Schering-Plough Extends Phase II Study With Vicriviroc

Schering-Plough has extended the phase II study with vicriviroc, its investigational CCR5 antagonist, for use in first-line therapy of adult treatment-naive HIV-infected patients with R5-type virus only.

The study is being conducted in two stages, with the first stage initiated in January 2008 and having enrolled 95 patients (47-48 per treatment arm). Following 24 weeks of treatment, a formal interim analysis was conducted and the safety results were reviewed by an independent Data Safety Monitoring Board. Based on these results, the study has been extended to stage two, in which the enrollment target is an additional 105 patients.

In the study, the virologic benefit of vicriviroc administered once-daily as a single 30mg tablet, in combination with ritonavir-boosted atazanavir, is being compared to a control group receiving Truvada (emtricitabine and tenofovir disoproxil fumarate) plus ritonavir-boosted atazanavir (which is a currently recommended option for first-line therapy).

Joseph Gathe, Jr., clinical instructor, Department of Internal Medicine, Baylor College of Medicine, and lead investigator for the study, said: CCR5 antagonists, such as vicriviroc, have a novel mechanism of action and may play a unique role as physicians seek to construct new HIV regimens to meet the specific needs of their patients.

A class-sparing vicriviroc regimen for initial treatment could potentially expand options for patients by offering a new first-line therapy, while having the additional benefit of preserving the current first-line therapy and subsequent regimens for future use, he added.