Glypican-3 and Cytokeratin-19 Expression in Pancreatic Cancer in a Canadian Population

Background/Objectives: One study of pancreatic ductal adenocarcinoma has found expression of glypican-3 (GPC3) and cytokeratin-19 (CK19) determined by immunohistochemistry to be associated with higher stage and grade disease, with a more adverse prognosis. The reported 44% rate of GPC3 expression in pancreatic cancer raises the important possibility that targeted immunotherapies currently in development for hepatocellular carcinoma may also prove useful for GPC3-expressing pancreatic cancers. The present study aims to determine if a similar expression pattern of these markers and stage/grade/prognostic associations is present in our Canadian patient population. Methods: Patients with a pancreatic surgical resection for adenocarcinoma or neuroendocrine tumor (NET) were identified from pathology records over a 5-year period. Immunohistochemistry for GPC3 and CK19 was performed on archived tumor tissue and the proportion of positive cells and intensity of staining were recorded. Grade, stage, and overall survival were compared in patients with NETs that were CK19-positive versus -negative. Results: All 72 pancreatic adenocarcinomas and 20 NETs tested were negative for GPC3, apart from a single case of pancreatic adenocarcinoma. All 72 adenocarcinomas were positive for CK19 expression. Half of the NETs were positive for CK19. There was no correlation between CK19 expression in NETs and tumor grade, lymph node metastasis, distant metastasis, or overall survival. Conclusions: We are skeptical of the reported prognostic value of GPC3 and CK19 in pancreatic adenocarcinomas. CK19 as a prognostic marker in NETs has potential for further study. The results with our protocol for GPC3 immunohistochemistry suggest that pancreatic cancer may be a less promising target for GPC3-targeted immunotherapies than previously thought.