Outcome for Children Treated for Relapsed or Refractory Acute Myelogenous Leukemia (rAML): A Therapeutic Advances in Childhood Leukemia (TACL) Consortium Study

Background. Current event-free survival (EFS) rates for children with newly diagnosed acute myeloid leukemia (AML) approach 50-60%. We hypothesize that further improvements in survival are unlikely to be achieved with traditional approaches such as dose intensive chemotherapy or hematopoietic stem cell transplants, since these therapies have been rigorously explored in clinical trials. This report highlights efforts to assess the response rates and survival outcomes after first or greater relapse in children with AML. Procedure. We performed a retrospective cohort review of pediatric patients with relapsed and refractory AML (rAML) previously treated at TACL institutions between the years of 1995 and 2004. Data regarding disease characteristics at diagnosis and relapse, treatment response, and survival was collected on 99 patients and 164 medullary relapses or treatment failures. Results. The complete response (CR) rate following the second therapeutic attempt was 56 +/- 5%. CR rates following a third treatment attempt was 25 +/- 8% while 17 +/- 7% achieved CR following the fourth through sixth treatments. The 5-year disease-free survival in patients achieving CR following a second therapeutic attempt was 43 +/- 7%. The 5-year EFS and overall survival (OS) rates for all patients receiving a second treatment attempt was 24 +/- 5% and 29 +/- 5%, respectively. Conclusions. This CR rate following a second therapeutic attempt and OS rate in patients with rAML is consistent with the literature. There are limited published data of CR rates for subsequent relapses. Our data can serve as a historical benchmark to compare outcomes of future therapeutic trials in rAML against traditional chemotherapy regimens. Pediatr Blood Cancer. (C) 2010;55:421-429. 2010 Wiley-Liss, Inc.