Safety and Clinical Outcomes of Pooled Donor, Nonengrafting Expanded Progenitor Cells in Single-Unit Cord Blood Transplantation.

Abstract

Cord blood transplantation (CBT) is limited by delayed hematopoietic recovery leading to frequent use of double-unit grafts. This phase II study evaluated the safety of adding dilanubicel, a cryopreserved, cord blood (CB)-derived, non-human leukocyte antigen-matched expanded progenitor cell product generated from pooled donors to single-unit CBT. Between March 2022 and July 2025, we enrolled 28 patients with hematologic malignancies in this single-center phase II trial. The infusion of a matched single CB unit was followed by a target dose of 800 × 10⁶ CD34⁺ cells of dilanubicel. All patients received a myeloablative conditioning regimen and graft-versus-host disease (GVHD) prophylaxis consisting of cyclosporine and mycophenolate mofetil. The median age was 36 years (range, 10-63). Underlying diagnoses included acute leukemias (n = 25) and other hematologic malignancies (n = 3). All patients engrafted neutrophils (median, 18 days; range, 14-30) and platelets (median, 31 days; range, 26-43). Dilanubicel induced transient myelomonocytic recovery, peaking on day 7 and absent by day 14. An early lymphocyte expansion, derived exclusively from the CB graft, occurred by day 9 and peaked by day 11. No grade 3 to 4 acute or chronic GVHD was observed. At a median follow-up of 1.4 years, 27 patients remain alive and disease-free. When evaluated alongside a contemporaneous institutional cohort receiving standard single- or double-unit CBT, patients treated with dilanubicel demonstrated faster hematopoietic recovery and a markedly lower incidence of severe acute GVHD. The addition of dilanubicel to single-unit CBT demonstrated a favorable safety profile, with no severe acute or chronic GVHD, and was associated with excellent clinical outcomes. These findings support further investigation of this strategy.