Pharmacokinetics and pharmacodynamics of TBR-652, a novel CCR5 antagonist, in HIV-1-infected, antiretroviral treatment-experienced, CCR5 antagonist-naïve patients.

TBR-652 is a novel CCR5 antagonist with potent in vitro anti-HIV activity. The objective of this study was to determine the pharmacokinetics (PK) and pharmacodynamics (PD) of TBR-652 in HIV-1-infected, antiretroviral treatment-experienced, CCR5 antagonist-naïve patients. A double-blind, placebo-controlled, randomized, dose-escalating study of TBR-652 monotherapy given once daily orally for 10 days was performed, followed by a 40-day follow-up period. Approximately 10 patients/dose level received 25, 50, 75, 100, and 150 mg TBR-652 or placebo (4:1). Blood was collected at different intervals for PK and HIV-1 RNA assessments. PK analysis of TBR-652 was performed using noncompartmental methods. PK/PD was modeled using a maximum inhibitory effect model (E(max)) and 50% inhibitory concentrations (IC50). TBR-652 was well absorbed in the systemic circulation. TBR-652 concentration levels declined slowly, with mean elimination half-lives ranging from 22.5 to 47.62 h across dose levels. TBR-652 treatment resulted in potent, dose-dependent decreases in viral load, with statistically significant decreases in nadir HIV-1 RNA compared to baseline for all dose levels. Suppression of HIV-1 RNA persisted over the 40-day follow-up period. A steep exposure-effect relationship was observed, with an E(max) of -1.43 log10 copies/ml and IC50 of 13.1 ng/ml. TBR-652 was generally safe and well tolerated at all dose levels studied. Short-term monotherapy treatments of TBR-652 in HIV-1-infected patients resulted in promising PK and PD results, with a clear exposure-response relationship at the current dose levels studied. Data from this study support further development of TBR-652 in HIV-infected patients.

Safety, efficacy, and pharmacokinetics of TBR-652, a CCR5/CCR2 antagonist, in HIV-1-infected, treatment-experienced, CCR5 antagonist-naive subjects.

OBJECTIVES: To determine the antiviral activity, pharmacokinetics, pharmacodynamics, safety, and tolerability of several dose levels of oral TBR-652 monotherapy in HIV-1-infected, antiretroviral experienced, CCR5 antagonist-naive subjects. DESIGN: Double-blind placebo-controlled study in the United States and Argentina. METHODS: Subjects were randomized in a ratio of 4:1 per dose level to TBR-652 (25, 50, 75, 100, or 150 mg) or placebo, taken once daily for 10 days. Changes from baseline in HIV-1 RNA and CD4 cell counts were measured through day 40 and for monocyte chemotactic protein-1 (MCP-1), high-sensitivity C-reactive protein (hs-CRP), and IL-6 at day 10. Pharmacokinetic data were analyzed using noncompartmental statistics. Laboratory and clinical adverse events (AEs) and electrocardiogram changes were recorded. RESULTS: Maximum median reductions in HIV-1 RNA values for the 25, 50, 75, and 150 mg doses were -0.7, -1.6, -1.8, and -1.7 log10 copies per milliliter, respectively. All changes were significant. Median time to nadir was 10-11 days. Suppression persisted well into the posttreatment period. Mean MCP-1 increased significantly by day 10 in the 50-mg and 150-mg dose groups. Effects on CD4 cell counts, hs-CRP, and IL-6 levels were negligible. TBR-652 was generally safe and well tolerated, with no withdrawals due to AEs. CONCLUSIONS: TBR-652 caused significant reductions in HIV-1 RNA at all doses. Significant increases in MCP-1 levels suggested a strong CCR2 blockade. TBR-652 was generally well tolerated with no dose-limiting AEs. Pharmacodynamics indicate that TBR-652 warrants further investigation as an unboosted once-daily oral CCR5 antagonist with potentially important CCR2-mediated anti-inflammatory effects.