Merck Reports Strong Phase 3 Results for DOR ISL Regimen

Merck, referred to as MSD outside the U.S. and Canada, revealed top-line findings from the crucial double-blind phase 3 trial of the experimental, once-daily, oral, two-drug, single-tablet regimen of doravirine/islatravir [DOR/ISL (100 mg/0.25 mg)] in adults with HIV-1 infection who had not yet undergone antiretroviral treatment (treatment-naïve) (MK-8591A-053).

The primary efficacy hypothesis's success criterion, indicated by the percentage of participants achieving HIV-1 RNA levels <50 copies/mL at Week 48, was fulfilled, showing that DOR/ISL was not inferior to the once-daily oral regimen of bictegravir/emtricitabine/tenofovir alafenamide [BIC/FTC/TAF (50 mg/200 mg/25 mg)]. The main safety goal of the trial was achieved, with the safety profile of DOR/ISL similar to that of BIC/FTC/TAF.

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The firm intends to share comprehensive results from this study at an upcoming scientific conference and to file applications that incorporate these findings to regulatory agencies. The US Food and Drug Administration (FDA) has received the New Drug Application (NDA) for DOR/ISL intended for treating HIV-1 infection in adults to substitute the existing antiretroviral therapy in patients who are virologically suppressed on a stable antiretroviral regimen, with a target action date of April 28, 2026, established under the Prescription Drug User Fee Act (PDUFA).

“We are encouraged by the results from this phase 3 trial with DOR/ISL, evaluating the regimen in adults with HIV who have not previously taken antiretroviral treatments. DOR/ISL is the first two-drug regimen without an integrase inhibitor showing non-inferior efficacy and safety when compared to the three-drug INSTI-based regimen BIC/FTC/TAF in this population,” said Dr. Eliav Barr, senior vice president, head of global clinical development and chief medical officer, Merck Research Laboratories.