The first part of this study was a phase IIa randomized, double blind, placebo controlled, multi-center study to investigate adding efprezimod alfa to standard of care tacrolimus and methotrexate in acute graft-versus host disease (GVHD) prophylaxis for allogeneic hematopoietic stem cell transplantation (HCT) with matched unrelated donors in treatment of leukemia and myelodysplastic syndrome. The primary objective was to evaluate the safety, tolerability and dose-limiting toxicities (DLTs) of efprezimod alfa in participants undergoing matched unrelated donor myeloablative allogeneic HCT for malignant hematologic disorders. Three dose cohorts were planned with 240 mg at day -1 (one day prior to HCT), 480 mg at day -1, and the multi-dose cohort of 480-240-240 mg at day -1, day 14 and day 28. The efprezimod alfa : placebo randomization ratio was 3:1.~The second part was a prospective open label phase IIa expansion cohort trial investigating the addition of efprezimod alfa to standard acute graft-versus host disease (GVHD) prophylaxis for allogeneic hematopoietic stem cell transplantation (HCT). Based on the first part's safety results and the pharmacokinetic data, the phase IIa expansion dose was the multi-dose 480-240-240 mg regimen administered on day -1, day 14 and day 28, respectively. The primary objective of phase IIa expansion was to determine if the addition of efprezimod alfa to standard GVHD prophylaxis improves 180 days post-HCT grade III-IV acute GVHD-free survival (AGFS) when compared to Center for International Blood and Marrow Transplant Research (CIBMTR) database registered control participants who had standard GVHD prophylaxis alone. Eligible participants were those requiring allogeneic HCT for malignant hematologic conditions and receiving a myeloablative conditioning regimen.
This is a multicenter prospective phase IIa dose escalation and phase IIa expansion cohort clinical trial designed to evaluate the safety and tolerability of efprezimod alfa for acute GVHD prophylaxis.