Safety and effectiveness of switch to bictegravir/emtricitabine/tenofovir alafenamide following dual regimen therapy in people with HIV: Insights from the Icona cohort

Objectives: Most treatment switches are for simplification from three-drug (3DR) to dual regimens (2DR). However, a proportion of people with HIV may switch back to 3DR, like bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) after 2DR. Methods: We included people with HIV enroled in the Icona cohort who switched to B/F/TAF after 2DR INSTI-based (3TC/DTG, RPV/DTG, RPV/CAB, or DOR + DTG). Virological rebound (VR), virological suppression (VS), and treatment discontinuation (TD) due to toxicity or failure were evaluated using Kaplan–Meier curves. Random intercept and slopes before and after the switch were used to evaluate the trajectories of triglycerides, cholesterol, CD4, and CD4/CD8. Viro-immunological analyses were stratified according to HIV-RNA at switch. Results: Among the 3662 people with HIV who started a 2DR INSTI-based regimen, 71 (1.9%) switched to B/F/TAF; 60 had been followed up after the switch, for a median of 10.9 months (interquartile range: 3.6–24.7). Forty people with HIV switched with HIV-RNA <50 copies/mL (uVL), 20 with HIV-RNA ≥50 copies/mL (dVL). Among the uVL group, one participant experienced VR (HIV-RNA: 99, 71 followed by 29 copies/mL). Among the dVL group, the 1-year cumulative probability of undetectable VL was 75% (95% confidence interval [CI] 57.6–95.1). Fourteen people with HIV interrupted B/F/TAF for simplification (50.0%), toxicity (28.6%), VR (14.2%), and patient's choice (7.1); the 1-year cumulative probability of TD for toxicity/failure was 10.7% (95% CI 14.5–24.5). We observed an increase in the CD4/CD8 ratio (+0.02 CD4/CD8/month, p = 0.026) only in the dVL group. Conclusions: Switching from 2DR-INSTI to B/F/TAF is infrequent; this switch results in a low rate of toxicity and failure, along with a favourable immunovirological and lipid profile. CD4/CD8 gain is observed in those switching with detectable HIV-RNA.