FDA Approves First Protease Inhibitor Drug for Treatment of HIV
The Food and Drug Administration today approved the first protease inhibitor, a new class of therapy for the treatment of advanced HIV infection. Saquinavir, the new drug, received approval for use in combination with older nucleoside analogue medications only three months after the agency received the application for its marketing.
This is some of the most hopeful news in years for people living with AIDS," said HHS Secretary Donna E. Shalala. "Today's approval introduces a new class of drugs for treating AIDS. This drug was approved in just 97 days -- evidence that FDA is carrying through on the Clinton Administration's priority to review new drugs, especially the most promising new drugs, on the fastest possible track consistent with safety."
Commissioner of Food and Drugs David A. Kessler, M.D., pointed out that five of the six AIDS therapies approved so far were reviewed in six months or less.
The review of saquinavir is the fastest approval of any AIDS drug so far, and demonstrates FDA's flexibility in situations when saving time can mean saving lives," Kessler said. "When it comes to AIDS and other life-threatening diseases, we have learned to take greater risks in exchange for greater potential health benefits."
Both protease inhibitors and nucleoside analogues chemically inhibit replication of the human immunodeficiency virus, although at different points in the replication process. Nucleoside analogues include the already-approved anti-HIV drugs AZT, ddC, ddI, d4T and 3TC.
The agency based its approval of saquinavir on clinical trials comparing three drug combinations in more than 900 HIV-infected individuals: saquinavir with AZT, saquinavir with ddC, and saquinavir with both AZT and ddC. The primary measure of drug effect was changes in patients' CD4 cell counts, an indication of immune system strength. (Values greater than 800 per milliliter of blood are normal in healthy individuals.)
Over 16 weeks of treatment, CD4 cell counts increased an average of 30 to 40 cells above entry levels in patients on saquinavir in combination with ddC or AZT or AZT plus ddC. Effects were attributable to combinations of saquinavir and a nucleoside analogue to which a patient had not been previously exposed. Saquinavir doses of less than 600 mg three times a day did not produce increases in CD4 cell counts. The duration of CD4 cell increases is not fully determined, although in general it lasted for at least the 16 weeks of the trials.
Few adverse events were associated with saquinavir, and for most patients the drug was well tolerated.
FDA's approval of the saquinavir marketing application was granted as an accelerated approval, a regulatory mechanism under which the agency bases early approval for a product on laboratory markers such as CD4 cell counts, rather than on clinical endpoints such as delay in death or reduction in opportunistic infections.
FDA may withdraw the approval of products granted accelerated approval if post-marketing studies fail to verify clinical benefits. Trials designed to demonstrate clinical benefits of saquinavir in combination with other nucleoside analogues are ongoing.
Saquinavir is manufactured by Roche Laboratories under the trade name Invirase.