
pleasure to be here to describe to you the results
21
of our non-clinical and clinical performance
22
studies on our COBAS AmpliScreen HBV test.
52
1 [Slide]
2 I am going to begin the talk with a
3
description of our non-clinical performance
4
studies, and Dr. Frank will conclude with a
5
description of our clinical study results.
6 [Slide]
7 Here is an outline of the talk. I am
8
going to give an overview of the COBAS AmpliScreen
9
system and then I am going to describe the
10
different portions of the non-clinical performance
11
studies and give you their results.
12 [Slide]
13
The COBAS AmpliScreen
system is designed
14
for screening of minipool samples or individual
15
donor samples. The samples are
put onto the
16
Hamilton microlab pipetting robot which prepares
17
the pools. Then the pooled or
individual samples
18
are processed to extract nucleic acid with the
19
generic sample processing method.
There are two
20
variations of the method, the multiprep method for
21
the pooled samples and the standard method for
22
individual donor samples, and I will describe them
53
1
in the next slide.
2 Aliquots of the extracted material can be
3
processed in parallel with our three different
4
COBAS AmpliScreen tests, the test for HBV and the
5
licensed tests for HCV and HIV.
The analysis is
6
done on the COBAS Amplicor analyzer which automates
7
the nucleic acid amplification and detection
8
processes. Then, the software
for the analyzer and
9
the software for the pipetting machine interact
10
with the data output management system.
11 [Slide]
12 This slide describes the two sample
13
preparation methods, the multiprep method which is
14
used for the minipools, and the standard method
15
that is used for individual donor samples. For the
16
minipool method, 1 ml of the pool is centrifuged at
17
23,500 g to enrich for the viral targets, HCV, HIV
18
and HBV. After the centrifugation,
900 mcL of the
19
supernatant is discarded, leaving behind the pellet
20
and 100 mcL of the supernatant.
The nucleic acids
21
are extracted by adding a k-atropic lysis reagent
22
which contains the internal control.
After a brief
54
1
incubation, isopropanol is added to precipitate the
2
nucleic acids. The nucleic acids
are collected by
3
centrifugation. The pellet is
washed with ethanol
4
and resuspended in a specimen diluent, and then an
5
aliquot of the specimen diluent can be used in each
6
of the AmpliScreen tests.
7 The standard specimen processing method
8
for individual samples is almost identical. All
9
the green steps are identical and the differences
10
are highlighted in red. So, the
starting specimen
11
volume is 200 mcL instead of 1 ml, and there is no
12
concentration step. The
k-atropic lysis reagent
13
with the internal control is added directly to the
14
200 mcL specimen and then the remaining steps are
15
the same.
16 [Slide]
17 Now I am going to describe the analytical
18
sensitivity studies that were performed. These are
19 the results using the multiprep procedure. We used
20
the World Health Organization HBV DNA international
21
standard and we prepared dilutions of it between
22
100 and 3 IU/ml and analyzed 120 replicates of each
55
1
dilution, at Roche, using 2 different kit lots.
2
This shows the results. So, we
had 100 percent hit
3
rate at 100, 30 and 10 IU/ml and a 95.8 percent hit
4
rate at 5 IU/ml. The predicted
95 percent limit of
5
detection, using the PROBIT statistical method, is
6
4.4 IU/ml.
7 [Slide]
8 This slide shows the results using the
9
standard specimen processing procedure.
In this
10
study we analyzed dilutions of the World Health
11
Organization standard from 300 to 10 IU/ml. There
12
was 100 percent hit rate on 100 replicates at 300
13
and 100 IU/ml, and 99 percent on 30 IU/ml, and 97
14
percent at 20, and 95.8 percent at 15 IU/ml. The
15
predicted 95 percent limit of detection, using the
16
PROBIT method, is 16 IU/ml for the standard
17
specimen processing method.
18 [Slide]
19 This slide describes the results on a
20
panel prepared by CBER. The
original panel
21
contained 3 members at 100, 10 and 0 copies/ml, and
22
at Roche we prepared 4 additional dilutions from
56
1
the 100 copy/ml member at 50, 25 5 and 2.5
2
copies/ml.
3 This slide shows the results using the
4
multiprep specimen processing method and on 6
5
replicates, 100 percent hit rate at 100 copies and
6
at 10 copies/ml, then 67 percent and 42 percent
7
hits at 5 and 2.5 copies/ml.
8 Using the standard specimen preparation
9
method, 100 percent hits at 100 copies/ml with 6
10
replicates and 92 percent and 75 percent at 50 and
11
25 copies/ml.
12 [Slide]
13 This slide shows the results of our
14
analysis of the performance of the test on HBV
15
genotypes A through H. These
samples were obtained
16
from commercial sources, and we analyzed up to 25
17
individual isolates for each genotype.
The samples
18
were quantified using the COBAS Amplicor HBV
19
monitor test or, in the case of genotypes G and H,
20
monitor tests that we have in development. Then
21
the samples were diluted to approximately 2-3 times
22
the limit of detection for the multiprep method and
57
1
the standard prep method, and then they were
2
analyzed using the COBAS AmpliScreen test. So,
3
with the multiprep method and the standard method
4
all the isolates yielded positive results. So, the
5
test detected HBV genotypes A through H.
6 [Slide]
7 This slide summarizes the results on 40
8
commercially obtained seroconversion panels using
9
the multiprep method and the standard prep method.
10
The slide shows the number of days that DNA was
11
detected prior to detection of surface antigen
12
using a licensed surface antigen test, the Ortho
13
surface antigen test system 3.
The orange bars
14
show the results with the multiprep test, and for
15
that analysis the samples were diluted 24-fold to
16
simulate minipool testing. The
blue bars show the
17
results with the standard prep on undiluted
18 samples. The panels are sorted by the number of
19
days prior to antigen that DNA is detected with the
20
multiprep method. So, using the
multiprep method,
21
in 38/40 panels HBV DNA was detected prior to
22
surface antigen, and in 2/40 panels HBV DNA was
58
1
detected in the same bleed as surface antigen.
2 Using the standard prep method on neat
3
samples in 39/40 panels HBV DNA was detected prior
4
to surface antigen, and in 1 panel HBV DNA was
5
detected on the same day as surface antigen. I am
6
going to show you the results on one of the panels,
7
this panel, 39.
8 Before that, with the multiprep method, on
9 the 38 panels on which
DNA was detected prior to
10
surface antigen, DNA was detected an average of 17
11
days earlier, and with the standard method DNA was
12
detected an average of 22 days earlier.
13 [Slide]
14
Here are the results on panel
39. This
15
panel had 14 bleeds. This column
shows the results
16
with the Ortho Surface Antigen Test System 3, and
17
you can see that this turned positive on bleed 12
18
at day 143. This column shows the
results with the
19
minipool test, and you can see that it was positive
20
on the first and third bleed and then positive
21
again at the 11th bleed on day 113.
22 On the previous slide, on this panel it
59
1
was described as having DNA detected prior to
2
antigen 30 days in advance this one bleed. Even
3
though DNA was detected intermittently earlier than
4
that, we made a conservative interpretation and
5
only counted the number of bleeds that DNA was
6
continuously detected prior to surface antigen.
7 In this column, the results with the
8
standard preparation method on undiluted samples is
9
shown. There were 11 bleeds
prior to detection by
10
surface antigen and the HBV DNA was positive in 7
11
of them but did not yield a positive result on
12
bleed 11. So, in the previous
graph the standard
13
prep method was described for this panel as being
14
detected on the same day as surface antigen.
15 [Slide]
16 This just illustrates that even though DNA
17
was detected intermittently earlier, on multiprep
18
method we only counted 1 bleed, which was 30 days
19
in this case.
20 [Slide]
21 This slide summarizes the results on the
22
40 seroconversion panels. Using
the multiprep
60
1
method on samples diluted 24-fold to stimulate
2
pooling, DNA was detected prior to surface antigen
3
in 38/40 panels and on the same bleed in 2/40
4
panels an average of 17 days prior to surface
5
antigen. Using the standard
procedure on undiluted
6 samples, DNA was detected prior to antigen in
39/40
7
panels an average of 22 days earlier, and on the
8
same bleed on the 40th panel.
9 [Slide]
10 This slide summarizes the results of the
11
analytical specificity testing and the testing of
12
potentially interfering substances.
For the
13
analytical specificity we looked at 38
14
microorganisms and cell lines, and all these
15
samples yielded negative results with the
16
AmpliScreen and valid internal control results.
17
There was no cross-reactivity observed.
18 For the potentially interfering
19
substances, we looked first at 95 clinical
20
specimens with different diseases in patients
21
infected with these viruses or with autoimmune
22
disease or with yeast infections, and multiple
61
1
specimens of each. These
specimens were tested
2
both with the addition of HBV target and without.
3
So, the testing with the addition of HBV target was
4
looking for interference. No
interference was
5
observed. Testing without HBV
target was looking
6
for cross-reactivity and no cross-reactivity was
7
observed.
8 Then we looked at these various
9
potentially interfering substances.
Again, they
10
were tested with and without the addition of HBV
11
target. On the tests with HBV
target there was no
12
inhibition and on the tests without HBV target
13
there was no cross-reactivity.
14 [Slide]
15 This slide and the next look at our
16
reproducibility study. This
slide shows the
17
results of the multiprep procedure.
The study was
18
conducted at 3 clinical sites using 3 lots of
19
reagent. The study was conducted
over 5 days with
20 2
operators at each site. Each day the
operators
21
analyzed the 6-member panel, blinded 6-member panel
22
consisting of 2 negative samples and 4 samples at
62
1
low and moderate target concentrations.
2
Essentially the same results were obtained with the
3 3
kit lots and at the 3 sites. So, there
was 1
4
false-positive result with lot 3 and that happened
5
at site 3. At the low copy
samples the percent
6
hits were nearly identical among the 3 lots and
7
among the 3 sites.
8 [Slide]
9 This slide shows the reproducibility study
10
with the standard procedure and the same outcome.
11
Essentially the same results between the 3 lots and
12
between the 3 lights on the negative and the
13
positive samples.
14 [Slide]
15 Finally, this slide describes the
16
performance of the AmpliScreen test alone or in
17
combination with the licensed anti-core test on 918
18
antigen-positive clinical specimens.
I am showing
19
the results with the multiprep test on samples
20
diluted 1:14 to simulate pool testing and with the
21
standard method on undiluted samples.
So, looking
22
at the results of the AmpliScreen test alone with
63
1
the minipool method, 871 of the 918 samples were
2
DNA positive for sensitivity of 94.9 percent.
3
Using the standard method on undiluted samples, 898
4
samples were positive for sensitivity of 97.8
5
percent. These 20 samples that
were not detected
6
by the standard test were among the 47 that were
7
not detected by the minipool test.
All the NAT
8
negative samples were sent out for anti-core
9
testing and all of them were positive by the
10
anti-core test. So, using the
multiprep method, 1
11
sample had insufficient volume for the testing, a
12
sample that was positive with the standard sample
13
prep and negative with multiprep so we couldn't get
14 a
result on that so it was excluded from the
15
sensitivity analysis. So, for
the 917 samples with
16
NAT positive results and anti-core results on the
17
NAT negative samples the sensitivity was 100
18
percent for NAT and core combined relative to
19
antigen. On the 1900 samples
with evaluable
20
results using the standard method, again, the
21
sensitivity was 100 percent.
22 [Slide]
64
1 To summarize the non-clinical performance
2
studies, the analytical sensitivity was determined
3
on the World Health Organization standard. With
4
the multiprep method the limit of detection at 95
5
percent probability is 5 IU/ml and with the
6
standard method the limit of detection at 95
7
percent probability is 15 IU/ml.
The performance
8
on the CBER panel with the multiprep method, 100
9
percent hits at 10 copies/ml and with the standard
10
method 92 percent hits at 50 copies/ml.
Genotypes
11 A
through H were detected by the test.
12 [Slide]
13 On the 40 seroconversion panels using the
14
multiprep method on samples diluted 24-fold, HBV
15
DNA was detected prior to antigen in 38/40 panels
16
an average of 17 days or earlier, and with the
17
standard method on undiluted samples DNA was
18
detected in 39/40 panels prior to antigen an
19
average of 22 days earlier, and there were no
20
panels in which antigen was detected prior to DNA.
21
There was no cross-reactivity or interference
22
observed in the analytical specificity and
65
1
potential interfering substances studies. And, the
2
sensitivity on antigen-positive specimens, in
3
combination with the anti-core assay, was 100
4
percent.
5 [Slide]
6 I would like to acknowledge all the people
7
who did this work, Yuanfeng Yang and his group at
8
Roche Molecular Systems did an excellent job
9
developing the assay and performing these studies.
10
Larry Pietrelli coordinated the clinical studies
11
and, in this part of the talk, he coordinated the
12
reproducibility studies. They
were conducted at
13
the Community Blood Center of Greater Kansas City,
14
Royal Blood Centers, Minnesota and the Gulf Coast
15
Regional Blood Center.
16 Now I think I will turn the microphone
17
over to Dr. Frank who will describe the results of
18
the clinical performance study.
19 DR. FRANK:
Thank you, Dr. Herman.
20 [Slide]
21 It is my pleasure to be here today to
22
describe to you a prospective study to evaluate the
66
1
screening of plasma pools from volunteer blood
2
donations for the presence of HBV DNA.
3 [Slide]
4 A clinical trial summary will focus today
5
on two areas of primary focus of improved safety of
6
blood donations by HBV minipool-NAT.
The key focus
7
in that particular area will be looking at the
8
potential window period or pre-seroconversion areas
9
of HBV. A secondary focus will
be replacement of
10 surface
antigen by HBV minipool-NAT. To focus
on
11
that, we will look primarily at the areas of
12
samples that were surface antigen positive that
13
were picked up by minipool-NAT and surface antigen
14
positive picked up by anti-core.
15 This clinical study was initiated in
16
August of 2002 at 5 U.S. sites, and was completed
17
in April of 2003. A total of
704,902 specimens
18
were tested with HBV minipool-NAT, of which 581,790
19
were included in the sensitivity and specificity
20
analysis. The differential
between the two numbers
21
occurred because specimens were excluded if no
22
electronic results for surface antigen and/or
67
1
anti-core were available from the site.
2 [Slide]
3 If you look at this chart, which is a
4
schematic of the results listing the analytes
5
anti-core, surface antigen and DNA--if you can't
6
see in the back of the room, the red means they
7
were HBV negative for that particular analyte; the
8
green means they were positive for that particular
9
analyte. The totals are on the
far right-hand
10
column, the numbers that had that criteria. As you
11
can see, the majority of the donors were, as
12
expected, negative for all three.
13 [Slide]
14 We were primarily interested in looking at
15
this group down here, and those were enrolled in
16
our follow-up study, the protocol for which I will
17
be describing briefly.
18 [Slide]
19 Of these 4 eligible for the follow-up
20
study, the 2 areas we wanted to look at are
21
primarily the last row, which is the potential
22
window cases, that is, those cases which were HBV
68
1
minipool DNA positive but negative for core and
2
surface antigen. This represents
the type of
3
pattern one would expect in pre-seroconversion
4
window cases, and then the potential surface
5
antigen false-positive results, that is, surface
6
antigen positive but core negative and HBV minipool
7
negative as well.
8 [Slide]
9 I mentioned the follow-up protocol that
10
was utilized and this is the follow-up protocol for
11
those columns that we followed up, the test index
12
donation was tested by alternate NAT, provided by
13
the National Genetics Institute.
If alternative
14
NAT was positive, the result was quantitated and
15
then the subject was offered enrollment in a
16
6-month follow-up study for weekly draws times 4
17
then monthly draws to complete 6 months of
18
follow-up. The analytes tested
during follow-up
19
are as listed on your screen.
20 [Slide]
21 The primary objective was to improve the
22
safety by use of HBV minipool-NAT for detection of
69
1
window period cases.
2 [Slide]
3 As stated previously there were 23 donors
4
that were HBV DNA positive, surface antigen
5
negative and core negative. Of
these 23, 14 were
6
enrolled in the follow-up study.
It should be
7
noted that 9 donors declined follow-up and for the
8
purposes of our calculations for sensitivity and
9
specificity these were presumed to be false
10
positive and were negative on additional index
11
testing as well.
12 Of the 14 enrolled donors, 2 were
13
confirmed window period cases, the details of which
14 I
will be showing next, and 12 were shown to be
15
valse positive on HBV due to persistently negative
16
anti-core, persistently negative surface antigen
17
and persistently negative HBV DNA, and negative by
18
alternate NAT index specimens.
19 [Slide]
20 This window period case is a 26 year-old
21
male repeat blood donor with no known risk factors.
22
His HBV DNA was positive for a quantitative level
70
1
of 2000 on index donation. On
day 17 post index
2
donation the surface antigen was positive, and on
3
day 48 anti-core was positive.
4 [Slide]
5 The next window case is a subject who is a
6
49 year-old female repeat blood donor, healthcare
7
worker, with a history of HBV vaccination. This is
8
an interesting case because she had a negative
9
anti-surface antibody result 2 months prior to her
10
index donation when she donated blood previously.
11
What is interesting is between that time, where
12
this result 2 months prior was negative, and here
13
index donation was 2,340--now, this normally
14
wouldn't be done during her blood screening but she
15
was HBV DNA positive and she quantitated out at 200
16
copies/ml, which would be an infectious dose. So,
17
this is a window period case of an individual who,
18
on follow-up, never did convert for surface antigen
19
and did, on day 22, convert for anti-core. What
20
this likely represents is that somewhere between
21
the 2 weeks prior to her index donation when this
22
was negative and the result of her index donation,
71
1
she became infected with HBV and had a nice immune
2
system response to her previous HBV vaccination.
3 [Slide]
4 There are additional window cases I would
5
like to show to you today, and these were detected
6
by sites continuing to use HBV NAT following
7
conclusion of our clinical study.
The dates for
8
those 3 sites were April, 2003 to the present, and
9
there are 3 additional window period cases that
10
were detected in the one million donations
11
screened.
12 [Slide]
13 The first case is a 27 year-old male
14
repeat blood donor who reported high risk male
15
sexual partners. He had HBV DNA
positive on
16
donation with a quantitative level of 61,000. On
17
day 7 his surface antigen turned positive and on
18
day 36 his core was repeat reactive.
19 [Slide]
20 This case is a window period case of a 29
21
year-old male repeat donor who has no appreciable
22
risk factors for hepatitis B, other than a possible
72
1
acupuncture treatment for 8 weeks prior to his
2
donations, weekly treatments.
His HBV index was
3
positive at a quantitative level of 2,300. His
4
surface antigen turned positive 7 days later and
5
his core turned positive 28 days later.
6 [Slide]
7 This last case is still on follow-up but
8
this is a 50 year-old male repeat blood donor,
9
positive on index donation with 37,000 copies/ml.
10 On follow-up he remains positive on HBV DNA
and the
11
traditional blood banking serologies are still
12
pending.
13 [Slide]
14 In summary, I thought it was interesting
15
to look at the 5 cases that HBV minipool-NAT picked
16
up. If you look at the left-hand
column, and as I
17
have noted in the footnotes of your slides, all of
18
these are repeat blood donors who could normally be
19
expected to be donating blood regularly to the
20
blood pool, and all donated blood units that would
21
have been missed by the current blood banking
22
algorithms. All of them had
infectious dose
73
1
concentrations on their index donations. In fact,
2
even the lowest dose at 200 copies/ml, if the unit
3
were divided appropriately, would be sufficient to
4
infect everyone in this room.
5 [Slide]
6 Well, what is the yield for HBV
7
minipool-NAT? If you look at the
clinical study
8
yield alone we had 2 cases that I showed you out of
9
approximately 0.7 million donations for a yield of
10
1/350,000. If we look at the
continuing site data,
11
which I also showed you for the 3 cases in
12
approximately 1 million donations, the yield is
13
similar, 1/330,000.
14 Well, what does this mean in perspective
15
of what we are already doing in blood banking to
16
protect the nation's safety of the blood supply?
17
The yield for HBV minipool-NAT is approximately
18
equal to the yield for hepatitis C minipool-NAT and
19
the yield for HBV minipool-NAT is far greater than
20
the yield for HIV minipool-NAT.
21 [Slide]
22
If we look at this data
that was presented
74
1
by Mike Busch in Paris of this year, this
2
emphasizes what I have just stated, that for HBV
3
the yield is approximately 1/340,000, based upon
4
his presentation. For hepatitis
C, 1/230,000, but
5
for HIV, 1/3.1 million. Although
these aren't
6
quite comparable, West Nile Virus was included for
7
because there aren't a plethora of antibody and
8 antigen tests available yet implemented for
West
9
Nile Virus but that yield is 1/5,000.
10 [Slide]
11 This brings us to a sensitivity and
12
specificity calculation. You can
see how we
13
assigned HBV status, on the screen here, for
14
positives, negatives, the HBV status unknown for
15
those that were surface antigen negative but core
16
positive.
17 [Slide]
18 So, again, in summary, here are the totals
19
and the results of the initial testing.
These are
20
the potential surface antigen false-positive
21
results. These are the potential
window cases.
22
This last row I have gone into detail on, the row
75
1
above, the 4 and the 3 will be going into the
2
secondary objective.
3 [Slide]
4 The final status determination is here, on
5
the fir right-hand column. The
ones that could not
6
be determined are yellow, for those of you in the
7
back of the room. The green is
HBV positive. The
8
red is HBV negative. The window
cases that were
9
proven in the clinical study are shown here as 2.
10
The remaining 21, which will be accounted for in
11
sensitivity and specificity calculations, were
12
counted as HBV positive but final status HBV
13
disease negative.
14 [Slide]
15 To that point, our specificity
16
calculations, if you look at the total number of
17
subjects for which we have data--the difference
18
between the numerator and the denominator is the 21
19
cases that I just spoke about a second ago to yield
20 a
specificity calculation of 99.9964 percent, with
21 the
ranges noted on your screen. For
sensitivity
22
we looked at the positive AmpliScreen minipool HBV
76
1
results in specimens with positive HBV status and
2
divided by the total number of specimens with
3
positive HBV status. Again,
these calculations are
4
for HBV minipool-NAT alone and the sensitivity here
5
is 89 out of 105 or 84.7 percent, with a range of
6
74.4 to 91 percent.
7 [Slide]
8 So, the primary objective conclusion is
9
that COBAS AmpliScreen HBV test has identified
10
individuals in
pre-seroconversion window period
11
that would otherwise have been undetected by the
12
blood banking system. The COBAS
AmpliScreen HBV
13
test is suitable for blood screening with minipool
14
strategies presented today, and these data indicate
15
that HBV minipool-NAT will increase the blood
16
safety.
17 [Slide]
18 Let's turn now to the secondary objective,
19
and that is consideration for the HBV minipool-NAT
20
and anti-core for replacing surface antigen and
21
anti-core.
22 [Slide]
77
1 The index donations of interest for this
2
discussion then would be those that were anti-core
3
negative/ surface antigen positive and we will
4
discuss those first. Those
donors fitting this
5
category were 7 out of the total number for which
6
we have data, or 0.0012 percent.
Those that had
7
core-negative/surface antigen positive HBV DNA
8
negative were 3. Of those 3, 1/3
enrolled and
9
converted to anti-core. The
other 2 remaining
10
donors declined the follow-up study.
These were
11
determined to be HBV final status positives. For
12
DNA negatives, that is DNA negative, core negative,
13
surface antigen positive donors, 2 out of these 4
14
enrolled in follow-up. Two of
the remaining
15
declined to enroll in follow-up but we do have
16
additional data that has been available and I will
17
make available and show to you today.
All 4 of
18
these were assessed to be HBV negative.
Let's look
19 at
some of those details.
20 [Slide]
21 This first subject was HBV DNA negative,
22
surface antigen positive, core non-reactive. On
78
1
follow-up this subject remained core non-reactive
2
throughout the follow-up study.
On surface antigen
3
the subject has non-reactivity on follow-up, and
4
HBV DNA remained negative, as did the other
5
follow-up indicators.
6 [Slide]
7 This would indicate a case of an initial
8
surface antigen test which did not repeat on
9
follow-up, and all other negative serology results
10
indicate this patient had an initial surface
11
antigen positive that is consistent with
12
contamination or carryover.
13 [Slide]
14 The next case is a little bit more
15
interesting. This case is
surface antigen positive
16
again on index donation, HBV negative, core
17
non-reactive. It should be noted
that the surface
18
antigen was positive and repeat reactive throughout
19
follow-up but that the surface antigen was negative
20
on neutralization for all of these testing time
21
points. The donor also states a
history of HBV
22
vaccination. Of note, the core
never did react
79
1
throughout the course of follow-up and HBV DNA was
2
negative throughout the course of follow-up. The
3
anti-surface antibody was positive and that we
4
attribute to his vaccination status, and the repeat
5
reactive, again, was negative on neutralization
6
throughout.
7 In summary for this case, the anti-surface
8
antibody is explained by the donor's vaccination
9
history. And, the persistent
surface antigen EIA
10
repeat reactivity, which is negative on
11
neutralization, combined with all the other
12
negative results such as anti-core, is consistent
13 with a false-positive surface antigen result
due to
14
cross-reactivity.
