A Retrospective Study of Pediatric Patients With Low- or Intermediate-Risk Acute Myeloid Leukemia Who Underwent Allogeneic Hematopoietic Cell Transplantation for the AML-05 Study Conducted by the Japanese Pediatric Leukemia/Lymphoma Study Group

The AML-05 study aimed to examine the efficacy and safety of a therapeutic strategy based on risk stratification for low-, intermediate-, or high-risk acute myeloid leukemia (AML) pediatric patients. Allogeneic hematopoietic cell transplantation (allo-HCT) was not indicated for low- or intermediate-risk AML patients in first complete remission. The present retrospective study for the AML-05 study aimed to identify prognostic factors for survival and to determine optimal allo-HCT according to multivariate analysis on overall survival (OS), event-free survival (EFS), cumulative incidence of relapse (CIR), and cumulative incidence of nonrelapse mortality for and between low- and intermediate-risk AML group patients in the AML-05 study who had undergone allo-HCT after its completion and relapse. The unique patient numbers (UPNs) of the AML-05 study were matched with the Transplant Registry Unified Management Program (TRUMP)-registered numbers, and the tied data on the AML-05 study's UPNs and the TRUMP-registered numbers were analyzed. The primary endpoint was 3-yr OS. Among 443 AML patients in the AML-05 study, 79 (32 low-risk AML and 47 intermediate-risk AML) were analyzed. The following statistically favorable prognostic factors were identified by multivariate analysis on the low- and intermediate-risk AML groups, respectively: UCB (OS—hazard ratio [HR], 0.105; 95% CI, 0.011 to 0.941; P = .004 and EFS—HR, 0.065, 95% CI, 0.007 to 0.577, P = .014) and late relapse (OS—HR, 0.212; 95% CI, 0.072 to 0.626; P = .005 and EFS—HR, 0.236; 95% CI, 0.088 to 0.630; P = .004). Three-year OS, 3-yr EFS, and 3-yr CIR were significantly different between the low- and intermediate-risk AML groups. UCB may be a safe and beneficial donor source for low-risk AML patients, while late relapse was a favorable prognostic factor for intermediate-risk AML patients. Intermediate-risk AML patients with late relapse and low-risk AML patients may benefit from allo-HCT after relapse.