A new Food and Drug Administration advisory committee yesterday recommended that the FDA not approve a highly touted experimental cancer treatment called interleukin-2. The committee urged instead that the drug's manufacturer conduct further studies to identify which patients will benefit from the highly toxic therapy.
Interleukin-2 or IL-2 gained international prominence a few years ago when Steven Rosenberg, a National Cancer Institute researcher, reported that it had produced dramatic shrinkage of tumors in patients with advanced, supposedly incurable cancer. IL-2 is one of a number of substances that are normally made in small amounts by the body to control the immune system. Many of these substances are now being synthesized and tested as drugs.
At yesterday's inaugural meeting of the new Biological Response Modifiers Advisory Committee, panel members were asked to consider whether IL-2 should be approved for the treatment of kidney cancer that cannot be surgically removed because it has spread to other parts of the body. No treatment is currently approved for such cancers, and most patients die in less than a year.
About 18,000 new cases of kidney cancer occur in the United States each year. About half have spread beyond the kidney at the time they are discovered.
Representatives of Cetus Corp., the maker of IL-2, presented data from several studies showing that in about 15 percent of kidney-cancer patients treated with the drug, tumors shrank to less than half their original size. In about 4 percent of patients, tumors disappeared completely. Of five patients whose tumors disappeared, three have been cancer-free for at least 2 1/2 years.
But 85 percent of patients do not appear to benefit from the drug and many suffer severe side effects. About 4 percent of treated patients died of infections, heart problems or other complications brought on by the treatment. The drug causes massive fluid retention, which can lead to temporary heart or kidney failure.
Because large-scale studies began only in the last three years, none so far has proven that IL-2 improves the overall survival of kidney-cancer patients. So the panel was faced with weighing a few apparent dramatic "cures" against the drug's widespread, toxic side effects.
Panel chairman Jerome E. Groopman of Boston's New England Deaconess Hospital asked Cetus to analyze its data further "and come up with a series of proposals for targeting individuals who may benefit" from IL-2 treatment.
Earlier yesterday, the committee voted unanimously to recommend approval of gamma interferon, manufactured by Genentech, Inc., for the treatment of chronic granulomatous disease. People with this rare immune-system disorder suffer from frequent serious infections, and studies have shown that gamma interferon helps prevent that complication.