Distinct Impact of Imatinib on Growth In Prepubertal and Pubertal Children with Chronic Myeloid Leukemia

Abstract 2277

Imatinib is now widely used for treating chronic-phase chronic myeloid leukemia (CML) in children as well as in adults, and long-term adverse effects of imatinib therapy in children are now gaining attention. One of its adverse effects is the negative impact on growth in children, suggested by 3 recently published case reports. However, the incidence or prospect of growth impairment resulting from imatinib treatment has not been fully elucidated.

In this study, we retrospectively analyzed the clinical records of 48 children with chronic-phase CML who were treated with imatinib as a first-line therapy between 2001 and 2006. The median age at diagnosis was 9 years (2 to 15 years). Cumulative change in height while on imatinib was assessed using the height standard deviations score (height-SDS), the converted height data from age- and sex-adjusted Japanese norms. Our data indicated that growth impairment (decrease in height-SDS) was observed in 72.9% of the patients, with median maximum reduction in height-SDS of 0.61 during imatinib treatment. Growth impairment was noticeable in children who were prepubertal at the commencement of imatinib treatment, while only mild or no growth impairment (with no decrease of height-SDS) was observed in most patients who were pubertal at the commencement of imatinib treatment. Furthermore, in prepubertal children with growth impairment, growth velocity tended to recuperate concomitant with pubertal maturation, suggesting that imatinib has little impact on growth during puberty. To our knowledge, this is the first report to describe and compare the distinct inhibitory effect of imatinib on growth in prepubertal and pubertal children with CML.

Although the introduction of imatinib was a breakthrough in CML therapy, the possibility of continuous remission after discontinuation of imatinib remains uncertain. Thus, the possibility of adverse effects of long-term exposure to imatinib has become a huge issue, especially when treating children. We consider that it is important to promote awareness of growth deceleration in children, especially in young children who started imatinib treatment before puberty and are inevitably going to be subject to prolonged exposure.