FDA Approves Doravirine/Islatravir, a First-in-Class 2-Drug HIV Regimen

The FDA has approved doravirine/islatravir (Idvynso), a single-tablet, once-daily regimen combining doravirine and islatravir, for adults living with HIV who have virologic suppression and have no history of treatment failure or resistance to doravirine. Developed by Merck, the therapy is designed to replace existing antiretroviral regimens in eligible patients. Doravirine/islatravir stands out as the first and only non–integrase strand transfer inhibitor (INSTI), tenofovir-free, complete 2-drug regimen to demonstrate noninferior efficacy in a head-to-head phase 3 trial against the widely used 3-drug regimen bictegravir/emtricitabine/tenofovir alafenamide (Biktarvy).

“In my own clinical trial population, that as people age their medication their medical profile and their medication preferences may shift. It's a very safe and simple two-drug option for people managing multimorbidity and polypharmacy,” Amy Colson, MD, MPH, medical director of the Zinberg Clinic at Cambridge Health Alliance and research director at Community Resource Initiative, told Contagion.

Phase 3 Data Demonstrate Noninferior Efficacy

Approval of doravirine/islatravir is supported by findings from 2 phase 3 trials involving more than 700 adults with virologic suppression. Across both studies, the regimen met its primary end point, showing noninferior efficacy compared with both bictegravir/emtricitabine/tenofovir alafenamide and baseline antiretroviral therapies at 48 weeks.

In one trial, only 1% of participants who switched to doravirine/islatravir had viral loads above 50 copies/mL at week 48, matching results seen in patients who remained on bictegravir/emtricitabine/tenofovir alafenamide. In another study, 96% of patients who switched to doravirine/islatravir maintained viral suppression compared with 92% who stayed on their prior regimens.

Safety Profile and Clinical Considerations

The safety profile of doravirine/islatravir was generally comparable to existing therapies, with low rates of treatment discontinuation due to adverse events across both trials. Common adverse effects included diarrhea, dizziness, fatigue, and headache, though most occurred at low frequencies.

However, clinicians should note important considerations, including contraindications with strong CYP3A enzyme inducers and certain antiretrovirals such as lamivudine or emtricitabine. Rare but serious skin reactions have also been reported with doravirine-containing regimens.

Merck said the treatment will become available in the US after May 11.

Reference
FDA approves Merck’s once-daily IDVYNSO (doravirine/islatravir). Press release. Merck. April 21, 2026. Accessed April 21, 2026. https://www.merck.com/news/fda-approves-mercks-once-daily-idvynso-doravirine-islatravir/