Low relapse without excessive transplant-related mortality following myeloablative cord blood transplantation for acute leukemia in complete remission: a matched cohort analysis

Abstract

Growing evidence supports the efficacy of cord blood transplantation (CBT), and the number of CBTs is increasing. Numerous studies confirm the presence of a graft-versus-leukemia (GVL) effect following CBT, and preliminary data suggests that double-unit CBT may be associated with a decreased risk of relapse. We have observed a low relapse rate following CBT among patients with acute leukemias in morphologic complete remission (CR) at the time of myeloablative (MA) transplant. To further assess this observation, we conducted a matched cohort analysis comparing relapse rates and outcomes for patients receiving CBTs versus patients receiving matched unrelated donor (MURD) and mismatched unrelated donor (MMURD) transplants at our center. Thirty-one consecutive CBT patients (aged 0.6-42 years, median 22 years), transplanted between April 2006 and June 2008, were compared to matched subjects selected on the basis of disease type and remission number, cytogenetic risk status, minimal residual disease status (MRD), time from diagnosis to first relapse (for patients beyond CR1), use of imatinib for chronic myelogenous leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL) patients, age, and date of transplant. With a median follow-up among surviving CBT patients of 21.1 months (range: 6.6-32.6 months), there has been 1 relapse among cord patients versus 8 relapses among MURD patients (P=.018) and 7 relapses among MMURD patients (P=.019). Treatment-related mortality (TRM) between cohorts is comparable. Although we have observed a high incidence of acute graft-versus-host disease (aGVHD) following CBT, the incidence of National Institutes of Health (NIH) consensus criteria chronic GVHD (cGVHD) has been low. These data support increased investigation of the use of CBT.

Figure 1. Cumulative incidence of relapse and transplant related mortality by cohort

Relapse (A) and transplant related mortality (B).

Figure 2. Cumulative incidence GVHD by cohort

Grade II-IV GVHD through day 100 (A), grade III-IV GVHD through day 100 (B), and composite endpoint of ≥ moderate chronic GVHD or grade II-IV late, persistent, or relapsing acute GVHD (C).

Figure 3. Overall and relapse free survival

Kaplan-Meier estimates of overall survival (A) and relapse free survival (B).