15 [Slide]
16 We have additional data for the 2 donors
17
who declined the follow-up protocol.
Of the
18
remaining 2 donors, 1 donor retested 1 month
19
following his index donation and was negative for
20
surface antigen, anti-core and anti-surface
21
antibody. The other donor was
retested a year and
22 a
half post index and was negative for surface
80
1
antigen and for core antibody.
2 [Slide]
3 This slide may look somewhat familiar.
4
This is a look at the total HBV infected, HBV
5
surface antigen positive specimens.
In our study
6
there were 103 specimens fitting that
7
categorization. If we look at
sensitivity from
8
that perspective alone, HBV detected 87 of the 103
9
specimens and was negative on 16, for a sensitivity
10
as a stand-alone of 84.5 percent in this clinical
11
study. However, the proposal of
HBV minipool-NAT
12
plus anti-core antibody yielded positive in all 103
13
of 103 HBV positive cases and missed none of the
14
cases, for a sensitivity of 100 percent. This
15
parallels the non-clinical data shown to you
16
earlier today by Dr. Herman.
17 [Slide]
18 What are the secondary objective
19
conclusions? All 105 HBV
positive donors were
20
identified by anti-core and HBV minipool-NAT
21
combined. These 105 include 2
window case donors
22
that would have been missed by anti-core and
81
1
surface antigen combined, and 103 surface antigen
2
positive cases that were identified by the HBV
3
minipool-NAT and anti-core as an alternative.
4
These data then suggest that HBV minipool-NAT
5
combined with anti-core provide an alternative to
6
combined surface antigen and anti-core screening.
7 [Slide]
8 In summary conclusion today, I offer that
9
the COBAS AmpliScreen HBV test improves the safety
10
of blood transfusion. I offer
that COBAS
11
AmpliScreen HBV test combined with anti-core may be
12
considered as replacement for surface antigen
13
combined with anti-core. This is
supported by the
14
clinical trial data, and also supported by the
15
non-clinical trial data, specifically
16
seroconversion panel data shown here today and the
17
other HBV positive clinical specimens shown here
18
today by Dr. Herman.
19 [Slide]
20 With that, I would like to acknowledge the
21
blood centers that participated in this large
22
study, as well as the Roche Molecular personnel.
82
1
Thank you.
2 DR. NELSON:
Thank you very much.
3
Questions or comments? Yes.
Harvey?
4 DR. KLEIN: On
the two window period cases
5
that you detected with HBV alone, what was the
6
antigen assay that was used for those?
7 DR. FRANK: In
the two in the clinical
8
study, the first window period case was Ortho Test
9
System 2, and all remaining four window cases that
10
were presented were Abbott Auzyme.
11 DR. KLEIN:
And, do you by any change have
12
any data with head-to-head comparisons with PRISM?
13 DR. FRANK: I
don't believe we ran this
14
test against any test that was not approved by the
15
FDA.
16 DR. KLEIN:
Even in Europe?
17 DR. HERMAN: We
analyzed the
18
seroconversion panels against the PRISM and the
19
Ortho and I can show that data if you would like to
20
see it. That was the European
version of the PRISM
21
test that has the Paul Ehrlich Institute approval.
22
Do you want to see that data?
83
1 DR. NELSON:
Yes, I think so.
2 [Slide]
3 DR. HERMAN:
These are the same 40
4
seroconversion panels that I showed you previously
5
and the same NAT results but compared to the Paul
6
Ehrlich Institute licensed Abbott PRISM test, and I
7
guess this is the lot number.
Again, these are
8
sorted by the results with the multiprep test on
9
samples that were diluted 1:24-fold.
Those are the
10
orange bars. The blue bars
represent the results
11
with the standard test.
12 [Slide]
13 With the multiprep method DNA was detected
14
an average of 14 days prior to antigen, and with
15
the standard method DNA was detected 19 days prior
16
to antigen.
17 [Slide]
18 This slide has the summary. Compared to
19
the European PRISM test, with the multiprep method
20
DNA was detected prior to antigen in 34 of the 40
21
panels, and with the Ortho DNA was detected prior
22
to antigen in 38 of the 40 panels.
On the other 6
84
1
panels DNA and antigen were detected in the same
2
bleed. Using the standard method
compared to the
3
PRISM test, DNA was detected prior to antigen in 38
4
of the 40 panels, and on the same bleed in the
5
other 2 panels.
6 DR. NELSON:
Thank you.
7 DR. HOLLINGER:
I just have a question.
8
We talk about the mean and the median between the
9
appearance of one antigen for nucleic acid before
10
the other one. But these are not
tests that are
11
done every day so the panels do not include--and to
12
say 14 days or 19 days is a little misleading I
13
think in some cases because theoretically if you
14
draw blood today and you drew one 200 days from
15
now, and that is all you had, you would say, well,
16
it would detect things 200 days before one was
17
positive and one was negative.
So, you know,
18
unless samples are collected every single day for a
19
period of time, this is somewhat misleading. So,
20
give me some feeling about the days between each
21
one of these sample collections.
22 DR. HERMAN: It
varies between the panels.
85
1
So, the only data that I have available on the
2
slides here is the one panel I showed you where the
3
interval between bleeds I think was as few as a few
4
days and as large as 30 or 40 days.
5 DR. HOLLINGER:
It is not your fault in
6
doing this; it is just that, unfortunately, that is
7
how panels are set up. But I
think all of us have
8
to understand that it may be much less than that.
9
It won't be more than that but it certainly could
10
me much less than that.
11 DR. HERMAN:
That is absolutely correct,
12
and that is a limitation of these studies so one
13
shouldn't interpret this to conclude that if
14
testing was done every day these would be the
15
numbers. This is an
approximation, subject to the
16
limitations of the interval between the bleed dates
17
and the different panels.
18 DR. NELSON:
Actually, often
19
epidemiologists would assume a median--a mid-point
20
seroconversion between the two days.
So, if you
21
had a sample that was taken on day zero and day 14,
22
you would assume that the one that the one that was
86
1
positive on day 14 seroconverted on day 7. That
2
would be one way, a different analysis of the data
3
than probably what you have done.
4 DR. EPSTEIN:
Could I get you to clarify
5
whether the apparent window period samples
6
themselves were tested with HBsAg assays with known
7
sensitivities of 0.1 ng/ml?
8 DR. HERMAN:
Let me defer to my
9
colleagues. The window period cases
from the
10
clinical study?
11 DR. EPSTEIN:
Correct, and you say you had
12
five of them. Right? Two from the trials that
13
analyzed sensitivity and specificity and the
14
additional three--you have five available samples
15
that could have been retested with the most
16
sensitive available HBsAg assays.
17 DR. STRONG: I
have to declare my conflict
18
here because I am one of the clinical test sites,
19
but we have been able to test four of the five.
20
The most recent one hasn't been tested, but the
21
four have been tested on the Ortho system 3, the
22
new licensed test. It picked up
one of the four
87
1 but missed three.
2 DR. KUEHNERT:
Could you clarify what
3
those are? You said five.
4 DR. STRONG:
The five window cases that
5
are described here. The first
four were tested and
6
it picked up the one that you would expect it to
7
pick up, which is the high copy number sample. The
8
fifth sample, which hasn't been tested, also has a
9
relatively high copy number and you might expect it
10
to be picked up as well, with 37,000 copies.
11 DR. NELSON:
Are there blood donor
12
policies or recommendations for the interval
13
between receiving hepatitis B vaccine and donation?
14
Because that is a source of a false-positive
15
infection for the surface antigen.
Are there any
16
policies on that?
17 DR. EPSTEIN:
FDA has no policy for donor
18
deferral after HBV vaccination.
I am not certain
19
whether AABB has a voluntary policy, but I think
20
for non-live vaccines they would also not recommend
21
deferring. Someone else would
need to clarify
22
that.
88
1 DR. KLEINMAN:
I think that is right, Jay,
2
except that there have been some instances where
3
people have had false-positive surface antigen so
4
it is sort of unspoken that you might want to defer
5
people for a week or so, but there is no absolute
6
AABB requirement to do that.
7 DR. LEITMAN:
Can I ask a different
8
question. I am not sure I am
following what is
9
going on in the 16 donors who were HBsAg positive,
10
anti-core positive but multipool-NAT, COBAS
11
negative. Were those individuals
individual donor
12
NAT-negative? In other words,
are they infectious
13
or are they not infectious? If
they are not
14
infectious, do they just happen to have a lot of
15
HBsAg particles circulating but not infectious
16
virion?
17 DR. FRANK: I
have to apologize, I can
18
only hear parts of the question because of where I
19
am standing.
20 DR. LEITMAN: I
don't think I can do that
21
again. The 16 donors who were
HBsAg positive,
22
anti-core positive but NAT-multipool negative, were
89
1
they retested in individual donor NAT to see if
2
they have low level viremia or DNA nucleic acid, or
3
are they, in fact, true HBsAg positive but not
4 infectious
because they don't have intact virion
5
but just have particles circulating?
6 [Slide]
7 DR. FRANK: You
are talking about these
8
16?
9 DR. LEITMAN:
Those 16, yes.
10 DR. FRANK: The
final status here is that
11
they were HBV positive. The
question you are
12
posing is are these 16 patients infectious. They
13
have surface antigen positivity and core
14
positivity. I have to defer to
my colleague as to
15 whether or not we tried to quantitate with NGI the
16
HBV minipool NATs.
17 DR. PIETRELLI:
I am Larry Pietrelli, from
18
Roche Molecular Systems. Yes, on
those 16 donors a
19
sample was supposed to be tested by alternate NAT
20
and also by individual donation.
One donor was not
21
tested by either assay. Of the
15 remaining, 10
22
were positive by ID-NAT, of which 7 sere also
90
1
positive by alternate NAT. Two
were negative. One
2
was not done. Of the 5 that were
negative by
3
ID-NAT, 2 were positive by alternate NAT; 2 were
4
negative; and 1 was not tested.
The viral
5
concentration was low, as expected.
6
DR. LEITMAN: Thank you.
7 DR. KUEHNERT:
I have a follow-up question
8
about those 16. They were core
antibody positive.
9
Is there any way to quantitate that level of core
10
antibody positivity? Were any of
these at an
11
equivocal level? I am just sort
of getting at, you
12
know, whether you had greater numbers whether some
13
of these might have been close to a threshold for
14
missing them by core antibody positivity.
15 DR. FRANK: I
don't have that data. I
16
don't know whether my colleagues have access to
17
that data today.
18 DR. PIETRELLI:
No, we did not collect
19
that information but we could go back to the sites
20
to see what the S to CO was.
21 DR. HOLLINGER:
I have a technical
22
question. Is there are a reason
you used 24,000
91
1
times g for pelleting? I know
others have used
2
40,000 times g for pelleting for an hour at the
3
enhancement stage, so to speak.
Also, why did you
4
use 24 samples in your minipool or multipool?
5 DR. HERMAN: I
can answer the first
6
question about the centrifugation.
It is a
7
limitation of the instrument that is widely
8
available, which is a table-top centrifuge. It is
9
not quite an ultracentrifuge so it is more
10
convenient and easier to use.
That was a choice of
11
what equipment would be the most suitable for the
12
multiprep procedure for all three virus targets.
13 DR. HOLLINGER:
And the other question?
14 DR. HERMAN:
The choice of pool size, I
15
will defer to Mike.
16 DR. STRONG:
The pool size is one that was
17
selected for the HIV, HCV trials which were
18
concluded a couple of years ago and were licensed.
19
So, it was just to continue with the logistical way
20
in which laboratories operate to be consistent with
21
the other testing, and it is what the software does
22
for us.
92
1 DR. NELSON: It
is interesting that there
2
are many places, in the Orient particularly, where
3
core antibody testing is not done because of very
4
high rates of positivity. So,
that would cast some
5
limitation. Even though the NAT
assay would be
6
useful under those circumstances, it wouldn't
7
perhaps be as useful as continuing using the core
8
antibodies as is done in the U.S. and Europe. You
9
had a question, Donna?
10 DR. DIMICHELE:
Thank you. I was just
11
wondering if anybody can estimate, based on these
12
data or based on your data, what the residual
13
risk--in using your assay, if your assay was to be
14
implemented with core antibody testing, what do you
15
estimate the residual risk of transmission of HBV
16
would be through transfusion?
17 DR. FRANK:
That is a good question, and I
18
can say that we have shown the yield today but in
19
terms of discussion of residual risk, Dr. Kleinman,
20
would you like to comment?
21 DR. KLEINMAN:
Yes, Steve Kleinman. I am
22 a
consultant to Roche Molecular Systems on this
93
1
project. The residual risk
estimate is dependent
2
upon what you think the risk is now prior to
3
initiating HBV NAT. We have
estimated that risk
4
through the REDS study on two occasions, one that
5
was published in 1996 and then we kind of confirmed
6
the same numbers about six years later as about
7
1/60,000. The risk estimate is
based on the
8
incidence window period model and the data for that
9
model with HBV are not as strong as they are for
10
HIV and HCV. So, other people
have estimated the
11
residual risk now prior to NAT as being lower than
12
1/60,000, being about 1/200,000.
13
At any rate, if you accept
the 1/60,000
14
risk estimate, and then you take a look--the
15
question is how much does this new assay decrease
16
the window period. If you draw
on data that was
17
published by Robin Biswas and colleagues on their
18
panel testing of decrease of the window period, you
19
get about a 10-day decrease of the window period in
20
that study, and in this study it looks like the
21
window period decreases by 17 to 20 days based on
22
the panel. But, as Dr. Hollinger
mentioned, that
94
1
is a maximum case because you don't have closely
2
spaced samples.
3 At any rate, if you take a 10-day
4
lessening of the window period and you apply it to
5
what we think the current window period is, about
6
59 days, and you work this through with the window
7
period and the incidence of HBV, you would probably
8
get that the residual risk is still 1/200,000 to
9
300,000 even with this test being implemented.
10
Actually, it may even be 1/100,000.
So, you are
11
removing some of the risk but because you are only
12
cutting the window period back 10 days out of a
13
potential 59 days, the likelihood is that most of
14
the risk still remains even with minipool-NAT and
15
that in order to decrease that risk further you
16
have to go to either smaller minipools or
17
individual donation NAT, which would buy you more
18
in terms of lowering the window period.
So, you
19
are making an incremental step in decreasing the
20
risk; you are not decreasing the majority of what
21
we think is the residual risk.
22 DR. NELSON:
These data are heavily
95
1
dependent on what the window period is, which may
2
vary in different populations.
3 DR. STRONG:
Yes, they are dependent on
4
the incidence and what you think the current window
5
period is, and that is something that there hasn't
6
really been good data on. We
have estimated the
7
current window period as 59 days based on some
8
older work from the TTVS study and then, through
9
REDS, we made a revised estimate of the window
10
period through mathematical modeling to be about 45
11
days now, the infectious window period.
So, these
12
are estimates. We don't really
know what the
13
current window period is so it is a little bit
14
difficult. We don't know exactly
how much we
15
shortened it so that is why I think you have to say
16
that we can't make the kinds of precise estimates
17
that we have made about HCV and HIV.
18 DR. DIMICHELE:
Can I just ask you a
19
follow-up question then? What is
the
20
estimate--let's say given that residual risk, what
21
is the estimate of the impact of vaccination,
22
widespread vaccinations now going on in the younger
96
1
population with respect to when they become blood
2
donors? Does anybody know how
the risk of
3
transmission will be decreased just by vaccination,
4
widespread vaccination alone?
5 DR. KLEINMAN:
I don't know the answer to
6
that. I will answer kind of a
related question,
7
which is what is the risk to recipients? As more
8
recipients get vaccinated, then they should be
9
immune to a challenge, you would think
10
theoretically even if they were exposed. However,
11
most of our recipients are in the older age group,
12
60 and above, and some have compromised immune
13
systems. So, I don't think that
vaccination is
14
going to protect much of the recipient population.
15
Your question is different, whether it makes donors
16
less likely to acquire new HBV infection and I
17
don't know that anybody has worked that through
18
mathematically.
19
DR. ALTER: Harvey Alter, NIH. The
20
mathematical models have been extremely useful but
21
there has always been a little discomfort with HBV
22
in that you just don't see the cases as frequently
97
1
as you would have predicted from the model.
2 It seems to me now that if you make the
3
assumption that the real risk would be coming from
4
HBV DNA positive donors, you could actually
5
determine what the actual risk is now by taking the
6
best or maybe all the different HBV DNA assays and
7
testing these samples as single donations. If you
8
are picking up 1/350,000 now in a minipool format
9
you will pick up even more in an individual donor
10
format. That theoretically would
be the risk. If
11
we can exclude those donors, that risk would be
12
removed. It seems too simplistic
to be true but I
13
would like to hear a counter argument.
14
DR. BUSCH: Mike Busch.
I wanted to
15
comment on the vaccine issue. In
this study, I
16
think of the yield cases one of the yields that is
17
in the original clinical trial, clearly by history
18
vaccinated person, had an anamnestic anti-surface
19
response, low viremia in the setting of the index
20
sample. I think one of the
additional yield cases
21
also had anti-surface on index.
It is interesting
22
that the data from Taiwan is showing that when they
98
1
have applied NAT to donor screening--this is a
2
massively vaccinated population--they are seeing as
3
these young people, you know, enter adolescence and
4
in their 20s, they are seeing a fairly high rate of
5
the same kind of phenomenon.
These are essentially
6
vaccine breakthrough infections.
So the vaccine,
7
rather than being sterilizing--still people are
8
getting exposed and infected and, in a sense,
9
boosted from a wild exposure. In
their setting the
10
vast majority of their NAT yield are people who
11
have been vaccinated and have anti-surface and
12
never develop surface antigen, never develop
13
chronic infection. So, the critical
question of
14
whether these could transmit I think is still on
15
the table.
16 DR. STRONG:
Another point to follow-up on
17
what you were commenting on, on the value of
18
anti-core, I think this clinical trial also
19
demonstrated, as has been published, a small yield
20
of DNA positives from the anti-core positive group,
21
roughly in the same area of 5.5 percent or
22
thereabouts. Also, I think it
demonstrated a
99
1
difference in specificity with the anti-core assays
2
between the two licensed tests.
So, there is
3
clearly a large number of false-positive anti-core
4
donors that we have excluded on the basis of
5
false-positive reaction. I think
those of us who
6
have been involved in this trial, we have been
7
anxious to try to push the sensitivity of the assay
8
to allow us to reenter a lot of those donors
9
because it is a very large number.
10 DR. HOLLINGER:
I just want to follow-up
11
briefly on what Mike said. I
mean, this shouldn't
12
really surprise us very much, if you look at most
13
of the vaccine trials and follow patients for ten
14
years or so you will see anti-core appearing in
15
these patients. I just mentioned
that anti-core is
16 a
marker of viral replication. So,
somewhere along
17
the line these patients will probably have DNA in
18
the bloodstream. The issue is
whether it is
19
infectious or not and that is, of course, I think a
20
very critical issue with it.
21 Then I just wanted to ask a question
22
either of Harvey or Steve about how many cases are
100
1
recorded now of transfusion-transmitted hepatitis
2
B? I don't see very many. I don't want to get
3
back to this argument we had about 20 or 30 years
4
ago when we said there was no hepatitis C or
5 non-A/non-B hepatitis when really there was a lot.
6 DR. KLEINMAN:
No, I think that is exactly
7
right, Blaine. There are very
few post-transfusion
8
hepatitis B cases reported. As
you know, it is a
9
question about whether those people become
10
symptomatic. So, there may be
asymptomatic cases.
11
Some may go on to be chronic carriers.
That is
12
certainly possible. Secondarily,
even if a case
13
occurs, is it recognized by the clinician?
14
It is certainly a correct
statement that
15
we don't see the number of HBV clinical cases
16
reported as post-transfusion cases as the
17
mathematical models would predict.
So, then you
18
have two potential explanations.
One, the
19
mathematical models are wrong and these cases don't
20
occur or, two, the cases occur and they are not
21
recognized and reported. I don't
think we have a
22
way to sort out which one of those hypotheses is
101
1
correct. Harvey's point is that
we would have to
2
take a different approach to estimate risk, that
3
is, we would have to use the most sensitive DNA
4
assay available, hoping we could pick up one
5
copy/ml or even less. By that,
we could basically
6
make the equivalence that if we have a DNA-emic
7
specimen that equates to an infectious specimen,
8
and we could do that kind of study that was done 15
9
years ago or I guess 17 or 18 years ago for HIV,
10
but that would be an extremely laborious and
11
expensive study to do.
12 DR. NELSON: I
think we will take a break
13
at the moment and then come back for the open
14
public hearing. Maybe 20 minutes.
15 [Brief recess]
16 DR. NELSON:
The meeting is now in session
17
again and we will start with an open public hearing
18
on the topic presented of HBV DNA testing. Before
19
we start I will read this statement.
20 Both the FDA and the public believe in a
21
transparent process for information gathering and
22
decision making. To ensure such
transparency at
102
1
the open public hearing session of the advisory
2
committee meeting, FDA believes that it is
3
important to understand the context of an
4
individual's presentation.
5 For this reason, FDA encourages you, the
6
open public hearing speaker, at the beginning of
7
your written or oral statement to advise the
8
committee of any financial relationship that you
9
may have with the sponsor, its product and, if
10
known, its direct competitors.
For example, this
11
financial information may include the sponsor's
12
payment of your travel, lodging or other expenses
13
in connection with your attendance at the meeting.
14
Likewise, the FDA encourages you at the beginning
15
of your statement to advise the committee if you do
16
not have any such financial relationships. If you
17
choose not to address this issue of financial
18
relationships at the beginning of your statement,
19
it will not preclude you from speaking.
20
With that, Mike Busch?
21 Open Public Hearing
22 DR. BUSCH:
Thank you.
103
1 I wanted to just briefly touch on three
2
items. One is just one slide
sort of summarizing
3
the different context of some of the issues that
4
were raised in the questions as to the value of HBV
5
minipool-NAT both relative to the other NAT systems
6
and ID-NAT. Then in most of my
comments I want to
7
focus on the issue of can we drop either anti-core
8
surface antigen and, if not or if the data doesn't
9
support it at this point, what further studies
10
would be useful to address that.
I have Roche's
11
computer here--
12 DR. NELSON:
That sounds like a conflict
13
of interest!
14 [Slide]
15 DR. BUSCH: The
committee does have this.
16
This is a published analysis of cost-effectiveness
17
and I am not going to talk at all about sort of
18
cost-effectiveness but I just wanted to show one
19
slide that sort of emphasizes the relevant clinical
20
impact of these three viruses.
We tend to talk
21
numbers as if each of these viruses is equivalent
22
and the NAT yield is equivalent, but what this is
104
1
showing is the number of quality life years lost
2
per transmission.
3 What you can see is that for HIV it is
4
about 7 quality life years to the average 60 years
5
old transfusion recipient.
Transmission of HIV
6
would cost that person 7 quality life years; HCV,
7
0.6 and HBV, only 1.6. This is
because most
8
recipients are older people who naturally resolve
9
the acute infection of HBV, and even if chronic it
10
rarely evolves to significant morbidity/mortality
11
over the persistent life span of the average
12
recipient. So, you can see that
essentially HBV is
13
one-quarter as clinically important as HCV and 44
14
times less important than HIV.
15 The other point I wanted to make has to do
16
with this issue of going from current serologic
17
testing to minipool versus serologic testing to
18
ID-NAT, and how much of the yield that would be
19
accomplished by going to ID-NAT is detected by
20
minipool-NAT. For HIV we had
very sensitive
21
antibody tests in place so NAT by minipool closes
22
the window by about 5 days and ID closes it by
105
1
another 5. So, we picked up
about 50 percent of
2
what could be picked up but the risk is very low.
3 With HCV, because of the long plateau
4
phase, 95 percent of the window period is detected
5
by minipool-NAT. With HBV,
because of the slow
6
ramp-up, at least the model estimates and some of
7
the empiric data like in the Biswas paper would
8
suggest that minipool is only picking up about 23
9
percent or a quarter of what could be detected by
10
ID.
11 Next slide.
The issue of anti core and
12
could we get rid of anti core--there are three
13
studies that have been either fully published or in
14
abstract form, actually the Roche data, that have
15
looked at high numbers of donations that were
16
anti-core only reactive--so surface antigen
17
negative, anti-core positive--and subjected then
18
HBV NAT. Each of these studies,
as you can see,
19
has given almost identical rates both on a per
20
anti-core and, if you extrapolate, on a
21
per-transfused unit basis of detecting DNA in
22
donations that were surface antigen negative. So,
106
1
about a quarter to a half percent in all these
2
studies.
3 What is interesting is that in each of
4
these studies there was quantitation done in one
5
context or another, and all of these viremic
6
anti-core reactive units, surface antigen negative
7
have very low viral loads. In
Roche's data, for
8
example, 92 percent based on previously presented
9
work of their viremic anti-core only were negative
10
by minipool but only detected by ID-NAT. So, these
11
are very low viral loads that really would require
12
ID-NAT to detect.
