Clinical characteristics and treatment outcome of pediatric patients with chronic myeloid leukemia.

As chronic myeloid leukemia is rare in children, most data on imatinib mesylate therapy is derived from adult studies. We retrospectively evaluated pediatric (<14 years) patients with Ph+ chronic myeloid leukemia treated with imatinib mesylate, from January 2003 through June 2008. Of the 12 chronic myeloid leukemia patients (2% of all leukemias) 11 were in chronic phase while one had myeloid blast crisis. Six subsequently underwent stem cell transplantation. Five patients had grade 3-4 arthralgia requiring therapy alteration. None achieved complete molecular remission (MR) with imatinib mesylate alone. In contrast 3/6 patients post stem cell transplantation have undetectable BCR-ABL. Three patients relapsed to chronic phase (1 imatinib mesylate; 2 stem cell transplantation). Relapse free survival is 65.6% at four years and all are alive. Imatinib mesylate is effective therapy for children with chronic myeloid leukemia. However, cure probably requires stem cell transplantation. Acute toxicity of imatinib mesylate is tolerable, but long-term effects on growing children are unknown. Pediatric patients with chronic myeloid leukemia should undergo stem cell transplantation when appropriate related donors are available.