TUPE026 - Poster Exhibition
Five-year efficacy and safety of maraviroc versus efavirenz, each in combination with zidovudine/lamivudine, in treatment-naive HIV‑1‑infected patients: open-label extension of the randomized, double-blind merit study
D.A. Cooper1, J. Heera2, P. Ive3, M. Botes4, E. DeJesus5, R. Burnside2, J. Goodrich6, N. Clumeck7, S. Walmsley8, C. Craig9, A. Lazzarin10, G. Mukwaya11, M. Saag12
1Kirby Institute, University of New South Wales, Sydney, Australia, 2Pfizer Inc., Groton, United States, 3University of Witwatersrand, Johannesburg, South Africa, 4Private Practice, Pretoria, South Africa, 5Orlando Immunology Center, Orlando, United States, 6ViiV Healthcare, Research Triangle Park, United States, 7Saint-Pierre University Hospital, Brussels, Belgium, 8University of Toronto, Toronto, Canada, 9Pfizer Global Research and Development, Sandwich, United Kingdom, 10San Raffaele Scientific Institute, Milan, Italy, 11Pfizer Inc., New York, United States, 12University of Alabama at Birmingham, Birmingham, United States
Background: Maraviroc (MVC) has demonstrated comparable efficacy and safety to efavirenz (EFV) over 96 weeks in the MERIT study. Here we report findings from the subsequent open-label phase extending to 5 years.
Methods: MERIT was a randomized, double-blind, multicenter Phase IIB/III study that included treatment-naïve patients (aged ≥16 years) with CCR5-tropic HIV-1 (initially determined using the original Trofile assay), and screening viral load (plasma HIV-1 RNA) ≥2000 copies/mL. Patients received MVC 300 mg once daily (QD), MVC 300 mg twice daily (BID), or EFV 600 mg QD, each in combination with zidovudine/lamivudine 300 mg/150 mg BID. After the last patient's Week 96 visit, the study was unblinded and patients could enter a nominal, 3-year open-label phase. Efficacy endpoints included proportion of patients with viral load < 50 and < 400 copies/mL, and change from baseline in CD4+ cell count. Primary analyses were based on the cohort with re-confirmed CCR5 HIV-1 following re-testing of screening samples using the enhanced sensitivity Trofile assay. Safety and tolerability were secondary endpoints.
Results: Overall, 917 patients were randomized, and 895 treated (MVC QD=174; MVC BID=360; EFV=361). Baseline characteristics, including mean age (37.2 years), viral load (4.8-4.9 HIV-1 RNA log10 copies/mL), and CD4+ cell count (264.5‑274.0 cells/µL) were similar among treatment arms. The proportion of patients achieving viral load < 50 copies/mL was similar between the MVC BID and EFV treatment arms throughout the study, and at Week 240 (MVC BID 50.8% versus EFV 45.9%). MVC QD was discontinued following a planned interim analysis. Key findings are summarized in the tables.
Conclusions: MVC maintained similar long-term antiviral efficacy to EFV over 5 years in treatment-naïve patients with CCR5-tropic HIV-1. Based on an observed trend for increased counts, MVC may be associated with favorable CD4+ cell response through this period. MVC was generally well-tolerated: there were no unexpected safety findings.
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