Imatinib is an inhibitor of the
BCR–ABLfusion gene product that characterizes chronic myeloid leukemia (CML), and of the related tyrosine kinases c‐KIT and platelet‐derived growth factor (PDGF) receptor. The drug is now included as front‐line therapy for CML and Philadelphia chromosome‐positive acute lymphoblastic leukemia in children and adolescents, though valid concerns about serious late sequelae remain unresolved and are important issues for further study. European and North American consortia have conducted phase I and II clinical trials of imatinib in children and adolescents with brain and other solid tumors that have provided little evidence of efficacy. Pediatr Blood Cancer 2010;55:18–25. © 2010 Wiley‐Liss, Inc.