Nafamostat mesilate, a serine protease inhibitor, suppresses interferon-gamma-induced up-regulation of programmed cell death ligand 1 in human cancer cells.

Programmed cell death ligand-1 (PD-L1) plays a pivotal role in the suppression of antitumour immunity by binding to programmed cell death-1 (PD-1) on tumouricidal cytotoxic T lymphocytes (CTLs), rendering them inactive. As blockade of PD-1/PD-L1 interaction by the monoclonal antibodies induced effective T cell-mediated antitumour response, suppression of PD-L1 expression in tumour cells by the chemical agent might contribute to treatment against malignant tumours. Nafamostat mesilate (NM), a serine protease inhibitor that is frequently used in the clinic, potently suppressed interferon-gamma (IFN-gamma)-induced up-regulation of PD-L1 in cultured human lung cancer cells (HLC-1) at both the messenger RNA (mRNA) and protein levels. Interestingly, suppression of IFN-gamma-induced up-regulation of human leukocyte antigen (HLA)-ABC by NM was limited, suggesting that NM did not block CTL responses to tumour cells. NM treatment did not affect the activation status of signal transducer and activator of transcription (STAT) 1 or the induction of interferon regulatory factor (IRF)-1 expression in IFN-gamma-treated HLC-1 cells. Although NM treatment promoted the phosphorylation of extracellular signal-regulated kinases (Erk) 1/2, an Erk inhibitor, U0126, could not reverse the suppression of PD-L1 up-regulation by IFN-gamma. Suppression of IFN-gamma-induced up-regulation of PD-L1 by NM was not associated with the inhibition of nuclear factor kappa B (NF-kB) or protease-activated receptor (PAR)-1 pathway. Besides HLC-1 cells, NM suppressed IFN-gamma-induced PD-L1 up-regulation in three human pancreatic cancer cell lines. NM could potentiate the antitumour effect of cancer vaccines or immune checkpoint inhibitors by preventing IFN-gamma-induced PD-L1 up-regulation and blocking immune checkpoint suppression.

Prognostic markers for patient outcome following vaccination with multiple MHC Class I/II-restricted WT1 peptide-pulsed dendritic cells plus chemotherapy for pancreatic cancer.

BACKGROUND/AIM: Treatment combining dendritic cells (DCs) pulsed with three types of major histocompatibility complex (MHC) class I and II (DC/WT1-I/II)-restricted Wilms' tumor 1 (WT1) peptides with chemotherapy may stabilize disease in pancreatic cancer patients. MATERIALS AND METHODS: Laboratory data from seven patients with pancreatic cancer who underwent combined DC/WT1-I/II vaccination and chemotherapy were analyzed. The DC phenotypes and plasma cytokine profiles were analyzed via flow cytometry. RESULTS: The post-treatment neutrophil to lymphocyte (N/L) ratio was a treatment-related prognostic factor for better survival. Moreover, the mean fluorescence intensities (MFIs) of human leukocyte antigen (HLA)-DR and cluster of differentiation (CD)83 on DCs were significantly increased after chemoimmunotherapy. Interestingly, interleukin (IL)-6 level in plasma was significantly increased after chemoimmunotherapy in non-super-responders. CONCLUSION: An increased N/L ratio, as well as HLA-DR and CD83 MFI levels may be prognostic markers of longer survival in patients with advanced pancreatic cancer who undergo chemoimmunotherapy.

Immunogenic modulation of cholangiocarcinoma cells by chemoimmunotherapy.

BACKGROUND/AIM: Chemoimmunotherapy has been used to treat intrahepatic cholangiocarcinoma (ICC). However, little is known about the phenomena underlying the immunomodulation of ICC cells elicited by chemoimmunotherapy. MATERIALS AND METHODS: Primary ICC cells from a patient with ICC who received gemcitabine followed by 5-fluorouracil (5-FU), both combined with dendritic cells pulsed with Wilms' tumor 1 (WT1) peptides were cultured. ICC cells were treated with gemcitabine, 5-FU or interferon (IFN)-γ in vitro. The phenotype of the ICC cells was examined by flow cytometry and quantitative reverse transcription polymerase chain reaction. RESULTS: Stimulation of the ICC cells with gemcitabine resulted in up-regulation of WT1 mRNA, programmed death receptor ligand-1 (PDL1) and calreticulin. Gemcitabine, 5-FU and IFN-γ induced up-regulation of mucin-1. Moreover, human leukocyte antigen (HLA)-ABC, HLA-DR and PDL1 were extremely up-regulated by IFN-γ. CONCLUSION: Chemoimmunomodulating agents alter the immunogenicity of ICC cells, resulting in complex clinical efficacy results.