Unboosted atazanavir-based therapy maintains control of HIV type-1 replication as effectively as a ritonavir-boosted regimen

Background: Triple combination therapy based on a ritonavir (RTV)-boosted protease inhibitor plus two nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) has improved outcomes in HIV type-1 (HIV-1)-infected patients. For patients unable to tolerate these regimens, alternative therapeutic approaches are needed. Methods: We report a comparative, open-label study in treatment-naive patients who underwent initial induction treatment with a triple combination including RTV-boosted atazanavir (ATV; 300/100 mg once daily). Patients who achieved an HIV-1 viral load <50 copies/ml after the induction period were then randomized in the maintenance phase either to continue on current treatment or to switch to unboosted ATV 400 mg once daily (plus two NRTIs unchanged). Results: A total of 252 patients entered the induction phase, of whom 172 were eligible for randomization in the maintenance phase (ATV/RTV n=85 and ATV n=87). The unboosted ATV regimen demonstrated non-inferior efficacy to the ATV/RTV regimen with 78% and 75% of patients, respectively, maintaining virological suppression (HIV-1 RNA <50 copies/ml) up to week 48 after randomization (difference estimate 2.9, 95% confidence interval -9.8-15.5). Time to virological failure and change from the end of the induction phase in mean CD4(+) T-cell counts were also similar between the treatment arms. Although both regimens were well-tolerated, unboosted ATV was associated with fewer adverse events, fewer total bilirubin abnormalities and an improved lipid profile compared with ATV/RTV. Conclusions: An HIV-1 combined treatment regimen based on unboosted ATV is a feasible treatment option for patients with established virological control who are unable to tolerate triple combination therapy including ATV/RTV.