Abstract 2 Results of an Open Label Expanded Access Study of Omidubicel-onlv for Allogeneic Transplantation (allo-HCT) in Patients with Hematologic Malignancies

Abstract

Abstract Introduction Omidubicel, a nicotinamide expanded allogeneic hematopoietic progenitor cell therapy derived from umbilical cord blood (UCB) was recently FDA approved for use as a sole donor source in allo-HCT based on phase III study results showing improved hematopoietic recovery and decreased infection rate compared to standard UCB. Objectives Open label, single arm expanded access program (EAP) evaluating clinical outcomes for patients with hematologic malignancies following omidubicel allo-HCT. Methods Eligible patients (>12 years) received myeloablative conditioning with supportive care per institutional guidelines. Patients were followed for engraftment, infections, graft versus host disease (GVHD), and two year post-transplantation outcomes. Results Between July 2020 and April 2023, 36 patients were enrolled at 5 US centers, and 29 (18 male, 11 female) were transplanted; median age was 38 years (range: 20-73); 55.2% white, 17.2% Black, 20.7% Asian, 10.3% other. Diagnoses included AML (37.9%), ALL (27.6%), MDS (20.7%) and other (13.8%). Median transplanted CD34+ cell dose was 5.6x106 cells/kg and HLA match was 4/6 in 51.7%, 5/6 in 44.8%, and 6/6 in 3.5%. Median follow-up was 6.25 months (range 0.33-27.7). At 100 and 365 days post-transplant, PFS rates were 95.5% and 82.9%, and OS rates were 96.3% and 84.4%, respectively. No infusion reactions were reported. Median neutrophil (>500/µl x3 days) and platelets (>20,000/µl x7 days) engraftment times were 12 and 33 days, respectively. Primary graft failure occurred in 2 (6.9%) patients, both alive >100 days after second transplant. Incidence of first grade 2 or 3 bacterial, viral, or invasive fungal infections through 100 days post-transplantation were 13.8%, 24.1% and 0%, respectively. Acute GVHD was reported in 13 (44.8%) patients (grade II: 34.5%, grade III: 10.3%) and mild chronic GVHD in 1 (3.5%). There were 4 deaths (13.8%): 2 due to relapse @275 and 381 days, 1 due to infection (day 135) and 1 due to pulmonary failure on day 10. Post-transplant lymphoproliferative disease was reported in one. Discussio In this real-world EAP setting, allo-HCT with omidubicel was well tolerated, and observed engraftment and infections consistent with published Phase 3 data. These data further support the role of omidubicel particularly for patients from diverse racial backgrounds.