FDA Releases Review of Merck’s Antiretroviral Raltegravir Ahead of Panel Meeting To Determine Whether Drug Should Be ApprovedFDA on Friday released a review of Merck's experimental antiretroviral drug raltegravir ahead of a panel meeting, scheduled for Wednesday, to determine whether the drug should be approved, the Wall Street Journal reports (Corbett Dooren, Wall Street Journal, 8/31). Merck in June announced that FDA granted priority review status to raltegravir, an experimental integrase inhibitor. Raltegravir effectively decreases HIV viral loads after 24 weeks of use among HIV-positive people who have not responded to other treatments, according to a study published in the April 14 online edition of the journal Lancet. Raltegravir works by blocking an HIV enzyme called integrase. Integrase is one of the three enzymes necessary for HIV to replicate in the body, and integrase inhibitors stop HIV from inserting its genes into uninfected DNA. The other two enzymes necessary for viral replication, reverse transcriptase and protease, already are targeted by a variety of antiretrovirals (Kaiser Daily HIV/AIDS Report, 7/13).
According to the FDA review, which was posted on the agency's Web site, raltegravir is effective at treating HIV-positive people who have shown resistance to available treatments. Rash and increased levels of creatine in the blood were the most common side effects of the drug, according to the review (Perrone, AP/Las Vegas Sun, 8/31). Other potential side effects include liver injuries and cancer, the Journal reports (Wall Street Journal, 8/31). In clinical trials, a higher number of cancers were found among people taking raltegravir than among those taking a placebo, but the difference could be because of a lower rate of cancers among people in the placebo group, FDA said (Cohen, Newark Star-Ledger, 9/1).
The FDA panel of outside experts will be asked if available data supports accelerated approval of raltegravir. The panel also will be asked whether raltegravir should be used only by people enrolled in clinical trials or by people "with few or no remaining treatment options," according to the Journal (Wall Street Journal, 8/31). FDA also will ask the panel if Merck should be required to conduct postmarketing studies on the drug (AP/Las Vegas Sun, 8/31). The agency is expected to make a final decision about raltegravir in mid-October (Wall Street Journal, 8/31). Merck said that if the drug is approved, it will be used in combination with standard oral antiretrovirals by HIV-positive people who have developed resistance to their current treatments. Raltegravir will be sold under the brand name Isentress (Kaiser Daily HIV/AIDS Report, 7/13). This is part of the KHN Morning Briefing, a summary of health policy coverage from major news organizations. Sign up for an email subscription.