Pharmacokinetic/pharmacodynamic modeling of the antiretroviral activity of the CCR5 antagonist Vicriviroc in treatment experienced HIV-infected subjects (ACTG protocol 5211)

Citation: Crawford KW1, Li C, Keung A, Su Z, Hughes MD, Greaves W, Kuritzkes D, Gulick R, Flexner C; ACTG A5211 Study Team. Pharmacokinetic/pharmacodynamic modeling of the antiretroviral activity of the CCR5 antagonist Vicriviroc in treatment experienced HIV-infected subjects (ACTG protocol 5211). J Acquir Immune Defic Syndr. 2010 Apr;53(5):598-605. doi: 10.1097/QAI.0b013e3181c9caac.

Access full article:

https://www.ncbi.nlm.nih.gov/pubmed/20071999

OBJECTIVE:
This substudy of AIDS Clinical Trials Group (ACTG) Protocol 5211 explored the relationship between antiretroviral effect and plasma concentrations of vicriviroc, an investigational CCR5 antagonist for HIV infection.

METHODS:
Eighty-six treatment-experienced subjects failing their current antiretroviral regimens were randomized to add vicriviroc 5, 10, or 15 mg once daily or placebo for 2 weeks. Beyond week 2, subjects were changed to optimized background antiretroviral treatment while continuing vicriviroc or placebo. Plasma samples collected at weeks 2 and 8 were assayed for vicriviroc concentrations and combined with vicriviroc concentration data from 110 seronegatives enrolled in 5 phase 1 studies. An inhibitory Emax model was used to assess pharmacokinetic (PK)/pharmacodynamic relationships and recursive partitioning was applied to determine the breakpoint in vicriviroc PK parameters associated with virologic suppression.

RESULTS:
A 2-compartment model was fitted to the drug concentration data. At week 2, a higher vicriviroc Cmin was associated with a greater mean drop in HIV RNA (viral load) and a higher percentage of subjects experiencing a >1 log10 copies/mL drop in viral load. In subjects with Cmin > 54 ng/mL, the mean viral load decrease was 1.35 log10 copies/mL vs. 0.76 log10 with Cmin < 54 ng/mL (P = 0.003, Student t test). At this Cmin breakpoint, 70% of subjects with the higher Cmin had a >1 log drop in HIV RNA, compared with 44% with a lower Cmin (P = 0.048, Fisher exact test). Similar results were seen with an area under the curve breakpoint of 1460 ng h/mL. At weeks 16 and 24, all vicriviroc-treated subjects experienced better viral load responses than placebo recipients, but there was no apparent relationship between PK and change in viral load among these vicriviroc-treated subjects.

CONCLUSIONS:
There was a positive correlation between vicriviroc Cmin, area under the curve, and viral load changes at week 2 in treatment-experienced HIV-infected subjects receiving no other new active antiretroviral drugs. This correlation did not persist beyond week 16, probably because treatment response at that point also depended on having other active drugs in the regimen.

Categories

CRS
Topics

Clinical Trials

P1070, Dose-Finding and Pharmacogenetic Study of Efavirenz...

Efavirenz (EFV) is an anti-HIV medicine that is commonly used to treat HIV infection in adults and children older than 3 years...

Read More

HPTN 078: Enhancing Recruitment, Linkage to Care and...

The purpose of this study is to develop and assess the efficacy of an integrated strategy that includes feasible and scalable...

Read More

P1078: A Phase IV Randomized Double-Blind Placebo-Controlled...

P1078 is a Phase IV, randomized, double-blind, placebo-controlled study of HIV-infected pregnant women and the infants born to...

Read More

A5342: Evaluating the Safety, Tolerability, and Effect of a...

The purpose of this study is to evaluate the safety, tolerability, and effect of an experimental human monoclonal antibody...

Read More

P1077BF: Breastfeeding Version of the PROMISE Study...

1077BF is a randomized strategy trial, which is part of the PROMISE studies (1077BF, 1077FF, P1084s, and 1077HS). The Promoting...

Read More