In the current study, we identify that niclosamide in combination with PD-1/PD-L1 antibody can act a synergistic anti-tumor effect in vitro and in vivo for treatment of NSCLC through decreasing PD-L1 expression and further promoting cytotoxic T cell activity and enhancing antitumor immune responses. Here, CD274 is linked to non-small cell lung carcinoma.