The US Food and Drug Administration (FDA) has accepted MSD’s doravirine/islatravir (DOR/ISL) new drug application (NDA) for review to treat adults with virologically suppressed human immunodeficiency virus (HIV)-1.
A target action date of 28 April 2026 has been set under the Prescription Drug User Fee Act (PDUFA).
The NDA for the once-daily oral regimen is supported by week 48 data from two Phase III trials, MK-8591A-051 and MK-8591A-052.
In these studies, DOR/ISL proved non-inferior to both baseline antiretroviral therapy (bART) in trial MK-8591A-051 and to bictegravir/emtricitabine/tenofovir alafenamide [BIC/FTC/TAF (50mg/200mg/25mg)] in the double-blind trial MK-8591A-052.
DOR/ISL demonstrated a safety profile generally comparable to that of comparator baseline antiretroviral regimens in MK-8591A-051 and BIC/FTC/TAF in MK-8591A-052.
MSD Research Laboratories global clinical development senior vice-president and head, chief medical officer Dr Eliav Barr stated: “MSD 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.
“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.”
Islatravir (MK-8591) is an investigational nucleoside reverse transcriptase translocation inhibitor (NRTTI) that disrupts HIV-1 replication through several mechanisms.
It inhibits the translocation of reverse transcriptase, leading to immediate chain termination. Additionally, it induces structural changes in the viral DNA, which contribute to delayed chain termination.
In early July 2025, MSD agreed to purchase Verona Pharma in a transaction worth $10bn. The deal will strengthen MSD’s cardio-pulmonary product lineup by incorporating Ohtuvayre (ensifentrine), approved by the FDA for treating chronic obstructive pulmonary disease in adults.
