Abstract
BACKGROUND: The BASE study (NCT03998176), a phase 4, 48-week (W), single-arm, prospective trial, revealed that the use of bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) in people with HIV and substance use disorders (PWH/SUD) was safe and effective without emergent antiretroviral resistance despite incomplete adherence. Here, we present the W96 results. METHODS: A retrospective analysis of all participants enrolled in the BASE study was completed from W48 to W96. End points of interest at W96 included the proportion of participants with viral suppression (VS; HIV RNA <50 copies/mL [c/mL]), incidence of protocol-defined virologic failure (PDVF; 2 consecutive ≥400 c/mL), safety, adherence (percentage of days covered [PDC]), retention in care, and prevalence of ongoing substance use. RESULTS: All enrolled BASE participants (n = 43) were included in the W96 analysis. At W48, 21 participants (49%) had achieved VS (intent-to-treat [ITT]). Thirty-six (84%) participants completed W96, with 19 achieving an HIV RNA <50 copies/mL (ITT, 44%; per-protocol, 54%). Seven participants (19%) met PDVF; genotyping was performed on 2, with no evidence of treatment-emergent antiretroviral resistance noted. No safety signals were identified or attributed to B/F/TAF. Adherence to B/F/TAF decreased 18% after W48 (mean PDC: W0-W48, 72%; W48-W96, 54%; P < .01). Participants exhibiting adherence rates of ≥4 doses/wk (PDC ≥57%) were more likely to achieve VS (PDC ≥57%, 84.2%, vs PDC <57%, 15.8%; P < .01). Retention in care remained stable, and participants continued to use substances through W96. CONCLUSIONS: At W96, the proportion of PWH/SUD achieving VS with B/F/TAF decreased to 44%, along with an adherence decrease of 18%, with no evidence of treatment-emergent HIV drug resistance occurring.