Virologic Response, Early HIV-1 Decay, and Maraviroc Pharmacokinetics With the Nucleos(t)ide-Free Regimen of MaravIroc Plus Darunavir/Ritonavir in a Pilot Study

Abstract

To address the need for nucleos(t)ide reverse transcriptase inhibitor (NRTI)-sparing regimens, we explored the virologic and pharmacokinetic characteristics of maraviroc plus ritonavir-boosted darunavir in a single-arm, open-label, 96-week study. Twenty-four antiretroviral-naive R5 HIV-1-infected participants received maraviroc 150 mg and darunavir/ritonavir (DRV/r) 800/100 mg (MVC/DRV/r) once daily. The primary outcome was virologic failure (VF) = confirmed viral load (VL) >50 copies per milliliter at week 24 in the modified intent-to-treat population. To determine viral dynamics, participant-specific first- and second-phase empirical Bayes estimates were compared with decay rates from efavirenz (EFV) plus lopinavir/ritonavir, lopinavir/ritonavir plus 2NRTIs, and EFV plus 2NRTIs. Maraviroc plasma concentrations were determined at weeks 2, 4, 12, 24, and 48. Baseline median (Q1, Q3) CD4 count and VL were 455 (299, 607) cells per cubic millimeter and 4.62 (4.18, 4.80) log10 copies per milliliter, respectively. VF occurred in 3 of 24 participants {12.5% [95% confidence interval (CI): 2.7 to 32.4]} at week 24. One of these resuppressed, yielding a week 48 VF rate of 2/24 [8.3% (95% CI: 1.0 to 27.0)]. The week 48 failures were 2 of the 4 participants (50%) with baseline VL >100,000 copies per milliliter. Week 96 VF rate was 2/20 [10% (95% CI: 1.2 to 31.7)]. Phase 1 decay was faster with MVC/DRV/r than reported for ritonavir-boosted lopinavir plus 2NRTIs (P = 0.0063) and similar to EFV-based regimens. Individual maraviroc trough concentrations collected between 20 and 28 hours post dose (n = 59) was 13.7 to 130 ng/mL (Q1, 23.4 ng/mL; Q3, 46.5 ng/mL), and modeled steady-state concentration was 128 ng/mL. MVC/DRV/r 150/800/100 mg once daily has potential for treatment-naive patients with R5 HIV-1.