Merck announced results from its Phase 3 study of once-daily Isentress (raltegravir tablets) for the treatment of HIV-1. This study evaluated the safety and efficacy of an investigational once-daily dose of raltegravir (800mg once-daily) versus the approved twice-daily dose (400mg twice-daily), each given in combination with a once-daily fixed-dose combination of emtricitabine and tenofovir disoproxil fumarate, in adult treatment-naïve HIV-1-infected patients. In this study, 775 patients were randomized, and 770 patients received study drug and are included in the current analyses. After 48 weeks in the study, 83.2% (n=318/382) of patients receiving the regimen including Isentress once-daily achieved undetectable viral levels (HIV-RNA <50 copies/mL), compared to 88.9% (n=343/386) of patients receiving the regimen including Isentress twice-daily. The treatment difference between the 800mg once daily group and 400mg twice daily group was -5.7%, with an associated 95% confidence interval (CI) of (-10.7%, -0.83%). 

Although the Isentress once-daily regimen enabled more than 80% of patients to achieve viral suppression, Isentress once-daily did not demonstrate non-inferiority to the treatment regimen that included Isentress twice-daily. Based on these initial results and following the recommendation of an independent Data Monitoring Committee, Merck will end the study. Merck is notifying clinical investigators of this decision this week and is recommending that patients enrolled in the once-daily dosing arm of the study be switched to Isentress twice daily, the FDA-approved dose.

Isentress is Merck’s integrase inhibitor for the treatment of HIV-1 infection in treatment-naïve and treatment-experienced adult patients. It is available in a 400mg dosage strength.

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