13 [Slide]
14 This is just a summary and I am not going
15
to walk through this but with respect to low
16
viremic anti-core reactive donations or anti-core
17
only's there are a number of studies that have
18
documented transmissions, rare but there are
19
transmissions from these low viremic units. Again,
20 I
don't have time to go into these but we also know
21
that in liver transplantation from anti-core
22
reactive, surface antigen negative donors very
107
1
frequently transmits the virus.
So, these people
2
who have low viremia do harbor infectious virus
3
and, obviously, the anti-surface status is a
4
factor. But I personally don't
think there is any
5
prospect for dropping anti core.
6
[Slide]
7 Next slide.
This was alluded to earlier.
8
There was one study where purposeful transfusion of
9
these anti-core reactive, DNA positive, surface
10
antigen negative units into chimps was done. This
11
was by Fred Prince and was published.
These did
12
not transmit. Three patients who
had remote
13
hepatitis B, persistent anti-core, negative
14
antigen, low-level DNA. However,
the caveat is
15
that all three of these donors had anti-surface and
16
the volume inoculated into chimps was quite small,
17 1
ml. So, I think larger studies with
larger
18
volumes may be indicated to potentially explore the
19
infectivity of these units.
20 [Slide]
21 Next slide. In
terms of dropping antigen,
22
which I think is the more likely and I believe
108
1
optimistically we will get there, I think clearly
2
for these viruses like HIV, HCV, HBV where there is
3
not only the acute phase but there are chronic
4
carriers and some of these chronic carriers have
5
low-level infectious viremia the optimal paradigm
6
really is the combination of a front-end sensitive
7
direct assay and a serologic test for antibody.
8
For HBV we have both antigen and NAT which could be
9
viewed as redundant, analogous to P24 antigen in
10
HIV NAT. Clearly, on the front
end we know, and
11
saw from Roche and other studies, that HBV NAT is
12
clearly more sensitive than antigen during the
13
acute phase.
14 Next slide.
But the problem is, as Blaine
15
summarized, HBV is really an unusual virus in that
16
it produces in chronic infections amazingly high
17
levels of circulating antigen in the absence of
18
infectious particles. Therefore,
this excess
19
antigen can occasionally be detected in the absence
20
of detectable DNA by minipool or even ID-NAT. I
21
want to present a recent study on that.
Therefore,
22
to really be sure that we are not taking a step
109
1
back and dropping antigen when we have NAT, we need
2
to do large studies and I think Roche's data is
3
very impressive but whether it is enough is for the
4
committee to decide. But these
studies need to
5
look at these issues in a different context,
6
obviously, the front-end window period anti-core
7
negative as well as chronic carriers.
But also I
8
think they need to reflect populations with
9
different endemnicity and different routes of
10
transmission; populations that have been vaccinated
11
because we are, as I mentioned earlier, seeing
12
vaccine breakthrough infections, and how would they
13
play out in terms of antigen versus DNA; and also
14
genotypes and mutants.
15 Next slide.
Just to contrast, one of the
16
big differences in acute phase versus chronic is
17
the relationship between the DNA load and the
18
antigen reactivity. This is one
of a number of
19
studies. This is a Japanese
study. During this
20
acute phase these were all anti-core negative
21
front-end infections. They were
actually all
22
detected, 181 units detected as negative by the
110
1
Japanese particle agglutination antigen test.
2
Actually, 105 of these were reactive by the PRISM
3
assay. So, only a subset, about
40 percent of
4
these remained negative. But
what you are seeing
5
here is a very nice linear regression relationship
6
between the reactivity in the antigen test and DNA
7
load. That is typical of the
front-end acute
8
viremic phase.
9 Next slide. I
want to summarize now a
10
paper that is in press in collaboration with Mary
11
Kuhns and Steve Kleinman from the REDS group, where
12
we took 200 antigen positive, anti-core positive
13
donations in REDS. We first
subjected them to
14
quantitative HBV DNA using the Amplicor Roche
15
assay. This assay has a
sensitivity of 400 copies,
16
and 64 percent of the antigenic units had DNA above
17
400 copies. Those samples that
were negative, the
18
72, were taken through a more sensitive assay that
19
had a sensitivity of about 65 copies, which is
20
probably comparable to minipool type NAT, and 12
21
remained negative even at that level.
Those 12
22
samples were taken to a very high sensitivity,
111
1
essentially 1 copy/ml assay, high volume, and still
2
there were 6 that were negative.
So, we ended up
3
with still 3 percent negative even after taking it
4
through sequential increasing sensitivity assays.
5
So, these are the chronic carriers in whom DNA is
6
undetectable with at least one time point and one
7
high sensitivity assay.
8 Next slide.
This is showing the
9
relationship between antigen reactivity and viral
10
load. Unlike that nice linear
relationship, here
11
there it is essentially a scatter plot.
These are
12
the 3 that were negative by all NAT.
These are the
13
ones that were detected only by the high
14
sensitivity. These are the
Amplicor negative but
15
single input, not as sensitive, positive. And,
16
these are the quantifiable. You
can see that
17
relationship is not observed in chronic carriers.
18 Next slide.
That is people who have
19
anti-core. I think Roche did a
nice job of sort of
20
saying that if we keep anti-core the issue is not
21
that problem with anti-core positives, antigen
22
positives having absence of DNA.
It is really are
112
1
there donations that are antigen positive that lack
2
anti-core that are truly infectious and not
3
detectable by NAT?
4 In the REDS program and in other studies
5
varying 1-5 percent of antigen positive donations
6
lack anti-core. Now, when these
are worked up most
7
of these are window phase seroconverters so they
8
have high-level DNA very consistent with acute
9
infection. But in a proportion
of DNA negative,
10
and we saw those cases in Roche, the issue is
11
studying enough of those cases to sort out are they
12
true HBV infections, that either there is a
13
mutation not detected by NAT or individuals who
14
have failed to form anti-core, chronic carriers who
15
have low-level DNA and have failed to form
16
anti-core. Do they lack
contamination, which I
17
think most of them are? Are they
persistent,
18
non-specific antigen reactivity, and Roche showed
19
us an example of that? Or, are
they possibly
20
recent vaccinees?
21 Next slide.
This is three studies, two
22
published papers and some unpublished data from
113
1
REDS that have looked for these people who are
2
antigen positive, anti-core negative and either
3
lack or have very low-level DNA.
I am not going to
4 go through these in detail but in Japan one study
5
identified three such donors who had no history of
6
vaccination and who remained low-level PCR-reactive
7
with only a very high sensitivity enhanced assay;
8
remained anti-core non-reactive, so never
9
converted; and, again, remained antigen positive
10
and very low-level PCR-reactivity for over a year.
11 The French group, Couroce's group reported
12
two donors from endemic countries as well, with 0.1
13
percent of their antigen-positive donors who had
14
this pattern of persistent antigen without
15
anti-core and very low-level HBV DNA, and no
16
history of vaccination or immunosuppression and no
17
evidence of mutations to explain the failure of
18
this person to form anti-core.
19 In REDS--this is a cross-sectional study
20
so we weren't able to do follow-up, but we had 20
21
antigen-positive donors who lacked anti-core.
22
Sixteen of these were positive for DNA and were
114
1
probably typical acute phase, but 4 were negative.
2
Three of these were probably contaminations. They
3
had no other serologic markers, probably represent
4
surface antigen carryover. But
one had anti-e and
5
could represent an atypical carrier.
6 So, just a caution that there are some
7
studies, particularly from endemic settings where
8
there may be people who have antigen in the absence
9
of anti-core and low-level or absent DNA, and I
10
think we just need to study these further.
11 Next slide.
Just in conclusion, I do
12
think that we would see a small incremental yield
13
by minipool-NAT but the clinical impact of that I
14
think needs to be considered as well as the yield,
15
and we also need to view the context of what would
16
we get were we to get all the way to ID-NAT.
17 I am optimistic that we will eventually be
18
able, with ID-NAT or very small pools or high
19
sensitivity HBV DNA, to get rid of antigen,
20
however, I think this is going to require further
21
studies. Particularly, we are
capturing units
22
daily that could be worked up to accrue large
115
1
numbers with high volume of the plasma components
2
from these various sort of atypical patterns.
3
Particularly relevant is that I do think the
4
combination of NAT anti-core is the ultimate goal.
5
Particularly relevant are these samples that are
6
antigen positive, anti-core negative, and really
7
both studying these samples and particularly
8
enrolling and following the donors, as Roche did,
9
to determine whether these are false positives or
10
contamination. Thank you.
11 DR. NELSON:
Thank you. Comments? Yes,
12
Harvey?
13 DR. KLEIN:
Mike, we heard from Dr. Alter
14
earlier that, with the problems in trying to
15
calculate what the residual risk is, it might be
16
reasonable as a start to do a study simply by
17
taking 400,000, 600,000 specimens and using a
18
single unit detection system along with the
19
serology. I would just like to
know what your
20
opinion on doing that kind of a study might be.
21 DR. BUSCH:
Yes, I think that is a good
22
idea. I mean, we have the Biswas
paper included
116
1
comparing assays on window period panels neat
2
versus minipool. That is kind of
these model
3
estimates that minipool picks up only a quarter of
4
what might be detected neat.
But, yes, I think
5 such a large-scale
study either with neat--you
6
know, one of the issues with Roche's system is
7
their multiprep high extraction volume assay--we
8
saw the data that was comparing the multiprep pool
9
of 24 versus the standard prep neat, but had they
10
applied their high sensitivity multiprep neat,
11
which is what was done in the Biswas paper, they
12
would have seen a greater incremental closure than
13
was documented by ID-NAT. So,
doing a head-to-head
14 comparison
study of a very small pool with proposed
15
minipool, I expect, would double or greater than
16
double the yield.
17 DR. KLEIN:
That might give us at least an
18
idea of what the risk is now. It
seems as if no
19 one
is very confident about that.
20 DR. NELSON:
One other issue too I
21
think--I know you didn't talk about the
22
cost-effectiveness in any detail but your initial
117
1
slide assumes that it is a 60 year-old person that
2
is transfused but there are kids with thalassemia
3
and pediatric, depending on the life expectancy,
4
etc. of the patient, I think those are different
5
issues. Yes?
6 DR. KUEHNERT:
On that slide you were
7
reviewing surface antigen positive, core antibody
8
negative donors in the last bullet of the REDS.
9
What is the denominator of those tested?
10 DR. BUSCH:
Unfortunately, I don't have
11
that number.
12 DR. KUEHNERT:
The other question I had is
13
you had 20 antigen positive and 16 DNA positive by
14
the standard PCR assay. So, the
PRISM assay was a
15
false negative.
16 DR. BUSCH:
These were people who were
17
antigen positive, anti-core negative and 16/20 had
18
ample levels of DNA and were probably acute phase.
19
They were picked up but at that point it was
20
Auzyme's. So, they were picked
up by Auzyme and
21
those 16 would have been sort of, if you will,
22
run-of-the-mill acute hepatitis B.
118
1 DR. KUEHNERT:
So, 16/20 were DNA positive
2
originally.
3
DR. BUSCH: Yes.
They were all antigen
4
positive and 16 were DNA positive.
5 DR. KUEHNERT:
And then 4 that were
6
negative. Okay, thanks.
7 DR. ALLEN:
Mike, thanks for that very
8
nice overview. Obviously, the
committee and the
9
FDA, when they are considering how to place these
10
things, is looking at just one test at a time.
11
What is the implication of adding this into the
12
whole system that is already there in a blood bank
13
laboratory with or without discontinuing the
14
surface antigen test?
15 DR. BUSCH:
Well, it is certainly
16
possible. Certainly, at sites
that are doing Roche
17
today the system is optimal and they have actually
18
already done the extraction and they are just
19
taking a residual aliquot of the resuspended pellet
20
lysate and directing it to an automated system, you
21
know, to get the results. So, it
is a moderate
22
workload impact. The other
platform, the Gen-Probe
119
1
Chiron platform, you know, that test is I believe
2
in clinical to try that version assay.
Especially
3
if you are deriving it off the current pool, I mean
4
that sort of becomes the challenge.
You know, to
5
do it on individual donation samples while we are
6
still doing the licensed pooled assay for HIV/HCV,
7
that becomes, you know, a substantially greater
8
task. To go to smaller pools--I
mean, the licensed
9
assays for HIV/HCV are approved for up to a
10
particular pool size so it is possible to go to
11
smaller pool sizes. You are
still retaining the
12
licensed status of those other assays, which I
13
personally think is the more appropriate way to go
14
to get to pools of 4 or 6.
15 DR. ALLEN: And
in terms of integrating a
16
test into the laboratory software system for--
17 DR. BUSCH: I
think that is not a huge
18
problem.
19 DR. ALLEN: And
do you foresee that
20
availability of this test will enable algorithms
21
that will enable entry of donors that are currently
22
deferred who clearly are not infected in any way
120
1
with hepatitis but have some false-positive tests?
2 DR. BUSCH:
Right, there has been a lot of
3
discussion about anti-core reentry and, certainly,
4
the current expectation is that that would require
5
that the donors be negative on anti-core on a
6
follow-up period so they can't be the real
7
HBV-exposed population or the old false positives.
8
They not only need to be negative on current test
9 of record or improved anti-cores, but they also
10
need to be DNA negative with a single input assay,
11
potentially with a single input assay run on
12
multiple reps in order to make sure everybody is
13
confident that these people do not have occult
14
viremia.
15 DR. ALLEN:
Thank you.
16 DR. NELSON:
Thanks, Mike. Donna?
17 DR. DIMICHELE:
I just want to actually
18
comment on your comment, and that was sort of the
19
basis of my previous comment.
You know, in the
20
pediatric populations that are getting chronically
21
transfused, I just want to say that all of them
22
have been vaccinated ever since this vaccine has
121
1
been licensed, and we pay a lot of attention to
2
documenting primary serological response so that,
3
you know, their risk is primarily of getting
4
reinfected bit certainly not chronically infected
5
unless they happen to be immunosuppresed because
6
they have already been HIV infected or HCV
7
co-infected. But, for the most
part, you know, in
8
the chronically transfused sickle cell thalassemic
9
and hemophilia populations, they have been
10
vaccinated and monitored for a very long time.
11 DR. NELSON:
Thank you. Dr. Andrew
12
Heaton, from Chiron?
13 DR. HEATON:
Thank you for the opportunity
14
to present early Ultrio or Triplex test results as
15
part of our worldwide introduction.
16 As you may be aware, Chiron Gen-Probe
17
received CE approval in January of this year. We
18
are beginning to see significant implementation on
19 a
worldwide basis. We anticipate, by the
end of
20
the year, the availability to those countries
21
covered by that application to be able to perform
22
individual donor testing. We
also have reduced
122
1
pool size software under review at the moment in
2
order to allow our customers a wide range of
3
testing options in terms of sensitivity.
4 Next slide, please.
As I mentioned, CE
5
approval of our Ultrio test occurred in January,
6
and it allows the availability of HBV NAT testing
7
to European countries. As I will
show you in a
8
minute, the high prevalence countries are those who
9
have adopted this first. There
has been
10
significant early adoption and I will show you some
11
of the early yield cases that we have experienced.
12 Next slide, please.
As you might expect,
13
the countries which have adopted the Ultrio test,
14
dots marked in green, represent the southern
15 European
countries who have a higher prevalence of
16
HBV. The second group of
countries where we have
17
conducted or are conducting in-country evaluations
18
include the more eastern countries in Europe who
19
are joining the European Union and, therefore, will
20
become the subject to blood safety directive; and
21
then a number of very high prevalence countries in
22
the East. So, there is
significant worldwide
123
1
introduction of HBV NAT testing and it is clearly
2
related to the prevalence in the countries
3
involved.
4 Next slide, please.
We have had 2 yield
5
cases. The first yield case
occurred in Spain, in
6
the Madrid Community Blood Center, where the sample
7
was tested in pools of 8 and they got their
8
positive after 11,000 units had been tested. They
9
have now tested 13,000 so, if you are running the
10
clock, about 1/13,000 is the incidence rate. The
11
donor was hepatitis B core antibody positive and
12
the HBV quantitation, using an in-house
13
quantitative method, was 88 IU/ml and 650 copies/ml
14
when the test was performed by NGI.
15 In Italy, individual donor testing
16
identified 1 positive yield case in 9,732. The
17
donor was also hepatitis B core antibody positive.
18
In-house testing revealed 11 IU and it was tested
19
out at 215 copies by another reference method.
20
Next slide, please. In terms of yield
21
then, or predictive yield, really the world falls
22
into three major categories. The
first of those is
124
1
the low incidence countries which use hepatitis B
2
core antibody testing, where the predicted yield
3
may be expected to be very low.
The second is
4
really the rest of the world excluding the United
5
States and France, which are the only two countries
6
that now do core antibody testing as routine, where
7
you would expect the yield to be associated with
8
the incidence of hepatitis B core antibody
9
positivity and the yield, which is about 0.5
10
percent DNA positive in that population or around
11
1/40,000. Then, in the very high
prevalence
12
countries in the East we have somewhere around 20
13
and 70 percent hepatitis B core antibody positive
14
where you would expect a much higher yield.
15 So, if you average out the first two yield
16
studies, we are running about 1/10,000, which is
17
slightly higher than we would have predicted. It
18
is interesting in that respect that Canada, which
19
has just started HB core antibody testing on a
20
North American type donor population, noted 1.5
21
percent hepatitis B core antibody positive in a
22
donor population that would be expected to be very
125
1
similar to the U.S.
2 Next slide, please.
The current questions
3
then as we go through the implementation process,
4
there is a rapidly growing tissue bank sector in
5
the United States which is looking for nucleic acid
6
testing to assure the quality and safety of their
7
components. An issue that badly
needs attention
8
there is a definition of sample standards because
9
sometimes what the tissue banks call a blood sample
10
is really neither blood nor a sample, and it
11
certainly isn't subject to consistent standards.
12 In another area, the blood banks have
13
asked us to look carefully at hepatitis B core
14
antibody false-positive reentry and correct
15
classification of hepatitis B core antibody and
16
they would like to see HBV NAT testing used to
17
assist in preventing the false classification of
18
donors who are not truly positive for the hepatitis
19 B
core antibody.
20 There is certainly a need for infectivity
21
studies of NAT negative, HBsAg positive donations.
22
We have received requests from a couple of centers
126
1
to work with them on reviewing these issues,
2
particularly those centers in the East.
3 Finally, we have made dHBV available under
4
IND and, indeed, 4-5 blood centers have completed
5
our clinical trial and are now using dHBV on a
6
routine basis.
7 The worldwide implementation key
issues
8
then are higher than expected yield that will
9
nearly always be core antibody positive. We now
10
need to look at the rate of DNA positivity in a
11
B-core positive population. In
the U.S. that is
12
only about 0.5 percent but in Taiwan it is reported
13
to be as high as 10 percent.
14 We need to look at the implications of
15
vaccination. We have already
seen one donor who
16
silently seroconverted from anti-HBs to anti-HBc
17
without having a period of HBsAg positivity. So,
18
the implications of bringing this test to make it
19
available on a highly vaccinated population will
20
clearly be significant.
21 Lastly, in the East we are facing the
22
issue of wide-scale vaccination in a highly endemic
127
1
population, a population which is now loaded then
2
with vaccine-escape mutants. In
Taiwan they report
3
about 1/1,000 vaccinees seroconverts to HB-core
4
antibody per year. So, there is
a significant
5
ongoing breakthrough in a community situation.
6 Finally, as we complete our clinical trial
7
we will be looking to carefully evaluate the
8
relationship between test pool size and the desired
9
sensitivity. Thank you.
10 DR. NELSON:
Thank you, Dr. Heaton.
11
Questions? Comments? Yes, Susan?
12 DR. LEITMAN: I
have a question on slide
13
5. We have seen that you can't
measure residual
14
risk because it is so low that you don't see it
15
clinically and there is not a large enough
16
prospective study to detect that.
So, it is all
17
based on mathematical models. We
heard of
18
1/60,000, by Dr. Kleinman on behalf of REDS. What
19
is published I think on behalf of American Red
20
Cross is 1/100,000 or 1/120,000, by Dr. Dodd. And,
21
you have 1/300,000.
22 DR. HEATON: Yes,
the 1/300,000 was based
128
1
on the result reports the HBV DNA testing in the
2
U.S. The bulk of numbers are
really based on the
3
level of hepatitis B core antibody and the
4
frequency with which hepatitis B core antibody
5
only's are HBV DNA positive. The
point I was
6
making here is that we are experiencing a much
7
higher rate in our highly endemic European
8
countries in any of these models that are
9
predictive.
10 DR. SCHREIBER:
On that same slide those
11
numbers that you showed for the endemic countries,
12 I
think those are prevalence rates with the new
13
cases incidence rates and not residual risks. The
14
residual risks would actually be at least a factor
15
of 10 times lower. So, you are
talking about
16
something on the order of 1/110,000 and then with
17
the adjustments that were made in the other you are
18
roughly talking about multiplying those by another
19
2.5. So, you are talking about
1/300,000 or so for
20
Spain, if my rough math is right, so that Spain did
21
not come out a hell of a lot different, I don't
22
believe, than the United States.
129
1 DR. HEATON: I
accept that, and in
2
discussions with experts in Taiwan, one of the
3
points they made there is that so many of their
4
recipients have, in fact, been previously infected
5
with HBV that it is extremely difficult to model
6
out the risk because you have such a high basic
7
resistance level.
8 DR. NELSON:
Next is Dr. Sherrol
9
McDonough, from Gen-Probe.
10
DR. MCDONOUGH: Good morning. I will
11
continue the discussion of detection of hepatitis B
12
DNA using NAT, and I will be talking more about the
13
Procleix assay.
14 [Slide]
15 As you can see, it was developed for core
16
detection of HIV-I, HCV and hepatitis B in pools of
17
up to 16 down to individual donor testing. In
18
addition, there are 3 discriminatory assays to
19
allow Ultrio reactors to be discriminated.
20 This assay is based on the same
21
technology, same equipment as assay procedures that
22
are used in the licensed Procleix HIV/HCV assay.
130
1
There are a large number of common reagents so we
2
made as few changes as we could.
And, the assay
3
reagents and the formulations that are used in the
4
licensed semi-automated Procleix format are the
5
same as those on the fully automated Procleix
6
Tigris system.
7 Next slide. So, I am talking about the
8
assay type shown on the left, the multiplex Ultrio,
9
as well as discriminatory HBV, HIV and HCV, and I
10
am talking about the semi-automated Procleix system
11
as the licensed system and the fully automated
12
Procleix Tigris system. The two
rows at the top
13
are what I will be talking about today, focusing on
14
HBV detection.
15 Next slide. To
mention some of the
16
features of the Procleix Tigris system, after setup
17
this system is designed to process up to 500
18
samples in a 10-hour period or 1,000 samples in a
19
14-hour period. For the
multiplex Ultrio assay
20
that represents 1,500 results in 10 hours. That is
21
500 for each of the analytes, or in 10 hours that
22
would be 3,000 results. Then, of
course, the
131
1
specimens are tested in pools of up to 16. That
2
would be 24,000 results in 10 hours or 48,000 in 14
3
hours.
4 Next slide, please.
The validation that
5
is ongoing for this assay includes the following:
6
the clinical evaluation is taking place at 5
7
clinical sites, with 3 reagent lots with both the
8
Ultrio and all 3 discriminatory assays and on the 2
9
different instrument platforms.
We have included
10
specificity studies in pools of both 16 as well as
11
IDT, and several different populations are being
12
studied for clinical sensitivity.
Of course, there
13
is a reproducibility study. The
items that are
14
highlighted here, specificity, seroconversion
15
panels or reproducibility are what I will describe
16
today.
17 Next slide, please.
In-house analytical
18
testing includes the following.
You can see
19
multiple operators, reagent lots and instrument
20
platforms. They include
analytical sensitivity,
21
genetic variants, the donor, donation factors,
22
interfering substances, etc., specimen collection
132
1
handling and the validation of use of the assay on
2
cadaveric specimens. Today I
will only be
3
describing the analytical sensitivity of the assay.
4 Next slide, please.
Analytical
5
sensitivity is demonstrated in this slide. This
6
was performed by taking known concentrations of HBV
7
and preparing panels at various international unit
8
per/ml concentrations. Each
group of bars
9
represents a different concentration.
The first is
10
45 IU/ml and then we are going down 3-fold, 15 IU,
11 5
IU, etc. The different bars represent
either the
12
Ultrio assay on the semi-automated system or the
13
Procleix Tigris system, as well as the
14
discriminatory HBV assay on both semi and fully
15
automated systems.
16 Before you spend too much time scrunching
17
your eyes, I will just say there is no statistical
18
difference between either assay or either
19
instrument platform for any of the copy levels.
20 Next slide, please.
Of course, another
21
way of looking at clinical sensitivity is to look
22
at seroconversion panels. We have
had a lot of
133
1
discussion about seroconversion panels already
2
today. This is a set of panels
that we have
3
analyzed. What I am showing here
are the days
4
earlier that you can detect hepatitis B DNA
5
compared to surface antigen. The
surface antigen
6
test was the PRISM using the European cut-off. The
7
results are shown for the Ultrio multiplex assay at
8
dilutions of 1:16 as well as neat, and on both
9
instrument platforms. The final
set are
10
discriminatory HBV results on both platforms.
