Immunology is a rapidly developing field in clinical oncology. Combination drug therapy is being studied for various tumors. In recent years, immunotherapy has been developed based on the inhibition of checkpoints by monoclonal antibodies that act on the PD-1 protein and its PD-L1 ligand. Breast cancer, unlike other tumors, came to be considered relatively late in immuno-oncology. This review presents the results of international and proprietary clinical trials of immune checkpoint inhibitors (ICIs) in the treatment of various biological subtypes of breast cancer. The prognostic and predictive value of the level of tumor-infiltrating lymphocytes (TILs), in particular CD3, CD4, CD8, their correlation with regulatory genes (PD-1, PDL-1, FOX-P3) is also discussed.

Keywords: tumor-infiltrating lymphocytes, PD-L1, PD-1, immunotherapy, breast cancer