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| |  HIV Patients With High Viral Load Worsen on Fixed-Dose Abacavir/Lamivudine Compared With Fixed-Dose Tenofovir/Emtricitabine: Presented at AIDS 2008 By Ed Susman MEXICO CITY -- August 9, 2008 -- Human immunodeficiency virus (HIV)-infected patients who have viral loads of >100,000 copies/mL appear to gain better suppression of the virus when initially treated with a combination of tenofovir/emtricitabine rather than abacavir/lamivudine, according to research from an AIDS Clinical Trials Group (ACTG) study presented here at the 17th International AIDS Conference (AIDS 2008). The Data Monitoring Safety Board recommended that the researchers unblind the study when they found an excess number of virologic failures among patients who were taking abacavir/lamivudine fixed-dose tablets. Lead author Paul Sax, MD, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, noted that, when the data were reviewed, most of the excess events occurred among patients with high viral loads. "In the abacavir/lamivudine group there were 57 virologic failures," Dr. Sax said in an oral late-breaker presentation here on August 7. "In the tenofovir/emtricitabine arm of the study there were 26 events at 24 weeks. These results reveal highly significant differences in the treatments (P = .0003)." The lower potency in maintaining virologic suppression was seen predominantly in treatment-naïve patients who began the head-to-head comparison with viral loads of >100,000 copies/mL, Dr. Sax said. The study initially had 4 arms, comparing the 2 fixed-dose pills with placebo in combination with either efavirenz or atazanavir. The primary efficacy endpoint was time to virological failure, defined as either a viral load of >1,000 copies/mL after 16 weeks of treatment and before 24 weeks, or >200 copies/mL after 24 weeks. The study also examined safety and tolerability endpoints. In late January, the Data Safety Monitoring Board noted an excess of virological failures in the abacavir/lamivudine arms and asked that the data be combined and analysed as a 2-arm comparison of the combinations. In the study, 398 patients were getting the abacavir combination and 399 were assigned to the tenofovir dose. Patients in the abacavir group were also significantly more likely to switch their regimens early, and the time to the first predetermined safety event was significantly shorter (both at P < .0001), Dr. Sax concluded. [Presentation title: ACTG 5202: Shorter Time to Virologic Failure (VF) With Abacavir/Lamivudine (ABC/3TC) Than Tenofovir/Emtricitabine (TDF/FTC) as Part of Combination Therapy in Treatment-Naïve Subjects With Screening HIV RNA ³100,000 c/mL. Abstract THAB0303]
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