Approximately 10-15% of pediatric and adult patients with B-cell acute lymphoblastic leukemia (B-ALL) have a high-risk form of the disease characterized by rearrangements of a gene called CRLF2. Alterations of this gene result in increased expression of the CRLF2 protein and promote leukemia development. When treated with conventional chemotherapy, patients with CRLF2 gene alterations do poorly. Their leukemias are dependent on an enzyme called JAK2 for survival, yet no targeted therapies with proven efficacy are currently available. Dr. Li has unique access to a new drug called CHZ868, which turns off JAK2 enzyme activity, potently kills B-ALL cells, and improves overall survival in mice with JAK2-dependent B-ALL. Treatment with CHZ868 alone is not curative, however, and all mice eventually succumb to progressive leukemia. Using JAK2-dependent B-ALL cells and mouse models, she will study how leukemia becomes resistant to JAK2 inhibitors. Her goal is to identify combinations of agents that can prevent or overcome resistance to a single therapy and also guide the development of new JAK2 inhibitors for patients.