Efprezimod Alfa (CD24Fc, MK-7110) for the Prevention of Acute Graft Versus Host Disease (GVHD) Following Myeloablative Hematopoietic Stem Cell Transplantation (HSCT) (MK-7110-005)

The study compares two acute graft-versus-host disease (aGVHD) prophylaxis regimens: efprezimod alfa vs placebo with the standard GVHD prophylaxis of tacrolimus / methotrexate. The study compares two acute graft-versus-host disease (aGVHD) prophylaxis regimens: efprezimod alfa/tacrolimus / methotrexate (efprezimod alfa/Tac/MTX) versus placebo/tacrolimus / methotrexate (placebo/Tac/MTX) in the setting of myeloablative conditioning (MAC), matched unrelated donor (MUD) allogeneic hematopoietic stem cell transplantation in participants with acute leukemia (AML/ALL) or myelodysplastic syndrome (MDS). The study agent, efprezimod alfa, will be administered through IV infusion on days -1, 14, and 28 at the dose of 480mg, 240 mg and 240mg, respectively. The placebo will be 100 ml normal saline intravenous (IV) solution.