Merck known as MSD outside of the United States and Canada, today announced topline results from two pivotal Phase 3 trials of the investigational, once-daily, oral, two-drug, single-tablet regimen of doravirine/islatravir [DOR/ISL (100 mg/0.25 mg)] in adults with HIV-1 infection that is virologically suppressed on different antiretroviral therapy regimens [baseline antiretroviral therapy (bART)]; MK-8591A-051 or bictegravir/emtricitabine/tenofovir alafenamidei [BIC/FTC/TAF (50 mg/200 mg/25 mg)]; MK-8591A-052.
The success criterion for the primary efficacy hypothesis, as measured by the percentage of participants with HIV-1 RNA levels ≥50 copies/mL at Week 48, was met in both trials. DOR/ISL was demonstrated to be non-inferior to bART in open-label trial MK-8591A-051 and non-inferior to BIC/FTC/TAF in double-blind trial MK-8591A-052. The superiority criteria were not met in trial MK-8591A-052. Primary safety objectives of both trials were also met.
The company is planning to present detailed findings from these trials at a future scientific congress and will also plan to file these data with regulatory authorities. In the U.S., doravirine is approved for the treatment of adults with HIV-1 in combination with other antiretrovirals, as a single agent (PIFELTRO) and a component of a single-tablet regimen [DELSTRIGO; doravirine, lamivudine, and tenofovir disoproxil fumarate (DOR/3TC/TDF)].
We are encouraged by the results from these Phase 3 trials evaluating a once-daily, oral, two-drug, single-tablet regimen of doravirine and islatravir,” said Dr. Eliav Barr, senior vice president, head of global clinical development and chief medical officer, Merck Research Laboratories. “We are committed to advancing our clinical programs for islatravir in combination with other antiretrovirals as potential options to help address the needs of people living with HIV.
Islatravir (MK-8591), Merck’s investigational nucleoside reverse transcriptase translocation inhibitor (NRTTI), exhibits both transcriptase and translocation inhibition (which prevents nucleotide binding and incorporation to the DNA chain, resulting in immediate chain termination) and delayed chain termination (which prevents nucleotide incorporation even in the event of translocation). Islatravir is being evaluated in multiple early and late-stage clinical trials in combination with other antiretroviral therapies for the treatment of HIV-1. In addition to the MK-8591A-051 and MK-8591A-052 trials, ongoing Phase 3 trials of DOR/ISL include MK-8591A-053 in people with HIV who had not previously received treatment (treatment-naïve), and MK-8591A-054 evaluating open-label DOR/ISL (100 mg/0.25 mg) in individuals who participated in earlier Phase 3 trials of DOR/ISL (100 mg/0.75 mg).
