SILVER SPRING, Md--The FDA's Antiviral Drugs Advisory Committee took action on three anti-HIV agents at its most recent meeting, recommending approval for Hoffmann-La Roche's protease inhibitor saquinavir(Drug information on saquinavir) (Invirase) and Glaxo Wellcome's 3TC (Epivir) in combination with other AIDS drugs, and favoring a new indication for Bristol-Myers Squibb's stavudine(Drug information on stavudine) (d4T, Zerit), to treat patients who no longer respond to zidovudine(Drug information on zidovudine) (AZT, Retrovir).
If approved, the protease inhibitor Invirase would represent the first new class of anti-HIV agents since the nucleoside analog AZT became available in 1987. Other available anti-HIV agents, didanosine(Drug information on didanosine) (ddI, Videx), zalcitabine(Drug information on zalcitabine) (ddC, Hivid), and stavudine, are all nucleoside analogs.
In a 6 to 1 vote, the panel stated that there was sufficient evidence of effectiveness for the FDA to expedite approval. But the panel voted against recommending use of the drug alone, saying there was not enough evidence that Invirase alone is clinically effective at the low doses tested in the preliminary studies.
FDA Commissioner David Kessler expressed enthusiasm over the recommendation, saying that the availability of Invirase would allow physicians to attack HIV from two different routes. He said that six protease inhibitors are currently being tested in the United States.
The advisory committee also recommended approval of 3TC in combination with AZT. [The FDA has since approved this combination.] Preliminary data suggest that the addition of 3TC delays development of resistance to AZT and could even reverse such resistance, Glaxo Wellcome said. Studies show that the combination raises CD4 counts while reducing HIV viral burden for at least 6 months, company representatives said.
The panel noted that the combination appeared more effective when given as initial HIV therapy, since greater effects were seen in patients who had never been exposed to AZT than in those who had previously received AZT monotherapy.
The panel also recommended 4 to 3 that the indication for stavudine (d4T) be extended to include treatment of patients who no longer respond to AZT. The drug is currently approved for use in adults with advanced HIV infection who are intolerant of approved therapies or who have had significant deterioration while receiving these therapies.