Efficacy of bictegravir/emtricitabine/tenofovir alafenamide versus dolutegravir-based three-drug regimens in people with HIV with varying adherence to antiretroviral therapy.

Objective: Five Phase 3 bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) clinical studies demonstrated that the efficacy of B/F/TAF was non-inferior to dolutegravir (DTG) + 2 NRTIs. We retrospectively assessed drug adherence and effect on virologic outcomes.

Methods: Studies (NCT02607930, NCT02607956, NCT03547908, NCT02603120 and NCT03110380) were double-blind, placebo-controlled and enrolled treatment-naïve or virologically suppressed adults. Adherence was calculated by pill count from returned pill bottles; virologic outcome was assessed by last on-treatment HIV-1 RNA.

Results: Altogether, 2622 participants (B/F/TAF: n = 1306; DTG + 2 NRTIs: n = 1316) were categorized as having high (≥95%), intermediate (≥85% to <95%) or low (<85%) adherence. Through Week 48, low adherence was observed in 46 (3.5%) participants in the B/F/TAF group (78% median adherence) and 69 (5.2%) in the DTG + 2 NRTI group (80% median adherence). Overall, 1287 (98.5%) participants in the B/F/TAF group and 1292 (98.2%) in the DTG + 2 NRTI group had virologic suppression (VS; HIV-1 RNA < 50 copies/mL) through Week 48. VS in participants with low adherence versus high or intermediate adherence was similar in the B/F/TAF group, but lower in the DTG + 2 NRTI group (P ≤ 0.002). Similar results were observed at Weeks 96 and 144. Two participants (<95% adherence) in the DTG + 2 NRTI group receiving DTG and abacavir/lamivudine developed M184V; there was no treatment-emergent resistance to B/F/TAF.

Conclusions: Participants with suboptimal (<85%) adherence to B/F/TAF maintained high levels of VS, whereas suboptimal DTG + 2 NRTI adherence was associated with lower VS.