Abstract 564: The expression of fetal oncogene 5T4 in CTCs obtained from NSCLC patients is discordant with the expression measured in the primary tumor

The fetal oncogene 5T4 is a cell surface protein, with over-expression observed in a variety of cancers as compared to normal adult tissue. Recent studies have shown that expression of 5T4 appears to be associated with the undifferentiated state and the epithelial-mesenchymal transition (EMT), and thus has been associated with a more invasive phenotype. We have developed assays to measure the expression of the fetal oncogene, 5T4, in both the primary tumor compartment and in the circulating tumor cell compartment. These assays were then used to investigate 5T4 expression in a small cohort of patients with NSCLC. We obtained matched primary tumor and blood samples, with the blood being obtained prior to resection of the primary tumor. The expression of 5T4 was found to be robust and measurable in both the primary and circulating tumor compartments. We observed expression of 5T4 in both adenocarcinoma and squamous cell carcinoma, in all stages and grades of tumor, with no specific correlation between expression and stage, grade or pathology. We further observed robust enumeration of CTCs in NSCLC samples. The expression of 5T4 was heterogeneous in the CTC compartment with no correlation to grade, stage or pathology. Finally, we observed no concordance between 5T4 expression in the primary tumor and the circulating tumor cell compartment. We discuss the current utility of target expression in predicting response to targeted therapy in the context of antibody based therapy, and the role that CTCs may have in the clinic. Citation Format: Steven R. Pirie-Shepherd, Shibing Deng, Jonathon Golas, Pamela Vizcarra, Eric Tucker, Dena Marrinuci, Hans-Peter Gerber, Eric L. Powell. The expression of fetal oncogene 5T4 in CTCs obtained from NSCLC patients is discordant with the expression measured in the primary tumor. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 564. doi:10.1158/1538-7445.AM2015-564