Merck & Co. Inc. has revealed encouraging top-line outcomes from its Phase 3 clinical evaluation of a novel, once-daily, two-drug oral combination, doravirine/islatravir (DOR/ISL), designed for adults newly diagnosed with HIV-1 who have not yet undergone antiretroviral therapy. This marks a significant development in the ongoing efforts to simplify and improve HIV management, offering a potential new option that could streamline daily medication for patients.

The primary efficacy endpoint of the study was successfully achieved, demonstrating that DOR/ISL was non-inferior to the established once-daily oral three-drug regimen, bictegravir/emtricitabine/tenofovir alafenamidei (BIC/FTC/TAF). This critical measure was based on the percentage of participants maintaining HIV-1 RNA levels below 50 copies/mL after 48 weeks of treatment. This finding suggests that Merck's investigational therapy could offer a comparable level of viral suppression to current leading treatments.

Gilead Sciences Inc. currently markets the comparator drug, BIC/FTC/TAF, under the brand name Biktarvy, which is a widely recognized and effective treatment for HIV-1. The head-to-head comparison with such a prominent therapy underscores the potential impact of Merck's new regimen. Beyond efficacy, the trial also successfully met its primary safety objective, indicating that the safety profile of DOR/ISL was consistent with that observed for BIC/FTC/TAF, an essential factor for long-term patient adherence and well-being.

In light of these promising results, the U.S. Food and Drug Administration (FDA) has formally accepted Merck's New Drug Application (NDA) for DOR/ISL. The application seeks approval for the use of this two-drug regimen in adults with HIV-1 infection who are virologically suppressed on their current stable antiretroviral treatment, aiming to provide an alternative therapeutic option. The FDA has set a target action date of April 28, 2026, under the Prescription Drug User Fee Act (PDUFA), which will determine the regulatory fate of this innovative treatment.

Previously, Merck had also presented favorable results from two other Phase 3 trials involving DOR/ISL in March. These studies focused on adults with HIV-1 infection who were already virologically suppressed on either BIC/FTC/TAF (trial MK-8591A-052) or other existing antiretroviral therapies (trial MK-8591A-051). In both instances, DOR/ISL successfully met its primary efficacy criterion for non-inferiority to the comparator antiretroviral therapies and achieved its primary safety objectives at the 48-week mark, reinforcing the consistent performance and safety of the regimen across different patient populations.

This ongoing research and development by Merck represents a crucial step forward in the battle against HIV, with the potential to offer a simplified yet equally effective treatment alternative, enhancing the quality of life for individuals living with HIV-1.