Nonhematologic toxicity of imatinib mesylate in pediatric patients with chronic myelogenous leukemia: a predominance of musculoskeletal pain.

Therapy with the tyrosine kinase inhibitor imatinib mesylate has become standard initial treatment for adult and pediatric patients with chronic myelogenous leukemia. Long-term follow-up data are now available in the adult population, and the toxicity profile of imatinib mesylate among adults has been extensively studied and reported. Despite its increasing use in the pediatric population, there are limited data regarding adverse event profiles of imatinib mesylate in children, and few reports exist in the literature focusing on nonhematologic toxicity in this population. We reviewed our institutional experience with imatinib therapy for chronic myelogenous leukemia over an 8-year period of time. Nine pediatric patients began therapy with imatinib mesylate and were included in this review. We reviewed the occurrence of nonhematologic toxicity in this cohort and the impact of that toxicity on continuation of therapy. Eight patients experienced nonhematologic toxicity, including nausea/vomiting (44.4%) and musculoskeletal pain (88.9%). Three patients (33.3%) required discontinuation of imatinib therapy due to grade 3/4 musculoskeletal pain, a rate that is significantly higher than that seen in the adult population. As imatinib therapy becomes increasingly widespread in the treatment of pediatric malignancies, there may be different patterns of clinically significant nonhematologic toxicity, including higher grade musculoskeletal pain.