Merck's New Once-Daily HIV Pill Moves Closer to FDA Approval With April 2026 Decision Date

Merck (NYSE:MRK), known as MSD outside of the United States and Canada, today 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).

"Merck has been at the forefront of HIV research for more than 35 years and we are pleased to continue our work to innovate and deliver new options that aim to meet the needs of the HIV community," said Dr. Eliav Barr, senior vice president, head of global clinical development and chief medical officer, Merck Research Laboratories. "The health needs of people living with HIV often change over time – whether it's managing comorbidities or navigating complex medication regimens. We believe DOR/ISL, if approved, will represent an important new complete regimen option designed to help meet their diverse needs."

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-051 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-8591A-051 and BIC/FTC/TAF in trial MK-8591A-052. Data from these trials were presented during the 2025 Conference on Retroviruses and Opportunistic Infections (CROI) in San Francisco.