PDCD1 and neoplasm: In a clinical trial, entinostat (an inhibitor of HDAC) was utilized in the treatment of advanced non-small cell lung cancer that had disease progressed on prior anti-PD-1/PD-L1 therapy, and showed that the entinostat combined with pembrolizumab (an anti-PD-1 mAbs) group demonstrated a robust anti-tumor response, with 9% of of patients had an objective response [245].