Background: Many AML patients have received hematopoietic stem cell transplantation (HSCT) from HLA-matched unrelated donors. According to many of the previous reports, those patients could achieve long-term, disease-free survival after HSCT from multinational unrelated donors with tolerable transplant-related complications, even when there are HLA-mismatches.

Methods:
We present the results of 35 unrelated hematopoietic stem cell transplantations from multiple international donor banks including the Korean (n=24), and Japan Marrow Donor Program (n=3), the Taiwan Tzu Chi Marrow Donation Registry (n=6), as well as using Caucasian donors from the National Marrow Donor Program (n=2), for the treatment of AML patients.

Results:
The median age of patients was 36 (range: 16∼53) and the median follow-up duration was 21 months (range: 5∼60). Also, the median age of the donors was 28 (range: 20∼53). The majority of the patients had intermediate or unfavorable cytogenetic features. The main conditioning regimen we used consisted of cyclophosphamide plus TBI (n=31) with our standard GvHD prophylaxis that contained tacrolimus plus a short course of methotrexate. Some patients (n=10) received an additional two-day course of ATG (thymoglobulin, Sangstat) in addition to the standard regimen. All the transplanted patients achieved engraftment. The incidence of acute GvHD was 42%, and that of chronic GvHD was 56%. Four (11%) patients have relapsed to date. The two-year non-relapse transplant-related mortality was 26%. The estimated probability of DFS and the event-free survival at five-years were 80% and 53%, respectively.

Conclusion:
These results suggest that multinational unrelated donors HSCT may provide a feasible option for the treatment of high-risk Korean AML patients.

Keywords: Multinational unrelated donor, HSCT, AML, GvHD