Unrelated Cord Blood Transplantation Using Myeloablative Regimen for Acute Leukemia Patients Aged between 50 and 55 Years: Single Institutional Retrospective Comparison with Patients Less Than 50 Years of Age.

Background: Increasing age has been well-known as an obvious risk factor for graft-versus-host disease (GVHD) and transplant-related mortality (TRM) resulting negative impact on allogeneic transplantation including cord blood transplant (CBT). The incidence of sever GVHD after CBT, on the other hand, is lower than that after transplants using graft from adult cells, so we have expected the better results of CBT in older patients.

Objectives and Methods: This study aimed to evaluate safety and efficacy of CBT using myeloablative regimen for older patients with acute leukemia.

Patients and Methods: We retrospectively compared outcomes of older patients with acute leukemia with younger adults in our institute. Nineteen elderly patients (median age 52, range 50–55) and 81 young patients (median 49, range 16–49) received myeloablative conditioning regimen including 12 Gy of total body irradiation. GVHD prophylaxis comprised cyclosporine with (N=96) or without (N=4) methotrexate.

Results: Comparisons of characteristics in the 2 age groups showed similar distributions for weight, gender ratio, diagnosis [de novo acute myeloid leukemia (AML), myelodysplastic syndrome related secondary AML, or acute lymphoblastic leukemia], disease status at transplantation, total nucleated cell dose and CD34⁺ cell dose in the graft before cryopreservation and proportions of HLA and sex compatibility between donors and recipients. The median period of follow-up for survivors after CBT was 730 days for older group and 1331 days for younger group, respectively. Grade II to IV acute GVHD occurred in 10 of 17 evaluable older patients and 49 of 75 evaluable younger patients (P = 0.61), while no older patients, but 6 younger patients developed grade III to IV acute GVHD. Extensive-type chronic GVHD occurred in 4 of 15 evaluable older patients and 18 of 69 evaluable younger patients (P = 0.96), respectively. The cumulative incidence of TRM at 100 days was 5% versus 6% (P = 0.70), and of relapse at 3 years was 29% versus 20% (P = 0.33) and the estimated disease-free survival at 3 years was 67% and 71% (P = 0.53) for older or younger patients, respectively. There was no significant difference in GVHD, TRM, relapse, and DFS between 2 age groups.

Conclusion: The use of cord blood as a stem cell source might contribute to be decreased in the incidence of acute and chronic GVHD resulting in decreased TRM in older patients. Our results suggest that myeloablative CBT might be as safe and effective in patients with acute leukemia aged between 50 and 55 years as in younger patients.