Project Summary Disruptions of epigenetic mechanisms that regulate gene expression are frequently found in cancer and collaborate with genetic alterations to drive cancer phenotypes such as therapy resistance and immune escape. Since 2016, Dr. Bennett, the research specialist for this R50 award application, has supervised teams of researchers and performed key experiments for the NCI-funded research program of the unit director, Dr. Jonathan Licht, at the University of Florida Health Cancer Center to study how epigenetic mechanisms are disrupted in cancer. Dr. Bennett has strong track record of important contributions to cancer research, and his work has been instrumental to the success of CA195732, U54CA193419 and U01CA225566. He has demonstrated that a glutamate to lysine mutation at amino acid 76 of histone H2B fundamentally alters chromatin dynamics and accessibility, causing changes in gene expression and cell growth properties that favor tumorigenesis. Dr. Bennett showed that treatment of acute lymphoblastic leukemia cells harboring mutant histone methyltransferase NSD2 with PRC2 inhibitors can reactivate glucocorticoid (GC) receptor expression and restore sensitivity of these cells to GC therapy. In addition, he has determined genetic dependencies for growth and therapy resistance in uveal melanoma as well as identified an HDAC8-driven permanent lineage switch maintained after drug withdrawal in melanoma. This R50 award will provide career stability for Dr. Bennett to continue making important contributions to cancer research and advancing the unit director’s larger NCI- funded research program. Dr. Bennett will lead research teams and perform key experiments to accomplish the aims of the Dr. Licht’s three NCI-funded R01 awards: R01CA266078 (Histone fold Mutations in Cancer Pathogenesis), multi-PI R01CA256193 (Characterization and targeting of the epigenetic state underlying uveal melanoma liver metastasis) and multi-PI R01CA262483 (Defining and targeting epigenetic plasticity-driven drug resistance and immune escape in melanoma). In addition, funding of this award will allow Dr. Bennett to pioneer new directions for each project especially by applying cutting-edge technologies and building collaborations with other NCI-funded investigators. Dr. Bennett is an expert in a wide spectrum of epigenomics techniques such as biochemical assays, gene expression analysis, chromatin profiling and CRISPR screens that are essential for the success of these awards and advancing the unit director’s NCI-funded cancer research program. These studies will reveal new epigenetic mechanisms of oncogenesis that contribute to tumor progression, heterogeneity, and therapy resistance, with the aim of finding new targets and pathways of intervention for cancer patients that will ultimately lead to better patient outcomes.