Merck announced that the U.S. Food and Drug Administration (FDA) has accepted for review the New Drug Application (NDA) for doravirine/islatravir (DOR/ISL), an investigational, once-daily, oral, two-drug regimen for adults with HIV-1 infection that is virologically suppressed on antiretroviral therapy. The FDA has set a target action date of April 28, 2026, for the application under the Prescription Drug User Fee Act (PDUFA). The NDA is based on findings at Week 48 of two pivotal Phase 3 clinical trials (MK-8591A-051 and MK-8591A-052) where DOR/ISL was demonstrated to be non-inferior to baseline antiretroviral therapy (bART) in the open-label trial MK-8591A-05 1 and non-inferior to bictegravir/emtrictabine/tenofovir alafenamidei [BIC/FTC/TAF (50mg/200mg/25mg] in the double-blind trial MK-8591A -052.

Across both trials, the safety profile of DOR/ISL was generally comparable to comparator baseline antiretroviral regimens in trial MK-8591 A-051 and BIC/FTC/TAF in trial MK-8591A the052. Data from these trials were presented during the 2025 Conference on Retroviruses and Opportunistic Infections (CROI) in San Francisco. MK-8591A-071 is a Phase 3, open-label, randomized, active-controlled clinical trial evaluating the efficacy and safety of a switch to investigational, oral, once-daily DOR/ISL (100mg/0.25mg) in adults with HIV-1 infectionthat has been virologically suppressed using ART.

The primary efficacy endpoint was the percentage of participants with HIV-1 RNA 50 copies/mL at Week 48 (non-inferiority margin 4%). In this trial, 551 adults with HIV-1 RNA Serum ALT and AST Elevations: In the DRIVE-SHIFT trial, 22% and 16% of participants in the immediate switch group experienced ALT and AST elevations greater than 1.25 X ULN, respectively, through 48 weeks on DELSTRIGO. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual results may differ materially from those set forth in the forward-looking statements.

R risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company's ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of the company's patents and patents.