A novel somatic JAK2 kinase-domain mutation in pediatric acute lymphoblastic leukemia with rapid on-treatment development of LOH.

We report a novel somatic mutation in the kinase domain of JAK2 (R938Q) in a high-risk pediatric case of B-cell acute lymphoblastic leukemia (ALL). The patient developed on-therapy relapse at 12 months, and interestingly, the JAK2 locus acquired loss of heterozygosity during treatment resulting in 100% mutation load. Furthermore, we show that primary ALL mononuclear cells harboring the JAK2 R938Q mutation display reduced sensitivity to the JAK1/2 ATP-competitive inhibitor ruxolitinib in vitro, compared to ALL cells that carry a more common JAK2 pseudokinase domain mutation. Our findings are in line with previous reports that demonstrate that mutations within the kinase domain of JAK2 are associated with resistance to type I JAK inhibitors. Importantly, given the recent inclusion of ruxolitinib in trial protocols for children with JAK pathway alterations, we predict that inter-patient genetic variability may result in suboptimal responses to JAK inhibitor therapy in a subset of cases. The need for alternate targeted and/or combination therapies for patients who display inherent or developed resistance to JAK inhibitor therapy will be warranted, and we propose that kinase-mutants less sensitive to type I JAK inhibitors may present a currently unexplored platform for investigation of improved therapies. Copyright © 2017. Published by Elsevier Inc.

Citation

Teresa Sadras, Susan L Heatley, Chung H Kok, Barbara J McClure, David Yeung, Timothy P Hughes, Rosemary Sutton, David S Ziegler, Deborah L White. A novel somatic JAK2 kinase-domain mutation in pediatric acute lymphoblastic leukemia with rapid on-treatment development of LOH. Cancer genetics. 2017 Oct;216-217:86-90

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PMID: 29025600

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