Mechanisms of tumor-associated macrophages promoting tumor immune escape

Abstract The phenomenon of tumor immune escape involves multiple mechanisms that enable tumor cells to evade recognition and assault by the host's immune system, facilitating their survival and growth within the organism. Furthermore, tumor immune escape represents a critical mechanism in tumor progression and significantly contributes to the unsuccessful outcomes of immunotherapy. Tumor-associated macrophages (TAMs) are recruited into the tumor microenvironment (TME), serving a pivotal role in modulating tumor immune escape. An increasing body of research has demonstrated that TAMs are linked to unfavorable cancer prognosis and drug resistance. They suppress immune cell activity, hinder antigen presentation, and inhibit T cell activation, thereby helping tumor cells evade immune attacks. Consequently, elucidating the mechanisms by which TAMs promote tumor immune escape is crucial for developing novel immunotherapeutic strategies and improving the efficacy of cancer immunotherapy. In terms of clinical relevance, studies on TAMs have revealed their significant roles in various types of cancer. In recent years, transformational therapies such as CSF-1R inhibitors and CD40 agonists targeting TAMs have entered clinical trials and are expected to reverse immunosuppression and enhance immunotherapy response. These studies provide new directions for improving the effectiveness of existing immunotherapies and overcoming drug resistance.