By VETTAPHARMA reporter – Derek Roche: Merck & Co., Inc. announced late-breaking data from three Phase 3 clinical trials evaluating doravirine/islatravir (DOR/ISL), an investigational once-daily, oral, two-drug regimen for the treatment of adults living with HIV-1 infection, presented at the 33rd Conference on Retroviruses and Opportunistic Infections (CROI) 2026.
In the Phase 3, double-blind trial MK-8591A-053, DOR/ISL (100 mg doravirine/0.25 mg islatravir) was compared to a standard three-drug regimen of bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) (50 mg/200 mg/25 mg) in adults with HIV-1 who had not previously received antiretroviral treatment. At Week 48, DOR/ISL demonstrated non-inferior efficacy in the proportion of participants achieving viral suppression (HIV-1 RNA <50 copies/mL) compared with BIC/FTC/TAF (91.8 % vs 90.6 %, treatment difference 1.2 %, 95 % CI −3.7, 6.2; p < 0.001), with a similar safety profile between groups. Drug-related adverse events (AEs) occurred in 14 % of participants on DOR/ISL versus 18 % on BIC/FTC/TAF, and discontinuations due to AEs were 1.1 % versus 2.2 % respectively.
Additional late-breaking data from the Phase 3 MK-8591A-052 and MK-8591A-051 trials showed that DOR/ISL maintained high rates of virologic suppression at Week 96 in adults with virologically suppressed HIV-1 who switched from other antiretroviral regimens, with safety profiles comparable to BIC/FTC/TAF and baseline antiretroviral therapy (bART). These findings build on prior Phase 3 evidence of non-inferior efficacy and similar safety compared with standard regimens in people living with HIV-1.
In summary, the late-breaking Phase 3 results support DOR/ISL as a potential simplified treatment option for adults living with HIV-1, showing sustained virologic control and comparable safety to existing standards of care across multiple clinical settings.
