Response dynamics of pediatric patients with chronic myeloid leukemia on imatinib therapy

摘要

Tyrosine kinase inhibitors (TKI) provide an efficient targeted therapy against the constitutively expressed BCR-ABL1 oncoprotein characterizing chronic myeloid leukemia (CML). Due to its success in adult CML patients, the continuing treatment with TKI, namely imatinib, has also replaced allogeneic stem cell transplantation in pediatric patients as front-line therapy.~(~(1))Tight molecular monitoring of tumor load reveals that imatinib monotherapy induces a biphasic decline of BCR-ABL1 transcript levels in most adult CML patients. While the initial steep decline most likely results from the rapid depletion of actively cycling BCR-ABL1 positive cells, the second moderate decline may represent the slow elimination of quiescent residual leukemic stem cells owing to their comparatively low turnover.~(~(2)) However, CML is rare in cohorts of patients under 20 years of age, and data on the kinetics of the BCR-ABL1 expression in response to TKI treatment in children and teenagers are still scarce. While it is widely agreed that the cellular and molecular features of CML in children are identical to adults, it must be remembered that the host is still a growing organism,~(~(3)) and initial tumor cell burden and treatment responses may vary according to age.~(~(4),~(5)).