Unboosted atazanavir plus co-formulated lamivudine/abacavir as a ritonavir-sparing simplification strategy in routine clinical practice.

Objective: To assess the effectiveness and safety of antiretroviral therapy with unboosted atazanavir (400 mg once daily) plus co-formulated abacavir/lamivudine as a treatment simplification strategy in HIV-infected patients with sustained viral suppression in routine clinical practice.

Methods: We performed a retrospective study including patients who were switched to unboosted atazanavir plus abacavir/lamivudine and whose HIV-1 RNA was <50 copies/mL. The primary endpoint was the percentage of subjects who maintained viral suppression after 48 weeks of follow-up. Secondary endpoints included the percentage of subjects who maintained viral suppression after 96 weeks of follow-up, the incidence of adverse events, changes in CD4+ T-cell count and in lipid profile, and the percentage of patients with subtherapeutic atazanavir trough concentrations during follow-up.

Results: Forty-six patients were included. None had a prior history of resistance to protease inhibitors or to lamivudine or abacavir. The percentage of patients with viral suppression at Week 48 was 73.9% when all the included patients were considered (full dataset analysis) and 85.0% when only subjects on treatment were considered. There was a continuous immune recovery and an improvement in lipid profile during follow-up. Two thirds of the patients had subtherapeutic atazanavir trough concentrations in plasma in at least one determination during follow-up.

Conclusion: Antiretroviral therapy with unboosted atazanavir plus abacavir/lamivudine is safe and effective in the long term as a treatment simplification strategy in HIV-infected patients with sustained virological suppression in routine clinical practice.