Fig. 4

Tumor microenvironment-mediated immune tolerance in breast cancer. (A) Tumor microenvironment-mediated immunotherapy resistance mechanisms. Different cell types of the tumor microenvironment, such as CAF, TAM, and MDSC, contribute to immune tolerance by inducing differentiation of Treg cells, antigen uptake and maturation of dendritic cells, and M2 polarization. These cells also suppress CD8⁺ and NK cell activation and recruitment. Tumor metabolism, particularly glycolysis and TCA cycle, are also associated with immune tolerance in breast cancer. (B) Therapeutic strategies to overcome immunotherapy resistance. Nanoparticles, photoimmunotherapy, and several drugs and inhibitors may target CAF, TAM, MDSC, and tumor metabolism for sensitizing breast cancer to immunotherapy