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