Antitumor strategies based on targeted modulation of tumor-associated macrophages

Tumor-associated macrophages (TAMs) are the most abundant innate immune cells in tumors, which generally exhibit anti-inflammatory M2 phenotypes, and are the key inducers of tumor development, metastasis and drug resistance, and thus becoming a popular target in the field of antitumor immunotherapy.The study and application of nanocarriers optimize TAMs-targeted antitumor therapy.According to the characteristics and functions of TAMs, modulation strategies based on TAMs are elaborated, including TAMs depletion, inhibition of TAMs recruitment and TAMs repolarization.At the same time, in order to apply the above strategies more efficiently and overcome the general off-target problems in treatment, specific TAMs-targeted therapies based on nanocarriers are reviewed and analyzed, including passive targeting to TAMs, active targeting to macrophages and specifically active targeting to M2-TAMs. Finally, based on the limitations of targeting TAMs alone, new therapeutic strategies of targeting both TAMs and tumor cells via nanocarrier based delivery systems are introduced to provide new ideas for the application of these strategies in the field of tumor immunotherapy and combination therapy with other antitumor strategies.