Recombinant human adenovirus type 5 synergizes with anti-PD-L1 antibody to promote anti-hepatocellular carcinoma effects through multilevel remodeling of the immune microenvironment.

BACKGROUND: Overcoming resistance to immune checkpoint inhibitors (ICIs) remains a critical challenge in the treatment for hepatocellular carcinoma (HCC). METHODS: Our study evaluated the combined efficacy of the recombinant human adenovirus type 5 (H101) and an anti-PD-L1 antibody (APA) in C57BL/6N mouse model. Gene expression of STAT1 and CD274 (PD-L1) was analyzed by qPCR, and protein levels of PD-L1 and p-STAT1 were assessed via western blot and immunohistochemistry. IFN-γ secretion and immune cell infiltration were measured by ELISA and flow cytometry, respectively. RESULTS: In vitro, H101 inhibited the proliferation and invasion and IFN-γ induced apoptosis in HCC cells, with IFN-γ upregulating the expression of STAT1 and CD274. Transfection with si-STAT1 significantly reduced the levels of both STAT1 and CD274/PD-L1. In vivo, the combination of H101 and APA demonstrated stronger anti-tumor activity, with upregulated IFN-γ expression and increased infiltration level of CD8+ T cell. Notably, si-STAT1 transfection reduced the expression of p-STAT1 and PD-L1, thereby diminishing the efficacy of both APA monotherapy and the H101+APA combination treatment. The combination therapy significantly reshaped the tumor microenvironment (TME) after si-STAT1 transfection. CONCLUSION: The combination of H101 and APA exhibited excellent anti-HCC efficacy, which may reshape the TME partially through the IFN-γ/STAT1/PD-L1 axis. These findings provide a promising strategy to overcome resistance to ICIs in HCC treatment.