Nano-strategies for Targeting Tumor-Associated Macrophages in Cancer immunotherapy

Tumor-associated macrophages (TAMs) are one type of the most abundant immune cells within tumor, resulting in immunosuppresive tumor microenvironment and tumor resistance to immunotherapy. Thus, targeting TAMs is a promising therapeutic strategy for boosting cancer immunotherapy. This study provides an overview of current therapeutic strategies targeting TAMs, which focus on blocking the recruitment of TAMs by tumors, regulating the polarization of TAMs, and directly eliminating TAMs using various nanodrugs, especially with a new categorization based on the specific signaling pathways, such as NF-κB, HIF-1α, ROS, STAT, JNK, PI3K, and Notch involved in their regulatory mechanism. The latest developments of nanodrugs modulating these pathways are discussed in determining the polarization of TAMs and their role in the tumor microenvironment. Despite the challenges in clinical translation and the complexity of nanodrug synthesis, the potential of nanodrugs in enhancing the effectiveness of cancer immunotherapy is worthy of expecting.