Autologous Purified Peripheral Blood Stem Cell Transplantation Compare to Chemotherapy in Childhood Acute Lymphoblastic Leukemia After Low-Risk Relapse

Background. The treatment of childhood B-cell precursor acute lymphoblastic leukemia (ALL) after isolated extramedullary or late relapse is mostly based on chemotherapy or allogeneic transplantation. The aim of this study is to provocatively assess the role of purified autologous transplantation compared with best chemotherapy results in the same setting. Procedure. We reported a series of 30 pediatric patients who underwent purified peripheral blood autologous transplantation for ALL in CR2, after isolated extramedullary (7), or late medullary (23) relapse from January 1997 and March 2004. Among 246 patients treated with chemotherapy within Berlin-Frankfurt-Munster relapse protocols during the same period, we found 103 controls who matched our 30 cases, according to site of relapse, CR1 duration, time elapsed in CR2, and period of relapse. Results. Event-free survival and survival at 5 years after relapse were 73.3% (SE 8.1) and 86.5% (SE 8.2) for auto-transplanted cases and 40.0% (SE 9.7) and 62.5%(SE 9.6) for chemotherapy-treated controls (P-values: 0.012 and 0.025, respectively). The risk of relapse after auto-transplantation at 1 and 4 years was approximately half and one-fifth, respectively, of the same risk obtained with chemotherapy. Conclusions. This matched analysis showed an advantage of purified autologous transplantation compared with chemotherapy in low-risk relapsed ALL, possibly explained by the single-center effect, the myeloablation of total body irradiation, the documented low tumor burden at mobilization and the stem cell isolation procedure. Pediatr Blood Cancer 2011;57:654-659. (C) 2011 Wiley-Liss, Inc.