Optimizing preparative regimen for umbilical cord blood transplantation in adult acute leukemia patients: Acute lymphoblastic leukemia requires myeloablative conditioning but not acute myeloid leukemia

Cord blood transplantation (CBT) is a valuable alternative to bone marrow transplantation in adults without readily available donors. We conducted this study to investigate the feasibility of CBT for adult patients with acute leukemia with regards to impact of different conditioning and graft-versus-host disease (GVHD) prophylaxis regimens on clinical outcomes. From 16 centers in Korea, 41 acute myeloid leukemia (AML) and 29 ALL (acute lymphoblastic leukemia) patients undergoing CBT were enrolled. For AML patients, the neutrophil engraftment was observed in 87.5% of reduced intensity conditioning (RIC) and 72.0% of myeloablative conditioning (MAC) (p = 0.242). The median RFS was 5 months and OS 7 months. Conditioning regimen did not affect relapse free survival (RFS) or overall survival (OS). GVHD prophylaxis using calcineurin inhibitors (CNI) plus methotrexate was associated with better RFS compared to CNI plus ATG (p = 0.032). For ALL patients, neutrophil engraftment was observed in 55.6% of RIC and 90.0% of MAC (p = 0.034). The median RFS was 5 months and OS 19 months. MAC regimens, especially total body irradiation (TBI)-based regimen, were associated with both longer RFS and OS compared to other conditioning regimens. In conclusion, individualized conditioning regimens will add value in terms of enhancing safety and efficacy of CBT.