Background: Fixed-dose combination B/F/TAF is recommended regimen for HIV-1 treatment. We report week (W) 96 results from a phase 3 study evaluating switching to B/F/TAF in a globally distributed cohort of women. Primary outcome at W48 demonstrated noninferior virologic response, good tolerability, and no emergent resistance.
Methods: In the randomized phase of this multicenter, open-label trial, women living with HIV who were virologically suppressed (HIV-1 RNA < 50 copies/mL) on a baseline regimen (elvitegravir/cobicistat/F/TAF, E/C/F/tenofovir disoproxil fumarate [TDF], or atazanavir+ritonavir+F/TDF) were assigned (1:1) to switch to B/F/TAF (50/200/25 mg) or stay on baseline regimen (SBR) for 48W. At W48, women in the SBR arm switched to B/F/TAF; all participants received B/F/TAF through W96. Secondary efficacy endpoints included proportion with plasma HIV-1 RNA ≥50 copies/mL (missing=excluded [M=E]) at W96 (for those on B/F/TAF throughout the study) and W48 (for those switched to B/F/TAF after W48). Adverse events (AEs) and laboratory test results were assessed through W96.
Results: 470 women from the Dominican Republic, Russian Federation, Thailand, Uganda, and the US were treated in the randomized phase (234 B/F/TAF, 236 SBR); 231 continued on B/F/TAF and 228 in the SBR arm switched to B/F/TAF. At W96, virologic suppression (M=E) was maintained in 99.5% (95% CI 97.4%, 100.0%) of the women who received B/F/TAF throughout the study and in 98.5% (95% CI: 95.5%, 99.7%) of women who switched to B/F/TAF at W48. No individual who received B/F/TAF developed treatment-emergent resistance. Over a median exposure of 76.6W, B/F/TAF was well tolerated, with low frequencies of grade 3 or 4 AEs (6.7%), treatment-related AEs (5.8%), or serious AEs (5.2%). One participant who received B/F/TAF in the extension phase discontinued treatment due to drug-related AEs (grade 2 elevated ALT, AST, and GGT). Grade 3 or 4 laboratory abnormalities occurred in 22.1%; most were menses-associated urine RBCs.
Conclusions: B/F/TAF was safe and well tolerated through 96 weeks. Women who switched to B/F/TAF maintained high levels of virologic suppression without emergence of resistance. This analysis supports the efficacy and safety of B/F/TAF observed in other B/F/TAF studies and contributes important long-term data on safety, tolerability, and efficacy in women living with HIV.