11 So, if you focus on the highlighted
12
numbers at the bottom, the median days earlier that
13
we can detect HBV at 1:16 dilution is 6 or 7 days;
14
neat, 17 days on either instrument platform; and
15
the discriminatory assay shows 15 or 14 days
16
earlier.
17 Next slide. I
will focus on the word
18
preliminary. This is not final
but this is a
19
snapshot in time of where we are with specificity
20
testing. The first row shows the
results with the
21
Ultrio multiplex assay on the semi-automated system
22
testing pools. Specificity is
99.5 percent and
134
1
that overlaps with the specificity observed with
2
the licensed HIV/HCV assay.
3 The next slide shows the results from the
4
Ultrio multiplex test again on the semi-automated
5
system, now testing IDT, and we see the same
6
specificity of 99.5 percent.
Finally, the results
7
with the Ultrio multiplex assay on the Tigris
8
system, testing individual donor samples, is 99.8
9
percent.
10 Let me address the hatchmarks on the first
11
two rows. The first hatchmark
reminds me to tell
12
you that there was a potential HBV yield case in
13
that population. The second row
with the 2
14
hatchmarks--there were another 2 potential HBV
15
yield samples from that population.
All 3 of these
16
samples were Ultrio reactive, discriminatory HBV
17
reactive, as well as alternative NAT reactive from
18 a
different specimen.
19 Next slide, please.
These are the
20
preliminary discriminatory HBV specificity results.
21
Testing IDT, the specificity is 99.9 percent.
22
This, again, includes one of the yield cases
135
1
identified in the previous slide.
We are calling
2
that potentially yield case number 3.
3 Next slide.
The reproducibility study has
4
been done on both instrument platforms.
It
5
includes Ultrio, discriminatory assays, 3 clinical
6 sites,
3 reagent lots, 2 operators per site, and
7
both negative and low panel positive samples.
8 Next slide.
The constituents of each
9
panel member are shown at the left.
We have both
10
HIV, HCV and HBV positive panel members, as well as
11
negatives and co-infected samples.
The agreement
12
in this study was 100 percent for every panel
13
member, and the total variability is shown on the
14
right column at 15.2 percent or lower.
15 Next slide, please.
In conclusion, the
16
Ultrio and discriminatory HBV assays show similar
17
performance on the semi-automated Procleix and
18
fully automated Procleix Tigris systems. We
19
believe that the automated system will allow IDT
20 testing
to be performed much more easily in the
21
laboratory.
22 HBV was detected in seroconversion panels
136
1
on an average 14-17 days and 6-7 days earlier than
2 PRISM HBsAg in neat and
1:16 diluted samples
3
respectively. There are 3
potential HBV yield
4
samples to date that were identified in the
5
specificity study. Also, we have
an additional 6
6
potential yield cases from our high risk study.
7
Again, each of these samples was Ultrio reactive,
8
discriminatory HBV reactive and alt-NAT reactive on
9 a
different sample. Thank you.
10 DR. NELSON:
Thank you, Dr. McDonough.
11
Questions or comments?
12 [No response]
13 Thank you.
Next is Dr. Richard Smith,
14
from National Genetics Institute.
15 DR. SMITH:
Good morning. Richard Smith,
16
from National Genetics Institute.
I believe that
17
NGI has a financial relationship with probably
18
every company in this room so I will just do a
19
blanket statement.
20 [Slide]
21 This morning I will tell you about HBV NAT
22
IND for whole blood donations, just started at NGI
137
1
for the American Red Cross, in June of this year.
2
In this study, only those donations that have been
3
found to be repeat reactive for the anti-HBV core
4
antigen antibodies are tested for HBV DNA.
5 Next slide.
There are 3 reasons listed in
6
our IND for performing this testing.
First, the
7
results are being used as a donor counseling tool
8
for anti-core repeat reactive donors.
9 Next. Second,
we plan to analyze the
10
results of this study to help design another IND
11
for establishing a donor reentry algorithm and for
12
potentially false-positive anti-core reactive
13
donors. The new study would also
involve a second
14
licensed anti-core assay, hopefully, with improved
15
sensitivity.
16 Next. Finally,
to limit the viral load in
17
plasma pools destined for further manufacture.
18
Currently, anti-core repeat reactive donations are
19
included in these pools and we would expect some
20
number of these to be positive for HBV DNA.
21 Next slide.
The NAT assay used for this
22
study is the same assay being used for the IND
138
1
established to screen source plasma donors for HBV
2
DNA, and is performed on the same platform as the
3
FDA-approved HCV and HIV PCR assays that have been
4
used for source plasma donor screening for the past
5
several years. DNA extraction
for HBV is performed
6
with an initial sample volume of 0.1-2 ml,
7
depending on the desired level of sensitivity and
8
the volume of the sample that is available.
9
For HBV, we use 4
distinct HBV specific
10
primer pairs in separate amplification reactions,
11
and we perform duplicate reactions when increased
12
sensitivity is required for a total of up to 8
13
separate amplification reactions per assay. If
14
just one of those reactions is positive the assay
15
is considered positive. Each
reaction also
16
includes an internal control specific primer so
17
that the success of each reaction can be
18
independently determined.
Detection of specific
19
amplification products are performed by southern
20
blot analytical on every reaction.
21 Next slide.
This slide shows what the raw
22
data of one of NGI's HBV NAT assays looks like.
139
1
The underlying image is a scan of an HBV specific
2
southern blot and this membrane represents analysis
3
of just 1 of the 4 HBV specific primer pairs used
4
for each HBV assay.
5 After
scanning, the same membranes are
6
rehybridized with an internal control specific
7
probe and bands appear in all positions,
8
representing successfully extracted and amplified
9
material. A reaction such as the
one depicted
10
here, in position 14, would be considered invalid
11
and negative for the target but invalid so it would
12
have to be repeated. Membranes
also include
13
diluted amplified material, shown here in the last
14
position, to ensure adequate southern blot
15
detection sensitivity.
16 Next slide, please.
The testing and
17
algorithm being used for this particular study
18
first involves combining up to 16 individual
19
samples into one pool, and then performing an assay
20
with a 95 percent detection cut-off of 0.9 IU/ml,
21
which translates to a 85 percent detection cut-off
22
of 14.4 IU/ml on an individual sample basis.
140
1 Next slide, please.
When a pool of 16 is
2
found to be positive for HBV each individual sample
3
is tested with an assay with a 95 percent detection
4
cut-off of 1.6 IU/ml or
5
if the sample volume is limited we can perform an
6
assay with only 100 mcL but involving twice the
7
number of amplification reactions and, therefore,
8
producing the 95 percent detection cut-off of 9
9
IU/ml. With an anti-core
reaction rate of
10
approximately 0.6 percent, we are expecting to test
11
approximately 42,000 donations per year for the Red
12
Cross for HBV DNA. The next
slide shows the
13
results we have obtained since starting this
14
project, just in June of this year.
15
Next slide, please. To date, we have only
16
reported results for 1,255 anti-core reactive
17
donations; 900 have been found to be not
18
implicated, which means that the pool they were in
19
was negative; 302 were tested individually and
20
found to be negative for HBV DNA, 50 of them found
21
positive for HBV DNA and 3 had insufficient volume
22
for testing.
141
1 Of the HBV DNA positive donations, we have
2
HBV surface antigen data for 37.
Data for the
3
other 13 is forthcoming but was unavailable to me
4
at the time I was preparing this presentation.
5
And, 22/37 are antigen positive and neutralizing,
6
and 15 are antigen negative. So,
so far, about 40
7
percent of the HBV DNA positive donations are
8
antigen negative, or about 1.6 of all the anti-core
9
reactive donations screened.
10 Next slide, please.
We have gathered some
11
additional data on the DNA positive donations. The
12
average antigen reactive HBV DNA positive donation
13
has an antigen neutralization value of 98.8
14
percent, with a range of 89.3 to 100 percent. The
15
average viral load in these samples is 70 million
16
international units/ml, with some having very low
17
viral loads, in the range of 10
2 and
some as high
18
as 10
8.
19 Next slide. In
contrast, the average
20
viral load in the antigen-negative DNA positive
21
donations is just 70 IU/ml, one million times lower
22
than the antigen positives, with a range of below
142
1
the sensitivity of the quantitative assay up to
2
just 150 IU/ml.
3 Next slide, please.
Prior to initiating
4
the current study we performed a pilot study on
5
anti-core reactive donations.
This study was
6
blinded, with no knowledge of whether the donors
7
tested anti-core reactive on a previous donation.
8
So, the population most likely included a mixture
9
of donors that would be ineligible for inclusion in
10 a
donor reentry study.
11 In this study only antigen-negative
12
donations were tested for HBV DNA.
Of the 3,000
13
anti-core reaction, surface antigen negative
14
donations, 19 were found positive for HBV DNA using
15
an individual PCR test, with a 95 percent detection
16
cut-off of 9 IU/ml. Viral loads
for the 19
17
positive donations were determined and the range
18
observed for these was also from below cut-off up
19
to 150 IU/ml, which corresponds to about 500
20
copies/ml. The "greater
than" sign on the bottom
21
actually should be a "less than" sign. Those are
22
all less than the cut-off of the quantitative
143
1
assay. The next slide compares
these data with
2
findings from the REDS study, published in 2003 by
3
Steve Kleinman and others in The Journal of
4
Transfusion.
5 Next slide, please.
I was going to thank
6
Sue Stramer for this slide but maybe I should thank
7
Mike Busch, or maybe Mike should thank Sue--I am
8
not sure. Data from the REDS
study, conducted over
9 a
much longer period, also shows a very low rate of
10
the HBV DNA positivity in anti-core reactive
11
donations. DNA positive
donations from the REDS
12
study also had very low viral loads.
These are the
13
same results that you have seen presented in
14
multiple talks earlier today.
15 As part of the study currently being
16
carried out, we will enroll antigen negative, HBV
17
DNA positive donors for follow-up to determine the
18
predictive value of the test. We
will also follow
19 2
time anti-core reactive donors that test HBV DNA
20
negative upon initial screening.
That is it, just
21 a
short but sweet presentation.
22 DR. NELSON:
Thank you. Comments?
144
1 DR. SCHREIBER:
One question, one of your
2
objectives seemed to indicate that you are
3
interested in trying to reduce the viral load in
4
plasma pool. I think you need to
be clear that you
5
are talking about recovered plasma since I believe
6
that all source plasma collected is already
7
subjected to HBV testing, NAT testing, in the
8
United States, probably worldwide.
9 DR. SMITH:
Yes, you are right. That is
10
absolutely correct. Really this
was to help the
11
plasma fractionaters justify the use of recovered
12
plasma that wasn't being HBV NAT tested. Likewise,
13
the source plasma units that they use are not being
14
anti-core tested. So.
15 DR. NELSON:
Thank you. Harvey Alter?
16 DR. ALTER:
Thank you. Could I have my
17
first slide, please--oh, I don't have any slides!
18 [Laughter]
19 DR. NELSON:
How can you talk without
20
slides?
21 DR. ALTER: I
am substituting for Steve
22
Kleinman because he has a relationship with Roche
145
1
and I realized today that I am on the scientific
2
advisory board for Roche, that I have to admit to
3 although,
after reading this statement I suspect
4
that will be very short-lived!
5 [Laughter]
6 Lastly, I have this horrible bronchitis
7
and I may not make it through this so I am going to
8
give my quick overview and then read the statement.
9
Also, I am representing both the AABB and the
10
American Blood Centers.
11 The three issues that we saw were, one,
12
the company provides sufficient evidence for
13
licensure. Secondly, if the test
is licensed,
14
should it be mandated or optional?
Thirdly, can
15
the test replace surface antigen in its current
16
minipool format? So, in case I
break down or you
17
fall asleep, our position is yes, no and no.
18
I am going to skip the first
paragraph,
19
which tells you how great AABB is, and then go on.
20
HBV remains the most common clinically important
21
viral infection recognized from transfusion since
22
the control of HIV and HCV infections through
146
1
improved donor selection and serologic and NAT
2
screening. The data presented by
Roche Molecular
3
Systems from its IND study of HBV NAT in minipools
4
of 24 samples are an important contribution to the
5
ongoing improvement of donor testing.
6 AABB sees three issues of primary
7
importance to the blood community to be addressed
8
by BPAC and the FDA. First, is
the Roche HBV assay
9
approvable as a donor screening test?
Second, if
10
approvable, shall its implementation be required in
11
blood collection facilities? A
third question is
12
whether a claim for HBV NAT in minipools to replace
13
HBsAg testing should be granted.
14 Regarding the first question, the data
15
that were available for review by the AABB's
16
Transfusion-Transmitted Diseases Committee indicate
17
that the Roche minipool HBV NAT assay appears to
18 perform
adequately in terms of analytical
19
sensitivity and specificity, and generates
20
incremental yield of NAT positive specimens over
21
current serologic tests. This
suggests that the
22
assay may be approvable in the currently proposed
147
1
minipool NAT context, but its efficacy should be
2
greater if it were applied to individual donations
3
or significantly smaller minipools.
4 The second question is more difficult to
5
answer. The minipool-based assay
under
6
consideration appears to yield between
7
1/250,000-300,000 positive donations that are
8
negative on currently licensed tests for HBsAg and
9
anti-HBc. This rate is similar
to the yield rate
10
for HCV minipool NAT, and substantially higher than
11
that for HIV NAT. It is
comparable to or slightly
12
higher than predicted by the Biswas et al. study in
13 a
comparative study of NAT and serologic assays.
14 As suggested from the data on the
15
evolution of markers of HBV infection, these
16
donations tend to contain low copy numbers of HBV
17
genome, and incomplete data suggests that some
18
HBsAg assays, either available or under development
19
for evaluation by FDA, maybe able to interdict some
20
of these yield donations. These
include HBsAg
21
tests from Abbott, Ortho Clinical Diagnostics and
22
Genetic Systems. It is critical
for the accurate
148
1
analysis of the true impact of HBV minipool NAT
2
that samples from these current yield cases, and
3
those identified in the future by HBV NAT assays,
4
be tested not only by the currently licensed
5
serologic tests, but also by the developmental
6
tests that are likely to be licensed in the future.
7
Studies of the infectivity of yield cases are also
8
desirable, and particularly or units that
9
concurrent HBV DNA and anti-HBs in the absence of
10
detectable HBsAg and anti-HBc, as seen on two of
11
the yield cases in the Roche trial.
12 Thus, despite measurable yield,
13
introduction of HBV minipool NAT will offer only a
14
minuscule increment in transfusion safety compared
15
to currently required tests for HBsAg and anti-HB
16
core. The result of this low
incremental yield,
17
coupled with low rates of chronic infection and
18
clinical disease after HBV transmission, renders
19
the marginal cost-effectiveness of HBV NAT in
20
minipools very poor. There is a
reference to
21
Jackson's paper in Transfusion.
This
22
cost-effectiveness will decline further into the
149
1
future as a larger and larger proportion of the
2
population has vaccine-induced immunity to HBV
3
infection.
4 Regarding the third question, current data
5
are not robust enough to support elimination of
6
either serologic marker. It is
possible that HBV
7
NAT will eventually allow discontinuation of HBsAg
8
screening, but this will require a larger data set
9
including parallel testing by HBV DNA, likely on
10
individual donations rather than minipools, anti-HB
11
core, and HBsAg, using maximally sensitive antigen
12
assays.
13 In summary, minipool HBV NAT is an
14
expensive new screening assay that offers little
15
clinical benefit and that will not be offset by
16
discontinuation of any current testing.
More
17
sensitive HBsAg tests are available now and more
18
will become available in the foreseeable future.
19
More specific anti-HB core tests will also become
20
available. Based on these
considerations, AABB
21
does not support--and that would be American Blood
22
Centers as well--a requirement for the use of NAT
150
1
in minipools for blood donor screening at this
2
time. Rather, if HBV DNA NAT is
licensed, its use
3
should be optional. The
requirement for HBV NAT
4
testing should be reconsidered when technology
5
allows for individual unit testing.
Thank you.
6 DR. NELSON:
Questions for Harvey? Yes?
7 DR. STRONG: I
am curious about your
8
clinical opinion since there are yield cases that
9
will be missed if we don't do that testing, and you
10
are recommending that we don't have to do NAT
11
testing. Do you see that as a
significant clinical
12
risk?
13 DR. ALTER:
Well, we really struggled with
14
this. You have so many variables
that you have to
15
measure. First of all, we think
the test is
16
licensable. Secondly, if
licensable, it will be
17
easy for places that have Roche testing in place
18
but it is going to be a major, major implementation
19
for people who are using other systems.
Is the
20
yield sufficient to warrant that, knowing that
21
within a reasonable short time there will be
22
alternate NAT assay and there will be improved
151
1
surface antigen assays? I guess
an interim measure
2
would be that the FDA could set a time interval in
3
which to implement this test that was sufficiently
4
long that non-Roche establishments could possibly
5
catch up.
6 But when you get to the issue of if you
7
pick up one or two cases a year, does that make it
8
mandatory to do this test, that is a very difficult
9
thing. I think this decision is
similar to that
10
for third generation anti-HCV assays versus second
11
generation assays where the yield was considered to
12
be sufficiently small that blood banks were allowed
13
to use either second or third generation testing,
14
even though it was known that third generation
15
testing was slightly more sensitive.
It is a
16
complex issue. Would I want to
go on a stand? I
17
don't know.
18 DR. STRONG:
Just a follow-up, it sounds
19
like part of that is logistical, which I certainly
20
understand as a blood tester.
But I am still
21
interested in whether or not you think there is a
22
significant clinical risk for those that are
152
1
missed.
2 DR. ALTER:
There is some clinical risk.
3
You know, if this was HIV I would be talking
4
differently but HBV generally is a recoverable
5
disease in 95 percent of the people and the other 5
6
percent has this long duration of usually
7
non-progressive disease. So, in
the current
8
setting it is a very, very small margin of
9
significant clinical disease.
Nonetheless, we
10
don't want to transmit disease so that is a tough
11
issue. You know, my feeling is
we need to get to
12
individual testing as soon as possible and then we
13
should we should be doing HBV DNA testing on NAT
14
when the yield will be higher.
15 DR. EPSTEIN:
Harvey, AABB has suggested
16
that it feels, based on its own review of data made
17
available, approval would be reasonable but the
18
test should remain optional.
What would be the
19
practical consequence if FDA acted to approve such
20 a
test and was silent on a recommendation?
Would
21
it not be a chaotic situation in the marketplace
22
where some entities might implement it?
153
1 DR. ALTER:
Well, yes. I mean, FDA has
2
always tried to license two tests at once sort of
3
to get around this issue. It
will create some
4
chaos if it is licensed and it is mandated
5
immediately. We feel that Roche
has proven its
6
case that it is a good assay and it has yields. I
7
can't say it shouldn't be licensed.
They got there
8
first and they shouldn't be punished for that. But
9
for those people who are not using the Roche assay
10
it will create chaos if it is mandated immediately.
11 Then the other issue is the PRISM issue
12
and when will that be licensed, and will that be
13
implemented, and will that decrease the yield even
14
further and make the need for HBV DNA less in a
15
minipool format? So, there are a
lot of things
16
riding here, and when do you go from minipool to
17
individual testing or to mini-minipool?
So, there
18
are really three things going on simultaneously and
19 I
am glad I am not you.
20 [Laughter]
21 But I think one possible scenario would be
22
to license, to leave it optional for the time
154
1
being, to re-address this at some time interval.
2
The second option is to license it and make it
3
mandatory but give sufficient lag time that it will
4
be reasonable that the alternate assay will be
5
available also.
6 DR. NELSON:
Thank you. the open public
7
hearing is closed, I am told.
Could you restate
8
the questions for the committee?
9 DR. HOLLINGER:
Just a question, is there
10
not a statement from Red Cross?
11 DR. NELSON:
Not on the list here.
12 DR. PAGE: Red
Cross has chosen not to
13
make a statement on this issue.
14 DR. HOLLINGER:
Do you have a reason why
15
not?
16 [Laughter]
17 Committee Discussion and Recommendations
18 DR. KAPLAN: I
will try to wrap up this
19
session and then given the FDA perspective and then
20
go through the questions. What I
will try to do is
21
to just put together some of the elements that Dr.
22
Blaine Hollinger gave us in his great talk, with
155
1
some of the points from the clinical trial that Dr.
2
Herman and Dr. Frank, from Roche, explained to us,
3
and also bring up some of the points that Dr. Busch
4
and Dr. Alter brought to this equation.
Basically,
5
most of the things I am going to say you have
6
already heard so I will try to wrap it up.
7 [Slide]
8 The Roche clinical trial for HBV NAT, 059,
9
was done in about 600,000 volunteer whole blood
10
donations. The index donations
were tested for
11
surface anti-core with their minipool NAT test.
12
These are the concordant results.
Basically, all
13
three markers are positive.
However, as you might
14
expect, there are many discordant results here
15 which
are important for analysis of this trial and
16
licensing. Basically, you can
have the possibility
17
that the surface antigen is positive and the other
18
two markers are negative. So,
what this trial did
19
is they performed alternative NAT, quantitative NAT
20
and then they followed up the donors.
21 Another possible discordant result is that
22
the surface is positive and DNA is positive. What
156
1
they did is an alternative NAT and quantitative NAT
2
and then they followed up the donors.
3 The third possibility is that the surface
4
and anti-core are positive, and what they did was
5
an alternative NAT and quantitative NAT.
6 Another possible discordant is that only
7
the core is positive and all the others are
8
negative. So, what they did is
the alternative
9
NAT, individual donation NAT, quantitative NAT
10
anti-surface, IgM anti-core and then they followed
11
up.
12 The other possibility is that the core was
13
positive and DNA was positive and then they
14
performed alternative NAT, quantitative NAT and
15
they followed up.
16
The last discordant possibility
is that
17
the DNA was positive. So, what
they did was
18
alternative NAT, quantitative NAT and then they
19
followed up the donors.
20 [Slide]
21 So, I will give you an idea of the
22
numbers. About 600,000. As expected, most of them
157
1
were negative for the 3 markers.
What they found
2
in trial 059 is that 84 donations were positive for
3
the 3 markers. They found 4
positive for the
4
surface; 3 positive for surface and DNA; 16
5
positive for surface and anti-core; 2,988 positive
6
for core; 1 for core and anti-core DNA; and 23 for
7
DNA. I will focus o the last
one. This is pretty
8
important because it gives you the yield of the
9
whole trial that was discussed several times here.
10 From these 23, what they found is that 21
11
samples were false-positive samples and only 2 were
12
window period samples. So, the
whole yield would
13
be 2 in about 500,000 to 600,000 donations. That
14
will imply about 3-4 per million.
If you have 15
15
million donations a year you have around 60 units
16
that can be interdicted with this test.
17 Several considerations were raised here
18
regarding which of these donations could progress
19
to severe clinical outcome after transfusion, and
20
that is a consideration that we want the committee
21
to address.
22 The other group that I would like to point
158
1
out to you is related to the safety of the
2
implementation of the company claim regarding
3
alternative use to surface. I
would mainly like
4
you to focus on these 4 cases that were only
5
surface positive. Upon
follow-up, 2 out of the 4,
6
as the company mentioned, were negative in
7
follow-up in the trial.
Basically, 1 was a
8
false-positive surface antigen and it was
9
vaccinated.
10 Two were not followed up in the initial
11
clinical trial, however, the company just showed
12
you some of the data and basically both cases did
13
not seroconvert. So, for these 2
cases that were
14
not followed up, the alternative and ID-NAT or the
15
index samples were negative and after follow-up,
16
after the trial was finished, they did not
17
seroconvert. So, I think we have
a good take here
18
that these 4 were false positive for infection.
19
From this, 3 that had both markers, only 1 was
20
followed up and was positive, and the others were
21
not followed up.
22 So, regarding the sensitivity in general
159
1
of this test, there were 107 donations that were
2
positive for surface; 100 donations were surface
3
anti-core positive; and 7 of them were anti-core
4
negative. As a note, Roche, indeed,
accounted for
5
the 4 surface only donations in support of the
6
replacement claim. However,
these numbers are
7
small and several points were raised by Dr. Busch
8
and Dr. Alter, and we are asking the committee to
9
consider whether with this small number of
10
discordants this data is enough to support the
11
Roche claim to use it as an alternative of the
12
surface.
13 [Slide]
14 I would like to talk a little about the
15
surface and anti-core positives, and in this case
16
they found 16. This pertains to
the sensitivity of
17
the assay. So, when they did
ID-NAT they found 10
18
positives and 5 negatives using their own ID test.
19
Using the alternative NAT, a test by NGI that was
20
described by Dr. Smith, none were positive and 4
21
were negative. These are not
exactly the same.
22
There is no exact agreement here.
160
1
When they quantitated the 16,
3 of them
2
were 100 copies/ml; 1 was 200 copies/ml; 1 was 700
3
copies/ml; 1 was 1,200 copies/ml; 1 was 2,600
4
copies/ml; and 1 was 5,900 copies/ml.
The rest
5
were below the detection level.
The sensitivity of
6
this then is that 12/16 were detected by ID-NAT and
7
alternative NAT; 3/16 were negative by NAT and
8
alternative NAT and 1 was not tested.
