Long-Term Safety Study of Vicriviroc Presented

A study presented at the joint 2008 ICAAC/IDSA meeting in Washington, DC found long-term use of vicriviroc to be safe and effective. The poster was an analysis of an open-label rollover study of just over 200 people who had taken vicriviroc in one of two studies, and found little illness, few side effects, and sustained suppression of HIV for an average of 96 weeks. This study supports the further development of vicriviroc, an experimental CCR5 inhibitor being developed by Schering-Plough.

All participants had taken vicriviroc for 48 weeks in either the VICTOR-E1 or ACTG 5211 studies. People were offered open label, 30mg vicriviroc once a day along with other HIV drugs and then followed for up to 216 weeks. 84% of participants were male and 73% were white. Almost half had a history of an AIDS-defining illness. Average CD4 count was around 200 when people started taking vicriviroc for the first time.

A total of 196 of the 205 people who initially enrolled took vicriviroc for at least 12 weeks in this rollover study, with over 100 completing at least 96 weeks. At 96 weeks, the average drop in HIV levels was around 2 logs, while CD4 counts went up an average of around 140 cells.

A total of 11 AIDS-defining illnesses occurred in the study along with 15 cancer diagnoses. These are both low rates, considering the advanced HIV disease of the participants when they started vicriviroc. There were also low rates of lab abnormalities.

This study is important as it suggests that long-term use of vicriviroc, and possibly other CCR5 drugs like Selzentry (maraviroc), is safe. As CCR5 drugs have been developed, many are concerned about their safety. Thus far, these fears have not been borne out by either clinical studies or real world use, although the number of people who have taken them is relatively small.

Vicriviroc is currently being examined in several studies, including a large phase 3 study in people with experience taking HIV drugs and an interesting head-to-head study vs. Truvada (tenofovir + emtricitabine/FTC) when either is combined with Reyataz (atazanavir) boosted with Norvir (ritonavir). For information on these and other HIV clinical studies, see www.clinicaltrials.gov.