Clinical Outcomes of Cord Blood Transplantation from Unrelated Donors Comparable with Marrow or Blood Transplantation from Related Donors in Adults: A Single Institute Analysis.
Authors: Takahashi Satoshi , Ooi Jun , Tomonari Akira , Konuma Takaaki , Fukuno Kenji , Tsukada Nobuhiro , Monna-Ooiwa Maki , Yamaguchi Takuhiro , Tojo Arinobu , Asano Shigetaka 
Published: April 2020

We previously reported some promising results of cord blood transplantation (CBT) compared with bone marrow transplantation (BMT) from unrelated donors in terms of graft-versus-host disease (GVHD), transplant-related mortality (TRM), and disease-free survival (DFS) in our institute (Blood104: 3813, 2004). If the patient was eligible for allogeneic transplantation without any related donors, we performed CBT immediately, rather than waiting for the results of an unrelated marrow donor search. This might be one of the reasons for our favorable CBT results in adults compared with most previously published studies.

We studied the clinical outcomes of 163 adults with hematological malignancies who received unrelated CBT (n=92), or BMT or peripheral blood stem cell transplantation (PBSCT) from related donors (n=71, 55 BMT and 16 PBSCT) between January 1997 and February 2005. All patients received myeloablative regimens including 12 Gy of total body irradiation and almost the same supportive care. We analyzed the hematopoietic recovery, rates of GVHD, risks of TRM and relapse, and DFS using Cox proportional hazards models. The age, sex, cytomegalovirus serological status, time from diagnosis to transplantation, and GVHD prophylaxis regimens were not significantly different between both groups. Overall rates of high-risk patients in the CBT and in BMT/PBSCT groups were 58% and 63%, respectively. Human leukocyte antigen (HLA) was scored serologically for HLA-A and B and genetically for DRB1 alleles. There were no complete matches in CBT and 54 (76%) matched grafts in BMT/PBSCT. Median numbers of leukocytes and CD34+ progenitor cells before freezing of cord blood grafts were 2.4x107/kg and 0.9x105/kg, respectively. Median follow-up was 27 months for CBT and 50 months for BMT/PBSCT.

Significant delays in neutrophil and platelet engraftment rates occurred after CBT; however, overall myeloid engraftment rates were almost the same for both grafts (94% in CBT and 98% in BMT/PBSCT). The cumulative incidences of grades II to IV acute GVHD, of grades III and IV acute GVHD, and of requiring steroids for treating acute GVHD among CBT recipients were 58%, 8%, and 18%, respectively. Those among BMT/PBSCT recipients were 58%, 19%, and 38%, respectively. Chronic GVHD affected 68 of 75 CBT and 49 of 60 BMT/PBSCT evaluable recipients. Twenty-two CBT and 30 BMT recipients developed extensive GVHD. The 1-year cumulative incidence of TRM, the 3-year cumulative incidence of relapse, and the 3-year probability of DFS in CBT recipients were 9%, 18%, and 71%, compared with 13%, 26%, and 60% in BMT/PBSCT recipients. Multivariate analysis demonstrated no apparent difference in those outcomes between both groups.

Taken together, engraftment speed was slower and severe acute GVHD and extensive chronic GVHD tended to be lower in CBT recipients compared with BMT/PBSCT recipients; however TRM, relapse and DFS were comparable in both groups. These data suggest that cord blood from unrelated donors could be as safe and effective a stem cell source as bone marrow or mobilized peripheral blood from related donors for adults when it is used as a primary unrelated stem cell source.