96-week real-world effectiveness of bictegravir/emtricitabine/tenofovir alafenamide in HIV-infected adults with pre-existing NRTI resistance: a retrospective cohort study

Objectives: This study evaluated the impact of pre-existing resistance-associated mutations (RAMs) to nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) on treatment outcomes in people living with HIV (PWH) receiving bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) in a real-world setting. Methods: We conducted a single-centre, retrospective review of treatment-experienced adult PWH switched to B/F/TAF, comparing those with and without NRTI RAMs. The primary endpoint was virological success at week 96 (<50 HIV RNA copies/mL). Secondary endpoints were changes in absolute CD4+ counts and CD4+/CD8+ ratio. Continuous variables were analysed using the Wilcoxon rank sum test and categorical variables with the Chi-square or Fisher's exact test. Longitudinal changes in absolute CD4+ counts and CD4+/CD8+ ratio were assessed using linear mixed-effects models, accounting for repeated measurements over time. Results: A total of 257 PWH were included, of whom 21 were viraemic at the time of switch; 41 had pre-existing NRTI RAMs, while no RAMs were documented in the remaining 216 participants. At week 96, virological suppression was achieved in 100% of individuals with RAMs and 97.2% of those without NRTI RAMs, respectively (p=ns). Absolute CD4+ counts increased in 44.4% of participants, with no significant impact of NRTI RAMs. The CD4+/CD8+ ratio showed an apparent increase of more than 50% in 73.2% and 62.0% of participants with and without NRTI RAMs, respectively. However, longitudinal trend analysis revealed a significant negative rate of change in both groups, which was less pronounced among participants with RAMs. Conclusions: B/F/TAF is an effective treatment option for PWH with NRTI RAMs.