ABSTRACT
Cancer immunotherapy uses the host′s immune system to mobilize immune cells to rec-ognize and eventually eliminate cancer cells .At present, studies in terms of cancer immunotherapy mainly focus on programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) antibody, cytotoxic T-lymphocyte-associated protein 4 ( CTLA-4 ) antibody, chimeric antigen receptor T-cell immunotherapy (CAR-T), T cell receptor Immunotherapy (TCR-T), etc.Despite the fact that cancer immunotherapies elicit unprecedented durable responses in clinical therapy , they appear to be ineffective to some patients .In addition, some responders relapse and show resistance to immunotherapies even if their symptoms are re -lieved for a time .Resistance to cancer immunotherapy can be categorized into primary , adaptive and ac-quired, which can occur in every stage during the process of anti-tumor response.In this review, we discuss the known mechanisms of resistance and provide a rationale for the use of combination therapy to overcome resistance.