Impact of donor source on allogeneic stem cell transplantation for Philadelphia chromosome-negative acute lymphoblastic leukemia.

6533 Background: Although allogeneic stem cell transplantation (allo-SCT) could improve the outcome of adult Philadelphia chromosome-negative acute lymphoblastic leukemia [Ph(-) ALL], the impact of the donor source, particularly the position of cord blood (CB) transplantation, is still uncertain. Methods: We retrospectively analyzed 1726 adult Ph(-) ALL patients transplanted at the first time between 1998 and 2009 with myeloablative preparative regimens who were registered in the Japan Society for Hematopoietic Cell Transplantation database. Two hundred and thirty-three received CB transplantation [first complete remission (CR1): 95, subsequent CR: 53, non-CR: 85], 809 received allo-SCT from unrelated donor (URD) (CR1: 434, subsequent CR: 158, non-CR: 217), and 684 received allo-SCT from related donor (RD) (CR1: 388, subsequent CR: 89, non-CR: 207). Results: Overall survival (OS) in patients after CB transplantation in CR1 was comparable with that after allo-SCT from URD or RD [57% in CB, 64% in URD, and 65% in RD at 4 years, respectively, P=0.11]. Donor source was not a significant risk factor for OS in multivariate analysis. Although URD was a favorable factor for relapse and an unfavorable factor for non-relapse mortality (NRM), CB was not a significant factor for them [Relapse: 22% in CB, 17% in URD, and 24% in RD at 3 years, respectively (P=0.02); NRM: 27% in CB, 23% in URD, and 13% in RD at 3 years, respectively (P=0.0001)]. Among CB recipients in CR1, age at allo-SCT (45 years or older) was solely a significant adverse prognostic factor in multivariate analysis. Among patients younger than 45 years who received allo-SCT in CR1, OS after CB transplantation was significantly better than that after allo-SCT from mismatched URD (4-year OS: 68% vs. 49%, P=0.04). Similarly, OS was not different by donor source in subsequent CR or non-CR [Subsequent CR: 48% in CB, 39% in URD and 48% in RD, P=0.33; non-CR: 18% in CB, 21% in URD, and 15% in RD, P=0.20 at 4 years, respectively]. Conclusions: Allo-SCT using CB led to similar outcomes as either RD or URD in any disease status. CB transplantation is a good alternative for adult Ph(-) ALL patients without a suitable RD or URD.