Antitumour mechanisms of traditional Chinese medicine elicited by regulating tumour-associated macrophages in solid tumour microenvironments

Abstract

Tumour-associated macrophages (TAMs), particularly M2-TAMs, constitute the largest proportion of immune cells in the solid tumour microenvironment, playing a crucial role in tumour progression and correlating with poor prognosis. TAMs promote the proliferation, invasion, and metastasis of tumour cells by remodelling the extracellular matrix, inhibiting immunity, promoting immune escape and tumour angiogenesis, and affecting cell metabolism. Traditional Chinese medicine (TCM) has been used clinically in China for millennia. Chinese herbs exhibit potent antitumour effects with minimal to no toxicity, substantially contributing to prolonging the lives of patients with cancer and improving their quality of life. TCM has unique advantages in improving the solid tumour microenvironment, particularly in regulating TAMs to further inhibit tumour angiogenesis, reduce drug resistance, reverse immunosuppression, and enhance antitumour immunity. This review highlights the TAM-associated mechanisms within the solid tumour microenvironment, outlines the recent advancements in TCM targeting TAMs for antitumour effects, emphasises the superiority of combining TCM with standard treatments or new nano-drug delivery systems, and evaluates the safety and efficacy of TCM combined with conventional treatments via clinical trials to provide insights and strategies for future research and clinical treatment.