Outcomes of pediatric chronic myeloid leukemia diagnosed in chronic phase in Hong Kong

Abstract

PURPOSE/OBJECTIVE: To determine the outcomes in children with chronic myeloid leukemia (CML) diagnosed in chronic phase (CP) in Hong Kong. Materials and METHODS: We retrospectively reviewed the clinical data of children with CML diagnosed in CP treated in all 5 pediatric oncology units in Hong Kong from 1996 to 2011. RESULTS: Thirty-one children were diagnosed with CML in CP (median age 12.7 years, range 5.6-17.9 years, 24 were males). Treatments included imatinib (n = 1), hydroxyurea followed by imatinib (n = 18), hydroxyurea and cytarabine followed by imatinib (n = 4), hydroxyurea and interferon followed by imatinib (n ? 1), hydroxyurea alone (n = 5), or hydroxyurea followed by interferon (n = 2). Five patients proceeded to allogeneic hematopoietic stem cell transplant (HSCT) (matched sibling donor: n = 4, matched unrelated donor: n = 1). All 24 patients on imatinib achieved complete hematological response at a median of 5.2 weeks (range, 0.7-20.1 weeks), 16 patients achieved complete cytogenetic response at a median of 10.9 months (range, 3.2-44.6 months), and 16 patients achieved major molecular response at a median of 20.1 months (range, 6.7-48.3 months). Seven patients progressed to blastic phase at a median of 8.6 months after diagnosis (range, 0.8-76.9 months), 4 of whom had not received imatinib. Five-year overall survival (OS) and progression-free survival (PFS) were 89.5% and 80.1% for all patients, and were better for patients treated with imatinib compared to those who were not (OS: 95.5% vs. 66.7%, p ? 0.024; PFS: 91.7% vs. 34.3%, p < 0.001). Patients who remained on imatinib also appeared to have better survivals compared to those who proceeded to HSCT (OS: 95.0% vs. 80.0%; PFS: 90.9% vs. 80.0%), though the differences were not statistically significant. CONCLUSIONS: Outcome of pediatric CML diagnosed in chronic phase is favorable, especially for those who were treated with imatinib. Imatinib or other tyrosine kinase inhibitors could be a durable form of first-line treatment and the role of HSCT may have to be reevaluated in future study.