vicriviroc and Viremia

Vicriviroc, a novel HIV CCR5 antagonist, demonstrated significant efficacy and favorable tolerability in phase II trials in treatment-experienced subjects, supporting further evaluation in phase III studies.. Two identical double-blind, placebo (PBO)-controlled trials in CCR5-tropic HIV-infected subjects with documented resistance to two antiretroviral classes were conducted. Subjects were randomized to vicriviroc 30 mg QD (N = 571) or PBO (N = 286) with open-label optimized background therapy (OBT) containing ≥2 fully active antiretroviral drugs. The primary endpoint was percentage of subjects with <50 copies/mL HIV RNA at 48 weeks. It was analyzed in a logistic regression with treatment (vicriviroc + OBT/PBO + OBT), use of enfuvirtide in baseline OBT (yes/no), and baseline HIV RNA (≤100,000/>100,000 copies/mL) as covariates. In addition, a pre-planned analysis to examine other efficacy and safety endpoints was conducted.. Baseline characteristics of the pooled mITT population (vicriviroc, n = 486; PBO, n = 235) included mean HIV RNA of 4.6 log(10) copies/mL and mean CD4 count of 257 cells/μL. Approximately 60% of subjects received ≥3 active drugs in the OBT. The percentage of subjects with <50 copies/mL HIV RNA was not significantly different between vicriviroc and PBO at week 48 (64% vs 62%, p = 0.6). However, in subjects receiving ≤2 active drugs in their OBT, the proportion achieving <50 copies/mL HIV RNA was higher in those receiving vicriviroc compared with PBO (70% vs 55%, p = 0.02).. The studies failed to show significant efficacy gains when vicriviroc was added to OBT. However, given the efficacy results of earlier vicriviroc trials and other CCR5 antagonist, studies are needed to define the role of this class of drugs in the treatment of HIV. Clinical trial identifier: http://www.clinicaltrial.gov/: VICTOR-E3 (NCT00523211) and VICTOR-E4 (NCT00474370).

Topics: Adult; Anti-HIV Agents; Double-Blind Method; Female; HIV Infections; HIV-1; Humans; Male; Middle Aged; Piperazines; Placebos; Pyrimidines; Receptors, CCR5; Receptors, HIV; RNA, Viral; Treatment Outcome; Viral Load; Viremia

Viral reservoirs that persist in HIV-1 infected individuals on antiretroviral therapy (ART) are the major obstacle to viral eradication. The identification and definition of viral reservoirs in patients on ART is needed in order to understand viral persistence and achieve the goal of viral eradication. We examined whether analysis of episomal HIV-1 genomes provided the means to characterize virus that persists during ART and whether it could reveal the virus that contributes to treatment failure in patients on ART. For six individuals in which virus replication was highly suppressed for at least 20 months, proviral and episomal genomes present just prior to rebound were phylogenetically compared to RNA genomes of rebounding virus after therapy interruption. Episomal envelope sequences, but not proviral envelope sequences, were highly similar to sequences in rebounding virus. Since episomes are products of recent infections, the phylogenetic relationships support the conclusion that viral rebound originated from a cryptic viral reservoir. To evaluate whether the reservoir revealed by episomal sequence analysis was of clinical relevance, we examined whether episomal sequences define a viral population that contributes to virologic failure in individuals receiving the CCR5 antagonist, Vicriviroc. Episomal envelope sequences at or near baseline predicted treatment failure due to the presence of X4 or D/M (dual/mixed) viral variants. In patients that did not harbor X4 or D/M viruses, the basis for Vicriviroc treatment failure was indeterminate. Although these samples were obtained from viremic patients, the assay would be applicable to a large percentage of aviremic patients, based on previous studies. Summarily, the results support the use of episomal HIV-1 as an additional or alternative approach to traditional assays to characterize virus that is maintained during long-term, suppressive ART.

Topics: Adolescent; Antiretroviral Therapy, Highly Active; CCR5 Receptor Antagonists; DNA, Complementary; Drug Resistance, Viral; Genome, Viral; HIV Infections; HIV-1; Humans; Phylogeny; Piperazines; Pyrimidines; RNA, Viral; Treatment Failure; Viral Load; Viremia; Virus Replication