Mentor Name: Clara Libbrecht

Mixed Phenotype Acute Leukemia (MPAL) is an understudied high-risk leukemia with poor outcomes. Patients have been historically excluded from clinical trials, leading to poor genomic characterization and a lack of standardized therapeutic management. Deepening our understanding of the molecular mechanisms driving MPAL is crucial to refine treatment strategies and identify novel therapies. ZNF384 rearrangements have been identified in 50% of patients with childhood B/Myeloid MPAL. These rearrangements give rise to a chimeric fusion protein that consists of the amino terminus of over 10 functionally diverse fusion partners juxtaposed to the entire amino-acid sequence of ZNF384 at the carboxy terminus. ZNF384 fusion proteins can transform hematopoietic progenitors in vitro and give rise to leukemia in vivo, but how exactly they exert their oncogenic properties remains unclear. Understanding the specific mechanisms through which these proteins drive leukemic transformation is essential for identifying new therapeutic targets. We hypothesize that the oncogenic properties of ZNF384 fusion proteins depend heavily on the physiologic properties of wild-type ZNF384, a known transcription factor, whose entire amino-acid sequence is retained. To test this hypothesis, we will over-express GFP-tagged wild-type ZNF384 or EP300::ZNF384 and TCF3::ZNF384, the 2 most common ZNF384 rearrangements in a representative panel of acute leukemia cell lines. After selecting for transduced cells, we will assess for changes in growth, immunophenotype, and gene expression. These studies will provide essential models for understanding the transforming mechanisms of ZNF384 fusion proteins. Based on data generated from this project, future work will investigate changes in chromatin organization to interrogate therapeutic vulnerabilities.