Factors Predictive of Relapse of Acute Leukemia in Children after Allogeneic Hematopoietic Cell Transplantation

The presence of minimal residual disease (MRD) before transplantation is the most important prognostic risk factor predictive of post-transplantation relapse in hematologic malignancies. However, MRD alone does not adequately predict relapse in all patients. To improve upon the ability to identify patients likely to relapse, we evaluated risk factors, in addition to MRD, that may be associated with development of post-transplantation relapse. In this single institution, retrospective cohort study of children with acute leukemia or myelodysplastic syndrome who had undergone a first allogeneic transplantation and had pretransplantation MRD evaluation, 40 of 93 patients (43%) experienced relapse. Univariate analysis demonstrated that African American race, high initial white blood cell count, central nervous system (CNS) disease at diagnosis, short first complete remission, nonmyeloablative (NMA) conditioning, lack of remission, and MRD before transplantation were associated with worse relapse-free survival (RFS). In a Cox multivariable analysis, CNS disease (P = .009), lack of remission (P = .01), and NMA conditioning (P = .04) were independently associated with inferior RFS. Among those in a morphologic complete remission who underwent a myeloablative transplantation, having both CNS disease at diagnosis (specifically in acute lymphoblastic leukemia) and MRD positivity was an independent risk factor predictive of relapse, which has not been previously reported. Results from our study support the existence of risk factors complimentary to pretransplantation MRD. Validation in a larger independent homogenous cohort is needed to develop a prognostic tool for clinical use to predict post-transplantation relapse.