PDCD1 and neoplasm: In hepatocellular carcinoma mice model, HDACi belinostat and anti-CTLA-4 combination increases IFN-γ tumor-reactive CD8+ T cell production and decreases splenic Treg cells number [238], however in syngeneic tumor mice models, HDACi CG-745 and anti-PD1 treatment increases effector helper and cytotoxic T cells proliferation while inhibiting that of Treg cells [239].