Clinical efficacy and safety of imatinib treatment in children and adolescents with chronic myeloid leukemia: A single-center experience in China.

Chronic myeloid leukemia (CML) is relatively rare in childhood and few studies have reported the clinical use of imatinib (IM) in pediatric CML. In this study, we evaluated the efficacy and tolerability of IM in children and adolescents with CML.We investigated 21 patients under 18 years of age with newly diagnosed CML and treated with IM in Children's Hospital of Chongqing Medical University between May 2014 and February 2018. The disease was staged according to the European LeukemiaNet criteria and the IM dose was determined based on the disease stage. Cumulative responses and survival probabilities were estimated according to the Kaplan-Meier method.The estimated complete hematologic response rate of chronic phase-chronic myeloid leukemia (CML-CP) was 89.5% at 3 months. The complete cytogenetic response rates increased with time, reaching 47.4%, 73.7%, and 80.3% at 6, 12, and 24 months, respectively. The cumulative major molecular response rates were 42.1% and 76.3% at 12 and 24 months, respectively. With a median follow-up time of 33.8 months (range, 3.2-61.7 months), the estimated 2-year overall survival (OS) rate for CML was 95.2% (95% confidence interval [CI], 70.7%-99.3%). None of the CML-CP patients progressed to the accelerated phase or had a blast crisis. The 2-year OS and progression-free survival rates for the CML-CP cohort were both 100%, while the estimated 2-year event-free survival rate was 68% (95% CI, 42.1%-84.2%). None of the patients in this group had treatment-related deaths or IM discontinuation due to drug toxicities, and only 1 patient had a grade III-IV nonhematologic adverse event. Overall, anemia was the most common adverse effect and 42.9% of patients had a decrease in bone mineral density.IM was effective and the adverse effects were well-tolerated throughout the follow-up period in Chinese CML patients under 18 years of age.