Advances in traditional Chinese herbal medicine and their pharmacodynamic mechanisms in cancer immunoregulation: a narrative review

Background and objective: The cancer-immunity cycle (CIC) is defined as a series of progressive events that cause an anticancer immune response leading to the killing of the cancer cell. The concept of CIC has important guiding significance for the clinical and basic tumor immunotherapy research. As one of the methods of traditional Chinese medicine (TCM), Chinese herbal medicine (CHM) has shown unique advantages in multitarget and multipathway immune regulation. However, the tumor immune circulation targeted by CHM is generally unclear at present. To provide reference for future clinical and basic research, we systematically reviewed the existing literature on CHM (including CHM monomers, CHM compounds, and CHM patent medicines) and the mechanisms related to its efficacy. Methods: We searched the PubMed and China National Knowledge Infrastructure (CNKI) databases for relevant Chinese-language and English-language literature published from January 1988 to October 2022. The literature was screened manually at three levels: title, abstract, and full text, to identify articles related to CHM and their mechanism of regulating tumor immunity. Key content and findings: By further classifying the CIC, it was confirmed that CHM can regulate the activation of dendritic cells (DCs) and macrophages and promote the presentation of tumor antigens. Meanwhile, CHM can also reverse tumor-immune escape by enhancing T-cell proliferation and infiltration. In addition, CHM can also enhance the antitumor ability of the body by regulating the killing process of tumor cells. Conclusions: The theory of a CIC is of guiding significance to regulating tumor immunity via CHM.