Merck, known as MSD outside of the United States and Canada, will initiate a new Phase 3 clinical program with once-daily islatravir for the treatment of people with HIV-1 infection.
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These new Phase 3 studies will evaluate a once-daily oral combination of doravirine 100 mg and a lower dose of islatravir (DOR/ISL).
One study will evaluate DOR/ISL in previously untreated adults with HIV-1 infection and two studies will evaluate DOR/ISL as a switch in antiretroviral therapy (ART) in adults with HIV-1 infection who are virologically suppressed.
Certain study participants currently enrolled in once-daily treatment studies with DOR 100 mg/ISL 0.75 mg will have the option of transitioning to a new study with the lower islatravir dose. The U.S. Food and Drug Administration (FDA) has reviewed and agreed with this plan.
The investigational new drug application (IND) for the once-daily oral DOR/ISL treatment program remains under a partial clinical hold for any studies that would use doses higher than the dose to be studied in the new Phase 3 program.
The Phase 2 clinical trial (NCT05052996) evaluating an investigational oral once-weekly combination treatment regimen of islatravir and Gilead’s lenacapavir in adults with HIV-1 infection who are virologically suppressed will resume under an amended protocol with a lower dose of islatravir.
The IND under which the islatravir + lenacapavir once-weekly treatment regimen is being investigated remains under a partial clinical hold for any studies that would use weekly oral islatravir doses higher than the doses considered for the revised clinical program.
Islatravir and lenacapavir, in combination, are investigational and not approved for use. The safety and efficacy of this combination has not yet been established.
Additionally, after careful evaluation and analysis, Merck will discontinue the development of once-monthly oral islatravir for PrEP. Participants in the ongoing Phase 3 PrEP once-monthly oral studies will continue to be monitored.
The company remains committed to developing compounds for long-acting HIV prevention and believes in the potential of the nucleoside reverse transcriptase translocation inhibitor (NRTTI) mechanism. A Phase 1b study in adults with HIV-1 infection assessing MK-8527, a novel NRTTI candidate, will commence shortly (NCT05494736). ■