PDCD1 and cancer: Immune checkpoint inhibitors represent new approaches in cancer treatment.4 PD-1 inhibitors, potentially one of the most studied inhibitors treatments, has shown clinical efficacy in various cancers, such as melanoma, non-small cell lung cancer (NSCLC) and renal cell carcinoma.5–8 However, anti-PD-1 antibody showed a low response rate in sarcoma.