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# Merck NDA Accepted for HIV Combination Therapy
- URL: https://www.fdaweb.com/merck-nda-accepted-for-hiv-combination-therapy/
- Published: 2025-07-10T12:00:00.000Z
- Updated: 2026-09-14T15:16:18.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5159484

FDA has accepted for review a Merck NDA for its investigational once-daily HIV treatment combining doravirine and islatravir (DOR/ISL). The two-drug regimen is intended for adults with HIV-1 infection who are already virologically suppressed on existing antiretroviral therapy. The agency has set a user fee review action target date of 4/28/2026.

The submission is based on data from two Phase 3 trials — MK-8591A-051 and MK-8591A-052 — that demonstrated DOR/ISL’s efficacy and safety in maintaining viral suppression, the company says. In the open-label MK-8591A-051 trial, 551 adults who were virologically suppressed on two- or three-drug antiretroviral regimens were randomized to either switch to DOR/ISL or continue their existing therapy. The DOR/ISL regimen demonstrated non-inferiority in maintaining viral suppression at 48 weeks, with a comparable safety profile, it says.

Merck says its double-blind MK-8591A-052 trial enrolled 513 adults on the triple-combination regimen of bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF). Participants were randomized to either switch to DOR/ISL or continue BIC/FTC/TAF. Again, DOR/ISL was found to be non-inferior at maintaining suppression of HIV-1 RNA levels, with a comparable safety profile, according to the company.