Tumor Microenvironment and Cancer Immunology: Implications for Therapy Resistance and Drug Development

The tumor microenvironment (TME) is a complex and dynamic ecosystem of cancer cells, immune cells, stromal components, vasculature, and secreted factors that profoundly influences tumor progression, metastasis, and therapeutic response. This chapter explores the cellular and molecular architecture of the TME, with emphasis on immunosuppressive mechanisms mediated by regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages, and critically evaluates therapeutic strategies targeting the TME to restore anti-tumor immunity and overcome treatment resistance.