Atazanavir/ritonavir monotherapy: 96 week efficacy, safety and bone mineral density from the MODAt randomized trial

OBJECTIVES To report the 96 week results on efficacy, safety and bone mineral density (BMD) in subjects with HIV-1 that were virologically suppressed and treated with atazanavir/ritonavir monotherapy versus atazanavir/ritonavir triple therapy. METHODS MODAt is a prospective, multicentre, open-label, non-inferiority, randomized, 96 week trial (NCT01511809) comparing efficacy of atazanavir/ritonavir monotherapy versus atazanavir/ritonavir triple therapy. Treatment success was defined as no occurrence of confirmed viral rebound (two consecutive HIV-RNA >50 copies/mL) or discontinuation for any cause of the ongoing regimen. RESULTS The 96 week treatment success was 64% in the atazanavir/ritonavir monotherapy arm and 63% in the triple-therapy arm (difference 1.3%, 95% CI: -17.5 to 20.1). In the atazanavir/ritonavir monotherapy arm, no PI- or NRTI-associated resistance mutations were observed at virological failure and all patients re-suppressed after re-intensification. In the monotherapy arm, treatment failure was more frequent in patients coinfected with hepatitis C virus [64% versus 28% (difference 35.4%, 95% CI: 3.7-67.2)]. Drug-related adverse events leading to discontinuation were 3 (6%) in the atazanavir/ritonavir monotherapy arm and 11 (21.5%) in the triple-therapy arm (P = 0.041). The 96 week adjusted mean percentage change in total proximal femur (not at lumbar spine) BMD was +1.16% and -1.64% in the atazanavir/ritonavir monotherapy arm and the triple-therapy arm, respectively (P = 0.012). CONCLUSIONS The 96 week analyses suggested that long-term efficacy of atazanavir/ritonavir monotherapy was inferior as compared with atazanavir/ritonavir triple therapy, particularly when administered in subjects coinfected with hepatitis C virus. In the atazanavir/ritonavir monotherapy arm, reintroduction of nucleosides, as needed, was always effective with no new resistance mutation; monotherapy was also associated with a lower incidence of adverse events and improvement in femur BMD.