Bone Abstracts

Objective: To examine the impact on growth and bone mineral density (BMD) of tyrosine kinase inhibitors (TKI) vs hematopoeitic cell transplant (HCT) for treatment of chronic myelogenous leukemia (CML) in patients <18 years of age.

Methods: We performed a retrospective review of children with CML in chronic phase treated between 1992 and 2011 at a single institution and evaluated available growth and BMD data.

Results: Twenty-five patients were included in the analysis. Ten patients were treated by HCT without TKI (group 1), nine with TKI followed by HSCT (group 2) and six with TKI alone (group 3). Overall survival at 3 years for HCT±TKI (groups 1 and 2) was 68%. All six patients in group 3 remained in complete hematological remission on TKI for a median of 10.5 months (range 5–72 months) at time of study but one has since gone on to HCT. Among four patients in group 1 with evaluable long-term growth data, only one patient was definitely prepubertal at diagnosis (defined as age <11 years girls and <12 years boys). Group 2 had 4/6 prepubertal and group 3 had 1/6. Mean change in height Z-score diagnosis to 1 year was +0.09 for group 1 (n=2), −0.4 for group 2 (n=3), and −0.03 for group 3 (n=5). Combining all treatment groups, change in height Z-score at 1 year was 0.01 for pubertal vs −0.3 for prepubertal children. For subjects evaluable at 3–5 years from diagnosis, height Z-scores tend to be most negatively affected in group 1, while group 3 shows consistently negative Z-scores over time but only one data point each at 3 and 5 years. BMD Z-score by DEXA (using the lowest value between lumbar or whole body less head as available) was positive for the single group 3 patient with a scan at 1 year, but trends for group 2 (n=4) appeared more negative at 3–5 years than for group 1 (n=2).

Conclusion: Our study looked at patients treated with CML at our institution in the last two decades. In the short term (1 year), growth retardation seems to be most affected by prepubertal status, but in the longer term both HCT and TKI are likely to affect growth. Limited data suggest the BMD appears to be negatively affected by TKI±HSCT. Long-term monitoring of growth and BMD in pediatric patients treated with TKI is needed.