Treatment success of rescue regimens after dual therapy failure in people living with HIV in a real-life setting

Objectives: Few data on management of two-drug regimen (2DR) failure in people living with HIV (PLWH) are available. Methods: Retrospective study of treatment-experienced PLWH on a 2DR who experienced virological failure (VF) [two consecutive viral loads (VLs) ≥50 copies/mL, single VL ≥1000 copies/mL, or antiretroviral therapy (ART) switch after single VL ≥50 copies/mL with previous blips] or discontinuation for toxicity (baseline). Integrase strand transfer inhibitor (INSTI)-based [one INSTI plus one nucleoside reverse transcriptase inhibitor (NRTI) (n = 78) or one non-NRTI (n = 20)] or boosted protease inhibitor (PI/b)-based [one PI/b plus one NRTI (n = 116) or one INSTI (n = 12)] 2DRs were included. Probabilities of treatment success (TS), VF and discontinuation for any other cause of rescue regimens were estimated by Kaplan-Meier curves. A stepwise Cox model was performed to assess predictors of TS. Results: Overall, 226 PLWH were evaluated: at baseline, 144 individuals discontinued 2DR for toxicity and 82 had VF [median viraemia 81 (63-212) copies/mL]; 171 switched therapy (49.7% to triple regimen, 40.9% to different 2DR), while 55 (exclusively with VF) maintained failing regimens. Probabilities of 12- and 24-month TS were 75.6% and 64.7%, respectively. Higher TS probabilities were observed in individuals who switched ART at 2DR failure (P = 0.003) and PLWH who discontinued 2DR for toxicity (P = 0.008). Therapy switch was the only predictor of TS (P = 0.002). Conclusions: Overall probability of rescue regimens' TS introduced after 2DR failure is good. Prompt ART switch after 2DR failure is advisable.