HDAC9 and neoplasm: Specifically, with CAR T cell combinations in solid tumors, strategies have included trying to increase tumor infiltration and tumor recognition with DDR inhibitors, angiogenesis inhibitors, MAPK inhibitors, and EZH2 inhibitors; trying to enhance cytotoxicity and reduce exhaustion with lenalidomide, TLR agonists, metabolic regulators, BET inhibitors, and DNMT inhibitors; and trying to increase memory phenotype with TET2 inhibitors, HDAC inhibitors, metabolic regulators, PI3K-AKT inhibitors, LCK/FYN inhibitors, and JAK inhibitors (39).