Reduced late mortality risk contributes to similar survival after double-unit cord blood transplantation compared with related and unrelated donor hematopoietic stem cell transplantation

Abstract

Cord blood transplantation (CB-T) is increasingly used as a treatment alternative for hematologic malignancies. However, how CB-T compares to related (RD-T) and unrelated donor transplantation (URD-T) is not established. We compared survival of 75 double-unit CB-T, 108 RD-T, and 184 URD-T recipients who received transplants over the same period for the treatment of hematologic malignancies. Patients had similar ages and disease risk, and a similar percentage had acute leukemia. The incidence of day 180 transplant-related mortality (TRM) of 21% (95% confidence interval [CI]: 12-31) after CB-T was higher than that of RD-T recipients. However, this was compensated for by a low risk of TRM after day 180, and a relatively low incidence of relapse. Hence, the 2-year progression-free survival (PFS) of 55% (95% CI: 45-68) after CB-T was similar to that after RD-T or URD-T (P = .573). In multivariate analysis, donor source had no influence on PFS, with the only significant factors being recipient age and disease risk. In a subanalysis of 201 patients with acute leukemia, CB-T, RD-T, and URD-T recipients also had similar 2-year disease-free survival (P = .482). These data provide strong support for the further investigation of double-unit CB grafts as an alternative hematopoietic stem cell source.

Figure 1

The cumulative incidence of TRM after CB-T, RD-T, and URD-T: increased early mortality after CB-T was compensated for by reduced late mortality such that the 2 year TRM after CB-T was not different to that of RD-T and URD-T recipients.

Figure 2

The Kaplan-Meier incidence of OS after CB-T, RD-T, and URD-T: OS after CB-T was similar when compared with RD-T and URD-T.

Figure 3

The Kaplan-Meier incidence of PFS after CB-T, RD-T, and URD-T: 2 year PFS after CB-T was not different to that of RD-T and URD-T recipients.

Figure 4

Comparison of causes of death in the 2 years post-transplant according to HSC source: relapse followed by organ failure were the most frequent primary cause of death in RD-T and CB-T recipients, whereas relapse and GVHD were the most frequent primary causes of death in URD-T recipients.

Figure 5

Comparison of relapse after CB-T, RD-T, and URD-T in patients with acute leukemia transplanted in remission: CB-T recipients had a low risk of relapse.