This review presents a systematic synthesis of the principal tumor immunotherapy strategies and their corresponding resistance mechanisms. Immunotherapies—including antibody-based therapies, adoptive cell therapies, immune modulators, and novel approaches such as oncolytic viruses and cancer vaccines—work by stimulating or enhancing the patient's immune system to target cancer cells. Nevertheless, they commonly encounter resistance in clinical applications. Resistance mechanisms predominantly stem from tumor-intrinsic factors and tumor microenvironment (TME) factors. To surmount resistance, combination therapies and personalized treatment strategies grounded in TME profiling and biomarke... More >