Annual advances of traditional medicine on tumor immunity regulation in 2020

Tumor burden remains a global health problem that threatens human life worldwide. Over the past few years, the evolution of immune checkpoint inhibitors has represented one of the most successful approaches in the field of tumor therapy. Drugs regulating tumor immune microenvironment or enhancing body immunity have indicated a novel perspective to treat tumors. Therefore, an increased number of scientists have been shifting their research focus to explore the immunity regulation effects of anti-tumor traditional medicine or natural products. In this review, we summarize the research progress of traditional medicines on tumor immunity regulation in 2020. Our findings suggest that more herbal medicine-derived phytochemicals and formulas were derived from traditional Chinese medicine, and more papers were published in comprehensive journals. Traditional medicine can comprehensively regulate the tumor immune microenvironment, including natural killer cells, dendritic cells, CD4+/CD8+T lymphocytes, regulatory T cells, myeloid-derived suppressor cells, tumor-associated macrophages, immunosuppressive factors, and immune checkpoints. In 2020, a greater number of research papers focused on active ingredients and formulas that regulate tumor-associated macrophages and immune checkpoints. Active ingredients such as flavonoids became a global hotspot in 2020. Certain natural products were also found to exert synergistic anti-tumor activity with immune checkpoint inhibitors, such as curcumin. However, a distinct lack of high-quality experimental and clinical studies remains a prevalent and challenging issue that hinders the further development of traditional medicine.