Pancreatic cancer is one of the most aggressive, heterogeneous and fatal type of human cancers for which more effective therapeutic agents are urgently needed. Here, we investigated the sensitivity of a panel of seven human pancreatic cancer cell lines (HPCCLs) to treatment with various tyrosine kinase inhibitors (TKIs), cyclin-dependent kinase (CDK) inhibitors, an inhibitor of STAT3 stattic, and a cytotoxic agent gemcitabine both as single agents and in combination. The membranous expression of various receptors and the effect of selected agents on cell cycle distribution, cell signaling pathways and migration was determined using flow cytometry, western blot analysis and scratch wound healing assays, respectively. While the expression of both HER-3 and HER-4 was low or negative, the expression of EGFR and HER2 was high or intermediate in all HPCCLs. Of all the agents examined, the CDK1/2/5/9 inhibitor, dinacicilib, was the most potent agent which inhibited the proliferation of all seven HPCCLs with IC 50 values of ≤10 nM, followed by SRC targeting TKI dasatinib (IC 50 of ≤258 nM), gemcitabine (IC 50 of ≤330 nM), stattic (IC 50 of ≤2 µM) and the irreversible pan-HER TKI afatinib (IC 50 of ≤2.95 µM). Treatment with afatinib and dasatinib inhibited the ligand-induced phosphorylation of EGFR and SRC respectively. Statistically significant associations were found between HER2 expression and response to treatment with the ALK/IGF-IR/InsR inhibitor ceritinib and fibroblast growth factor receptor (FGFR)1/2/3 inhibitor AZD4547, HER3 and IGF-IR expression and their response to treatment with TKIs targeting HER family members (erlotinib and afatinib), and c-MET and ALK7 expression and their response to treatment with stattic. Interestingly, treatment with a combination of afatinib with dasatinib and gemcitabine with dasatinib resulted in synergistic tumor growth inhibition in all HPCCLs examined. In contrast, the combination of afatinib with dinaciclib was found to be antagonistic. Finally, the treatment with afatinib, dasatinib and dinaciclib strongly inhibited the migration of all HPCCLs examined. In conclusion, the CDK1/2/5/9 inhibitor dinaciclib, irreversible pan-HER TKI afatinib and SRC targeting TKI dasatinib were most effective at inhibiting the proliferation and migration of HPCCLs and the combination of afatinib with dasatinib and gemcitabine with dasatinib led to synergistic tumor growth inhibition in all HPCCLs examined. Our results support further investigation on the therapeutic potential of these combinations in future clinical trials in pancreatic cancer.

Pancreatic cancer is one of the most aggressive, heterogeneous, and fatal types of human cancers. There is urgent need for discovery of biomarkers of prognostic significance, predictive value and as well as therapeutic targets in patients with pancreatic cancer. In this study, we examined the relative expression and prognostic significance of all HER family members and the type III EGFR mutant (EGFRvIII) in patients with pancreatic ductal adenocarcinoma (PDC). The expression levels of wild-type EGFR (wtEGFR), HER2, HER3, HER4 and EGFRvIII were determined in tumor specimens from 43 patients by immunohistochemistry using antibodies DAK-H1-WT, Neu 3B5, SP71, HFR1 and NBP2-50599 respectively. The staining was scored based on the percentage of positive tumor cells, the intensity (i.e. strong 3+, moderate 2+, weak 1+) and the cellular location of immunostaining (i.e. membranous, cytoplasmic or nuclear). The association between the expression level of the biomarkers and patient overall survival was evaluated using Chi-squared, Kaplan-Meier survival curves and log rank test. At cut-off value of above 5%, we found weak to moderate expression of wtEGFR, HER2, HER3, HER4 and EGFRvIII in 4.7%, 14%, 14%, 20.9% and 2.3% of the cases examined respectively. The cellular location of wtEGFR and HER2 was found to be predominantly cytoplasmic, HER-3 membranous and cytoplasmic whereas HER4 expression was found to be mainly nuclear. There was no statistically significant association between the expression level of these markers and patient overall survival. The expression levels of the above biomarkers were also evaluated in tissue microarrays (TMAs) from 40 cases of pancreatic ductal adenocarcinoma. Interestingly, at the same cut-off value, 62.5%, 75%, 0%, 55% and 5% of the TMAs were positive for wtEGFR, HER2, HER3, HER4 and EGFRvIII respectively. Overall, we found that the expression pattern of HER family members was heterogenous, and with EGFRvIII expression being very low in both whole tumor sections and TMAs from patients with pancreatic cancer. Taken together, our results provide support for more detailed studies of co-expression of all HER family members in a larger group of pancreatic cancer patients. Such studies should help to unravel their potential as targets for therapeutic interventions as well as their prognostic significance and predictive value for response to therapy. Citation Format: Tanzeel Khan, Said A. Khelwatty, Izhar Bagwan, Alan Seddon, Angus Dalgleish, Satvinder Mudan, Helmout Modjtahedi. Expression pattern and prognostic significance of HER family members and EGFRvIII in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2691.