Merck announced results from its Phase 3 study of Isentress (raltegravir) in combination therapy compared to efavirenz in combination therapy for treatment-naive HIV-1 infected adult patients. In this ongoing multicenter, double-blind, randomized, active-controlled, non-inferiority study, 563 previously untreated HIV-1 infected adult patients received either 400mg Isentress orally twice-daily (N=281) or 600mg efavirenz orally once-daily (N=282), each in combination with tenofovir/emtricitabine. The primary endpoint of the study was a reduction in HIV-1 viral load to <50 copies/mL. Secondary endpoints included antiretroviral (ARV) activity, as measured by the percentage of patients achieving HIV-1 viral load to <50 copies/mL, <400 copies/mL, and change from baseline in CD4-cell count at Week 96, as well as tolerability and safety at Week 96.

The analyses showed that the regimen containing Isentress demonstrated better efficacy compared to the regimen containing efavirenz at 192 weeks of treatment, as measured by the percentage of patients maintaining undetectable virus levels (<50 copies/mL) [76.2% (N=214/281) vs. 67% (N=189/282); 95% CI 1.6, 16.4]. The regimen containing Isentress also showed a greater immunological effect as measured by mean increase from baseline in CD4-cell count at Week 192 (360.7 vs. 300.9 cells/mm3; CI 24.1, 95.4) vs. the efavirenz regimen.

Isentress is an integrase inhibitor for the treatment of HIV-1 infection in treatment-naive and treatment-experienced adult patients as part of combination therapy.

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