Recent advances have provided novel mechanistic insights into the effectiveness of the PD1/PD-L1 pathway blockade-mediated tumor regression, with compelling evidence suggesting that PD-L1 expression in host antigen presenting cells (APCs), including DCs and macrophages, plays pivotal roles in the efficacy of PD1/PD-L1 checkpoint blockade-based immunotherapy [28]. The gene discussed is PDCD1; the disease is neoplasm.