Merck & Co says that a late-stage trial investigating the efficacy of a once-daily formulation of its HIV therapy Isentress has hit its primary target.

The Phase III ONCEMRK study, which is assessing the higher strength formulation in previously untreated HIV-1 infected adults, met its primary endpoint in showing that 1200mg of Isentress (raltegravir) once-daily was statically non-inferior to the approved 400mg twice-daily formulation.

In both arms treatment with Isentress was given alongside Gilead’s Truvada (tenofovir/emtricitabine), and efficacy was judged by the number of patients achieving HIV-1 RNA <40 copies/mL at Week 48.

Secondary endpoints of tolerability and immunologic efficacy - as measured by change from baseline in CD4 cell counts at Week 48 - were also comparable between the two treatment arms, the firm noted.

Merck, which is known as MSD outside of the US and Canada, said it is planing to present detailed findings of the study at an upcoming scientific conference, and is also gearing up to submit licensing applications for the new formulation on both sides of the Atlantic.