A clinical trial investigating the entry inhibitor vicriviroc in people new to HIV treatment has gotten the approval from a safety board to continue onto the second step of the study. The trial extension was announced July 15 by the drug’s developer, Schering-Plough.

Vicriviroc is a CCR5 inhibitor, very similar to Selzentry (maraviroc). It is currently being studied in Phase III trials in people who are heavily treatment experienced, as well as this Phase II study in people who’ve never taken antiretroviral treatment before.

The Phase II study in question had enrolled 95 treatment newbies and is comparing a regimen of vicriviroc plus Norvir (ritonavir)-boosted Reyataz (atazanavir) with a regime of Truvada (tenofovir plus emtricitabine) and Norvir-boosted Reyataz.

A safety committee had been scheduled to look at the data from the study after all the patients had received 24 weeks of treatment and to recommend that the study move into a second stage and enroll an additional 105 patients if everything looked good—which it did.