SOLO:: 48-week efficacy and safety comparison of once-daily fosamprenavir/ritonavir versus twice-daily nelfinavir in naive HIV-1-infected patients

Objective: To compare the magnitude and durability of the antiviral response to fosamprenavir (FPV) plus ritonavir (RTV) once-daily (FPV/r QD) with nelfinavir twice-daily (NFV BID), each administered with abacavir and lamivudine twice-daily. Methods: An international, phase III, randomized, open-label study in antiretroviral therapy-naive, HIV-infected adults. Results: Patients with advanced HIV disease received FPV/r QD (n = 322) or NFV BID (n = 327). At week 48, 69% of patients in the FPV/r QD group and 68% in the NFV BID group had plasma HIV-1 RNA (vRNA) < 400 copies/ml, whereas 55% of patients in the FPV/r QD group and 53% in the NFV BID group had vRNA < 50 copies/ml (intent to treat, rebound/discontinuation = failure). More patients in the NFV BID group (17%) experienced virological failure than in the FPV/r QD group (7%). Efficacy of FPV/rQD was maintained in patients with CD4+ cell counts < 50 X 10(6) cells/I or vRNA >= 100000 copies/ml at entry. At week 48, median CD4+ cell counts were increased to 203 X 10(6) cells/I (FPV/r QD group) and 207 X 106 cells/l (NFV BID group). Both regimens were generally well tolerated. Diarrhea was more common on NFV BID than on FPV/r QD (16 versus 9%; P = 0.008). Fasting lipid profile results were generally favorable in both treatment arms. FPV/rQD maintained plasma amprenavir (APV) trough concentrations above the mean phenotypic drug-susceptibility (IC50) for wild-type virus for APV. Conclusion: As a first choice protease inhibitor with a low daily pill burden, FPV/r QD was well tolerated and provided potent, durable antiviral suppression. (C) 2004 Lippincott Williams & Wilkins. Conclusion: As a first choice protease inhibitor with a low daily pill burden, FPV/r QD was well tolerated and provided potent, durable antiviral suppression. (C) 2004 Lippincott Williams & Wilkins.