A note which
9 I
would like to make is that although 16 donations
10
were minipool NAT negative, all were anti-core
11
reaction. This indicates a
sensitivity issue but
12
not a safety issue.
13 [Slide]
14 So, I would like to present the questions
15
to the committee. The first
question is do the
16
sensitivity and specificity of the Roche COBAS
17
AmpliScreen hepatitis B test in minipools of 24
18
samples support licensing of the assay as a donor
19
screen?
20 DR. NELSON:
Thank you, Dr. Kaplan.
21
Comments?
22 DR. KAPLAN: I
will go through the three
161
1
questions and then come back to the first one.
2 [Slide]
3 Second question, if so, (2(a), assuming
4
continued use of screening tests for anti-core, do
5
the data support the use of the Roche COBAS
6
AmpliScreen hepatitis B test in minipools of 24
7
samples to screen blood for transfusion as an
8
equivalent alternative to the surface antigen test?
9 2(b), if the data do not support use of
10
the Roche COBAS AmpliScreen hepatitis B testing
11
minipools of 24 samples as an equivalent
12
alternative to HBsAg to screen blood for
13
transfusion, what additional data would be required
14
to validation such use?
15 [Slide]
16 The third question, do the data support
17
the use of the Roche COBAS AmpliScreen HBV test on
18
minipools of 24 samples to screen blood for
19
transfusion as an added test in conjunction with
20
licensed donor screening tests for HBsAg and
21
anti-core?
22 And now we will go to the first one.
162
1 DR. NELSON:
Comments? Questions?
2
Anybody? Yes, Susan?
3 DR. LEITMAN: I
have a question for the
4
FDA. Is there precedent in the
past for this
5
committee recommending licensure of a screening
6 assay
without mandating its use? Dr. Alter
7
mentioned third generation HCV EIA.
Is that the
8
only example?
9 DR. EPSTEIN:
Of course, we did recommend
10
HCV EIA screening; it is just that we were neutral
11
whether the EIA-3 should replace EIA-2.
We let
12
them coexist on the market. CMV
EIA is approved as
13 a
screen and its use is voluntary. When
we first
14
reviewed the Abbott P24 test we ended up approving
15
it as a diagnostic but not a donor screen even
16
though studies had been done on its use for donor
17
screening. Of course, we had a
different set of
18
results. So, I think that really
the CMV is the
19
best example.
20 DR. ALLEN: Let
me just follow-up on that.
21
Again, as I understand the question, the committee
22
is being asked for a recommendation only on
163
1
supporting licensing and not on its use?
2 DR. EPSTEIN:
That is correct. In other
3
words, question one is should it be approved with a
4
claim as a donor screening test.
Questions two and
5
three have to do with what recommendations for use
6
FDA might make or not make. So,
question two is
7
could you replace HBsAg testing, treating them as
8
equivalent alternatives? That is
the EIA-3 versus
9
EIA-2 model for HCV. Then
question three is if we
10
do not regard it as an equivalent alternative,
11
should we consider recommending it as an additive
12
test? That is where we ended up
in 1996 with P24
13
where we recommended it as a screen that was
14
additive. Of course, there was
no issue of
15
replacing a test at that point.
16 DR. KLEIN:
Well, not being a lawyer, I
17
don't really care much about precedent.
It seems
18
to me what we saw this morning, in my opinion, is
19
that it is a sensitive assay that has been
20
developed, that has been applied in the screening
21
format that picks up additional cases of hepatitis
22
B. I think I find no reason why
it shouldn't be a
164
1
licensed screening assay.
2 DR. GOLDSMITH:
Are we just considering
3
this for screening blood donations?
In other
4
words, donors of source plasma would not be
5
subjected to this test?
6 DR. KAPLAN:
Yes, at this point we are
7
only considering the blood donations.
8 DR. EPSTEIN:
Let me just clarify that
9
source plasma donations are not screened for anti
10
core, and we have seen data that DNA NAT will miss
11
anti-core positives, some of which would have DNA
12
on an ID-NAT test or alternative test.
So, no one
13
contemplates, and the company has not requested a
14
label to screen source plasma.
So, this is blood
15
for transfusion.
16 DR. NELSON: I
agree with Harvey. I can't
17
see any reason that it shouldn't be licensed, and
18
this may not be as severe clinical outcome as HIV
19
but it is associated with chronic disease--cancer,
20
cirrhosis, etc. in some people and I think we
21
should try to prevent it.
22 There are some sub- populations in the
165
1
U.S. that have much higher rates of both prevalence
2
and incidence from HBV. Although
there were
3
600,000 donors screened, there was no attempt, I
4
don't think, to find the highest risk donors to
5
screen, or anything like that.
So, my guess is
6
that applied to the entire donor system the yield
7
will be somewhat irregular; maybe not entirely
8
predictable by the data that are available. I
9
mean, in some populations may be more useful than
10
others in terms of picking up higher numbers of NAT
11
positive surface antigen negative donors. Anybody
12
feel that this shouldn't be licensed?
13 DR. HOLLINGER: I guess the question is
14
really, at least in my mind, not that the assay is
15
going to pick up some samples I think prior to HBs
16
antigen positivity. There is a
lot of information
17
we don't have to make that decision, as I look at
18
it, anyway. One, we don't know
what the carrier
19
state potential is in the people who receive this
20
kind of blood. We don't know
what the disease
21
potential is in patients receiving this type of
22
blood. We don't know the
outcomes--I think is a
166
1
whole problem here.
2 We are trying to make a decision about
3
doing a licensing assay on something we have very
4
little, if any data on in the seronegative window
5
periods regarding a disease outcome.
Even if you
6
forget the disease outcome and look at it
7
straightforward with what we know in ordinary
8
circumstances, the fulminant hepatitis and you will
9
see numbers like three-tenths percent or
10
four-tenths percent of people will get the disease,
11 I
think that is very high and I think in reality it
12
is much less than that. So, if
you get one person
13
out of 200,000 donors who gets one of these units
14
of blood and four-tenths percent of 1/200
15
individuals eventually who will get this will
16
develop fulminant hepatitis, that is looking at
17
something--if my evaluation is simple, it would be
18
like one out of 40 million units of blood that
19
might result in fulminant hepatitis.
I may be
20
erroneous in that assumption, but the risk is
21
really very small.
22 On top of that, even people who get
167
1
chronic disease, which is probably less than 3
2
percent--now, some of these are immunosuppressed
3
patients and recipients so we can't probably use
4
that number appropriately but, certainly, half the
5
recipients will die over a certain period of time,
6
many of them around 60 years of age or so, getting
7
blood. If they do get this
disease, chronic liver
8
disease, to progress to cirrhosis takes decades, on
9
an average about 10 years a stage and if there are
10 4
stages, about 40--30 to 50 years probably before
11
you reach cirrhosis. Even people
who get
12
cirrhosis, 80 percent are still alive and doing
13
well 10 years after the diagnosis of cirrhosis is
14
made, and probably longer than that but that is
15
where the data leads us.
16 So, even with hepatitis B, those numbers
17
are probably very similar. So, I
think this is a
18
little different than the HIV situation that we are
19
dealing with here. So, while the
assay certainly
20
is a good assay and I have no problem with that,
21
the issue is whether it should be a donor screening
22
assay at this juncture. I mean,
I could see that I
168
1
would approve the assay because it can be useful to
2
any blood banking situation. The
issue is whether
3
we have enough information to make the
4
recommendations as a donor screening tool at this
5
stage.
6 DR. NELSON:
You have certainly raised
7
some of the unknowns about natural history. The
8
other side of the coin is that there are, if you
9
will, worse case scenarios for hepatitis B. It is
10
not an innocuous virus. It is
certainly more
11
significant than HAV and others that can be
12
transmitted by transfusion.
Chronicity varies,
13
certainly by immunosuppression, age and infection.
14
If these are kids that are transfused you are going
15
to see some liver cancer and some cirrhosis. So,
16
given this, I just can't see that this is totally
17
innocuous. It is unknown how
severe the outcome
18
is, but it is potentially significant.
19 DR. KLEIN: you
know, I agree with you,
20
Blaine, entirely but I guess the question in my
21
mind is that if it is not licensed, then if I have
22
patients in my cancer hospital and they are
169
1
primarily bone marrow transplant patients or
2
patients who are immunosuppressed, then I can't use
3
this as a screen unless it is licensed unless I get
4
an IND. If it is licensed I have
the choice of
5
using it in my high risk population as others do.
6 So, I guess what I am saying is I would
7
like to see it licensed although not necessarily
8
mandated, and I think there is a difference there.
9 DR. HOLLINGER:
I was under the impression
10
that makes it very difficult. I
could agree with
11
that but I thought Jay was saying this is a real
12
difficulty to license something without mandating
13
it.
14 DR. KLEIN:
Well, I guess that would be
15
his problem.
16 [Laughter]
17 DR. EPSTEIN:
We can license the test and
18
be silent whether its use is recommended. But I
19
think that that will create a chaotic situation.
20
Just as in the other direction, if we license it
21
and we recommend use within some period, even if it
22
is a fairly long period, since it would then become
170
1
available very quickly to users who have the right
2
platform, it would also be a chaotic situation.
3 In other words, you know, I think we have
4
disruption to our system whichever direction we go,
5
assuming that it is a licensed product, whether we
6
are silent on recommended use or whether we
7
recommend the use, either way.
8 DR. STRONG:
This is a bit of deja vu for
9
me. We had this very debate on
our medical staff
10
because we are one of the clinical trial sites.
11
When the trial came to an end, do we continue or
12
not continue since we have the platform in-house?
13
So, we spent half a day in discussions, many of the
14
same points being made. Now, in
Seattle, of
15
course, we do have a patient population with a lot
16
of bone marrow transplants, a lot of cancer
17
patients, a large clinical children's hospital,
18
etc. Our medical staff, which is
made up of 8
19
hematologists and a couple of lab medicine people
20 were unanimous to continue to test. In fact, the
21
three new cases are all our yield cases. So, they
22
feel justified in having continued testing.
171
1 DR. ALLEN: If,
as Dr. Epstein says, there
2
is no recommendation to mandate its use if it is
3
licensed, I understand the forces of the
4
marketplace and it is likely to drive it very
5
quickly and fairly uniformly.
There is the cost
6 factor. There are rising healthcare costs and the
7
pressure to try to maintain those as well as
8
possible, not add any unnecessary increase. There
9
are certainly liability concerns and
10
considerations. I think the
marketplace will speak
11
to this and that is the way that our system works.
12 I think the question before us is very
13
simple, do the sensitivity and specificity in the
14
minipools, as the data presented, support licensing
15
the assay as a donor screen? I
think Dr. Klein's
16
first comment spoke very clearly to that.
17 DR. STRONG: I
think there is a mixed
18
feeling in the marketplace, much as has been voiced
19
here. Of the five clinical sites
that were
20
involved, two have stopped testing and three have
21
continued. So, it is a debatable
issue.
22 DR. NELSON:
Are we ready to vote on
172
1
question one? Linda?
2 DR.
SMALLWOOD: Question one, do the
3
sensitivity and specificity of the Roche COBAS
4
AmpliScreen HBV test in minipools of 24 samples
5
support licensing of the assay as a donor screen?
6
Dr. Allen?
7 DR. ALLEN:
Yes.
8 DR. SMALLWOOD:
Dr. Davis?
9 DR. DAVIS:
Yes.
10 DR. SMALLWOOD:
Dr. DiMichele?
11 DR. DIMICHELE:
Yes.
12 DR. SMALLWOOD:
Dr. Doppelt?
13 DR. DOPPELT: Yes.
14 DR. SMALLWOOD:
Dr. Goldsmith?
15 DR. GOLDSMITH:
Yes.
16 DR. SMALLWOOD:
Dr. Klein?
17 DR. KLEIN:
Yes.
18 DR. SMALLWOOD:
Dr. Laal?
19 DR. LAAL: Yes.
20
DR. SMALLWOOD: Dr. Harvath?
21 DR. HARVATH:
Yes.
22 DR. SMALLWOOD:
Dr. Hollinger?
173
1 DR. HOLLINGER:
No.
2 DR. SMALLWOOD:
Dr. Kuehnert?
3 DR. KUEHNERT:
Yes.
4 DR. SMALLWOOD:
Dr. Leitman?
5 DR. LEITMAN:
Yes.
6 DR. SMALLWOOD:
Dr. Quirolo?
7 DR. QUIROLO:
Yes.
8 DR. SMALLWOOD:
Dr. Schreiber?
9 DR. SCHREIBER:
Yes.
10 DR. SMALLWOOD:
Dr. Whittaker?
11 DR. WHITTAKER:
Yes.
12 DR. SMALLWOOD:
Ms. Knowles?
13 MS. KNOWLES:
Yes.
14 DR. SMALLWOOD:
Dr. Nelson?
15 DR. NELSON:
Yes.
16 DR. SMALLWOOD:
Dr. Strong, your opinion?
17 DR. STRONG:
Yes.
18 DR. SMALLWOOD:
The resulting votes are 15
19
yes votes and 1 no. The
non-voting industry
20
representative agrees with the yes vote.
21 DR. NELSON:
Can we move on to the second
22
question?
174
1 DR. KAPLAN:
Question 2(a), assuming
2
continued use of the screening tests for anti-core,
3
do the data support use of the Roche COBAS
4
AmpliScreen HBV test in minipools of 24 samples to
5
screen blood for transfusion as an equivalent
6
alternative to the HBsAg test?
7 DR. NELSON:
Comments? Questions?
8 DR. KLEIN:
Since I want to get to lunch,
9 I
guess I will start off--
10 [Laughter]
11 I would address this in a similar way to
12
what Blaine said earlier. I
don't think that these
13
are equivalent. I think we have
seen data to
14
suggest that there may be more sensitivity in acute
15
cases and we don't know too much about chronic
16
cases, and we have a very small amount of data at
17
this point in time. So, I
certainly don't think
18
that I would accept that as an equivalent
19
alternative.
20 DR. ALLEN: I
concur with that assessment
21
and I think certainly we have had speakers this
22
morning during our discussion periods who have
175
1
spoken to the need for additional data, the type of
2
data that could be collected. I
think this is very
3
exciting and promising and look forward to the
4
collection of additional data so that we can make
5
further decisions down the road.
6 DR. LEITMAN: I
just want to say that it
7
is a relatively simple answer.
We saw data
8
presented to tell us that it is no an equivalent
9
alternative, not yet. We saw the
data that says it
10
is not.
11 DR. HOLLINGER:
I think the test is
12
probably a better test in general, I should say it
13
is a more sensitive test for detection at the
14 seronegative window period time.
But, again, I
15
agree. I think we need more
data. There are some
16
benefits to redundancy. If you
look at some of the
17
reproducibility assays you will see some false
18
negatives by log; you will see some false negatives
19
by site, and so on. So, there
has always been
20
benefit to redundancy with it is the HBs antigen
21
test or the anti-HBc test, and so on.
Until we
22
have enough information with testing down the line
176
1
in several assays and a variety of other things, I
2
think it is too early to make that determination at
3
this time.
4 DR. KLEIN: We
also have several
5
generations experience with HBsAg testing and I
6
would be very reluctant to step away from that
7
right now on the basis of a few hundred or even a
8
few thousand assays that we have seen here.
9 DR. NELSON:
One question for the blood
10
bankers in the audience and the panel is when a
11
surface antigen screening test is positive is a
12
neutralization assay performed routinely? Because
13 I
saw in some of the data that were presented that
14
they talked about surface antigen screening and
15
then they went back and said it was neutralization
16
positive or negative. I thought
that maybe that
17
was part of the routine. It is,
I guess.
18 DR. ALLEN: But
am I correct that that is
19
not to exclude a unit of blood, obviously; it is
20
only to give information back to the donor?
21 DR. KLEIN:
Well, the unit of blood is
22
going to be excluded anyway.
177
1 DR. NELSON:
Harvey?
2 DR. ALTER:
Just to reiterate what Harvey
3
Klein said, you know, this test is the apple pie of
4
blood banking. It was the first
test we introduced
5
for specific hepatitis screening.
It has really
6
served us incredibly well for 35 years, and one
7
would have to have overwhelming evidence to drop it
8
at this point. I think certainly
the evidence is
9
not overwhelming. And, I just
want to remind you
10
that we are still doing syphilis testing.
11 [Laughter]
12 DR. ALLEN: We
still have syphilis too!
13 DR. KLEINMAN:
I just wanted to comment
14
that surface antigen tests--obviously, there are
15
multiple licensed ones on the market and we have
16
seen that one recently introduced test has had
17
tremendous specificity problems.
My remarks really
18
aren't predicated on whether the test should be
19
dropped but in those cases having an HBV NAT will
20
help resolve some of the interpretation of a newly
21
introduced hepatitis surface antigen test that is
22
not performing in the way we expected it to. So,
178
1
there are different caveats.
2 DR. SCHREIBER:
We also know from the
3
Biswas paper that the improved antigen tests are
4
going to have incremental yield so that should
5
decrease the incremental yields of the NAT test
6
introduction. So, I think that
is not a
7
replacement.
8 DR. KLEINMAN:
I do have a sort of a
9
conceptual question to the FDA though.
I mean, we
10
know that there is a test out there in the pipeline
11
that is supposed to be more sensitive, but it seems
12
kind of odd to compare a test that is pending
13
licensure to one that isn't licensed yet. I mean,
14
it seems like a kind of odd bar to set that we
15
think that newer tests for another analyte are
16
going to be better, therefore, we should use that
17
information in deciding about whether a current
18
test should or should not be used or should replace
19
one. I mean, I can argue it both
ways. If we know
20
that something better is coming along, we can't
21
disregard that data and, yet, it is not an
22
FDA-licensed test that we are comparing to. So, it
179
1
is a sort of dichotomous way to think about things
2
and I just wonder how FDA thinks about this because
3
they know more about whether the tests coming
4
through the pipeline, in fact, are more sensitive
5
and, in fact, are going to be licensed.
6 DR. NELSON: As
I recall the Biswas paper,
7
certainly the individual NAT tests were still more
8
sensitive than any of the pipeline tests for
9
surface antigen, and it wasn't that the surface
10
antigen tests in the pipeline were more sensitive
11
than the NAT so these are two different assays.
12
Here is Robin. He can tell us
about it.
13 DR. BISWAS:
All I wanted to say is that
14
you have to deal with really the here and now. You
15
have a test which we are asking you questions
16
about, how we should manage it, whether we should
17
license it or not and whether it should replace the
18
HBsAg. Keep in mind that
technology improves and
19
changes. For example, the study
which has been
20
referred to several times today, remember that that
21
was published a year ago, over a year ago, and it
22
was actually done two or three years before that.
180
1
So, these tests do change. In a
nutshell, we
2
compared the then investigational tests to the at
3
that time currently licensed tests.
We compared
4
pooled NAT as it was then to the currently licensed
5
tests at that time. And, we
compared single unit
6
NAT as it was at that time to the currently
7
licensed tests at that time. I
should also say
8
that some of the investigational NATs a year ago,
9
two years ago, three years ago have, in fact been
10
licensed.
11
DR. NELSON: In the interest of lunch, are
12
we ready to vote on this question?
13 DR. HOLLINGER:
I am just a little
14
confused about this question. I
mean, the question
15
is asking should this assay replace HBsAg. Is that
16
correct? If that is what it is
then, of course, I
17
would say no.
18 DR. NELSON:
That is not the way, it says
19
is it an equivalent alternative, and in some ways
20
it is better and in others we don't have enough
21
data.
22 DR. HOLLINGER:
If the question is asking
181
1
should it replace the HBs antigen obviously, for
2
me, I would say no. But that is
not sort of the
3 way it is worded.
4 DR. NELSON: It
is worded is it an
5
equivalent alternative.
6 DR. KAPLAN:
Yes, because the company
7
claims it could be used instead of,
8
basically--instead of the surface, you could use
9
the surface or you could use the NAT.
That is the
10
claim.
11 DR. HOLLINGER:
So, basically it says
12
should it replace the HBs--I like the word
13
"replace" myself.
14 DR. NELSON:
Jay?
15 DR. EPSTEIN:
First of all, we are asking
16
the committee to comment on the strength of the
17
science and leave the policy decision to the FDA.
18
That said, the implication of this question is the
19
science base for considering replacement of HBsAg
20
by minipool NAT. So, I think you
have the question
21
right, it is just to clarify that we are asking how
22
strong is the science.
182
1 DR. BUSCH: It
is in the context of
2
anti-core screening. So, as
Roche presented, the
3
only concern is if anti-core failed to detect
4
something.
5 DR. NELSON:
Right, that is true. If
6
there were no core testing it would be a different
7
scenario, right, which, in much of the world, is
8
the case.
9 DR. BISWAS: I
just wanted to say for the
10
record that I think I said HBV NAT investigational
11
when I meant HBsAg investigational.
12
DR. NELSON: Okay.
Linda, we are ready.
13 DR. SMALLWOOD:
Question number 2(a),
14
assuming continued use of screening tests for
15
anti-HBc, do the data support use of the Roche
16
COBAS AmpliScreen HBV test in minipools of 24
17
samples to screen blood for transfusion as an
18
equivalent alternative to the HBsAg test? Dr.
19
Allen? DR. ALLEN: Not at the present time, no.
20 DR. SMALLWOOD:
Dr. Davis?
21 DR. DAVIS: No.
22
DR. SMALLWOOD: Dr. DiMichele?
183
1 DR. DIMICHELE:
No.
2 DR. SMALLWOOD:
Dr. Doppelt?
3 DR. DOPPELT:
No.
4 DR. SMALLWOOD:
Dr. Goldsmith?
5 DR. GOLDSMITH:
No.
6 DR. SMALLWOOD:
Dr. Klein?
7 DR. KLEIN: No.
8 DR. SMALLWOOD:
Dr. Laal?
9 DR. LAAL: No.
10 DR. SMALLWOOD:
Dr. Harvath?
11 DR. HARVATH:
No.
12 DR. SMALLWOOD:
Dr. Hollinger?
13 DR. HOLLINGER:
Gosh, I feel more
14
comfortable with this one now; I am not left out
15
hanging. No.
16 DR. SMALLWOOD:
Dr. Kuehnert?
17 DR. KUEHNERT:
No.
18 DR. SMALLWOOD:
Dr. Leitman?
19 DR. LEITMAN:
No.
20 DR. SMALLWOOD:
Dr. Quirolo?
21 DR. QUIROLO:
No.
22 DR. SMALLWOOD:
Dr. Schreiber?
184
1 DR. SCHREIBER:
No.
2 DR. SMALLWOOD:
Dr. Whittaker?
3 DR. WHITTAKER:
No.
4 DR. SMALLWOOD:
Ms. Knowles?
5 MS. KNOWLES:
No.
6 DR. SMALLWOOD:
Dr. Nelson?
7 DR. NELSON: I
guess you can't vote maybe
8
so I will vote no.
9 DR. SMALLWOOD:
Dr. Strong, your opinion?
10 DR. STRONG:
Despite my conflict, I guess
11 I
have to vote no.
12 DR. SMALLWOOD:
The results of voting for
13
question number 2(a), unanimous no.
The non-voting
14
industry representative agrees with the no vote.
15 DR. NELSON: Do
you want to read the next
16
question?
17 DR. KAPLAN:
Yes, 2(b), if the data do not
18
support use of the Roche COBAS AmpliScreen HBV
19
testing minipools of 24 samples as an equivalent
20
alternative to the surface to screen blood for
21
transfusion, what additional data would be required
22
to validate such use?
185
1 DR. NELSON:
This one isn't yes or no.
2 DR. ALLEN: In
the interest of time, I
3
would suggest that I think there have already been
4 a
lot of suggestions made earlier during the
5
discussion. In particular, I
think the
6
presentations by Dr. Alter and Dr. Busch addressed
7
this. Unless the FDA wants additional,
more
8
specific discussion, perhaps we can move on.
9 DR. NELSON: I
guess just more data.
10
Since blood donors are routinely screened for
11
surface antigen, you know, larger numbers could be
12
screened for DNA. That would
seem to be one way to
13
approach it. Harvey?
14 DR. KLEIN: I
would just like to see a
15
larger field experience, such as we would get if
16
this were a licensed assay and some people, such as
17
in Seattle, who are using it.
18 DR. KLEINMAN:
Yes, I wanted to pose one
19
question though because Mike, in his slides,
20
suggested that studies should not only be done in
21
blood donor populations but should be done in
22
subpopulations who acquire infection through
186
1
different means, and done in vaccinated recipients,
2
and I am not sure that I agree with that. I don't
3
know whether I agree with that or not at this point
4
because we are really looking at the assay in the
5
donor context, and if you find that there are
6
discrepancies in other contexts, if those people
7
don't become donors I don't know whether it is
8
important or not. Clearly, you
need to give some
9
direction to the manufacturers, or FDA eventually
10
needs to give some direction to the manufacturers
11
about whether studies in donors are sufficient or
12
whether they have to go and do their studies in
13
other population groups. So, I
think a little bit
14
of discussion on that might be helpful.
15 DR. NELSON:
Except that the donor
16
population is somewhat heterogeneous.
