Outcomes of Myeloablative Allogeneic Hematopoietic Cell Transplantation with Omidubicel vs Haploidentical and Unrelated Donor Sources

• Omidubicel was associated with faster neutrophil but slower platelet engraftment compared to unrelated and haploidentical donor transplants.

• Overall survival, disease-free survival, chronic GVHD, and grade III/IV acute GVHD were similar among all donor sources.

Omidubicel is a nicotinamide-expanded stem cell product derived from umbilical cord blood (UCB). In a phase III randomized trial for high-risk hematologic malignancies, omidubicel had faster neutrophil engraftment and fewer infectious complications than standard UCB transplantation. However, the clinical outcomes of omidubicel relative to other stem cell donor sources are yet to be determined.

Clinical data for patients who underwent allogeneic hematopoietic cell transplantation (HCT) with omidubicel and standard UCB were taken from the phase III trial. The Center for International Blood and Marrow Transplant Research (CIBMTR) registry provided contemporaneous comparator cohorts of patients fitting the trial eligibility criteria who received allogeneic HCT from matched unrelated (MUD), mismatched unrelated (7/8 MMUD), and haploidentical donors.

Nine hundred fifty-one patients met the eligibility criteria, including 52 for omidubicel, 56 for standard UCB, 65 for 7/8 MMUD, 450 for MUD, and 328 for haploidentical donors. Omidubicel was associated with more rapid neutrophil engraftment compared to all other donor sources, but slower platelet engraftment relative to other donor sources aside from UCB. There were no significant differences in overall survival, disease-free survival, and non-relapse mortality among the donor sources. Omidubicel had a higher incidence of grade II-IV acute GVHD but similar rates of grade III-IV acute GVHD and chronic GVHD compared to the CIBMTR cohorts. These results support the role of omidubicel as a viable donor source in the current transplant landscape.