02/18/10

PRN Report from 17th CROI: Phase 3 Trials of Vicriviroc in Treatment Experienced Subjects

Results of Phase 3 Trials of vicriviroc (VCV), a new CCR5 antagonist, was presented yesterday by Dr.Joseph Gathe. These were of similar design to Phase 2 studies that showed significant efficacy when VCV was combined with a ritonavir-boosted protease-inhibitor-containing regimen (PI/r) in subjects with few treatment options.

Two identical double-blind, placebo controlled trials enrolled CCR5-tropic, HIV-infected subjects who had documented resistance to at least 2 antriretroviral (ARV) classes. Regimens had to include a PI/r and at least 2 fully active drugs in their Optimized Background Therapy (OBT). Non-nucleosides, other than etravirine were excluded; raltegravir (RAL) and darunavir (DRV), which were newly available at time of study enrollment, were allowed.

857 subjects were randomized 2:1 to receive VCV 30mg QD vs. placebo. The primary endpoint was percent of subjects with less than 50 copies/ml of HIV RNA at 48 weeks in each study and a pooled analysis. Secondary endpoints looked at safety and efficacy. The pooled population consisted of 721 CCR5-tropic HIV-infected subjects who received treatment. It is important to note that over 61% had ≥ 3 fully active drugs in their OBT.

Of those completing the study, 64% in the VCV arm vs. 61% in the placebo group achieved VL<50 copies/ml at 48 weeks, which was not statistically significant (P=0.6). Also not significant were differences in AIDS-defining events or malignancies. Planned and post hoc pooled analyses showed that the use of RAL ± DRV in OBT strongly influenced outcome. The pooled subset (n=261) did however demonstrate that VCV showed efficacy with ≤ 2 active drugs in OBT: 70% vs. 50% (P= 0.02).

These results suggest that, for patients with limited treatment options, VCV may be of benefit.

Reference:
Joseph Gathe et al. Phase 3 Trials of Vicriviroc in Treatment-experienced Subjects Demonstrate Safety but Not Significantly Superior Efficacy over Potent Background Regimens Alone. Presented at 17th Conference on Retroviruses and Opportunistic Infections, San Francisco. Oral Abstract 54LB.

Source: Reporting for PRN News, Susan Weiss, FNP