HE4 regulates anticancer immune evasion by upregulating PD-L1 expression on macrophages through the IFN-γR-STAT3 axis [LLC tumors, scRNA-seq]

Current immune checkpoint inhibitors (ICIs) targeting PD-L1/PD-1 have achieved great success in clinical cancer treatment. However, it still faces great challenges, such as a low overall response rate and immune-related adverse events (irAEs). PD-L1 is transcriptionally induced by immune cell-secreted cytokines, such as IFN-γ, in the tumor microenvironment (TME), but whether the expression of PD-L1 is regulated by cancer cell-derived molecules is still unclear. Here, we show that HE4 is another critical transcriptional regulator of PD-L1 on macrophages in the TME through the IFN-γR1/IFN-γR2-JAK-STAT3 signaling pathway and that blocking mouse or human HE4 with monoclonal neutralizing antibodies has a significant therapeutic effect on multiple mouse or human cancers by downregulating PD-L1 expression on macrophages and promoting CD8+ T-cell activation in the TME. Furthermore, we showed that the expression level of HE4 is high in multiple human cancer samples and that the level of HE4 is correlated with the efficiency of anti-PD-1 immunotherapy in human adenocarcinoma patients. Together, we not only identify a critical molecule and mechanism regulating the expression level of PD-L1 on myeloid cells in the TME but also identify a cancer-derived therapeutic target upstream of PD-L1 for immunotherapy, which may be more specific and has fewer irAEs.