Alpha Interferon Approved for KS; Official Dose Too High?

On November 21 the Food and Drug Administration (FDA) approved use of alpha interferon to treat KS.
The drug, already available by prescription since June 1986 and previously approved to treat hairy cell leukemia and genital warts, is being marketed under two brand names, Intron- A (Schering Corp.) and Roferon (Hoffman-La Roche). The two versions have slightly different molecular structures.
After the FDA approval, AIDS Treatment News talked with Mathilde Krim, Ph.D., founding chairperson of the American Foundation for AIDS Research (AmFAR). While best known for her work with AmFAR, Dr. Krim is also a leading expert on interferon. In 1975 she became co-director and then director of an interferon laboratory at Memorial Sloan-Kettering Cancer Center in New York, a position she held until 1985 when she left to do AIDS work.
Dr. Krim is concerned that the doses on which the FDA based its approval may be much too high. Two weeks ago, at an international meeting on interferon research in Japan, Dr. Ernest Borden showed that as long as the dose was enough to produce the desired effect, a higher dose made little difference; this result was based on human as well as test-tube work. Other researchers, including Dr. Clifford Lane and colleagues, who used high dose interferon and published an article in The Lancet (November 26, 1988), showed that those who responded well usually started with over 150 T-helper cells, while those who did not respond had fewer. The important factor seemed to be the state of the immune system, not the dose.
Also, clinical studies with the high doses, 20 million units a day or more, caused such unpleasant flu-like side effects that in order to keep the patients in the study, physicians had to reduce the dose to half or a quarter. Yet the beneficial effects continued.
Dr. Krim also noted that much smaller doses have been found effective in treating hairy cell leukemia, in some cases as little as one and a half million units given twice a week.
But the early studies of alpha interferon for KS had used large doses, because the dominant thinking, derived from chemotherapy, was that the dose should be as high as the patient could tolerate. The FDA had to use the data available, much of it from early studies, as the basis for the approval. This may give patients and physicians the impression that they need high doses. But these doses cause unpleasant side effects, and also are very expensive, conceivably costing as much as $50,000 in a year.
Dr. Krim believes that alpha interferon would probably be effective at much lower doses, and would be well worth trying.
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