Merck Releases Promising Findings From Clinical Trials of Experimental Integrase InhibitorMerck's experimental integrase inhibitor antiretroviral drug might control HIV more effectively in some HIV-positive people than other common drugs on the market, according to the results of a preliminary study released Saturday ahead of the XVI International AIDS Conference, the Los Angeles Times reports (Chong, Los Angeles Times, 8/13). Integrase is one of the three enzymes necessary for HIV to replicate in the body, and integrase inhibitors would 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 antiretroviral drugs (Kaiser Daily HIV/AIDS Report, 2/9). The 24-week study involved HIV-positive people who recently began treatment. A group of 198 people took 100 milligrams to 600 milligrams of the drug, known as MK-0518, in combination with tenofovir and lamivudine twice daily. A control group took tenofovir and lamivudine in combination with 600 milligrams of efavirenz. The MK-0518 combination reduced HIV viral loads to undetectable levels in 90% of participants by the end of the trial period, the study finds. Most of the viral load reduction took place in the first four to eight weeks of taking the drug, Robin Isaacs, Merck's director of clinical research who was involved with the study, said. He added that the MK-0518 combination at all doses reduced the viral load faster than the control group's combination, which often is used as a first-line treatment in newly diagnosed HIV-positive people (Los Angeles Times, 8/13). There were no serious drug-related side effects among study participants, according to the study (Markowitz et al., "Potent Antiretroviral Effect of MK-0518, a Novel HIV-1 Integrase Inhibitor, as Part of Combination ART in Treatment Naive HIV-1 Infected Patients," 8/12). The company plans to begin Phase III trials, which are expected to involve 700 people, according to the Toronto Star. AIDS researcher Martin Markowitz, a lead investigator of the Merck data, said it is unclear when the drug will be available. Mark Wainberg, co-chair of the XVI International AIDS Conference and director of the McGill University AIDS Centre, said, "As a person who sees people with HIV infection, I wish it was yesterday" because "based on the preliminary data, this looks like a very potent drug, a well-tolerated drug" (Talaga, Toronto Star, 8/12). The drug must be put through several more years of testing before FDA can review it, according to the Times (Los Angeles Times, 8/13).
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