1. Survival after allogeneic hematopoietic cell transplant was better in patients treated with cord blood than in patients treated with either HLA-matched or HLA-mismatched bone marrow or peripheral blood transplant.
2. Patients treated with cord-blood showed a lower risk of acute leukemia or myelodysplastic syndrome relapse than patients treated with HLA-matched or HLA-mismatched bone marrow or peripheral blood transplant.
Evidence Rating Level: 2 (Good)
Study Rundown: The first and second line donors for patients in need of allogeneic hematopoietic stem cell transplant (HSCT) are an HLA-identical sibling or an unrelated 10/10 HLA-matched unrelated donor, respectively. As these are the ideal donors, there are a substantial proportion of patients who will require alternative sources such as from an HLA-mismatched unrelated donor or unrelated umbilical cord-blood. This retrospective study was undertaken to compare outcomes after HLA-matched, HLA-mismatched, and cord-blood HSCT in patients with acute leukemia or myelodysplastic syndrome after myeloablative therapy.
The most noteworthy findings of this study were that cord blood cohort demonstrated improved probability of survival over the HLA-matched or HLA-mismatched bone marrow or peripheral blood cohorts. The cord blood cohort also demonstrated the lowest probability of relapse among the three cohorts. This study draws strength from adjusted analysis of the presence or absence of minimal residual disease on outcomes of HSCT, but it is limited by its use of retrospective data that make its findings equivocal.
In-Depth [retrospective cohort]: This retrospective cohort study examined 582 patients, among whom 344 received allogeneic HSCT from an HLA-matched unrelated donor (107 bone marrow, 237 peripheral blood), 98 received HSCT from an HLA-unmatched unrelated donor (28 bone marrow, 70 peripheral blood), and 140 received umbilical cord-blood graft. The percentage of patients with minimal residual disease at the time of transplantation was similar in all groups: 45/137 (33%) in the cord-blood group, 104/331 (31%) in the HLA-matched group, and 35/90 (39%) in the HLA-mismatched group.
There was no significant difference between HLA-matched group versus the cord-blood group (HR 1.12, 95%CI 0.77 to 1.63; p = 0.57). Furthermore, there was no significant difference in the HLA-mismatched group versus the cord-blood group was (HR 1.91; 95%CI 1.23 to 2.98; p = 0.004). At 4 years, the unadjusted estimate of the rate of survival was 71% (95%CI 62 to 77) in the cord-blood group, 63% (95%CI 57 to 68) in the HLA-matched group, and 49% (95%CI 38 to 58) in the HLA-mismatched group.
The hazard ratio for relapse in the HLA-matched group was significantly higher compared to the cord-blood group (HR 1.95; 95%CI 1.16 to 3.27; p = 0.01), and the hazard ratio in the HLA-mismatched group versus the cord-blood group was significantly higher as well (HR 1.97; 95%CI 1.04 to 3.73; p = 0.04). The 4-year unadjusted estimate of the risk of relapse was 15% (95%CI 9 to 21) in the cord-blood group, 24% (95%CI 19 to 29) in the HLA-matched group, and 25% (95%CI 16 to 34) in the HLA-mismatched group.
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