ANTXR1 (TEM8) overexpression in gastric adenocarcinoma makes the protein a potential target of immunotherapy

BACKGROUND. Despite the promise of immunotherapy for gastric adenocarcinoma, choices for the selection of effective antigenic targets are very limited. Previously published data and our own in-house computational analysis have suggested that ANTXR1 is a potential target, simultaneously expressed in malignant tumor cells and the endothelial cells of the tumors. However, the expression pattern of ANTXR1 protein in clinical samples of gastric adenocarcinoma has not been fully evaluated. METHODS. Using immunohistochemistry (IHC), we recorded the percentage of ANTXR1 positive cells separately in tumor cells and endothelial cells in the primary tumor, non-tumor gastric tissue adjacent to the primary tumor, and tumor in metastatic sites of 140 gastric adenocarcinoma patients. We also evaluated the association of ANTXR1 expression with the Lauren histological classification of the primary tumors, the patient’s history of neoadjuvant chemotherapy and/or radiotherapy, and the patient’s overall survival. RESULTS. ANTXR1 was expressed in a mean of 73.89 ± 30.12 percent of tumor cells and 13.55 ± 20.53 percent of endothelial cells in the primary tumors. Intestinal adenocarcinomas had lower ANTXR1 expression in the tumor cells and higher ANTXR1 expression in the endothelial cells of the tumor regions, and a history of neoadjuvant therapy was associated with increased ANTXR1 expression in the endothelial cells of the tumor regions. Finally, above median expression of ANTXR1 in the tumor cells of the tumor regions was associated with significantly lower overall patient survival. CONCLUSIONS. Our findings suggest that ANTXR1 is a promising candidate for preclinical and clinical evaluation for gastric adenocarcinoma immunotherapy.