Prospective Evaluation of Alternative Donor from Unrelated Volunteer Donor and Cord Blood in Adult Acute Leukemia and Myelodysplastic Syndrome: No Difference between Unrelated Donor and Cord Blood

Background: Among HLA-well-matched unrelated donor (UD) and umbilical cord blood (CB), HLA-8/8 allele-matched UD transplantation (UDT) showed superior overall survival (OS) to 7/8 allele-matched UDT and CBT, while a similar OS has been demonstrated between the HLA-7/8 allele-matched UDT and the CBT. However, a fair comparison between UDT and CBT is difficult, because graft availability and time required for donor-search is completely different. Once patients relapsed during UD-search period, most of those patients would choose immediate CBT. This means that patients who maintained CR in UD group may have more favorable characteristics, because those patients have been longer in remission and selected as a group of patients who maintained CR. Thus we thought that the factor of “donor-search duration” is important upon conducting a comparative study between UDT and CBT. We planned a clinical study that also taken “donor-search duration” into consideration to compare CBT outcomes with HLA well-matched UDT in a prospective trial setting. Purpose: The purpose of the current study is to compare the transplant outcomes of HLA-well-matched UDT with those of CBT in a prospective trial. Patients and Methods: From 2007 to 2015, 231 patients were provisionally registered for a single-arm phase 2 study of CBT (manuscript submitted). All provisionally registered patients were subjects of current study (Figure 1). After provisional registration, we attempted to find appropriate UD within a decent time period. After approximately 180 days of donor-search, patients received CBT if an appropriate UD was not available. In total, 91 patients received UDT, and 119 patients received CBT. Six patients withdrew and three died before transplantation. Twelve patients did not receive either UDT or CBT, but five received HLA-mismatched SCT from family donor (seven chose not to receive allogeneic SCT). Of 119 CBT recipients, 62 patients were eligible and registered to a phase 2 clinical trial reported elsewhere. Herein we analyzed transplant outcomes of 91 UDT and 119 CBT (UDT group; 49 AML, 37 ALL, 5 MDS: CBT group; 68 AML, 38 ALL, 13 MDS). Risk factors were analyzed by cox proportional hazard model, and survival estimates were depicted by Kaplan-Meier estimation and tested by log-rank test. Results: Patient age was median 39 yrs in both UDT and CBT (p=0.80). Patient body weight was median 59kg (37-90kg) in UDT, and median 55kg (35-90kg) in CBT (p=0.10). Sixty-six of 91 (72.5%) in UD