The U.S. Food and Drug Administration (FDA) has accepted MSD’s new drug application (NDA) for its investigational once-daily oral HIV regimen, doravirine/islatravir (DOR/ISL), intended for adults with virologically suppressed HIV-1. The application will be reviewed under the Prescription Drug User Fee Act (PDUFA), with a target action date of April 28, 2026.
The NDA submission is backed by 48-week data from two Phase III clinical trials — MK-8591A-051 and MK-8591A-052. In these studies, DOR/ISL demonstrated non-inferiority to both baseline antiretroviral therapy (bART) and the standard comparator bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF).
Safety findings showed that the DOR/ISL regimen had a comparable safety profile to both existing bART and BIC/FTC/TAF, with no new safety signals reported in either trial.
Dr. Eliav Barr, chief medical officer and head of global clinical development at MSD Research Laboratories, emphasized the company’s longstanding leadership in HIV innovation:
“MSD has been committed to HIV research for over 35 years. DOR/ISL, if approved, would provide a new complete regimen tailored to the evolving needs of people living with HIV, especially those managing comorbidities or complex treatments.”
Islatravir (MK-8591), a novel nucleoside reverse transcriptase translocation inhibitor (NRTTI), works by blocking HIV-1 replication through multiple mechanisms — including translocation inhibition, immediate chain termination, and structural disruption of viral DNA, leading to delayed chain termination.
In a separate development, MSD recently announced a $10 billion acquisition of Verona Pharma, aiming to strengthen its cardio-pulmonary pipeline. The deal adds Ohtuvayre (ensifentrine) — an FDA-approved therapy for chronic obstructive pulmonary disease (COPD) — to MSD’s expanding respiratory portfolio.