Background: In virologically suppressed patients, switching to darunavir/ritonavir monotherapy could avoid resistance and adverse events from continuing nucleoside analogues.
Methods: Two hundred and fifty-six patients with HIV RNA <50 copies/mL on current antiretrovirals were switched to darunavir/ritonavir 800/100 mg once daily, either as monotherapy (n = 127) or with two nucleoside analogues (n = 129). Treatment failure was defined as two consecutive HIV RNA levels at least 50 copies/mL by week 96, or discontinuation of study drugs. The trial had 80% power to show non-inferiority (δ = -12%) at week 48. Results Patients were 81% male, 91% Caucasian, and had a median baseline CD4 count of 575 cells/mm(3). There were more patients with hepatitis C co-infection at baseline in the monotherapy arm (18%) compared with the triple therapy arm (12%). In the efficacy analysis, HIV RNA <50 copies/mL by week 96 (per protocol, time to loss of virological response, switch equals failure) was 78% versus 82% in the monotherapy and triple therapy arms [difference -4.2%, 95% confidence interval (CI) -14.3% to +5.8%]; in a switch included analysis, HIV RNA <50 copies/mL was 93% versus 92% (difference +1.6%, 95% CI -5.0% to +8.1%). The percentage of patients with HIV RNA <5 copies/mL (optical density from the sample equal to the negative control) remained constant over time in both treatment arms. Conclusions In the week 96 analysis of the MONotherapy in Europe with TMC114 (MONET) trial, switching to darunavir/ritonavir monotherapy showed non-inferior efficacy to darunavir/ritonavir plus two nucleoside analogues in the switch included and observed failure analyses, but not in the main switch equals failure analysis.