Long-term safety study of fosamprenavir-containing regimens in HIV-1-infected patients

Abstract

Background: Safety and efficacy of the protease inhibitor fosamprenavir (FPV) ± ritonavir (r) was evaluated in 3 pivotal 48-week phase III studies. A follow-on study provides long-term data on FPV-based regimens.

Methods: International, multicenter, uncontrolled open-label study APV30005 provided FPV as part of combination therapy to HIV-1-infected patients aged ≥13 years who had participated in previous FPV and amprenavir studies. Regimens included FPV/r 1400/200 mg once daily, FPV/r 700/100 mg twice daily, or FPV 1400 mg twice daily. Safety and efficacy were evaluated every 12 weeks, including incidence and frequency of adverse events and laboratory abnormalities, plasma HIV-1 RNA levels, CD4+ cell counts, and frequency of HIV disease progression. Because this was a nonrandomized, observational study, no significance testing was performed.

Results: Overall, 753 patients were enrolled. The most common reasons for premature discontinuation were lost to follow-up (88 [12%]) and insufficient viral load response (69 [9%]). The majority of patients had ≯192 weeks exposure to FPV, with 53 patients exposed for more than 8 years. Drug-related grade 2-4 adverse events were reported for 250 patients (33%), with the majority reported in the first 48 weeks of the study. Most commonly reported grade 3/4 laboratory parameters were increased lipase, triglycerides, and elevated liver enzymes. The observed proportions of patients with plasma HIV-1 RNA levels <50 copies/mL remained ≯70% from week 48 onwards.

Conclusions: Extended treatment of up to 8 years with FPV-containing regimens revealed no new safety concerns and was associated with sustained antiviral responses.

Keywords: fosamprenavir; long-term safety; protease inhibitors.