Schering-Plough Corporation (NYSE: SGP) today reported long-term data with vicriviroc, its investigational CCR5 receptor antagonist, from an ongoing, open-label extension of the Phase II VICTOR-E1 study in treatment-experienced HIV-infected patients. The results showed that vicriviroc plus optimized background therapy achieved durable virologic suppression and increased CD4 cell counts, and was generally well tolerated over two years of therapy. These 96-week results were presented at the 49th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC).
The study involved 85 treatment-experienced HIV-infected patients who received 48 weeks of open-label vicriviroc (30 mg once daily) plus an optimized antiretroviral regimen containing a ritonavir-boosted protease inhibitor after completion of 48 weeks of treatment in the double-blind phase of the VICTOR-E1 study (total of 96 weeks). More than half of these patients began open-label treatment with undetectable virus, i.e. an HIV-1 RNA level of less than 50 copies/mL, and about two-thirds had less than 400 copies/mL. Seventy patients remained on therapy at the time of the 96-week analysis. The virologic effect seen during the double-blind phase of the study was sustained in these patients during open-label vicriviroc treatment, with the percentage of patients achieving undetectable virus increasing over the course of therapy. Importantly, further improvements in CD4 counts were observed with longer vicriviroc therapy, with a mean increase of 50 cells/mm3 from week 48 of the double-blind study to the end of the 96-week period.