Prognostic analysis of relapsed acute leukemia following first allogeneic hematopoietic stem cell transplantation

Abstract

Relapse after allogeneic hematopoietic stem cell transplantation (HSCT) shows an extremely poor prognosis. Here, we retrospectively examined both the clinical outcome and the usefulness of minimal residual disease monitoring of nineteen patients who experienced relapse after the first HSCT with the aim of identifying significant prognostic factors. The median observation period from relapse after the first HSCT was 804 days. The three-year overall survival and disease-free survival rates were 25.2±9.9% and 18.5±10.3%, respectively. Fifteen of 19 patients developed bone marrow (BM) relapse and four experienced isolated extramedullary relapse. Fourteen (12 with BM and two with extramedullary relapse) underwent a second HSCT. Eleven of twelve patients with hematological relapse in BM failed to regain complete remission and succumbed. By contrast, two patients with molecular relapse regained molecular remission after post-transplant chemotherapy and remained disease-free after the second HSCT. The time of the second HSCT was the only factor significantly associated with improved outcome. Molecular relapse was detected in four of five patients in whom MRD levels were serially measured by WT1 mRNA PCR assay. Thus, early detection of post-transplant relapse by aggressive MRD monitoring and chemotherapeutic intervention at the time of molecular relapse are mandatory to improve the clinical outcome of patients who relapsed after allogeneic HSCT.