Comparison of Outcomes of Bone Marrow and Umbilical Cord Blood Transplants from Unrelated Donors in Adult Patients with Acute Myeloid Leukemia/Myelodysplastic Syndrome.

<Objectives> Promising results of cord blood transplants from unrelated donors have been reported in adults. To compare of outcomes of bone marrow transplants (BMT, n = 51), and umbilical cord blood transplants (UCBT, n = 110) from unrelated donors in adult patients with acute myeloid leukemia (AML) / myelodysplastic syndrome (MDS), we analyzed retrospectively the results of 161 adult patients with AML and MDS in our hospital.

<Patients and Methods> We reviewed medical records of 161 patients with AML/MDS who had received a hematopoietic stem cell transplant from an unrelated donor between August 2000 and April 2007 at Toranomon Hospital, Tokyo, Japan.

<Results> Patient’s median age was 55 years (17–71). Diagnoses include de novo AML (n =85), MDS overt AML (n=48), refractory anemia (RA) (n=13), and refractory anemia with excess of blasts (RAEB) (n=15). Disease status consisted of standard (CR1 of AML and RA, n=30) and advanced (other status, n=131). Recipients of UCBT had more advanced disease than recipients of BMT at the time of transplantation (89 percent vs. 65 percent, P<0.001). The median number of nucleated cells that were infused was 0.26×10⁸ per kilogram of the recipient’s body weight for cord blood and 2.5×10⁸ per kilogram for bone marrow (P<0.001). The major difference were higher number in the UCBT group of HLA mismatches (defined by serology for class 1 and molecular typing for DRB1).The donor was HLA mismatched in 96% of UCBT recipients, and in 41% of BMT recipients (P<0.001). Other significant differences were observed in preparative regimens, and graft-versus-host disease (GVHD) prophylaxis. Nonadjusted estimates of 2-year OS and DFS rates were 53% and 48% in the BMT group, and 33% and 25% in the UCBT group (P<0.001). However, 2-year OS and DFS rates in the standard group were not significantly different in the two groups (63% and 63% in the BMT group, and 75% and 58% in the UCBT group; p=0.98 and 0.32). Compared with BMT recipients, UCBT recipients had delayed hematopoietic recovery (Hazard ratio [HR]= 0.52; 95% confidence interval [95CI]: 0.36–0.75; p<0.001), increased 100 day TRM (HR=3.07; 95CI 1.45–6.51; p<0.01) and decreased grade II–IV acute graft-versus-host disease (aGVHD) (HR=0.58; 95CI 0.35–0.96; p=0.03). Two-year relapse rate was not significantly different in the two groups.

<Conclusion> We conclude that UCBT from an unrelated donor is a therapeutic option for adult AML/MDS patients who lack an HLA-identical donors. Higher mortality, especially from non-relapse causes, is the biggest problem to be solved to increase the feasibility of this approach.