Abstract:

Osteosarcoma (OS) is a common primary malignant bone tumor in children and adolescents. The high recurrence and metastasis rate have become a common clinical problem to be solved, but there is no effective treatment. In recent years, studies have suggested that targeting the tumor microenvironment will likely become a new treatment direction for OS. Immune cell infiltration in the tumor microenvironment can promote tumor inflammation and angiogenesis. Tumor-associated macrophages (TAMs) are the most important immune cells in the tumor microenvironment, which play important roles in the development and metastasis of OS. The article reviews the effect of TAMs polarization on tumor cells and describes the effect of TAMs on the occurrence and development of OS from five aspects, including TAMs affecting the growth, invasion and metastasis, mediating chemotherapy resistance, stem cell-like phenotype, and immunosuppression of OS. The review summarizes the research progress of targeting TAMs in the treatment of OS in the past years, including influencing the recruitment of TAMs, promoting the polarization of M2 type to M1 type, targeting CD47 to promote the phagocytosis of TAMs, and targeting the immune checkpoint of TAMs, aiming to provide new directions and ideas for targeted therapy of OS.

Key words: osteosarcoma, tumor-associated macrophages, tumor microenvironment, targeted therapy