Efficacy and safety of doravirine/islatravir for HIV-1: a GRADE-assessed systematic review and meta-analysis of randomized controlled trials

Background The combination of doravirine and islatravir (DOR/ISL) is a novel two-drug regimen for HIV-1. Early development faced challenges due to dose-dependent immunological signals. We aimed to synthesize the evidence on the efficacy and safety of DOR/ISL across all treatment-experience categories, specifically evaluating the impact of islatravir dosage (0.25 mg vs 0.75 mg) on clinical and immunological outcomes.Methods We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) following PRISMA guidelines. We searched PubMed, Embase, Cochrane Library, and Google Scholar from inception through April 2026. Primary outcomes were virological suppression (<50 copies/mL) and mean change in CD4+ T-cell count at week 48. Data were pooled using random-effects models. Islatravir dose was evaluated as a pre-specified moderator. Quality was assessed using Cochrane RoB 2.0 and certainty of evidence was graded using the GRADE approach.Results Seven RCTs (n = 3,600 participants) were included. At Week 48, DOR/ISL showed non-inferior suppression rates (RR 1.01 95% CI 0.99–1.02; p = 0.516; moderate-certainty evidence) and a statistically significant reduction in virological failure risk (RR 0.55 0.33–0.92; p = 0.022) compared to active control. Overall CD4+ gain was lower with DOR/ISL (MD −34.55 cells/μL; low-certainty evidence); however, a profound moderator effect of dose was observed (p < 0.0001). The 0.75 mg dose was associated with significant CD4+ and lymphocyte declines, whereas the approved 0.25 mg dose was immunologically neutral. DOR/ISL was weight-neutral compared to bictegravir/emtricitabine/tenofovir alafenamide (MD −0.25 kg −0.66 to 0.16; low-certainty evidence).Conclusion DOR/ISL 100/0.25 mg once daily achieved virological suppression comparable to standard-of-care ART regimens and was associated with lower rates of virological failure compared with active comparators. The immunological safety concerns observed in early trials were successfully resolved by dose optimization. These findings support the use of DOR/ISL (IDVYNSO) as a potential treatment option for both treatment-naïve and virologically suppressed adults while emphasizing long-term safety surveillance.