A single Cancer immunotherapy has ushered in a transformative era in oncology, bringing forth unprecedented promise and opportunities. However, even with its significant breakthroughs, the domain faces the continual issue of treatment resistance. Such resistance not only restricts the broad effectiveness of these pioneering treatments but also highlights the imperative need for further research. Delving into the complex world of cancer immunotherapy resistance, we identify a range of mechanisms, from primary and secondary resistance to the notable effects of genetic and epigenetic variables, and the pivotal importance of the tumor microenvironment (TME). Additionally, we emphasize the need for innovative strategies to mitigate this resistance, including combination treatments, customized immune checkpoints, and instantaneous monitoring. By advocating for these cutting-edge methods, we foresee a direction that incorporates personalized healthcare, enhanced treatment options, and a steadfast dedication to the welfare of patients. Through a comprehensive and diverse approach, we aim to address the hurdles posed by resistance, elevating cancer immunotherapy as a symbol of hope for patients worldwide.

Tumor-associated macrophages (TAMs) play critical roles in the tumor microenvironment (TME), where they are recruited by signals released by cancer cells. Although they have great potential as therapeutic targets for cancer treatment, the dual roles of TAMs in promoting or inhibiting tumor growth, invasion, and metastasis make their function in cancer progression complex. In this review, we provide an overview of the current understanding of TAMs, including their phenotypic diversity, regulatory signaling pathways, and interactions with other cells in the TME. We also discuss the challenges related to the standard isolation protocols of TAMs, inconsistent research results, and translation of TAM knowledge into clinical applications. Additionally, we review the status of clinical trials involving TAMs and potential strategies to overcome the limitations. The future direction of TAM research should focus on developing more targeted therapies that specifically regulate TAM function and non-invasive methods for monitoring TAM activity in cancer patients. A comprehensive understanding of the complex role of TAMs in cancer may lead to the development of more effective treatments and improved outcomes for cancer patients.