Abstract
B cell precursor acute lymphoblastic leukemia (BCP ALL) is the most common malignancy in children. While treatments have improved remarkably over the past four decades, resistant disease and late effects that result from cytotoxic chemotherapy remain serious problems for individuals with BCP ALL. Improved genetic tools have led to the discovery of numerous somatic mutations associated with BCP ALL, leading to a framework for the genetic classification of BCP ALL. In this issue of the JCI, Duque-Afonso et al. develop an accurate in vivo model for BCP ALL that recapitulates the key features of human disease, including acquired mutations in genes encoding PAX5 and components of the JAK/STAT pathway. The authors further show, as proof of principle, that this model can be used to evaluate the efficacy of drugs designed to target specific acquired mutations in patients with BCP ALL.