Cancer initiation and progression are associated with immune system responses. Tumor cells use various tricks to scape of immune system, such as activating immune checkpoint pathways that induce immunosuppressive functions. Among the different immune checkpoint receptors, CTLA-4 and PD-1/PD-L1 are prominent therapeutic targets in different cancers. Although the US FDA has approved some immune checkpoint inhibitors for several cancers, concerning breast cancer still different clinical trials are looking for optimizing efficacy and decreasing immune-related adverse events. This review will discuss the existing body of knowledge with regard to cross-talk between immune system and tumor cells and then explore immune checkpoint-related signaling pathways in the context of breast tumors. Finally, we highlight the application of different immune checkpoint blockers in breast cancer patients.
Keywords: CTLA-4; EGFR signaling; PD-1; PD-L1; PI3K signaling; TGFB signaling; breast cancer; checkpoint inhibitors; immune checkpoints; immunotherapy.
Lay abstract Breast cancer is the most commonly diagnosed female cancer around the world. Cancer initiation and progression are associated with immune system responses. Tumor cells use various tricks to scape of immune system, such as activating immune checkpoint pathways that induce immunosuppressive functions. Immune checkpoint inhibitors are drugs that help the patients’ immune system with effective antitumor response. Although the US FDA has approved some immune checkpoint inhibitors for several cancers, concerning breast cancer still different examinations are looking for optimizing efficacy and decreasing immune-related adverse events. The goal of this review article is to discuss the interactions between immune system and tumor cells as well as the current state, safety and efficacy of immune checkpoint-based therapies in breast cancer treatment.