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

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 5.6x10(6) 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.