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

TitlePharmacokinetic/pharmacodynamic modeling of the antiretroviral activity of the CCR5 antagonist Vicriviroc in treatment experienced HIV-infected subjects (ACTG protocol 5211).
Publication TypeJournal Article
Year of Publication2010
AuthorsCrawford KW, Li C, Keung A, Su Z, Hughes MD, Greaves W, Kuritzkes D, Gulick R, Flexner C
Corporate AuthorsACTG A5211 Study Team
JournalJ Acquir Immune Defic Syndr
Volume53
Issue5
Pagination598-605
Date Published2010 Apr
ISSN1944-7884
KeywordsAdolescent, Adult, Aged, Anti-HIV Agents, Area Under Curve, CCR5 Receptor Antagonists, Double-Blind Method, Female, HIV, HIV Infections, Humans, Male, Middle Aged, Nonlinear Dynamics, Piperazines, Pyrimidines, RNA, Viral, Young Adult
Abstract

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.

DOI10.1097/QAI.0b013e3181c9caac
Alternate JournalJ. Acquir. Immune Defic. Syndr.
PubMed ID20071999
PubMed Central IDPMC2862681
Grant ListAI-51966 / AI / NIAID NIH HHS / United States
AI-68636 / AI / NIAID NIH HHS / United States
AI-69419 / AI / NIAID NIH HHS / United States
AI-69465 / AI / NIAID NIH HHS / United States
AI68634 / AI / NIAID NIH HHS / United States
K24 AI051966 / AI / NIAID NIH HHS / United States
K24 AI051966-01A1 / AI / NIAID NIH HHS / United States
U01 AI068634 / AI / NIAID NIH HHS / United States
U01 AI068634-01 / AI / NIAID NIH HHS / United States