Trophoblast cell surface antigen 2 (TROP2) and epithelial cell adhesion molecule (EPCAM) are cell surface receptors that play a role in growth signal transduction and cell adhesion. Antibody drug conjugates against both proteins are approved or under development.
To comprehensively study expression patterns of TROP2 and EPCAM in tumors, a tissue microarray containing 14’766 samples from 120 different tumor types was analyzed by immunohistochemistry.
TROP2 positivity was found in 88 of 120 tumor categories, including 73 of 76 epithelial tumor types. Particularly high rates of TROP2 positivity were seen in squamous cell carcinomas of various origins and various categories of urothelial, breast, prostate, pancreatic, and ovarian cancers (>95% positive). EPCAM positivity was found in 99 of 120 tumor categories, including all 76 epithelial tumor categories. Highest EPCAM positivity (>95% positive) was seen in small cell lung cancers, urinary bladder cancers, adenocarcinomas of various organs, and tumors of the female genital tract. Comparison of TROP2 and EPCAM revealed co-expression in 84 of 120 tumor types, including 73 of 76 epithelial tumor categories. Co-expression was most frequent (>95% positive for both markers) in cancers of the urinary bladder, prostate, pancreas, breast, and ovary. Exclusive EPCAM positivity was found frequently (>75% EPCAM positive but TROP2 negative) in various neuroendocrine tumors, testicular cancers, thyroid cancers, and Merkel cell carcinomas. Tumor types with frequent exclusive expression of TROP2 included of squamous cell carcinomas of various origins.
TROP2 and EPCAM are abundantly co-expressed in a broad range of epithelial neoplasms, but exclusively expressed in individual tumor types. Anti-TROP2 cancer drugs and future anti-EPCAM drugs may be applicable to a broad range of tumor entities.
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G. Sauter: Financial Interests, Personal, Other: MSVA Antibodies. All other authors have declared no conflicts of interest.