Children with chronic phase chronic myeloid leukemia: characteristics and outcomes from the International Registry of Childhood CML

Abstract

Five hundred and thirty-five patients (median age 12.2 years, range: 8 months - 18 years; N=303 males, N=232 females) diagnosed with chronic myeloid leukaemia (CML) in chronic phase were registered in the International Registry of Childhood CML (www.clinicaltrials.gov NCT01281735). Clinical signs of leukostasis or bleeding were observed in 16.5% and 20% of the patients, respectively. The spleen was palpable in 76% of patients with a median of 9 cm (range, 1 to 32) below the costal margin. The median leukocyte count was 222 G/L (quartile 95-353). First-line therapy consisted of imatinib in 482 children. Among them, 40% remained on imatinib with a median follow-up 3.8 years (95% CI: 3.2-4.3 years); 3.1% died and 3.9% progressed to advanced phase disease. The overall survival rate at 36 months was 97.4% (95% CI: 95-99%). Progression free survival rate at 3-years was 97.1% (95% CI: 94.9-99.2%), 91.7% (95% CI:84.5-98.3%) and 72.0% (95% CI: 59-87.9%) in the Eutos Long Term Survival (ELTS) low, intermediate-, and high-risk group, respectively (p log rank<0.001). Pediatric CML is characterized by bulky disease (large splenomegaly, high leucocyte counts) and the ELTS score can identify children with the poorest outcome.