This thesis aims to advance anti-cancer therapy development through a comprehensive exploration.In Chapter 1, the focus is on understanding the immune system's role in breast cancer and... Show moreThis thesis aims to advance anti-cancer therapy development through a comprehensive exploration.In Chapter 1, the focus is on understanding the immune system's role in breast cancer and chemotherapy response. It examines the paradoxical roles of immune cells and macrophages, seeking novel biomarkers and immunomodulatory strategies.In Chapter 2, the impact of the adaptive immune system on HER2+ breast cancer is explored. Contrary to other breast cancer types, the adaptive immune system neither suppresses nor promotes spontaneous HER2-driven tumorigenesis or metastasis formation.Chapter 3 investigates the relationship between chemotherapy and the adaptive immune response using GEMMs. The study highlights that the endogenous adaptive immune system's role in chemotherapy response might not be as vital as previously believed when utilizing tumor cell line transplantation models. This finding leads to a reevaluation of the conventional understanding of the immune system's involvement in chemotherapy response.Chapter 4 focuses on macrophage-targeted cancer therapy. In non-immunogenic breast cancer, CSF-1R inhibition enhances chemotherapy, especially with platinum drugs. Intratumoral type I interferon activation drives their synergistic impact. Also, neutralizing immunosuppressive neutrophils is crucial for a strong anti-tumor immune response.In Chapter 5, the thesis discusses how its findings align with existing research and suggest clinical applications. Show less