FDA Approves Pfizer's Antiretroviral Maraviroc

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Pfizer's Antiretroviral Maraviroc

FDA on Monday approved Pfizer'santiretroviral drug maraviroc, which belongs to a new class ofantiretrovirals that could provide an alternative to HIV-positivepeople who have developed resistance to multiple drugs, the Los Angeles Times reports (Chong, Los Angeles Times, 8/7). FDA gave expedited approval of maraviroc for use in combination with other antiretrovirals (CQ HealthBeat, 8/6).


Maravirocworks by blocking a protein, called CCR5, on human immune system cellsthat HIV uses as a portal to enter and infect the cell. Pfizer hasproposed using the drug to treat people with advanced HIV or AIDS whohave not responded to other medications. Pfizer last month alsoannounced that maraviroc can reduce HIV viral loads among people whohave never taken antiretrovirals. The company plans to offer the drugwith a test developed by Monogram Biosciences that determines if people are likely to respond to the treatment (Kaiser Daily HIV/AIDS Report, 7/26). Pfizer will sell maraviroc under the brand name Selzentry (Wall Street Journal, 8/7).

FDAapproved maraviroc on the condition that the drug's label include ablack-box warning -- the "strongest possible advisory" -- according tothe Times. The drug also will have a warning about an increased risk of heart attack (Los Angeles Times, 8/7).

Accordingto Debra Birnkrant, director of FDA's division of antiviral drugproducts, the approval comes after the agency concluded thatHIV-positive people who have become resistant to other treatments needa new option. She added that FDA is requiring Pfizer to conduct furtherresearch into the drug's long-term side effects. According toBirnkrant, maraviroc is aimed at HIV-positive people who are quicklydeveloping resistance to other available antiretrovirals and not peoplenewly diagnosed as HIV-positive. For those people who are developingdrug resistance to other treatments, maraviroc's "benefits clearlyoutweigh the risks," Birnkrant said, adding, "That doesn't mean therearen't any risks." According to a Pfizer spokesperson, maraviroc willbe available in September and the wholesale cost will be about $900monthly, the AP/Washington Post reports (Neergaard, AP/Washington Post, 8/6).

Helmut Albrecht, director the University of South Carolina's Division of Infectious Diseaseswho was not involved with any maraviroc trials, said he was "cautiouslyoptimistic" about the drug. He added, "It's so completely new that itis sort of difficult to see how well this is going to do over time."The last new class of antiretrovirals was approved by FDA in 2003 (Los Angeles Times, 8/7).

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