The Role of Tumor-Associated Macrophages in Cancer Immunoevasion and Therapy Resistance

Abstract

Tumor-associated macrophages (TAMs) are crucial components of the tumor microenvironment, playing significant roles in cancer progression, immune evasion, and therapy resistance. Originating from circulating monocytes, TAMs can polarize into M1 and M2 phenotypes, with M2-like TAMs predominating in many cancers. This M2 polarization fosters an immunosuppressive environment that promotes tumor growth, metastasis, and resistance to therapies, including chemotherapy and immune checkpoint inhibitors. TAMs secrete various cytokines, chemokines, and growth factors that enhance tumor cell survival, promote angiogenesis, and recruit additional immunosuppressive cells such as regulatory T cells. They also express immune checkpoint molecules, further inhibiting effective anti-tumor immune responses. Given their dual role in supporting tumor survival and mediating immune evasion, TAMs represent an attractive target for therapeutic intervention. Current strategies to target TAMs include depletion, reprogramming, and combination therapies aimed at enhancing anti-tumor immunity. This review explores the complex biology of TAMs, their mechanisms of action in promoting cancer immunoevasion and therapy resistance, and the therapeutic strategies being developed to exploit their unique characteristics. By providing insights into the multifaceted roles of TAMs, this review aims to highlight potential avenues for improving cancer treatment outcomes and addressing the challenges posed by tumor-induced immune suppression. Keywords: Tumor-Associated Macrophages (TAMs), Immune Evasion, Therapy Resistance, Macrophage Polarization, Immunotherapy