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FDA Consumer
magazine
July-August 2003 Issue
Two cancer treatments have been approved by the FDA under an accelerated approval program that gives people suffering from serious or life-threatening diseases earlier access to promising new drugs. Approval of such drugs is based on an encouraging effect of a drug, such as tumor shrinkage, before there is actual evidence of improved survival or other clinical benefit. As required by the accelerated approval regulations, drug sponsors perform additional studies to verify the projected clinical benefit.
Velcade (bortezomib) is a new treatment for multiple myeloma, a cancer of the bone marrow. Multiple myeloma is the second most prevalent blood cancer after non-Hodgkin's lymphoma. Velcade, the first in a new class of anticancer agents known as proteasome inhibitors, is marketed by Millennium Pharmaceuticals Inc. of Cambridge, Mass.
Iressa (gefitinib) was approved as a single agent treatment for people with advanced non-small cell lung cancer, the most common form of lung cancer in the United States. Cancer of the lung and bronchus is the leading cause of cancer death in both sexes in the United States. Iressa is marketed by AstraZeneca LP of Wilmington, Del.
Velcade is indicated for people with multiple myeloma whose disease has relapsed after two prior treatments and who have demonstrated resistance to their last treatment. Out of 188 patients evaluated for response to Velcade, 28 percent showed a response, which lasted a median time of one year. Another trial in 54 people with relapsed multiple myeloma showed similar responses.
The most commonly reported adverse events reported in Velcade clinical trials were nausea, fatigue, diarrhea, constipation, headache, fever, vomiting, decreased appetite, decreased platelets and red cells in the blood, and peripheral neuropathy (numbness, tingling, and occasional pain in the extremities).
The FDA-based approval of Iressa on a study of 216 people with non-small cell lung cancer (NSCLC), including 142 people with tumors that were resistant or unresponsive to two prior treatments. The response rate, defined as at least 50 percent tumor shrinkage lasting at least one month, was about 10 percent. There were more dramatic responses in some people, and the median duration of response was seven months. On Sept. 24, 2002, the FDA's Oncologic Drugs Advisory Committee recommended that in third-line treatment of NSCLC, where there are no viable treatment options, a 10 percent response rate was reasonably likely to predict clinical benefit, and recommended that Iressa be approved.
There appeared to be substantial differences in response rates in subsets of patients. For example, there were higher response rates for women (about 17 percent) than for men (about 5 percent). Common side effects reported with Iressa in clinical trials were nausea, vomiting, diarrhea, rash, acne, and dry skin. Iressa may also cause fetal harm when given to pregnant women.
A significant safety concern emerged just after the advisory committee meeting. Reports from Japan described the occurrence of serious and sometimes fatal interstitial lung disease (ILD) in people treated with Iressa. The FDA extended its review of Iressa by three months to review these reports.
After careful review of information from all sources, including a comprehensive analysis of information from clinical trials and an expanded access program for Iressa involving 23,000 people, the FDA determined that the incidence of ILD was about 2 percent in the Japanese experience and about 0.3 percent in the U.S. expanded access program, with about one-third of affected patients dying from this toxicity. The FDA believes that this rare but serious toxicity of Iressa does not outweigh the benefits demonstrated in people with advanced NSCLC.