PDCD1 and cancer: Considering what was mentioned above about the inhibitory role of the PD-1 pathway, which leads to T cell exhaustion and formation of an immunosuppressive context in the TME, and also paying attention to the predominance of the increasing pattern in PD-1 expression in the TME after chemo(radio)therapy in some solid tumors, it seems that combining these conditional treatments with immunotherapeutic agents inhibiting PD-1 specifically, may promote the efficacy of these anti-tumor approaches and improve the prognosis of many cancers.