Virological outcomes with Bictegravir/Emtricitabine/Tenofovir alafenamide (B/F/TAF) in people previously treated with darunavir-based antiretroviral therapy.

BACKGROUND: Darunavir-based antiretroviral therapy (ART) is commonly used in people with HIV who experience adherence challenges and/or have complex resistance patterns. Changes in ART commissioning have led to an increased use of Bictegravir/Emtricitabine/Tenofovir alafenamide (B/F/TAF) in these populations despite limited real-world outcome data.

METHODS: Single centre, retrospective analysis of virological outcomes in individuals previously treated with Darunavir who initiated B/F/TAF before 01/01/2025. Logistic regression was used to analyse associations with sustained virological suppression (HIV RNA <200 copies/mL) on B/F/TAF.

RESULTS: Of the 223 individuals who initiated B/F/TAF, 207 (median age 52 [40-58] years, 38% female, 69% Black ethnicity, 24% with CD4 < 200 cells/mm3 and 36% with HIV RNA ≥200 copies/mL) contributed virological outcome data. Over a median of 2.4 [1.3-3.3] years, 153 (74%) maintained or achieved sustained virological suppression, 11 (5.3%) had a single viral load ≥200 copies/mL and 43 (20.8%) experienced virological failure. Participants with CD4 < 200 cells/mm3 (aOR 0.15 [95%CI 0.07-0.33]) and HIV RNA ≥200 copies/mL (aOR 0.17 [0.08-0.34]) at B/F/TAF initiation were less likely to achieve sustained virological suppression; historical resistance-associated mutations (RAMs) were not associated with virological outcome. Of the 32 participants successfully genotyped, 3 had novel INSTI mutations (E157Q, L74LM) and 4 had not previously documented NRTI mutations (M184V/I, D67DN, Y115F) mutations.

CONCLUSIONS: Substituting of Darunavir-based ART with B/F/TAF in this challenging population was associated with treatment-emergent INSTI and NRTI resistance. Historical resistance did not predict virological outcomes and treatment-emergent resistance did not preclude re-suppression on B/F/TAF, suggesting that adherence remains a major barrier to achieving long-term virological success.