Shorter Time to Discontinuation Due to Treatment Failure in People Living with HIV Switched to Dolutegravir Plus Either Rilpivirine or Lamivudine Compared with Integrase Inhibitor-Based Triple Therapy in a Large Spanish Cohort

INTRODUCTION: Standard therapy for HIV treatment has consisted of two nucleoside analogue reverse transcriptase inhibitors (NRTI) paired with a third agent. Use of two-drug regimens (2DR) has been considered for selected patients in part to avoid toxicities associated with the use of NRTIs. This study aimed to compare the real-world outcomes of integrase inhibitor (INSTI)-based three-drug regimens (3DR) versus 2DR of dolutegravir (DTG) + rilpivirine (RPV) or DTG + lamivudine (3TC). METHODS: All patients in the Spanish VACH cohort switching to INSTI-based 3DR or a 2DR consisting of DTG + RPV or DTG + 3TC between May 2, 2016 and May 15, 2019 were included. Kaplan–Meier curves and Cox proportional hazard models were used to assess time to/risk of discontinuation due to treatment failure (TF) (defined as virologic failure [VF], immunologic failure, or disease progression) and adverse events (AEs). Three secondary analyses were performed: (1) in restricting the analysis to patients who were virologically suppressed (HIV RNA < 50 copies/mL) at switch; (2) matched analysis (2:1, matched by age, sex, number of previous VFs, and line of regimen), and (3) using VF as the primary endpoint in all patients. RESULTS: Overall, 5047 3DR and 617 2DR patients were analyzed. Baseline characteristics differed between groups; 2DR patients were older, more treatment experienced, and more likely to be virologically suppressed at switch. Time to discontinuation due to TF was significantly shorter for 2DR (P = 0.002). The hazard ratio (HR) for discontinuation due to TF on 2DR vs 3DR was 2.33 (P = 0.003). No difference was observed for time to discontinuation (P = 0.908) or risk of discontinuation due to AEs (HR = 0.80; P = 0.488). Results were qualitatively similar in virologically suppressed patients, matched analysis, and for VF. CONCLUSION: In the real world, the risks of discontinuation due to TF and VF were more than two times higher in patients switching to DTG-based 2DR than INSTI-based 3DR, with no difference in discontinuation due to AEs. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40121-022-00630-y.