A Randomized, Prospective Study of the Efficacy, Safety and Tolerability of Two Doses of GW433908Ritonavir Given With Abacavir/Lamivudine Fixed Dose Combination

The optimal long-term management of HIV-1 infection necessitates the chronic use of highly effective, well-tolerated antiretroviral (ARV) combination therapy, which ideally can preserve future treatment options. Current preferred standard treatment for HIV consists of a regimen composed of a protease inhibitor (PI) or a non-nucleoside reverse transcriptase inhibitor (NNRTI) plus 2 nucleoside reverse transcriptase inhibitors (NRTIs). A recent trend that may contribute to improving rates of treatment response is to use regimens with fewer pills and once daily dosing. This study is designed to assess two PI options that consist of four or five pills taken once daily - these options may also offer advantages in terms of metabolic consequences. The primary objective of this multi-center, open-label, randomized, two-arm, pilot study is to evaluate the antiretroviral efficacy, safety, and tolerability (adverse events and metabolic profile) of fos-amprenavir (fAPV) boosted with either of two doses of ritonavir (RTV) when administered in combination with ABC/3TC (abacavir/lamivudine, Epzicom®) FDC (fixed dose combination) in a once-daily regimen over 48 weeks in ART-naïve, HIV-infected adults. Approximately 100 subjects will be enrolled from about 10 sites in the United States. Subjects must be \>18 years of age, be ART-naïve (\<7 days of prior therapy with any licensed or investigational ARV drugs) and have a plasma HIV-1 RNA\>1,000 copies/mL. A CD4+ cell count \>50 cells/mm3 was initially required for eligibility. Amendment 1 has dropped this as a requirement. Subjects will be stratified at entry according to their screening plasma HIV-1 RNA level (\<100,000 copies/mL or \>100,000 copies/mL). Eligible subjects will be randomized (1:1) to one of the following two treatment arms for 96 weeks; fAPV 1400 mg/RTV 100 mg QD plus ABC 600 mg/3TC 300 mg FDC QD (Treatment Arm A) or fAPV 1400 mg/RTV 200 mg QD plus ABC 600 mg/3TC 300 mg FDC QD (Treatment Arm B).