Objective: A 96-week clinical study was planned to estimate the antiviral activity and safety of lersivirine in treatment-naive HIV-1-infected patients.
Methods: This ongoing international, multicenter, double-blind, randomized, Phase IIb exploratory study evaluates the efficacy and safety of 2 doses of lersivirine or 1 of efavirenz, each combined with tenofovir disoproxil fumarate/emtricitabine. Patients were randomized 1:1:1 to receive lersivirine (500 or 750 mg once daily) or efavirenz (600 mg once daily), each administered with tenofovir disoproxil fumarate/emtricitabine (300 mg/200 mg, once daily). The primary endpoint is the proportion of patients with HIV-1 RNA <50 copies per milliliter (missing/discontinuation = failure) at week 48.
Results: For the 193 patients in the study, baseline mean plasma HIV-1 RNA was 4.7 log10 copies per milliliter, and median CD4 cell count was 312 cells per cubic millimeter. At week 48, the percentage of patients with HIV-1 RNA <50 copies per milliliter was 78.5% (51/65), 78.5% (51/65), and 85.7% (54/63) in the lersivirine 500 mg, 750 mg, and efavirenz groups, respectively. CD4 cell count changes from baseline were similar across groups. Virologic failure occurred in 7 patients (11%) in each of the lersivirine groups and 3 patients (5%) in the efavirenz group. The pattern of lersivirine resistance was distinct from other nonnucleoside reverse transcriptase inhibitors. Overall incidences of all-causality treatment-related or grade 3/4 adverse events (AEs) or AE-related discontinuations were lower with lersivirine than with efavirenz, and serious AEs occurred at similar rates across treatment groups.
Conclusions: Both lersivirine doses showed broadly comparable efficacy to efavirenz over 48 weeks in treatment-naive patients, with different AE profiles from efavirenz.