It is made
17
up of many subpopulations and I would see some
18
justification--when we looked at hepatitis
19
B-infected IV drug users we found a different
20
serologic pattern than was common among other
21
subpopulations. Whether or not
that would
22
translate to different HBsAg dynamics I don't know
187
1
because we were looking at core.
But there are
2
population variations and, you know, most donors,
3
thankfully, aren't drug users but some are.
4
Because of that, I think understanding this better
5
in subpopulations--I can see some justification for
6
that.
7 DR. KLEINMAN:
Kenrad, I don't doubt that
8
the dynamics might be different and the findings
9
might be different. I am really
posing the
10
question whether if you find different results in a
11
population of IV drug users, if they contradict the
12
results you get in screening of millions of blood
13
donors, would that be enough to persuade you that
14
you still don't want to drop the test if the
15
dynamics are different. Because
if it is not
16
enough to persuade you, then why require it? I
17
mean, the studies are interesting from a scientific
18
point of view and really need to be done, but they
19
wouldn't be a requirement for data to drop the
20
test. So, that is the question I
am posing.
21
Scientifically, it should be studied but whether it
22
needs to be studied for getting a claim is really
188
1
the issue I would like to hear discussed.
2 DR. NELSON:
Well, I would agree when you
3
talk about millions but there are small, hopefully
4
small subpopulations in a donor population that
5
comes from a different universe.
6 DR. BUSCH: The
reason I kind of argued
7
that that data are needed is I do think that the
8
donor pool here does have a sampling of these
9 atypical cases in endemic infections. For example,
10
the vaccine breakthrough infection that Roche
11
detected are seen routinely in Taiwan now. By
12
participating in studies there we would better
13
understand what is going on, get volumes from these
14
people and be able to look at infectivity. There
15
are two cases in France of surface antigen positive
16
donors persistent who lacked anti-core were both
17
people from Africa who were probably infected based
18 on
the work perinatally. So, it may be
they never
19
formed anti-surface because they were essentially
20
colonized in utero to the antibody.
21 So, I agree that the data that is relevant
22
for the U.S. decisions is large-scale donor data
189
1
but I think the numbers of these unusual cases that
2
trickle up in our setting are small and we can
3
better study them and understand them by these
4 collaborative
studies.
5 DR. ALTER: I
just want to go on record
6
that, as much as I love this test, the concept here
7
is correct. It is just
premature. I think
8
ultimately HBV DNA will replace HBsAg testing when
9
we go to smaller pools or individual testing and
10
when the data are larger, when we have a greater
11
database. But I think the
database will support
12
going from this test to the DNA.
13 DR. GOLDSMITH:
Just to add, I think that
14
this test will apply to blood donors and non-blood
15
donors, disease state subjects, that we might get
16
additional clinical information that might add to
17
the validity of the test. So, it
would be useful
18
for the manufacturer to apply the test outside the
19
primary donor group.
20 DR. DIMICHELE:
That is exactly what I was
21
going to say so I would like to second that.
22 DR. STRONG:
Just one comment, I mean, we
190
1
have continued to screen, as have two other
2
centers, so we are collecting more data. I think
3
these kind of cases that are surface antigen
4
positive only are going to be very hard to find. I
5
mean, they just don't happen, at least with the
6
numbers that we have which are approaching a couple
7
of million now. They are either
false positives
8
when they are surface antigen alone or they are
9
positive along with anti-core.
So, those surface
10
antigen only are going to be hard to come by.
11 DR. BUSCH: But
they could be found
12
routinely from the Red Cross Blood Systems. What
13
we are talking about is taking surface antigen
14
positives that are anti-core negative in programs
15
that aren't doing NAT studies, and those units are
16
being found all the time and if they are just
17
worked up in some sort of national collaborative
18
study by the different NAT assays, in follow-up I
19
think we could generate a larger data set fairly
20
quickly.
21 DR. STRONG: I
agree we can generate a
22
larger data set. I am just
saying with our limited
191
1
experience we have thus far, all of those have
2
turned out to be either false positives or core
3
positives.
4 DR. KAPLAN:
So, would you say Phase IV in
5 a
high risk population to get the correct numbers?
6 DR. BUSCH:
Yes, I mean, we routinely
7
screen for antigen and anti-core, and the units
8
that are antigen reactive and anti-core negative
9
are the problematic cases. I
don't know how many,
10
but we pick up a moderate rate of those and if we
11
were to simply put into place a protocol that
12
captured those units, and made them available to
13
Roche and any other company and enrolled those
14
donors, in a blood donor context we could capture
15
these cases.
16 DR. KAPLAN:
Yes, but it would require a
17
large number of these cases so you are talking
18
about a prolonged Phase IV, or what is your idea
19
about the number of total cases?
20 DR. KLEINMAN:
Well, we can address that
21
because when we looked at data from 1996, I think
22
it was, in REDS we documented surface antigen
192
1
positive in the absence of anti-core in about
2
1/100,000 tested donors, and then we did some DNA
3
studies, which have remained unpublished. If you
4
look here, in the Roche study, it was 7/600,000, so
5
about the same. So, I think this
finding with
6
stable HBsAg assays occur about 1/100,000 donors.
7
Now, the Ortho version 3 test that has some
8
specificity problems, this would not be a good test
9
by which to find such donors unless they fix those
10
problems because we know that that is the exact
11
profile of false-positive surface antigens so we
12
would be overwhelmed by samples that don't actually
13
fit the bill. But I think with
stable assays,
14
either with the Abbott Auzyme or presumably once
15
Ortho's assay gets fixed, we are looking at a rate
16
of 1/100,000.
17 So, if you had a program to say we are
18
going to try to do this in the large blood
19
collection systems across the U.S., so let's say
20
American Red Cross, BSL and a few others, so now
21
you have 8 million units or so a year, 9 million
22
units, 1/100,000 so what does that come out to be?
193
1
Ninety. So, 80 or 90. We might be able to accrue
2
80 or 90 units a year. Even if
the estimates are
3
half of that we might be able to accrue 40 units a
4
year. If we could get those
donors in for
5
follow-up and capture those plasmas and capture the
6
samples, test by various surface antigen assays,
7
various DNA assays, we might be able to accrue a
8
larger sample set, not in a short amount of time
9
but not in too long a period of time.
10 DR. NELSON:
This was an essay question,
11
which I think we have already answered.
So, let's
12
move on to the third one.
13 DR. KAPLAN:
The third question is do the
14
data support the use of the Roche COBAS AmpliScreen
15
HBV test on minipools of 24 samples to screen blood
16 for transfusion as an added test in
conjunction
17
with the licensed donor screening tests for HBsAg
18
and anti-hepatitis B core?
19 DR. NELSON:
Yes?
20 DR. SCHREIBER:
Based on all the
21
discussions, can we add the word "voluntary" after
22
"added?" Added
voluntary tests?
194
1 DR. KUEHNERT:
I thought the spirit of
2
this question was a required test.
That is what I
3 thought was being asked.
Which is it?
4 DR. EPSTEIN:
We are not asking you to
5
comment on the policy question, which is should we
6
recommend additive testing. We
are asking you to
7
comment on the strength of scientific data. In
8
other words, are these valid results?
What is
9
their magnitude? Are there
caveats?
10 DR. KUEHNERT:
I am sorry, how is question
11
one and three different?
12 DR. EPSTEIN:
Question one is whether the
13
sensitivity, specificity, reproducibility or
14
comparable to other tests for hepatitis B virus
15
that we have approved as screens.
So, does it meet
16
the standard of screening tests?
Question two was
17
if it does, is it sufficiently better as an advance
18
that it should replace HBsAg? We
heard your
19
answer. Question three is really
is there an
20
additive yield that we feel is meaningful? You
21
don't directly have to answer the policy question
22 of
should we go on to recommend it.
195
1 DR. NELSON:
Yes, this doesn't include a
2
"win." It just
includes do the data suggest that
3
added to the surface antigen and core antibody,
4
would it be an improvement or would it be
5
scientifically valid.
6 DR. EPSTEIN: I
mean, committee members
7
can express caveats if they wish.
8 DR. ALTER:
But, Jay, if there wasn't an
9
additive yield we wouldn't have voted yes to the
10
licensure. So, the two are
really--
11 DR. EPSTEIN: I
actually disagree with
12
that, Harvey. I mean, it could
have had no
13
additive yield and still be an adequate screen.
14 DR. ALTER: So,
we can't ask the question
15
we really want to ask.
16 [Laughter]
17 DR. EPSTEIN:
Well, I think committee
18
members can comment. I mean,
they are here to
19
advise the FDA and they can certainly express their
20
thinking about what we ought to do, but the
21
scientific advisory committees are intended to be
22
advisory on the science and we are trying to ask
196
1
you the science question.
2 DR. NELSON:
Well, it seems to me that the
3
data are pretty clear on this, that adding the NAT
4
test to the surface antigen and core true positives
5
were detected.
6
DR. KLEIN: Well, I would like to add a
7
caveat because I certainly agree more with what I
8
heard Blaine say at the very beginning, and that is
9
that while there is no question in my mind that you
10
picked up additional donors who might transmit, we
11
really don't have any evidence that the public
12
health impact is going to be significant, for all
13
of the reasons that were stated earlier. So, I
14
think we are too early in the game to say there is
15
going to be a public health impact of requiring
16
such a test, and I think I would leave it at that,
17
not recommending to the FDA whether they should
18
require it or not but saying that, in my mind, I
19
don't think the public health benefit would push me
20
to require it.
21 DR. NELSON: I
am not convinced that the
22
public health benefit or lack of benefit has been
197
1
adequately studied. I think that
what has been
2
adequately studied--not adequately but what we have
3
some data on is that NAT testing will pick up some
4
infectious units in the context of surface antigen
5
and core-antibody, all the testing that is being
6
done. Coupled with what we know
about hepatitis B,
7 I
think it is likely that there is some public
8
health benefit. The magnitude of
it is unclear I
9
think.
10 DR. KLEIN:
Just looking at the wording
11
here, it says did the data support use?
I mean,
12
everyone can express their opinion on whether they
13
think there would be additional yield with this
14
test but it asks specifically about the data
15
presented. But it is very
difficult to answer this
16
question because there is what is on the paper and
17
what people think it means if there is a yes vote.
18
So, that is what I think is very difficult for me
19
in voting on this.
20 DR. ALLEN: I
think Dr. Epstein is very
21
clear that we are basing our decision as a
22
scientific decision or recommendation on the data
198
1
presented, and not making a policy decision for the
2
FDA or even really a policy recommendation. I am
3
comfortable with that as long as that is the
4
interpretation. I have no doubt
that this will
5
prevent some hepatitis B infections because it does
6
move into the window period; that there will be a
7
relatively small number of infections eliminated.
8
The clinical impact of that I think is a little
9
more difficult. Certainly, in
children, in people
10
who are immunocompromised I think the clinical
11
impact for those individual people could be
12
significant although the numbers are going to be
13
relatively small and probably decreasing over time
14
as our donor population more and more becomes those
15
who have been immunized earlier.
16
I am a little conflicted in
terms of
17
exactly what the cost-benefit value is going to be,
18
but I don't think we are being asked to make that.
19
Very clearly, if you want to close the window
20
period as much as possible, given this test, you
21
would do individual testing rather than minipools
22
of 24. And, I think these are
some of the
199
1
questions that need to be investigated by blood
2
collection centers, by public health officials and
3
others as we move forward with a licensed test in
4
place and see how it best fits into the total
5
testing scheme. And, I would
certainly encourage,
6
as additional data become available, to reopen the
7
question of whether we then need three tests or can
8
move to a combination of two tests based on hard
9
data in actual situations and careful evaluation
10
over a period of time.
11 DR. NELSON:
Steve?
12 DR. KLEINMAN:
Judging by the comments of
13
the panel, I feel like the wording of the question
14
is not being interpreted the same by everybody on
15
the panel. By that, I mean the
specific words
16
support the use. I think you
could interpret the
17
words "support the use" as do the data indicate
18
that there is increased yield from this test. If
19
you interpret it that way you might answer the
20
question one way. The other way
you could answer
21
the question of "support the use" is not only do
22
the data show there is increased yield but do I
200
1
personally think the test should be done if I were
2
making the decision. That means
not only do they
3
support increased yield but I would then take into
4
account all the other factors and vote according to
5
that.
6 I don't think everybody on the panel is
7
even trying to answer the same question right now
8
so I think you need to know whether you are asking
9
the question do the data support that an increased
10
yield would be achieved by implementing this test
11
in conjunction with surface antigen and anti-core,
12 or is the question do the data support the
fact
13
that we recommend that this test be used? They are
14
different questions and I don't think they are
15
being interpreted the same by everybody on the
16
panel.
17 DR. NELSON:
There was no data presented
18
on the natural history of infection.
There were a
19
few opinions but there was no data.
We have to
20
deal with the data that was presented so I think
21
the first of your questions is the way we should
22
vote. That is my own
opinion. I am not sure that
201
1
all the potential hepatitis B infections are
2
benign. You know, there is no
data on that and
3
certainly we have people with a lot of clinical
4
experience but we need better data on this I think
5
if we are going to interpret it more broadly. Yes?
6 DR. HEATON:
There is one key issue that I
7
would like to add to the discussion, putting on my
8
advisory committee for blood safety and
9
availability hat. I made the
point that there is
10
an enormous reimbursement implication of this
11
recommendation. If it is
recommended that this
12
test does improve public safety and the BPAC would
13
support that, then it becomes a much better case
14
for the blood centers to get reimbursement. In the
15
absence of such a recommendation, for the average
16
blood center which might wish to implement this
17
test the hospitals will view this as entirely
18
discretionary and may, in fact, push back on
19
covering the cost.
20 From one of the manufacturer's
21
perspective, I can tell you that in pretty well
22
every case nucleic acid testing detects this virus
202
1
before the protein is present.
So, in terms of
2
safety, whilst you may argue about the level of
3
improved safety, on the front end of the case you
4
get good detection. So, there is
a reimbursement
5
issue here as well as a medical issue.
6 DR. NELSON:
Harvey?
7 DR. ALTER:
Yes, I think Steve framed the
8
issues very well. If you break it
down into two
9
separate questions. For the
first question, do the
10
data support that the test does something positive,
11
you can't vote no on that if you voted yes on
12
number one. Number one is sort
of a minimalistic
13
thing saying it can be licensed even if it is
14
equal, but everybody feels it is better so you have
15
to vote yes on number three.
16 But I think the way it is worded now, if
17
people outside this room are going to see that
18 question
and then see the vote, it is going to give
19
the other, the part two impression, that is, that
20
the committee is recommending that the test be
21
used. So, I think either the
wording needs to be
22
more specific or question three should be dropped.
203
1
You got the sense of the group and you don't want
2
our opinion on policy.
3 DR. HOLLINGER:
This is just sort of an
4
aside, but if you want public safety in this
5
country you vaccinate everybody.
The other two
6
diseases we talked about have no vaccines
7
available; we have an excellent vaccine for
8
hepatitis B. We are spending a
lot of money for
9
donor testing and screening on this issue which
10
could be spent for vaccine policies of the
11
population in this country. Then
there is no risk
12
if you immunize everyone.
13 DR. NELSON:
Providing everybody responds
14
and gets the vaccine, and all those kind of things.
15
Jay?
16 DR. SIEGEL: I
think, given the difficulty
17
of a consensus interpretation of the question, it
18
might be better not to have votes but to hear the
19
committee members' individual discussions of how
20
they see the issue of additive testing framed.
21
Clearly, we are saying something about additive
22
testing and people can just comment on what they
204
1
think about a scenario in which minipool HBV NAT
2
would be an additive test to HBsAg, and just avoid
3
up and down votes.
4 DR. LEITMAN:
Everybody said the data
5
suggests that at the front-end of an infection in
6
the seronegative window period this clearly adds
7
something, adds something small, and I heard
8
somewhere between one-fourth to one-sixth of all
9
cases undetected by current methods would be
10
detected by this assay. So, it
is not the
11
majority; it is the minority.
And, we heard
12
suggestions and data that one would head towards
13
the majority with individual donor NAT and that
14
that might be substantially equivalent to and
15
better than in all cases HBsAg but we are not there
16
yet.
17 So, Jay phrased it as is there an additive
18
yield? Yes, there is clearly
additive yield but I
19
have seen nothing to suggest that that additive
20
yield translates to something real in terms of
21
better outcomes in the patients that we transfuse.
22 I
have no idea what the risk of those very low
205
1
viremia window period donations is in the absence
2
of that. Given all the
substantial changes and
3
upheavals required to implement a new test, I would
4
wait until there is individual donor NAT data or
5
something that moves me further to do that.
6 I was also very moved by Dr. Hollinger's
7
comments. My oldest child is 16
and all three of
8
them have been vaccinated. So,
if you get
9
pediatric care, you are vaccinated.
I don't know
10
that there is a public health recommendation to
11
vaccinate the American adult population though.
12 DR. NELSON:
Well, there is for pregnant
13
women, screening and vaccination, and for the
14
military and for healthcare workers.
But this
15
country is very diverse. We get
people from all
16
over the world who, you know, sleep in subways and
17
what-have-you. Some of them
become blood donors,
18
unfortunately. I am all in favor
of vaccination
19
but I am not sure--it is going to take a while to
20
solve this problem by vaccination, and it is
21
primarily viewed I think as pediatric, pregnant
22
women and certain subpopulations with higher
206
1
exposure. So, you know, I think
it is a great
2
vaccine and it is very important but we are not
3
quite there yet.
4 DR. HOLLINGER:
The other thing that I
5
thought was interesting in the discussion today is
6
the fact that the assays, even very sensitive
7
assays, pick up something differently.
I think
8
there was some testing where one alternative test
9
picked up things that another test did not pick up.
10
That, of course, is an issue that has me somewhat
11
concerned in looking at false-negative tests, not
12
so much false-positive but false-negative assays.
13
That is what we are really worried about, not the
14
false positives. A lot of false
positives also
15
were in there--the number is small considering the
16
number of people that are tested so, I guess, in
17
that way it is not a real big issue.
But I think
18
that is another interesting part of what we have
19
been discussing.
20 DR. NELSON: I
guess we are not going to
21
vote on this. Yes?
22 DR. DIMICHELE:
I would just like to make
207
1
one comment, and that is that one of the statements
2
that was made earlier on the licensing question was
3
that the licensing would give people and blood
4
banks specifically options with respect to testing
5
in high risk populations. I
think we can't forget
6
those high risk populations. In
my opinion, the
7
data does support its use in picking up some
8
additional potentials for infections and I think we
9
have to recognize that we have both congenital and
10
acquired immunosuppressed populations.
We have the
11
cancer populations and even in pediatrics,
12
unfortunately, there is a population that isn't
13
covered by vaccine and that is our neonatal
14
population. Much like we do
tests, neonatal blood
15
for CMV and making sure neonatal blood is CMV
16
negative because of the risk in that particular
17
population, given the risk of hepatitis B in the
18
neonatal population, for instance, I could see this
19
as being a very important screening tool for
20
neonatal blood. So, I think it
is very important
21
to consider it as an additional tool because, if
22
not widespread use, certainly for selective
208
1
populations I think it would be extremely
2
important.
3 DR. ALLEN: I
would certainly hope, based
4
on what has been said today, that there will be
5
blood centers, once the test becomes licensed, that
6
will implement appropriate laboratory and
7
epidemiological studies that will enhance our
8 knowledge
in a variety of ways. I would hope that
9
other blood centers that are collecting blood from
10
populations that tend to have a higher incidence
11
and prevalence of hepatitis B infection might
12
choose to implement this as a routine.
And, I
13
think we certainly need to encourage the situation
14
where independent blood centers in areas of the
15
country where there is very little hepatitis B
16
incident infection, that they not feel compelled to
17
implement the test unless local data suggest that
18
it would be helpful.
19 DR. STRONG:
That is an interesting
20
comment because of the three test sites that have
21
continued to test, one of them is Minnesota which
22
probably has the lowest B activity in the country.
209
1
They have decided to test. But I
think it is
2
affected by, one, ease of implementation because we
3
already have it; two, the patient population we are
4
serving, and in our situation, in Seattle, it is
5
the cancer patients, the bone marrow transplant
6
patients, a large hemophilia population, and our
7
medical staff didn't have trouble with that
8
particular decision but I am sure it would be
9
complicated if we had to implement a whole new test
10
system.
11 DR. GOLDSMITH:
I guess we could also then
12
encourage the use of smaller minipools as they
13
proceed with their research, maybe with 12 or 6,
14
and there would still be some benefit of numbers,
15
or single donors to see if there is an additional
16
benefit that would actually improve the public
17
health.
18 DR. HOLLINGER:
And at the same time, in
19
terms of looking at these things in follow-up, it
20
would be important, as I think Jim mentioned, to
21
get a lot of other information, epidemiological
22
information. We saw they picked
up two people that
210
1
were within that window period.
I would like to
2
know more about those two people, their background,
3
their epidemiology, something of that nature, what
4
happened to them clinically, and so on.
We need
5
that kind of information to know if our
6
questionnaires are working and other things too.
7 DR. NELSON:
Yes, the sentinel county
8
study that the CAC has done has shown in the last
9
few years that the heterosexual transmission of
10
hepatitis B is one of the major routes.
The
11
incidence has actually declined overall in these
12
sentinel counties but heterosexual transmission--of
13
the incident cases that occur are probably the most
14
important in the general population.
These are
15
potential donors, some of them.
Let's break until
16
about 1:45.
17 [Whereupon, at 1:00 p.m., the proceedings
18
were recessed for lunch, to resume at 1:45 p.m.]
211
1 A F T E R N O O N
P R O C E E D I N G S
2 DR. NELSON: In
discussions with Dr.
3
Epstein after the conclusion, he would like to
4
either have a vote or a further statement--and I
5
hope we can make it brief--on the previous
6
question, question three, on hepatitis B NAT
7
testing. Jay?
8 DR. EPSTEIN:
Yes, I appreciate that there
9
was difficulty with getting a common understanding
10
of the question. This is
question three to the
11
committee on HBV minipool NAT.
What I would like
12
to do is try to clarify what exactly is FDA asking
13
and let you determine, Kenrad, with you feel the
14 committee can vote on the question with that
15
understanding. If not, it might
be helpful to the
16
FDA if we could have individual committee members
17
simply state their views.
18 So, on the question of what do we mean,
19 first of all, I need to explain that we are asking
20
the committee for scientific advice.
We understand
21
that in any ultimate decision there are factors
22
such as feasibility of implementation, the
212
1
logistics, time scales and cost-effectiveness of
2
intervention. But we are not
asking this committee
3
those questions. There will be a
process through
4
the DHHS, which has an advisory committee on blood
5
safety and availability, to ask more global
6
questions about public health significance and
7
cost-relatedness of any FDA decision.
8 So, it is with the understanding that the
9
question is narrowed to a scientific point of view,
10
putting aside issues of cost-effectiveness, and the
11
implication of that is that the committee members
12
should not feel that if they vote that there is
13
significant benefit that that will in any way
14
obligate the FDA to make a policy decision in favor
15
of additive testing.
16 Then, what we are asking is whether
17
additive testing with HBV minipool NAT as described
18
would provide a benefit, a benefit to blood safety,
19 a
benefit to patient health. We
understand that
20
there may be different points of view on the degree
21
of such benefit, but it is hard to avoid the
22
question because, after all, the committee has
213
1
basically has advised that the data support
2
approval as a screen; that the data do not appear
3
to be sufficient at this point in time for use of
4
the minipool test to replace HBsAg.
But, if FDA
5
were to approve it, what exactly do we say about
6
it? And, the question will hang
in the air whether
7
it ought to be recommended as an additive test.
8 So, the question won't go away. FDA will
9
ultimately have to make a policy stand.
So, what
10
we are then saying is, well, we would like to be
11
advised by this committee whether, on scientific
12
grounds, we are or are not looking at health
13
benefit. I think part of what
has concerned the
14
committee is that there are really two dimensions.
15
One is an additional pickup rate of positive units.
16
The other is the significance of transfusing any
17
such units in terms of medical outcome.
You know,
18
we assume that you will be considering both factors
19
if you decide to vote on the question.
20 Again, we are asking you in this question
21
whether additive testing is a benefit, and we would
22
like you to answer that question with the
214
1
understanding that that is putting aside the
2
questions of economics and logistics.
3 DR. SMALLWOOD:
The proceedings of an
4
advisory committee require that after we have
5
closed discussion on an issue that we do not reopen
6
it because we have not made it public that we are
7
doing something differently. We
had previously
8
stated that we would not vote on question number
9
three and to open it up again, after individuals
10
have left, even the principals that are involved
11
here, would not be fair. So, we
would be going
12
against the advisory committee procedures.
13 DR. NELSON:
Principles don't have a vote.
14
There may be one committee member that has gone. I
15
don't see why we couldn't--
16 DR. SMALLWOOD:
Excuse me, it is the
17
discussion, Dr. Nelson--
18 DR. NELSON: It
is not a discussion now.
19
We are only going to vote. The
discussion is over.
