Long-term results of initial therapy with abacavir and lamivudine combined with efavirenz, amprenavir/ritonavir, or stavudine

Objective: To compare alternative class-sparing antiretroviral regimens in treatment-naive subjects. Design: Open-label, multicenter, randomized trial of up to 3 consecutive treatment regimens over 96 weeks. Methods: Two hundred ninety-one subjects received abacavir (ABC) and lamivudine and efavirenz (normucleoside reverse transcriptase inhibitors [NNRTIs]), ritonavir-boosted amprenavir (protease inhibitor [PI]), or stavudine (nucleoside reverse transcriptase inhibitor [NRTI]) by random assignment. The primary end points were the percentages of subjects with plasma HIV-1 RNA levels < 400 copies/mL and time to treatment failure over 96 weeks. Results: Ninety percent of subjects completed 96 weeks of followup, and 79% remained on study treatment. At week 96, there were no differences between arms in the percentages of subjects with plasma HIV-1 RNA levels < 400 and < 50 copies/mL, mean changes in plasma HIV- I RNA levels, time to treatment failure, time to first or second virologic failure, or CD4(+) cell counts. The NNRT1 arm had a greater percentages of subjects with RNA levels <= 50 copies/mL at weeks 24 and 48 and a greater overall duration of plasma HIV-1 RNA levels < 400 copies/mL. Three subjects in the NNRT1 arm had treatment failure on their first regimen and switched therapy compared with 16 in the NRTI arm and 13 in the PI ann. Twentyone subjects had hypersensitivity reactions attributed to ABC (7.3%). Fewer drugs were used by subjects in the NTNRTI arm, and fewer subjects in the NNRTI arm used 3 drug classes. Conclusions: All treatment regimens demonstrated excellent 96-week results. Secondary analyses favored the NNRTI regimen over the PI and NRTI regimens.