The MONET trial: week 144 analysis of the efficacy of darunavir/ritonavir (DRV/r) monotherapy versus DRV/r plus two nucleoside reverse transcriptase inhibitors, for patients with viral load <50 HIV-1 RNA copies/mL at baseline

Background In the MONotherapy in Europe with Tmc114 (MONET) trial, darunavir/ritonavir (DRV/r) monotherapy showed noninferior efficacy vs. two nucleoside reverse transcriptase inhibitors (NRTIs) plus DRV/r at the primary 48-week analysis. The trial was continued to week 144 to assess the durability of the results. Methods A total of 256 patients with viral load <?50 HIV-1 RNA copies/mL on current highly active antiretroviral therapy (HAART) for at least 6 months switched to DRV/r 800/100?mg once daily, either as monotherapy (n?=?127) or with two NRTIs (n?=?129). Treatment failure was defined as two consecutive HIV RNA levels above 50 copies/mL [time to loss of virological response (TLOVR)] by week 144, or discontinuation of study drugs. Results Eighty-one per cent of patients were male and 91% were Caucasian, and they had a median baseline CD4 count of 575 cells/uL. More patients in the DRV/r monotherapy arm had hepatitis C virus coinfection at baseline than in the control arm (18% vs. 12%, respectively). By week 144, the percentage of patients with HIV RNA?<?50 copies/mL [intent to treat (ITT), TLOVR, switch?=?failure method] was 69% vs. 75% in the DRV/r monotherapy and triple therapy arms [difference?=?-5.9%; 95% confidence interval (CI) -16.9%, +5.1%]; by a strict ITT analysis (switches not considered failures), the percentage of patients with HIV RNA <?50 copies/mL was 84% vs. 83.5%, respectively (difference?=?+0.5%; 95% CI -8.7%, +9.7%). Twenty-one and 13 patients had two consecutive HIV RNA results above 50 copies/mL in the DRV/r monotherapy arm and triple therapy arm, respectively, of whom 18 of 21 (86%) and 10 of 13 (77%) had HIV RNA <?50 copies/mL at week 144. Conclusions In this study, for patients with HIV RNA <?50 copies/mL at baseline, switching to DRV/r monotherapy showed noninferior efficacy to DRV/r plus two NRTIs in a strict ITT (switches not considered failures) analysis, but not in a TLOVR switch equals failure analysis.