20 DR. SMALLWOOD:
Excuse me, this is an open
21
public meeting. Under the rules
for an open public
22
meeting we have to announce what we are going to do
215
1
in advance. We have closed out
the discussion. We
2
closed out the discussion on this issue before we
3
went to lunch, and I am just quoting what the rules
4
are.
5 DR. EPSTEIN:
Is it permissible to have
6
individual expressions of opinion?
7 DR. SMALLWOOD:
Dr. Freas?
8 DR. NELSON: Is
the Supreme Court in
9
session? Do we need to see what
Justice Thomas
10
thinks about it?
11 DR. FREAS: I
really believe that it is
12
okay. This meeting was announced
in the Federal
13
Register. There is nothing other
than a statement
14
of clarification and I believe that if we went
15
around the table quickly and the committee members
16 made their comments, that would be
permissible. I
17
would prefer no votes at this time.
18 DR. SMALLWOOD:
To be clear, there will be
19
no votes but there will be committee comments
20
coming from individual members.
21
DR. NELSON: It will take longer but do
22
you want to announce the names so they can make
216
1
comments then? Dr. Doppelt?
2 DR. DOPPELT: I
think that there is some
3
benefit clearly that you can pick up some cases in
4
the window period. It isn't a
lot of cases that
5
you pick up though you do pick up some.
So, you
6
know, I think most people would probably say if it
7
didn't cost anything, what the heck, just do it.
8
But it does. So, not commenting
on the issues of
9
cost benefit, but just from the simple fact of what
10
does the data show, yes, you pick up cases and
11
there is benefit.
12 DR. GOLDSMITH:
I think the information we
13
saw does support the idea that there were a couple
14
of cases found but the testing algorithm that was
15
used hasn't been studied long enough to see if this
16
is the most powerful way to find additional cases;
17
that the 24 samples used for screening is probably
18
not the best way to use this new technology.
19
Therefore, if I had to vote, I would probably say
20
no at this time about this question, that the
21
sponsor should do additional work to find out the
22
real utility of this test, and also do additional
217
1
clinical work to find out what the outcome is of
2
potential transmissions.
3 DR. KLEIN: For the record, I was not
4
considering either logistics or cost in my comments
5
this morning. I think the data
that was presented
6
clearly demonstrate that this assay will detect
7
some otherwise undetected donors infected with
8
hepatitis B virus. From what we
know about
9
hepatitis B virus, that would very likely infect
10
recipients. The amount of public
health benefit I
11
believe, based on those two statements, is finite.
12
It is real but it is very small.
13 DR. HARVATH: I
concur with the comments
14
that have just been made. It is
what I would have
15
said.
16 DR. KUEHNERT:
I think there is, you know,
17
the data presented and it is all we have to go on.
18
It seems to indicate that you pick up a small
19
number of additional cases. I
think you also have
20
to consider whether in implementing the test you
21
clarify or further muddy the picture as far as, you
22
know, possible false positives, and how those then
218
1
get reconciled. So, to me, that
all needs to be
2
added into the decision processes.
You might be
3
able to detect some additional cases but also what
4
is the full picture as far as the impact on false
5
positives? You have to resolve
those false
6
positives as well. So, this
question, to me, I
7
sort of have to consider those things as well. So,
8 to me, I am not sure that it is a benefit when you
9
add all that in.
10 DR. NELSON: I
thought that the results
11
were fairly impressive, that it could actually pick
12
up additional cases and narrow the window period
13 particularly
in the incident cases, and also pick
14
up some that were core positive who would have been
15
deferred with current screening.
So, when I look
16
at the international situation I see this as even a
17
more important application where core antibody
18
testing is not--I realize that is not part of the
19
U.S. algorithm, but I think that preventing
20
hepatitis B, which may be benign and self-limited
21
in many adults who have a normal immune system,
22
nonetheless, this is an oncogenic virus and it is
219
1
not all normal adults that are transfused, but
2
sometimes immunocompromised children.
So, I would
3
support it and I think it should be implemented
4
when it can be.
5 DR. ALLEN: I
would agree with the prior
6
comments. It seems to me that
the evidence is
7
fairly clear that this test, even in a minipool of
8
24, does narrow the window during the
9
seronconversion of early infection state and,
10
therefore, would result in a very slightly safer
11
blood supply, looking at the nation's blood supply.
12 I
think the impact for individual people who might
13
otherwise receive those units is variable. It
14
could be significant in some people.
15 In terms of the implementation, I think
16
there are many issues that need to be examined,
17
including cost benefit, the impact on the ability
18
of blood bank laboratories to implement the test
19
easily and successfully. I think
we need quite a
20
bit of additional research, as was discussed,
21
including examining the relationship between the
22
NAT test and the surface antigen test and, once we
220
1
have additional data, what the optimal combination
2
should be for routine screening in blood centers.
3 I
think we need to examine the issue of whether
4
smaller minipools or even individual donor testing
5
provides any additional benefit versus the cost.
6 DR. DIMICHELE:
Given the data that was
7
presented earlier today and the discussion that
8
followed, I believe that there is strong enough
9
evidence for the FDA to give strong consideration
10
to adding this test to the complement of tests
11
already used for hepatitis B detection.
I believe
12
that the preliminary data mandates further
13
research, the nature of which has already been
14
stated.
15 DR. DAVIS: I
think the test will pick up
16
cases that would not have been discovered
17
otherwise. I don't know that
those cases are
18
enough to justify adding the test. I would have
19
voted no.
20 DR. HOLLINGER:
I agree with much of what
21
has been said here. One thing
that has not been
22
added, I personally think the clinical impact will
221
1
be insignificant overall. We
have not talked even
2
about treatment, and there are some good nucleotide
3
and nucleoside analogs which are available which
4
work very well in acute viral hepatitis B in
5
stemming fulminant hepatitis, and so on. So, even
6
if someone were to get clinically sick, the
7
probabilities are that they would have good
8
response to therapy and that would make this even
9
less significant.
10 DR. QUIROLO:
Well, I am a pediatrician
11
and all the people that I transfuse are children.
12
So, all those people would have hepatitis B for
13
decades if they were to contract it from a
14
transfusion. Not only that, I
take care of
15
minority children and immigrants and most of those
16
people are not immunized, the families aren't, so
17
the child would transmit that to his parents and
18
his siblings.
19 So, I think that the test is worth
20
considering. I also don't see it
as a stand-alone
21
test. It says in conjunction
with those tests. I
22
don't think you can use it without using those two
222
1
tests; it is not a stand-alone test the way it is.
2 DR. WHITTAKER:
I think the data support
3
the use of this test, however, I think additional
4
testing is needed in smaller pools before we add it
5
as a mandated test for blood donor testing.
6
MS. KNOWLES: I think also the data
7
support using this test as an added test. I think
8
this is a part of the evolving armamentarium of
9
screening tools that we really need to keep pushing
10
on forward.
11 DR. STRONG: If
I were allowed to
12
comment--
13 [Laughter]
14 --we made the decision locally, as I have
15
already stated, with our medical staff that we will
16
continue to use it. I think it
has provided us
17
some additional benefits. One,
for example, is
18
that with the anti-core positive donors, and we
19
have a large number of false positives, but
20
remember that we are allowed to have two positive
21
anti-core results and we have had some pickups with
22
the first time anti-core that would be DNA
223
1
positives. So, that would
obviously be a
2
circumstance in which we would want to defer that
3
donor on a first time anti-core result.
So, it
4
adds that additional benefit.
5 It clearly has helped us pick up some
6
window cases, I think to some degree to our
7
surprise. Our yield is more like
1/150,000, but
8
because we have had the three cases recently that
9
number will be diluted with time.
But the staff
10
certainly feels that it has had an added benefit.
11 I
think there still needs to be data collected in
12
terms of the hepatitis B surface antigen issue and
13
core, clearly, will need to be continued.
14 DR. NELSON:
Now maybe we can move on.
15
Jay, is that satisfactory?
16 DR. EPSTEIN:
That is fine.
17 DR. NELSON:
The next item is current
18 trends
in plasma product manufacturing,
19
introduction and background with Dr. Weinstein.
20
V. Current Trends in Plasma Product Manufacturing
21 A. Introduction and Background
22 DR. WEINSTEIN:
Thank you, Kenrad. I am
224
1
going to curtail my talk severely and just bring
2
out the important points. I know
that people have
3
to go at three o'clock and we do want to hear the
4
industry presentation as well as further comments
5
from the audience here. So, let
me just comment
6
here that the plasma fractionation industry has
7
undergone a number of notable changes, significant
8
changes within the last year.
9 [Slide]
10 We have heard about closures of plasma
11
collection facilities. We have
heard about layoffs
12
of personnel. Some of the major
plasma
13
fractionaters have reduced their plasma collection
14 significantly
by a couple of million liters. We
15
have also heard about the consolidations and
16
restructuring of the industry.
Alpha Therapeutics
17
has been absorbed by Grifols and Baxter. Beyer has
18
put its fractionation plant up for sale. Aventis
19
has been purchased by CLS to form ZLB-Behring, and
20
Octapharma is the new player on the U.S. market.
21 The question is do we have to fear chronic
22
shortages because of these changes?
What is
225
1
industry doing? What is the
state of the industry?
2 I
called Jan Bult, representing the Plasma Protein
3
Therapeutics Association, to give us an overview of
4
where the industry is.
5 Presentation
6 MR. BULT:
Thank you, Dr. Weinstein, for
7
this introduction. I am going
to, hopefully, tell
8
you in my presentation that we don't see a
9
near-term threat for supply, just to immediately
10
respond to one of your opening comments, and in
11
this presentation I would like to explain why.
12 [Slide]
13 What I am going to cover today is changes
14
since '98, the last time when we were facing
15
serious shortages in the United States; a little
16
bit about our data collection and how we
17
fractionate and therapies; what has happened
18
recently; what is going on with supply; tell you a
19
little bit about economics of plasma fractionation;
20
and then conclude with our statements.
21 [Slide]
22 Well, I think the most important thing
226
1
that has changed since 1998 is that we have
2
immediately implemented monitoring systems to
3
assess changes in supply dynamics.
That
4
information is available on a monthly basis. It is
5
available on a website. We do
believe that
6
industry as a whole is much better positioned to
7
meet consumer demand. You have
seen from the list
8
from Dr. Weinstein that we have new companies
9
entering the market. In addition
to Octapharma
10
that you mentioned, also Grifols or Provitas has
11 entered
the U.S. market with their immune
12
globulins. So, we have companies
now with broader
13
product portfolios.
14 But it must also be said that a lot of
15
things have changed, especially when it comes to
16
economics. In order to guarantee
long-term
17
viability of industry, we have responsibility and a
18
need to address the current industry economics.
19 [Slide]
20 Coming back to April, '98 when we were
21
dealing with shortage of immune globulins, which
22
was also the subject for a congressional hearing
227
1
and a lot of media attention, we have made a
2
commitment, and the commitment was that we will
3
start a data collection effort, originally on a
4
quarterly basis so that all parties will understand
5
the dynamics of supply.
6 What has happened in the meanwhile is that
7
we quickly moved to monthly reporting.
That
8
information is available since six and a half
9
years. It is provided on an
Association website
10
and is publicly available. But
also the situation
11
that we have right now is that we use a traffic
12
light system, green, yellow and red.
Green means
13
there is sufficient supply of inventory. Yellow
14
means let's be careful, and red means we have a
15
problem. We haven't had a red
situation. We had
16
two months of a yellow indication and what we have
17
done, we immediately informed the patients about
18
the situation so we have been very transparent and
19
open about the developments.
20 [Slide]
21 A couple of things that need to be said
22
are that we can, as an association, talk about
228
1
publicly available information.
Some of that has
2
already been shown by Dr. Weinstein.
But we need
3
to be careful because this is a very concentrated
4
industry and, because of that, we cannot sit
5
together with individual companies and agree on
6
what is going to happen with production trends. We
7
have to respect anti-trust laws.
8 Also, we have to accept that certain
9
things are unpredictable. We
would like to know
10
everything in the world but that is simply not
11
possible so unpredictability is a factor that we
12
have to take into account. We
can only comment
13
about things that are within our control. We are
14
only part of the entire chain.
15 But, as I said before, we do not see a
16
near-term threat to supply. What
we will see is
17
that individual companies will take actions to make
18 sure that the economic situation that we are
facing
19
is going to be addressed, and I will explain to you
20
in the presentation later on why.
21 [Slide]
22 Don't be frightened by this slide, but I
229
1
have to do this. I just want you
to understand
2
what we can and what we cannot do.
The points that
3
are pointed out in red are things that are simply,
4
by law, illegal. We cannot as an
industry agree to
5
limit production or to reduce or increase
6
inventories. We cannot
coordinate output. We
7
cannot allocate capacity. We
cannot determine
8
quotas. We canon talk about
continuation or
9
discontinuation of products, and we cannot limit
10
supply of particular products.
11 This is important because you can have
12
those conversations with individual companies but
13
once you are together you can simply not talk about
14
that. And, if you have a lawyer
in the room, they
15
will immediately stop that discussion.
16 [Slide]
17 Now, having said that, we want to be
18
cooperative. We want to share as
much information
19
as we can. Therefore, I am going
to tell you what
20
we believe the situation is.
Let's focus on some
21
of the products that are made from plasma. As you
22
can see, I focus here only the major products,
230
1
alpha-1, Factor VIII, immune globulins, albumin.
2
As you can see, these are proteins that are
3
available in plasma in different amounts. What you
4
see here are the quantities estimated industry
5
aggregate, but that may differ from company to
6
company and differ in the technology that is being
7
used.
8 [Slide]
9 In the fractionation process a combination
10
of temperature, pH, time and alcohol is going to
11
separate the different fractions that are used to
12
manufacture the different therapies.
I am not
13
going to go in detail here.
14 [Slide]
15 What you have seen, and Dr. Weinstein
16
already pointed that out, is that in the last
17
couple of years we have seen consolidations. We
18
have seen companies making a decision to divest
19
their interests in the plasma industry.
We have
20
seen closures of plasma collection centers. We
21
have also seen some closures of fractionation
22
plants. As a result of that,
there is a reduction
231
1
of the plasma that is used for manufacture, and
2
also we have seen massive layoffs, people that are
3
losing their jobs. Of course,
everybody would like
4
to avoid that but this is the reality of today.
5 [Slide]
6 The good news is that we have seen new
7
companies entering the market.
We have seen new
8
product approvals. We have seen
upgrades and
9
build-outs in the facilities. We
have seen better
10
technology. We have seen
technology nowadays that
11
allows us to obtain products with a higher yield
12
which means that you need less plasma, and we see
13
utilization of both source and recovered plasma as
14
starting material.
15 [Slide]
16 Going back to 1998, the problem that we
17
were facing is that the supply did not meet demand.
18
if you look at this graph, which basically points
19
out the true distribution of immune globulins in
20
the United States since January, 1998, the bottom
21
line is that on an annual basis, in 1998, we were
22
supplying about 14,000 kg into the U.S. marketplace
232
1
and today it is between 26,000 and 27,000. I think
2
it is a very impressive improvement and it is a
3
clear demonstration that the commitment that the
4
industry made to act upon the shortage was turned
5
into practice.
6 [Slide]
7 What we need to understand is the
8
economics associated with the manufacture of these
9
therapies. The collection of
plasma, which is used
10
as a starting material, is not a static process.
11
It is a very dynamic process and it is dependent on
12
the type of products which you need what the driver
13
is for the total volume of collection plasma. As
14
you can see on the left side of this slide, in the
15
past the quantity of albumin was the one that
16
really determined how much plasma was needed. What
17
we see today is that it is the volume of immune
18
globulins that determines basically how much plasma
19
needs to be collected.
20 [Slide]
21 So, what I am going to do now, I am going
22
to try to explain to you with a model how this
233
1
really works. In this model, I
am going to explain
2
to you five possible therapies, immune globulins,
3
albumin, Factor VIII, alpha-1 and other proteins.
4 [Slide]
5 Here is how it basically works. If you
6
look at this slide, you can see that a company or a
7
country or global there is a certain capacity that
8
you can use to manufacture your products. If you
9
look at the bottom column, it shows you in this
10 particular
case the sales of immune globulins. As
11 I
mentioned before, the driver for collection is
12
plasma, so you need more plasma to manufacture
13
immune globulins but you are also manufacturing
14
albumin. What you can see in the
yellow column is
15
the volume of albumin that is being sold in this
16
particular model. Then,
companies sell Factor
17
VIII, other proteins and alpha-1.
On the left side
18
you can see there is a revenue per liter if you
19
calculate what the revenue for the industry is. As
20
you can see in the grey line, there is a cost to
21
manufacture and basically what you can see here is
22
that in order to recover the cost of manufacture,
234
1
you need to sell multiple products.
It is
2
impossible to make up your cost with the sale of
3
one product. This may differ
from company to
4
company based on their technology and so on. But
5
the reality is that some companies do not
6
manufacture Factor VIII. You can
imagine that the
7
cost of manufacture then needs to be recovered by
8
less products.
9 [Slide]
10 The other thing that we need to understand
11
is that if we manufacture immune globulins, here,
12
as a result of the fractionation process,
13
automatically you also end up with more albumin,
14
more albumin than can be sold on the marketplace.
15
What that means is that this volume goes in
16
inventories. There is no need
for it; there is no
17
demand for it but there is a cost to manufacture.
18 So, the simple question that one could ask
19
is, well, why not resolve any discussion about the
20 potential shortage in the future just by making
21
more?
22 [Slide]
235
1 Well, this is what is going to happen
2
then. What you can do is you can
make more, but
3
you can see this is what is being sold.
So, now
4
you are going to manufacture more products which
5
are not needed on the market.
They end up in
6
inventories. You also end up
with more albumin and
7
you are losing money. And, this
industry is not in
8 a
position to continue to lose money.
9 [Slide]
10 Look at what happened if we go back to the
11
year '98-99, and you see what the revenue per liter
12
was for the entire industry. You
see a significant
13
reduction of about 50 percent in income of the
14
industry as a result of multiple factors. That is
15
the reason why industry needs to make adjustments
16
and ensure that it is healthy or becomes healthy
17
again.
18 [Slide]
19 One of the reasons is that this industry
20
is totally different than the pharmaceutical
21
industry. In many cases we are
compared to the
22
pharmaceutical industry but if you just look at the
236
1
cost of manufacturing, two-thirds of the production
2
costs are the result of the cost of source
3
material, the testing and manufacturing compared to
4
about 20 percent for the pharmaceutical industry.
5 As a result of that, if you take into
6
account total cost, I have seen other slides that
7
basically said that the profit margin of this
8
sector is somewhere between 5-10 percent if
9
everything works well. But if
you go to the
10
pharmaceutical industry, it is about 20 percent.
11
It is this profit margin we need in order to make
12
further investments in researcher and development
13
and that margin is simply not there.
So, we need
14
to be very, very cost conscious for the future.
15 [Slide]
16 But there are implications of differences.
17
One is that what people tend to forget is that we
18
are not making products for diabetes patients or
19
high blood pressure. We are
talking about a
20
relatively small number of patients that are using
21
these therapies which means that the cost needs to
22
be shared by a limited number, which is totally
237
1
different than what we are seeing in the
2
pharmaceutical industry.
Nevertheless, when we
3
talk about public policy, public health policy, we
4
are many times caught in measures for
5
pharmaceuticals because we are considered to be the
6
same.
7 We are providing biologicals. The
8
technology that is being used is very specific,
9
very complicated. We are
certainly no generic
10
manufacturers that has a different product life
11
cycle development because those therapies are used
12
for decades, in contrast to the pharmaceutical
13
industry where 10, 15, 20 years maximum is a life
14
cycle. And, we are working in a
regulatory
15
environment which is the most stringent within this
16
sector. We are not complaining
about it. What we
17
are saying is that this is the case and should also
18
be recognized when it comes to compensation. The
19
working capital, the up-front investment is
20
enormous. It takes about 7-8
months to get your
21
product out of your manufacturing site after
22
collecting your plasma--enormous investments.
238
1 The clinical trial requirements are very
2
complicated because we have a small number of
3
patients. It is not that easy to
get large number
4
of trials, especially when you do it in a
5
randomized, placebo-controlled fashion.
It is
6
complicated.
7 Then, what we see is an enormous pressure
8
on reimbursement and, if this is going to continue
9
like we have seen in the last couple of years, this
10
may lead to further industry consolidation, further
11
company exits--we have already seen that
12
sufficiently. Then, it will
reduce the choice of
13
therapy, which is not a good thing.
14 [Slide]
15 If we look at the revenue factors, and I
16
am not going to talk about the details but just to
17
point out, because I know this is not on the
18
charter of the BPAC but I think it is important for
19
you to understand what is going on, what we see,
20
especially when we talk about the reimbursement
21
areas, is if you look at the lower expenditures you
22
might think about issues like prospective payment
239
1
and the sales price as a basis for reimbursement,
2
or competitive bidding. While
they may sound nice,
3
there are really important differences between the
4
products you cannot use--change immune globulins
5
from one patient to the other, what happens then
6
is, once this is done on the federal level, we see
7
also state average sales prices used as a basis for
8
reimbursement. We see other
issues like prior
9
authorization. We see single
source contracts, and
10
we see cluster pricing.
11 With these examples, what we see is
that
12
the private payers are going to use that to develop
13
their own measures and talk about what is the
14
coverage, what is the reimbursement, and you have
15
all kinds of managed care plans.
I am not going to
16
go into further detail here because I believe this
17
is an issue that most likely needs to be addressed
18
with the committee on blood safety and
19
availability, but it is important to realize that
20
what we can do is look at another factor which is
21
to take away, in my view, wrong perceptions.
22 [Slide]
240
1 If we talk about reimbursement of
2
therapies, a lot of people think that reimbursement
3
is what the manufacturers get.
That is absolutely
4
not the case. It is not the
case. The
5
manufacturer is the one who has to put in the
6
testing, the plasma collection and fractionation
7
and there is an enormous amount of added value in
8
this chain but if you go back to the reimbursement,
9
it goes to the providers, it goes to the
10
distribution chain and then, at the end, it is what
11
the manufacturers get. If you
make an analysis
12
about what the margins are, I think there is some
13
room for some further investigation.
14 [Slide]
15 Now, what can we do?
If you look at the
16
costs, that is an area where we can have a
17
meaningful discussion. I think
it is important to
18
look at a couple of areas, the regulation
19
requirements; we can look at team biologics; we can
20
look at clinical trials. Let me
give you one
21
example of a regulation requirement that, in our
22
view, needs some reconsideration.
241
1 About 20 years ago, 25 years ago, there
2
was a requirement that every donor needs to be
3
weighed before plasma collection to determine the
4
amount of volume that could be drawn from the
5
donor. In that period, when AIDS
developed, there
6
was also a significant weight loss seen as an
7
indicator to point out that you needed to do
8
further investigation. But
everybody knows that
9
with the introduction of testing and more knowledge
10
about HIV, this is a requirement that doesn't make
11 a
lot of sense.
12 So, FDA changed that, however, it is still
13
in the inspection protocols when centers are being
14
inspected and what happens now is that if you have
15 a
donor that has a deviation in weight of 10 lbs or
16
more, you need to do an enormous amount of
17
investigation. Well, look at
me. I would like to
18
lose 10 lbs. It doesn't mean I
am not healthy; I
19
am maybe even healthier. So, I
think this is a
20
kind of requirement that we should consider, and I
21
think that it would make sense if we could come
22
together with a group of experts, collection
242
1
experts, industry experts, FDA experts to see
2
whether we can make an analysis and find these kind
3
of requirements that don't really add a lot of
4
safety.
5 If you look at team biologics, I think FDA
6
and team biologics do a tremendous job going in to
7
make sure that companies are in compliance, and I
8
don't have to repeat the past but I think that we
9
have all learned a lesson and I honestly can say
10
that where we are today with quality and safety is
11
enormous if you compare that to ten years ago.
12
Maybe it is time to reconsider what needs to be
13
done, whether there are some redundancies in
14
systems that can be removed as well.
15 Then, when we talk about clinical trial
16
requirements, the difficulty is that because we
17
have a small number of patients, to set up the real
18
big trials is very difficult.
Sometimes we see a
19
discrepancy between products that are already
20
approved in Europe and are not approved in the
21
States because the requirements are different, or
22
vice versa. The way the information
is submitted
243
1
is different. There is no
consistency in format.
2 I
understand from a conversation earlier today that
3
this may be subject to see whether there is any
4
room for harmonization. These
are the kind of
5
things that we need to look at.
6 [Slide]
7 So, what we need to do is we need to
8
continue with having a clear monitoring system, as
9 I
explained in the beginning, while we continue to
10
measure inventory and distribution.
We do have an
11
emergency plan for supply in place.
In 1998 we
12
made a commitment. If you look
at the data you
13
will see that every month there is an emergency
14
supply available. In case
patients need it
15
immediately, there is always a quantity made
16
available by the industry to make it available for
17
patients, but also healthcare professionals because
18
we are not dealing with patients alone.
Healthcare
19
professional organizations are very important.
20 Then what we do, we have regular
21
communications with all stake holders.
We have
22
four meetings per year, here in the United States,
244
1
where we meet with consumers; where we meet with
2
physicians; where we meet with regulators; where we
3
have open dialogue about all these developments and
4
in case we see a deviation that requires attention
5
we have to form to do so.
