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Background Single-tablet regimens (STRs) can increase treatment success and improve adherence by simplifying antiretroviral therapy in people living with HIV (PWH). Bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) showed efficacy and tolerability in randomized trials as a switch strategy in virologically-suppressed PWH. The aim of this study was to assess, in a real-life setting of suppressed PWH who switched to BIC/FTC/TAF, the long-term durability of this regimen in terms of both virological suppression maintenance and treatment persistence.Methods This was a retrospective, observational, monocentric study including virologically suppressed (HIV-RNA <50 copies/mL) PWH who switched to BIC/FTC/TAF between 2019 and 2025. The primary endpoints were the rate of virological failure (VF, i.e. two consecutive HIV-RNA ≥ 50 copies/mL or a single HIV-RNA ≥1000 copies/mL) and treatment discontinuation (TD) for any reason. Survival analysis with Kaplan-Meier estimator was used to assess the cumulative probability of both VF and TD. Predictors of both outcomes were identified through multivariable Cox regressions.Results We included 615 PWH ( table 1). Overall, 39 VF occurred during a median follow-up of 2.6 years (3.6 per 100 person-years follow-up). The estimated probability of VF at 3 and 4 years was 5.3% and 7.8%, respectively. Higher viral zenith (aHR 1.64, 95%CI 1.08-2.48, p=0.020), was related to a higher probability of experiencing VF, while cumulative time (years) under suppression (aHR 0.991, 95%CI 0.98-0.99, p=0.033) was associated with a lower likelihood of VF. TD occurred in 101 cases (3.2 per 100 patients-year of follow-up), predominantly for simplification to dual regimen (55.5%) (59% 3TC/DTG and 31% cabotegravir/rilpivirine long acting, CAB/RPV LA). Seven discontinuations due to VF were reported (6.9%). Estimated probability of TD at 3 and 4 years was 15.5% and 19.4 %, respectively. Male sex (aHR 0.45, 95%CI 0.29-0.69, p<0.001) and Caucasian ethnicity (aHR 0.56, 95%CI 0.33-0.94, p=0.03) were associated with lower probability of TD. Among participants who did not discontinue BIC/FTC/TAF (n=514), 342 reached 3 years of follow-up, showing a marked increase in both CD4 cell count compared with BL (median change +6 cell/µL at 3 years, p<0.001), and CD/CD8 ratio (median change +0.09 at 3 years, p<0.001). Regarding to the lipid parameters, after 3 years we observed a significant decrease in both total cholesterol (-7.4 mg/dL, p<0.001), and triglycerides (-8.5 mg/dL, p<0.001). Similar results were confirmed among the 197 participants who reached 4 years of follow-up.Conclusions In this real-world setting of suppressed PWH, BIC/FTC/TAF demonstrated high long-term durability along with immunological recovery and improvements in lipid parameters. VF correlated with higher viral zenith and shorter cumulative time under suppression. TD was mainly driven by regimen simplification, with only seven cases attributable to VF.Abstract SC33 Table 1Characteristics of the study participants at switch