Durvalumab and T-DXd Synergistically Promote Apoptosis of Cholangiocarcinoma Cells by Downregulating EGR1 Expression Through Inhibiting P38 MAPK Pathway.

Cholangiocarcinoma is a hepatobiliary system tumor with a high mortality rate. Although durvalumab and trastuzumab deruxtecan (T-DXd) have shown efficacy in treating cancers such as non-small cell lung cancer, their effects and regulatory mechanisms in cholangiocarcinoma remain unclear. In this study, we aimed to investigate the role and mechanism of durvalumab and T-DXd in inducing apoptosis in cholangiocarcinoma cells. Cholangiocarcinoma cells were treated with varying concentrations of durvalumab and T-DXd, either individually or in combination, to evaluate their effects. Apoptosis was quantified using flow cytometry. Quantitative real-time PCR (qPCR) and Western blotting were used to measure the mRNA expression and protein levels of genes associated with apoptosis and cell cycle regulation. The underlying mechanism was further explored through pathway enrichment analysis of differentially expressed genes (DEGs) and corroborated by qPCR and Western blotting. Xenotransplantation models using immune-deficient NOD-SCID/IL2Rγnull (NSG) mice were established to assess the in vivo effects of durvalumab and T-DXd. Our results showed that both durvalumab and T-DXd inhibited cholangiocarcinoma cell proliferation in a dose-dependent manner. Both agents promoted apoptosis and arrested the cell cycle of cholangiocarcinoma cells, with the combination treatment having the most significant effect. Furthermore, treatment with durvalumab, T-DXd, and the combination downregulated the protein levels of early growth response 1 (EGR1) by inactivating the p38 mitogen-activated protein kinase (MAPK) pathway. In vivo experiments indicated that durvalumab and T-DXd prolonged the survival of NSG mice bearing cholangiocarcinoma xenografts. In conclusion, our findings demonstrated that durvalumab and T-DXd synergistically promoted apoptosis in cholangiocarcinoma cells by inhibiting EGR1 expression through inactivation of the p38 MAPK pathway. This study confirmed the potential of durvalumab and T-DXd for the treatment of cholangiocarcinoma.