Antiretroviral activity and safety of abacavir in combination with selected HIV-1 protease inhibitors in therapy-naive HIV-1-infected adults.

Author(s): McMahon D, Lederman M, Haas DW, Haubrich R, Stanford J, Cooney E, Horton J, Kelleher D, Ross L, Cutrell A, Lee D, Spreen W, Mellors JW

Affiliation(s): University of Pittsburgh/VA Medical Center, PA, USA. mcmahon@msx.dept-med.pitt.edu

Publication date & source: 2001-06, Antivir Ther., 6(2):105-14.

Publication type: Clinical Trial; Clinical Trial, Phase I; Multicenter Study; Randomized Controlled Trial

OBJECTIVE: To assess antiretroviral efficacy and safety of abacavir in combination with selected HIV-1 protease inhibitors. DESIGN: A 48-week, open-label study. MATERIALS AND METHODS: Eighty-two antiretroviral naive HIV-1-infected adults (CD4 cell count > or = 100 cells/mm3, plasma HIV-1 RNA > or = 5,000 copies/ml) were randomly assigned to receive abacavir (300 mg twice daily) in combination with standard doses of one of five protease inhibitors: indinavir, saquinavir soft-gel, ritonavir, nelfinavir or amprenavir. Adults who met protocol-defined switch criteria at or after week 8 could modify their randomized therapy. Antiretroviral activity was assessed by the proportion of subjects with plasma HIV-1 RNA < or = 400 and < or = 50 copies/ml, and by changes in plasma HIV-1 RNA levels and CD4 cell counts. Safety was assessed by monitoring clinical adverse events and laboratory abnormalities. RESULTS: At week 48, the proportion of subjects in the indinavir, saquinavir, ritonavir, nelfinavir and amprenavir groups with plasma HIV-1 RNA < or = 400 copies/ml was 53, 50, 50, 41 and 56%, respectively, and the proportion with HIV-1 RNA < or = 50 copies/ml was 47, 56, 50, 47, and 44%, respectively (by intent-to-treat analysis). Median reductions from baseline in plasma HIV-1 RNA for each group ranged from 1.7 to 2.4 log10 copies/ml. The median CD4 cell count increase from baseline was 195, 131, 116, 136 and 259 cells/mm3 in the indinavir, saquinavir, ritonavir, nelfinavir, and amprenavir groups, respectively. Overall, the most common adverse events attributed to study drugs were diarrhoea, nausea, malaise/fatigue, headache and perioral paresthesia. The frequency of treatment-limiting adverse events did not differ between groups. CONCLUSIONS: Abacavir is safe and effective when used in combination with a protease inhibitor.