6 [Slide]
7 In conclusion, we do not see a near-term
8
threat to the availability of plasma therapies. I
9
think that is a most important message.
We believe
10
that the current inventories and also the change
11
through technology that allows us to use higher
12
yields will most likely offset reductions in the
13
throughput that we have seen earlier from Dr.
14
Weinstein.
15 We will remain vigilant because it is our
16
task to make sure that this industry is healthy.
17
The health of the patients and the health of the
18
industry go together. We can't
do it without each
19
other, and we cannot afford to continue to
20
manufacture products and lose money.
That is not
21
in the interest of the industry but, most
22
importantly, not in the interest of the patients.
245
1
We will make sure, as an industry group, that we
2
make corrections. If we do that,
then we can
3
guarantee further access, choice and continue with
4
the profits that are necessary to continue to work
5
on innovation. Thank you very
much for your
6
attention.
7 DR. NELSON:
Thank you. Any comments or
8
questions?
9 DR. DIMICHELE:
Thank you for that. That
10
was very informative. I wanted
to ask a question
11
about the difference in the sort of profit margin
12
structure between biologics and pharmaceuticals.
13
My concern is that many of the plasma industry
14
companies or the plasma manufacturers are now part
15
of conglomerates that include pharmaceuticals. To
16
what extent will the economics of the
17
pharmaceutical industry threaten the companies or
18
the parts of the companies that produce plasma
19
products?
20 MR. BULT: It
is very difficult to go into
21
company specific situations but, again, going back
22
to 1998 where we had a situation in the United
246
1
States where basically the market was supplied by
2
four companies and the American Red Cross, three of
3
those four companies no longer exist.
One is gone,
4
another is taken over, another is in the process of
5
divesting. So, I believe we have
gone through a
6
process of adjustments.
7 What I do see is that companies are very
8
aware of the economic situation and the corrections
9
that need to be made, and one of the things is that
10
as a result of the commitment that we made in '98
11
to produce more and more and more, which was good,
12
now we have a situation where on some occasion you
13
may even talk about over-supply, and if we have
14
over-supply that is not really helpful.
So, I can
15
see the point of some of the companies, in order to
16
make these economic adjustments, will tighten
17
supply to balance demand and supply.
I think that
18
is what is going to happen.
19 DR. ALLEN:
Looking at the series of
20
slides you showed on the cost to manufacturer and
21
then the revenue generated by the different
22
products, I was a little surprised to see the
247
1
immune globulins right at the bottom.
I would not
2
have predicted that. In terms of
the cost to the
3
manufacturers, is there a significant difference
4
between the intravenous immune globulin products
5
and the injectable immune globulins?
6 MR. BULT: You
should not draw any
7
conclusion about the order of the therapies. The
8
only conclusion that you should draw is that if you
9
talk about fractionated plasma that is needed the
10
driver is immune globulin and, from that point of
11
view, the place in that graph is absolutely the
12
correct place. The vertical
access is absolutely
13
not an indicator of what the true revenue is
14
because that differs from company to company. What
15
was important to me is to share with you the
16
concept and the model to help everybody understand
17
how it works and how complex it is.
18 DR. KLEIN: I
always worry a little bit
19
when I see fractionation plants closing down in
20
terms of response time. I pretty
much have a good
21
idea of how long it takes to put collection sites
22
and license them but if you could give us an idea,
248
1
first of all, of how long it takes to build and
2
qualify a fractionation plant, and where we stand
3
right now in terms of fractionation capacity
4
worldwide.
5 MR. BULT: The
numbers that we have always
6
used in the past are that in order to get a plant
7
in function after going from the drawing board is
8 about five years,
building it up and going through
9
the validation processes, etc., etc.
When you talk
10
about collection, yes, of course it is true that
11
when you close your centers, and if a situation
12
occurs where you need to have more plasma, well, I
13
haven't spoken to the individual companies but I
14
would expect that they have not closed the most
15
efficient centers. I would
expect that they have
16
closed centers where there were some questions
17 about efficiency. In case we need more plasma it
18
is easier to work with efficient centers to improve
19
that and increase it than start all over again.
20 The other thing is that if you look at the
21
technology that is being used, and I mentioned that
22
in the presentation, most of the companies that I
249
1
know use the technology that obtains higher yields,
2
which means that you use less plasma.
So, that is
3
another important contributing factor.
4 DR. KLEIN: Do
you have an idea about the
5
fractionation capacity worldwide in terms of
6
current needs and what there is in reserve?
7 MR. BULT: I don't
have those numbers in
8
my head but maybe there is someone in the audience
9
that could help me out here and give me a number,
10
if that is available, but I don't have it at hand
11
here.
12 DR. KLEIN: I
guess what I am asking is if
13
we needed a ton of anthrax immune globulin or a
14
whole host of other things that one could guess at,
15
would we be in a position to manufacture it?
16 MR. BULT:
Well, I think if we start
17
talking about the anthrax issue, I mean that opens
18
up a whole--
19 DR. KLEIN: I
was only using that as an
20
example.
21 MR. BULT:
Yes. I do believe that if we
22
talk about existing products where you need to
250
1
expand capacity, that is easier than to develop new
2
products where you have to go through the whole
3
process. So, if we talk about
existing products,
4
that is easier to do. But,
again, I have no
5
indication that there is a near-term threat to
6
supply or availability. I think
that is the most
7
important message.
8 DR. KUEHNERT:
Looking at your slides on
9
supply trends and also distribution in the
10
handout--and maybe this is more of a question for
11
FDA also, but how are not only supply but demand
12
trends followed? I mean, what
system is there to
13
determine sort of what the supply is in relation to
14
demand in the United States on this products?
15 MR. BULT: Let
me make a couple of
16
comments about the slide that you have seen. The
17
numbers that you have seen on the slide are what we
18
call a true supply into the market.
Let's take one
19
example if you go to the first dot on the slide,
20
which is January, '98, the way this was constructed
21
with the help of experts on economics, they have
22
taken the production in the month of January; they
251
1
looked at the inventory on February 1st, and
2
deducted the inventory of January 1st.
So, what
3
that means is that you have the true supply in the
4
market.
5 Now, what you have seen cannot be a true
6
amount because there are too many fluctuations,
7
especially when you look on a month to month basis.
8
What we do is we provide this information to FDA so
9
FDA has full insight on all the information company
10
by company and what you see here is aggregated
11
information. But if you combine
that information
12
we believe we can say, with a high degree of
13
confidence, that the annual gross of immune
14
globulins is somewhere between 4-6 percent per
15
year.
16 DR. HOLLINGER:
What is the expiration
17
time of IVIG, for example, how long?
18 MR. BULT:
Sorry, I couldn't hear the
19
question.
20 DR. HOLLINGER:
The expiration time for
21
IVIG? How long?
22 MR. BULT: I
think I see a sign in the
252
1
back, three years. That is the
shelf life.
2 DR. HOLLINGER:
Three years?
3 MR. BULT: Yes.
4 DR. HOLLINGER:
How about specialty IVIG
5
products, like HcIG, HbIG, new bioterrorism
6
products and so on that might be manufactured for
7
the military, and things of that nature? And
8
albumin? I didn't see the
numbers for albumin but
9 I
can tell you it seems like albumin is being used
10 a
lot more than it has in the past, medically.
11 MR. BULT:
Yes. Coming back to your
12
question, it is a while since I, myself, was
13
working in the industry but I recall from those
14
days that there was no difference between the
15
shelf-life of hyper-immunes and polyvalent immune
16
globulins. What you do see is
that it is dependent
17
on the regulations of the country where you
18
distribute. Sometimes you can
have an expiry data
19
that goes for months and you have 36 months. There
20
are other countries where it is only twice a year.
21
So, you may have a difference of 6 months but that
22
is just a technical detail. When
it comes to
253
1
albumin, I think albumin goes up to 5 years, if i
2
am correct but I have seen different stability
3
numbers.
4 DR. STRONG: I
was interested in your
5
comment about harmonization.
Those of us who
6
provide plasma for recovered plasma, we are
7
noticing an increasing conflict between European
8
standards and American standards.
Even within
9
Europe there are country to country variations, for
10
example, a requirement for ALT testing in some and
11
not others. What is your
forecast for how
12
harmonization is going, and do you think that there
13
is a role here for us to do more?
14 MR. BULT: You
know, if you would have
15
asked medication that question two years ago I
16
would have said everybody wants to harmonize if you
17
do what I do. But today I would
say I see much
18
more willingness among regulators to really start
19
to realize what the differences are.
I already
20
mentioned before that in a conversation with Dr.
21
Weinstein we spoke about a potential workshop on
22
clinical trial requirements. We
have a dialogue
254
1
with regulators all over the world, from the United
2
States, from Europe, from Australia, to identify
3
those issues to see how we can help each other to
4
understand and work together to create better
5
harmonization.
6 A part of the problem that we have is that
7
this sector is not part of the ICH process, the
8
International Conference of Harmonization. This is
9
true for the pharmaceutical sector.
Because of the
10
specific nature, we were excluded.
But I see far
11
more willingness of regulators to work with us and
12
to find ways to harmonize.
13 DR. WEINSTEIN:
I should mention that we
14
are having actually a workshop on that very topic
15
to study standards for recovered plasma that will
16
be held on August 31, September 1st at the NIH. We
17
have invited speakers from Europe, from Australia,
18
from Canada to get international perspective on it.
19
We are looking for the scientific basis of these
20
standards. We are looking for
practicality and the
21
need for adopting certain standards.
So, we are
22
moving ahead on that.
255
1 DR. ALLEN: Two
questions, building on the
2
harmonization issue and also looking at what I
3
anticipate will increasingly become an enhanced
4
global demand for these kind of products, much of
5
it supplied by the plasma, I would assume,
6
collected in the United States and European
7
countries or certainly in North American and
8
Europe. What is the anticipation
in the industry
9
for the growth of global market sales, and are they
10
going to be able to meet that both in terms of
11
plasma collection as well as in terms of
12
manufacturing tank capacity?
13 MR. BULT: If
you look at the global
14
numbers, what I do know is that if you listen to
15
the consumer organizations you know that there is
16
an enormous amount of patients in the world who are
17
diagnosed. For example,
hemophilia patients, only
18
25 percent of the world population receive any form
19
of treatment. If you look at
immunodeficiency as
20
an example, here in the United States it is very
21
well developed but there are other parts of the
22
world where the awareness is not as high and the
256
1
diagnostic ability is not as high as here in the
2
States. The same is true for
alpha-1 for example.
3 It all depends on other factors such as
4
the economic situation in a country.
There are
5
certain countries that are crying for help but
6
there is no funding available to make that
7
available. But if you look
worldwide, as I
8
mentioned, for immune globulins worldwide there is
9
about a 4-6 percent increase for those countries
10
where immune globulins are being used.
For the
11
rest, it is dependent on individual companies and I
12
cannot talk about these issues with individual
13
companies because of the anti-trust laws.
14 DR. ALLEN: The second question I have is
15
what percentage of the Factor VIII concentrate used
16
in the United States and Europe today is
17
recombinant? You mentioned new
technologies making
18
allowing more efficient extraction of fractionation
19
products from plasma. To what
extent do you
20
visualize that new technologies in other arenas,
21
particularly recombinant products perhaps, will
22
replace the need for plasma-derived products?
257
1 MR. BULT:
Well, I originally had a slide
2
for this presentation which identified which
3
therapies could be replaced with alternative
4
technology, like recombinants and currently it is
5
Factor VIII, Factor IX and Factor VII.
If I focus
6
on Factor VIII, I would say that in the United
7
States the last number I have seen is about 75
8
percent, 80 percent use for recombinant Factor
9
VIII. When I go to Europe it is
about 50 percent.
10
If I go to Japan it is about 50 percent. If I go
11
to less developed countries there is a high use of
12
plasma-derived, mainly for cost reasons.
13 DR. DIMICHELE:
Just to say, yes, indeed,
14
most of the product that is used, or a large
15
proportion of it for hemophilia A and B is
16
currently recombinant. But one
of the things that
17
has become really apparent to those of us who treat
18
people with bleeding disorders is that there is a
19
vast array, you know, of other bleeding disorders,
20
most of which are more rare for which there is not
21
adequate therapy, and any therapy that is
22
potentially available, maybe with the exclusion of
258
1
Factor VII, has pretty much been plasma derived.
2
Also, within hemophilia A and B there are several
3
reasons to still need plasma-derived products with
4
respect to bypassing agents and certain
5
therapeutics.
6 So, one of the concerns that we have
7
certainly in the bleeding disorders field is that
8
the plasma industry continue to produce sufficient
9
supply and that we work with regulators and the
10
plasma industry to develop new technologies, new
11
treatments for the rare disorders.
And, you know,
12
with respect to modifications of clinical trials,
13
requirements, orphan drugs are the sort of things
14
that would sort of make these therapies accessible.
15
So, there is a lot more that we have to do. The
16
whole problem of clotting disorders hasn't been
17
solved by recombinant technology and we have a lot
18
more work to do, and it still involves
19
plasma-derived therapies.
20 Open Public Hearing
21 DR. NELSON: In
the open public hearing
22
Mr. Patrick Schmidt wanted to comment.
259
1 MR. SCHMIDT:
Good afternoon. I will
2
speak very quickly because I want to make sure I
3
don't make me miss my plane.
Good afternoon,
4
distinguished ladies and gentlemen of BPAC. My
5
name is Patrick M. Schmidt and I am the president
6
and CEO of FFF Enterprises. We
are the nation's
7
largest distributor of intravenous immune globulin
8
and human serum albumin.
Approximately 70-80
9
percent of the hospitals in the U.S. rely on the
10
distribution and management expertise of our
11
company as the primary source for these critical
12
care products. Countless other
physician offices,
13
home care companies and patients rely on us as
14
well.
15 From this unique perspective we see a new
16
marketplace reality unfolding.
The new marketplace
17
reality is characterized by rising prices,
18
declining inventories and a necessity to increase
19
vigilance on our industry's ongoing ability to meet
20
the needs of the patients we serve.
21 The plasma derivative market is very
22
complex. It is characterized by
steadily growing
260
1
demand for most products, met by the challenges of
2 a
very difficult, highly regulated and
3
capital-intensive manufacturing environment. We
4
encourage all participants in the marketplace to
5
recognize and understand this dynamic nature. We
6
have a saying within FFF once you think you
7
understand the marketplace, you end up realizing
8
you don't because it changes so rapidly.
9 The economics of plasma fractionation is a
10
study of supply and demand. An
example, just in
11
the past five short years, the price of albumin has
12
declined from the mid-50s to the mid-teens. During
13
the same period of time IVIG has vaccinated from
14
the low-30s to the upper-50's and back again.
15
While tremendous savings have been enjoyed by the
16
healthcare provider, those who understand the
17
financials associated with running a plasma
18
derivative business knew that in the long-term not
19
all manufacturers would survive this downward
20
spiral.
21 If you remember back to 1988, the
two
22
largest group purchasing organizations in the
261
1
United States, Premier and Novation, each had
2
contracts with seven different suppliers of IVIG
3
and albumin. They were Alpha,
Baxter, Centeon,
4
ARC, Bayer, Immuno and Novartis.
Four of those
5
seven suppliers no longer exist.
They have been
6
replaced by new business combinations or new market
7 entrants
like ZLB-Behring, Grifols or Octapharma,
8
as has been discussed before.
Sort through this
9
myriad of changes, mergers and acquisitions,
10
consolidations and plasma collection center
11
closures, and you are left with a new marketplace
12
reality--fewer suppliers.
13 The new look of today's marketplace will
14
feature three meta-suppliers that have global
15
reach, as was touched on earlier.
They have the
16
complete portfolio of products from the precious
17
alpha-1 therapies to the workhorse albumin
18
products. Today's marketplace
economics dictate
19
that the necessity that the manufacturers generate
20
revenue from multiple products per liter. I
21
believe the days that manufacturers fractionate
22
plasma for the purpose of producing a single
262
1
product, like IVIG, are gone. It
just doesn't make
2
economic sense any longer.
3
Worldwide cuts are necessary
from my
4
perspective and will result in a tightened supply
5
situation that will ultimately lead to shortages in
6
the IVIG marketplace and perhaps albumin market,
7
which is far less conceivable at this time.
8 This environment demands a supply solution
9
and distribution model that can manage rapidly
10
changing dynamics, a distribution model that
11
provides stability for both supply and pricing. We
12
must provide consumers a responsible distribution
13
channel that delivers the most reliable IVIG and
14
albumin supply in the United States today
15
regardless of the manufacturing changes.
16 In anticipation of a tightened supply, we,
17
at FFF, have already place four lyophilized IVIG
18
products on supply guideline status.
That means we
19
have put filters in our internal ordering systems
20
that prevent customers from ordering quantities
21
that far exceed their previous utilization
22
patterns.
263
1 But please be aware--it is very important
2
to emphasize this--there is plenty of IVIG on the
3
marketplace today to meet the needs of the current
4
patient demand. Please also be
aware that this
5
situation is highly likely to change in the future
6
and a great deal of collaboration that currently
7
exists between the manufacturers and distributors
8
of these products must continue to avoid 1998-like
9
shortages. Of course, the FDA is
proactively
10
seeking to understand and mange this industry's
11
complex challenges and that is why we are here
12
today.
13 What role can the FDA assume to help
14
manage the transitioning marketplace and protect
15
the continuity of care? We have
three brief
16
suggestions we wish to make to help accomplish
17
that. They are, first,
prioritize or expedite any
18
manufacturing process change applications that
19
improve yields. Second, engage
in discussions with
20
other federal agencies, like CMS--and I realize
21
that may not be the purview of this committee, to
22
ensure that the appropriate reimbursement rates for
264
1
these critical products exist.
Often the greatest
2
barrier to access to products is economic. Lastly,
3
consider implementing a pedigree requirement for
4 certain plasma products.
Six different IVIG
5
preparations exist on nationally published lists of
6
the 31 drugs most susceptible to counterfeiting.
7
IVIG products have been counterfeited, diverted and
8
subject to the voracious pricing policies of the
9
secondary grade markets.
Whatever you decide, I
10
encourage you to consider that the only ongoing,
11
viable solution must require the utmost in
12
distribution channel responsibility and
13
collaboration, managing the plasma product supply,
14
and necessitates the collective commitment of the
15
manufacturer, the distributor and the public
16
representatives, yourselves.
17 As our company has been involved in past
18
challenging marketplaces and markets surrounding
19
plasma derivatives, we remain ready and willing to
20
share data and perspective as the new market
21
reality crystallizes. So, thank
you very much for
22
the important work you do for our industry and for
265
1
the opportunity to address the committee today.
2
Thank you very much.
3 DR. NELSON:
Thank you. Are there any
4
questions or comments? Harvey?
5 DR. KLEIN: I
am not quite sure I
6
understood one of your statements.
If there is
7
plenty of IVIG why would you have filters in your
8
distribution system not to sell people as much as
9
they either want or need?
10 MR. SCHMIDT: Well, because we are seeing
11
our ability to replenish at the same rate we were
12
purchasing before, and we are seeing declining
13
inventory so our ability to replenish is going
14
down.
15 DR. KLEIN: So,
I guess there isn't plenty
16
of IVIG. Is that not correct?
17 MR. SCHMIDT:
At this time there is plenty
18
of IVIG. I think the question
that hasn't been
19
answered is what is the near-term, how long is the
20
near-term. While we have plenty
of IVIG, we are
21
beginning to proactively monitor the situation so
22
we don't get into an exacerbated situation of what
266
1
has happened in the past with decentralized, if you
2
will, management of these products.
We have 6,000
3
hospitals in the U.S. and if they believe there is
4
going to be a shortage, they train management to
5
increase their levels and possibly exacerbate
6
shortages.
7 DR. NELSON:
Jay?
8 DR. EPSTEIN:
Thank you, Patrick.
9 MR. SCHMIDT:
Thank you very much.
10 DR. EPSTEIN:
Could you just comment why
11
do you think that IVIG products have been more
12
susceptible to counterfeiting than some other
13
products? What is the driver?
14 MR. SCHMIDT: I
believe the driver, and
15
the criteria for being included in the list, is the
16
fact that one or two of the drivers have already
17
been counterfeited. There was an
issue of gamunin
18
[?] that was counterfeited.
Then, IVIG at times
19
has been highly sought after and people will do
20
almost anything to get their hands on IVIG in a
21
real tight marketplace because it is a critical
22
care drug and people, unfortunately, die if they
267
1
don't have it. We have
experienced times in our
2
business where people call and order IVIG without
3
any consideration of cost. I
would also like to
4
say we have never taken advantage of that situation
5
but there people who have.
6 DR. GOLDSMITH:
I probably should make
7
this statement from there because I put my IDF hat
8
on for a minute. I guess from
the perspective of
9
the Immune Deficiency Foundation, I would like to
10
recognize the members of industry for being so
11
frank today, coming forward and speaking about what
12
they are doing, what their plans are.
I think I
13
heard some promises there that they would maintain
14
supply that was kind of laced into all the bad
15
news.
16 I want to also recognize the fine work
17
that has been done by the FDA in terms of bringing
18
three new IVIG products to the U.S. market in the
19
last year, which is really an outstanding
20
accomplishment and shows that regulatory wheels can
21
grind fast when they need to, to respond to this.
22 I guess I would like everybody to
268
1
recognize the fact that IVIG is a life-saving drug
2
for people with immune deficiency and it must be
3
available on the U.S. market.
4 DR. NELSON:
Thank you. Dr. Carol Lee
5
Koski, University of Maryland?
6 DR. KOSKI:
Thank you. I am actually a
7
neurologist that heads the Neuromuscular Division
8
at the University of Maryland. I
also am on the
9
medical advisory board for the Guillain-Barre
10
Foundation. Although certainly
immunodeficiency I
11
think is a significant indication for intravenous
12
immunoglobulin, I think it is also important to
13
remember that there are actually other neurological
14
patients, including those with Guillain-Barre
15
syndrome, chronic inflammatory demyelinating
16
polyneuritis and also myasthenia gravis where
17
immunoglobulin is actually used to prevent and
18
limit their paralysis. It allows
these patients to
19
not only survive but to actually go on being
20
productive members of society, able to support
21
their families and do their daily activities of
22
living. So, don't forget the
patients that may not
269
1
have an FDA indication for that particular disease.
2 DR. NELSON:
Harvey?
3 DR. KLEIN: I
just want to know are you
4
getting all of the IVIG that you need for your
5
patients at the University of Maryland?
6 DR. KOSKI:
Yes, we do. But one of the
7
things that I will also tell you is that during the
8
shortage I did not have any problems in getting
9
intravenous immunoglobulin, but that was partially
10
because of the fact that our hospital pharmacy was
11
able to buy very large lots and was one of the
12
major suppliers. But I very
frequently had
13
patients that were referred to me from community
14
hospitals, that probably would have been treated in
15
that community hospital, because they simply didn't
16
have the intravenous immunoglobulin.
17 DR. GOLDSMITH:
May I make a quick
18
comment? One of the things we
need to watch--I
19
agree that there are certain neurological diseases
20
that are have clearly benefitted from IVIG and I
21
think the FDA, when it responded to the crisis, did
22
point out that there was a large amount of the IVIG
270
1
that was going for off-label use and it was up to
2
60 percent. These are estimates
made by large
3
medical centers, and part of the way we dealt with
4
the crisis was by interacting with practitioners at
5
big medical centers and indicating to them that
6
they need to form some kind of filter for how they
7
were using immune globulins. We
did not want to
8
curtail use for patients that had legitimate
9
diseases where there is a consensus that they
10
respond to IVIG. But we
identify, the community at
11
large identified a large number of patients or
12
patient groups that were being treated for causes
13
for which there was no evidence--so, something we
14
need to watch in the future in terms of
15
availability is off-label use, and make sure that
16
that off-label use is based on evidence that the
17
IVIG works for those patients.
18 DR. NELSON:
That is an important issue.
19
It is a therapy that could be, and I guess has
20
been, abused to some extent.
Yes, Dr. Koski?
21 DR. KOSKI:
Just to really reaffirm that
22
the particular indications that I was talking about
271
1
actually are really supported very heavily,
2
particularly Guillain-Barre syndrome, with
3
absolutely outstanding trials that comprise almost
4
600 patients, that were done in multicenters across
5
really Europe and North America.
6 I agree with you that there are perhaps
7
very, very rare disorders where some of the
8
randomized, controlled trials, such as stiff person
9
syndrome, comprise only about 15 patients. But
10
some of those trials are really still extremely
11
good, with very high efficacy.
12 DR. NELSON:
But there have been some
13
proposed used for which the data were pretty shaky.
14
At one point they consumed a fair amount of the
15
supply, as I recall. So, I think
the point is well
16
taken that this is an important commodity,
17
particularly if it is in short supply its use
18
should be supported by good scientific data.
19 Well, thanks.
I guess that is the end of
20
the session. I guess October 21
and 22 will be the
21
next meeting. Thanks.
22 [Whereupon, at 3:10 p.m., the proceedings
272
1
were adjourned.]
2 - - -