Switching to unboosted atazanavir combined with tenofovir and emtricitabine is effective as maintenance therapy

Purpose of the study Due to a pharmacokinetic interaction leading to reduced serum levels of atazanavir (ATV) when combined with tenofovir (TDF), it is recommended to add ritonavir (r) as a booster for atazanavir when combined with TDF. However, ATV is also licensed for use as an unboosted drug. In our clinic many patients switched to unboosted ATV after viral suppression was achieved, mostly for simplification. We report on the efficacy of unboosted ATV with TDF and emtricitabine (FTC) in our clinic cohort. Methods File review of all patients with no history of virological failure commencing unboosted ATV (400 mg)+TDF+FTC with a HIV‐1‐RNA of <400 copies/ml. Virological failure was defined as two consecutive HIV‐1‐RNA measurements >400 copies/ml. Summary of results 178 patients (pts) were observed for 1‐81 months (mean 21.9, median 18.5) totalling 325 patient‐years. Mean age was 44 years, mean weight 76 kg, mean CD4 516 cells/mm 3 . Duration of preceding viral suppression was 0‐177 (mean 32.4, median 20) months. Most common preceding regimen was ATV/r+TDF+FTC (89 pts). Most common reasons given for switching to ATV+TDF+FTC were simplification (83 pts), dyslipidemia (17), gastrointestinal toxicity (10), coronary risk (10), CNS toxicity (10), hyperbilirubinemia (6). No virological failure was observed. 113, 86 and 62 pts were observed for at least 12, 18 and 24 months; with 95% CI for virological failure 0‐2.6%, 0‐3.4% and 0‐4.7% respectively. 118 pts are still on the regimen. Most frequent reasons for discontinuing were: elevated creatinine (11 pts) viral load blips <200 copies/ml (7), death (5), pregnancy (4), pts’ own decision (4), gastrointestinal intolerance (3). Conclusions Switching to unboosted ATV combined with TDF and FTC is effective as maintenance therapy in patients with viral suppression and no prior treatment failure.