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CPI-203 improves the efficacy of anti-PD-1 therapy by inhibiting the induced PD-L1 overexpression in liver cancer.

ABSTRACT: Hepatocellular carcinoma (HCC) is one of the commonest lethal malignancies worldwide, and often diagnosed at an advanced stage, without any curative therapy. Immune checkpoint blockers targeting the programmed death receptor 1 (PD-1) have shown impressive antitumor activity in patients with advanced-stage HCC, while the response rate is only 30%. Inducible PD-L1 overexpression may result in a lack of response to cancer immunotherapy, which is attributed to a mechanism of adaptive immune resistance. Our study investigated that the overexpression of PD-L1 promoted the invasion and migration of liver cancer cells in vitro, and the induced overexpression of PD-L1 in the tumor microenvironment could weaken the effects of anti-PD-1 immunotherapy in a BALB/c mouse model of liver cancer. CPI-203, a small-molecule bromodomain-containing protein 4 (BRD4) inhibitor, which can potently inhibit PD-L1 expression in vitro and in vivo, combined with PD-1 antibody improved the response to immunotherapy in a liver cancer model. Cell transfection and chromatin immunoprecipitation assay manifested that BRD4 plays a key role in PD-L1 expression; CPI-203 can inhibit PD-L1 expression by inhibiting the BRD4 occupation of the PD-L1 promoter region. This study indicates a potential clinical immunotherapy method to reduce the incidence of clinical resistance to immunotherapy in patients with HCC.

SUBMITTER: Niu X

PROVIDER: S-EPMC8748230 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundDysregulated expression and activation of receptor tyrosine kinases (RTKs) are associated with a range of human cancers. However, current RTK-targeting strategies exert little effect on pancreatic cancer, a highly malignant tumor with complex immune microenvironment. Given that immunotherapy for pancreatic cancer still remains challenging, this study aimed to elucidate the prognostic role of RTKs in pancreatic tumors with different immunological backgrounds and investigate their targeting potential in pancreatic cancer immunotherapy.MethodsKaplan-Meier plotter was used to analyze the prognostic significance of each of the all-known RTKs to date in immune "hot" and "cold" pancreatic cancers. Gene Expression Profiling Interactive Analysis-2 was applied to assess the differential expression of RTKs between pancreatic tumors and normal pancreatic tissues, as well as its correlation with immune checkpoints (ICPs). One hundred and fifty in-house clinical tissue specimens of pancreatic cancer were collected for expression and correlation validation via immunohistochemical analysis. Two pancreatic cancer cell lines were used to demonstrate the regulatory effects of RTKs on ICPs by biochemistry and flow cytometry. Two in vivo models bearing pancreatic tumors were jointly applied to investigate the combinational regimen of RTK inhibition and immune checkpoint blockade for pancreatic cancer immunotherapy.ResultsMET was identified as a pancreatic cancer-specific RTK, which is significantly associated with prognosis in both immune "hot" and "cold" pancreatic cancers. MET was observed to be highly upregulated in pancreatic cancer tissues, and positively correlated with PD-L1 levels. Elevated MET and PD-L1 expressions were closely associated with lymph node metastasis, tumor TNM stage, and overall survival in pancreatic cancer. Mechanistically, MET could interact with PD-L1, and maintain its expression level in multiple ways. MET deficiency was found to facilitate lymphocyte infiltration into pancreatic tumors. Finally, significant benefits of combining MET inhibition with PD-1/PD-L1 blockage were verified in both orthotopic and subcutaneous mouse models of pancreatic cancer.ConclusionsThis study systematically investigated the potential effectiveness of a novel pancreatic cancer immunotherapy targeting RTKs, and revealed the function of MET in PD-L1 regulation as well as the combined therapeutic efficacy of MET and PD-L1 in pancreatic cancer.

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CPI-203 improves the efficacy of anti-PD-1 therapy by inhibiting the induced PD-L1 overexpression in liver cancer.

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