San Francisco Chronicle - The Voice of the West, 901 Mission Street, San Francisco, CA 94119 - 31 Jan 1996, Page A5
David Perlman, Chronicle Science Editor

The combinations, based on a relatively new class of compounds that prevent the virus from making copies of itself, are being described this week at a meeting in Washington, but AIDS experts are tempering their enthusiasm with a great deal of prudence. None of the claims of dramatic anti-viral activity has shown that it can cure or even prevent the development of disease, none indicates how quickly or how widely it might become available to patients and none has estimated the costs of the drug combinations, which could run up to tens of thousands of dollars annually, according to preliminary estimates.

The new announcements describe tests of the anti-viral compounds called protease inhibitors, which in combination with widely used AIDS drugs appear to lower the amount of virus circulating freely in the blood more effectively than any single AIDS drug or combination ever tested. One report Monday gave extremely sparse details of a drug developed by scientists at the Merck Research Laboratories. It said Merck's patented protease inhibitor called Crixivan reduced free- floating AIDS virus to undetectable levels in 24 of 26 patients for at least six months when combined with two other drugs -- AZT, trade-named Zidovudine, and 3TC, which is marketed as Epivir.

A second and competing report, from scientists at Abbott Laboratories, came out at the same conference yesterday. The researchers enlisted French scientists to test Abbott's patented protease inhibitor called Ritonavir in combination with AZT and its chemical relative ddC. The Abbott report said its combination reduced the viral load in the blood of 21 patients with advanced virus infection by 99 percent for five months.

Neither the Merck nor the Abbott drug has been approved for distribution by the U.S. Food and Drug Administration, although the first protease inhibitor, called Saquinavir and made by Hoffman- LaRoche, was finally approved for widespread use in AIDS by the FDA last month. What is significant about the two dramatic announcements by Merck and Abbott scientists is that both were heavily promoted by corporate researchers even before detailed data on the test results were presented to the scientists and AIDS doctors attending the meeting.

One scientist with significant experience using AIDS drugs estimated yesterday that the cost of the experimental combinations could run close to $15,000 a year for a single patient. And analysts at the San Francisco AIDS Foundation predicted that the cost might be at least $25,000 -- a price that neither private health plans nor government programs would be likely to underwrite.

In a telephone interview from Washington yesterday, Dr. Paul Volberding of the University of California at San Francisco said that the reports of protease inhibitors combined with other more conventional AIDS drugs appeared extremely promising but that much remains unknown about how they might be used. Still to be learned, he said, is whether such combinations might best be used when patients are only moderately infected by HIV, the AIDS virus, and when their own immune systems are still functioning -- or whether it would be better to save the drug combinations for patients with advanced infections and irreparably damaged immune systems. And, of course, Volberding said, more extensive testing over longer periods will be needed before researchers will know whether the effects of the drug combinations are merely temporary. There is also the problem of drug resistance.

Protease inhibitors were first discovered and tested in 1989, and since then some clinical trials have shown that the AIDS virus can mutate over time so that the drugs cease to be effective at all. The same is true of AZT and other AIDS drugs, which is why some researchers believe that combinations may offset the resistance.

Dr. Marcus Conant, another noted AIDS specialist in San Francisco, predicted that the drug combinations would become the first line of AIDS treatment within the next year or two. But he, too, cautioned about the expense and warned that because the drug combinations provide no hope for a cure they would have to be used for a patient's lifetime. "That's an enormous cost," Conant said by telephone from Washington, "and it's another example of how the haves can benefit while the have-nots can't.

These therapies are unlikely to help in the Third World, where the epidemic is worse than ever."
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