P-353. Ten Years Results on the Effectiveness and Safety of DTG+3TC as a Switch Regimen in a Multicenter Cohort

Abstract Background We aim to assess the efficacy, safety and tolerability of DTG+3TC as a switch regimen after 10 years of its introduction in clinical practice. Methods An observational study was conducted with virologically suppressed PLWH switching to DTG+3TC in a multicenter cohort. Exclusion criteria included HBsAg+ status and M184V resistance mutation. We employed Kaplan-Meyer survival analysis for virological failure (VF) and treatment discontinuation (TD), Cox-regression for VF or TD predictors, and linear mixed models for immunological and metabolic parameter changes. Results We enrolled 2430 PLWH: 1587 (65.3%) were males, with a median age of 54.5 yrs. Full population characteristics are shown in Table1. During 9199 PYFU, we observed 82 VF (0.9 per 100 PYFU); no emergent resistance mutations were registered among VF. Estimated probabilities of maintaining virological suppression (VS) at 240 and 480 wks were 96.2% and 92.8%, respectively. At a multivariate analysis, a history of at least one previous VF before switch (vs no event, aHR 2.09, p=0.005) and a time of VS < 8 years before switch (vs VS > 8 years, aHR 1.82, p=0.021) were significantly associated with a higher risk of VF. During 9287 PYFU, we observed 339 TD (3.7 per 100 PYFU). Estimated probabilities of maintaining DTG/3TC were 83.8% at 240 wks and 79.4% at 480 wks. Discontinuations for toxicity were 78 (23.0% of all TD), with CNS toxicity accounting for 25 cases. Other frequent reasons for TD were: switch to CAB+RPV (64, 18.9%) and treatment intensification (32, 9.4%). At a multivariate analysis, we found that a HIV-RNA peak > 500.000 cps/mL (aHR 1.55, p=0.006) and the presence of HBcAb (aHR 1.60, p=0.002) were significantly associated with a higher risk of TD; meanwhile, the presence of DTG in the ARV regimen before switch, (aHR 0.51, p=0.001) was inversely correlated with TD risk. After 240 weeks, we registered a significant improvement in both CD4+ count (+59, p < 0.001) and CD4/CD8 ratio (+0.1, p < 0.001). As to metabolic parameters, we observed significant improvement in total cholesterol, tryglicerides and HDL cholesterol at both 240 and 480 weeks (p < 0.02 for all). Conclusion We assessed the efficacy and safety of DTG+3TC in the long term while also showing neutral impact on metabolic parameters. Disclosures All Authors: No reported disclosures