Objective
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.
Methods
24 antiretroviral-naïve R5 HIV-1-infected participants received maraviroc 150 mg and DRV/r 800/100 mg (MVC/DRV/r) once-daily. The primary outcome was virologic failure (VF) = confirmed viral load (VL) >50 copies/mL 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 to decay rates from efavirenz plus lopinavir/ritonavir, lopinavir/ritonavir plus 2NRTIs and efavirenz plus 2NRTIs. Maraviroc plasma concentrations were determined at weeks 2, 4,12, 24 and 48.
Results
Baseline median (Q1, Q3) CD4 count and VL were 455 (299, 607) cells/mm3 and 4.62 (4.18, 4.80) log10 copies/mL, respectively. VF occurred in 3/24 participants (12.5 % [95% CI 2.7, 32.4]) at week 24. One of these resuppressed, yielding a week 48 VF rate of 2/24 (8.3 % [95% CI 1.0, 27.0]). The week 48 failures were 2 of the 4 (50%) participants with baseline VL >100,000 copies/mL. Week 96 VF rate was 2/20 (10 % [95% CI 1.2, 31.7]). Phase 1 decay was faster with MVC/DRV/r than reported for ritonavir-boosted lopinavir plus 2 NRTIs (p=0.0063) and similar to efavirenz-based regimens. Individual maraviroc trough concentrations collected between 20–28 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.
Conclusion
MVC/DRV/r 150/800/100 mg once-daily has potential for treatment-naïve patients with R5 HIV-1.