January 11, 1996

A combination of two antiviral drugs is more effective than either drug alone for controlling recurrences of a blinding eye infection common in people with AIDS, according to new clinical trial results from a federally-sponsored study.

In January’s Archives of Ophthalmology, researchers report that daily intravenous administration of both foscarnet and ganciclovir is a more effective way to treat repeat episodes of cytomegalovirus (CMV) retinitis than treatment with either drug alone.

“This finding advances the treatment of chronic, destructive eye infection that causes blindness if it is not controlled,” said Carl Kupfer, M.D., director of the National Eye Institute (NEI). The NEI, part of the National Institutes of Health (NIH), sponsored the CMV Retinitis Retreatment Trial. Additional NIH support was provided by the National Center for Research Resources and the National Institute of Allergy and Infectious Diseases.

For patients who received both drugs, the CMV retinitis was controlled for about four months on average. Among those treated with either foscarnet or ganciclovir alone, the eye infection recurred in one to two months on average. The combination treatment was associated with the least reduction in the field of vision, but visual acuity was preserved equally well in all drug regimens tested.

However, researchers cautioned that the two-drug therapy takes longer, because each drug has to be administered separately. In addition, the side effects associated with two-drug therapy may be more difficult to tolerate than those with one drug alone. Also, because two drugs are required, the treatment is more expensive than it would be if only one drug was used.

CMV retinitis is an infection of the retina, the light-sensing tissue that lines the back of the eye. The virus that causes it can infect the eye, colon, lung, and other organs of people with AIDS or other diseases that result in weakened immune systems. According to some studies, up to 40 percent of people with AIDS develop CMV retinitis, the most common cause of vision loss from the disease.

Currently, CMV retinitis is typically treated with twice-daily intravenous infusion of either foscarnet or ganciclovir for two weeks followed by daily infusions which are usually continued for the rest of the patient’s life. There also is an oral form of ganciclovir that is available for long-term suppressive therapy. While the two drugs work equally well for a first episode of CMV retinitis, nearly all patients suffer a relapse of the retinitis at some point. With each relapse, more retinal cells are destroyed and more vision is lost.

“Combination therapy was much better than treatment with either foscarnet or ganciclovir alone in controlling the retinitis progression,” said study chairman Douglas A. Jabs, M.D., of The Johns Hopkins University and Hospital. “However, combination therapy was more inconvenient, required two infusions, and will be more expensive. But for those patients who have suffered a relapse of their retinitis and can tolerate combination therapy, its improved control of the retinitis offers distinct advantages.”

The CMV Retinitis Retreatment Trial involved 279 patients who had already had the eye infection and had been treated with either foscarnet or ganciclovir, but experienced a relapse and needed further treatment. They were randomly assigned to foscarnet alone, ganciclovir alone, or both drugs.

The trial was part of an ongoing clinical research project called Studies of the Ocular complications of AIDS (SOCA).

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June 2001