Efficacy of imatinib mesylate-based front-line therapy in pediatric chronic myelogenous leukemia

Abstract

Purpose: Despite the established role of imatinib (IM) in chronic myelogenous leukemia (CML) in adults, there are few reports on its efficacy in children. In this study, we compared the outcomes of children with CML before and after the advent of IM-based treatment.

Methods: The study cohort consisted of 52 patients treated for CML at the Department of Pediatrics, The Catholic University of Korea from January 1995 to October 2010. Patients were divided and analyzed according to the preImatinib group (pre-IMG) and imatinib group (IMG).

Results: Median age at diagnosis for the overall cohort (pre-IMG, n=27; IMG, n=25) was 9 years, with a median follow-up duration of survivors of 84 months. Except for 5 patients in the IMG, all were diagnosed in chronic phase (CP). The overall survival (OS) of patients diagnosed in CP was 45.7% and 89.7% for pre-IMG and IMG, respectively (P=0.025). The OS of hematopoietic stem cell transplantation (HSCT) recipients in the 2 groups was similar, but the OS of patients diagnosed in CP who did not receive HSCT was superior in IMG (91.7% vs. 16.7%, P=0.014). Of the 12 patients in IMG who remained on IM without HSCT, 2 showed disease progression, compared to 11 of 12 in pre-IMG. No difference was observed in the progression free survival (PFS) of matched donor HSCT recipients and IM-based treatment recipients.

Conclusion: Similar PFS of patients treated with IM and those who received matched donor HSCT underscore the potential of IM as effective first-line treatment in childhood CML.

Keywords: Allogeneic transplantation; Children; Chronic myelogenous leukemia; Imatinib mesylate.

Fig. 1

Treatment and clinical outcome of the patient cohort. Pre-IMG, pre-imatinib group; CP1, first chronic phase; HSCT, hematopoietic stem cell transplantation; CP2, second chronic phase; HUR, hydroxyurea; AP, accelerated phase; CCyR, complete cytogenetic response; TKI, tyrosine kinase inhibitor; IM, imatinib; PD, progression of disease; IMG, imatinib group;BC, blastic crisis; TRM, treatment related mortality; DFS, disease free survival; NR, no response.

Fig. 2

Overall survival of patients diagnosed in chronic phase in the PreImatnib era vs. imatinib era.

Fig. 3

Overall survival of patients who underwent hematopoietic stem cell transplantation in first chronic phase in the preimatinib era vs. imatinib era.

Fig. 4

Progression free survival of patients who did not receive hematopoietic stem cell transplantation according to imatinib use.

Fig. 5

Progression free survival of patients who underwent matched donor hematopoietic stem cell transplantation vs. imatinib only treatment.