Isentress: significant HIV load suppression up to 48 weeks

US drug major Merck & Co's HIV integrase inhibitor Isentress (raltegravir) maintained significant HIV-1 viral load suppression and increased CD4 cell counts through 48 weeks of therapy compared to placebo in combination with anti-HIV medicines, in two Phase III studies of 699 treatment-experienced patients failing antiretroviral therapies.

Patients in the studies had HIV resistance to at least one drug in each of three classes of oral HIV agents, noted Merck, which presented the data at this year's Conference on Retroviruses and Opportunistic Infections, held in Boston, USA. These included non-nucleoside and nucleoside reverse transcriptase inhibitors, as well as protease inhibitors.

In one of these studies, called BENCHMRK-1, at 48 weeks, Isentress plus optimized background therapy maintained suppression of HIV RNA levels below 400copies/mL in 74% of patients compared to 36% of those receiving placebo plus OBT (p<0.001). In the companion trial, BENCHMRK-2, the drug plus OBT suppressed viral loads below 400copies/mL in 71% of patients versus 38% (p<0.001). BENCHMRK-1 Isentress patients also saw 48-week viral load suppression to below 50 copies/mL in 65% vs 31%.