STAT3 and neoplasm: Studies have demonstrated that the bioactive compounds in TCM, such as saponins, terpenes, alkaloids and flavonoids, can down-regulate PD-L1 expression through various signaling pathways such as PI3K/Akt/mTOR, P38, NF-κB and JAK/STAT3, among others, thereby intervening in tumor immune escape (Table 6).