Chromosome 1q23.3 is commonly amplified in metastatic urothelial carcinoma (UC). This region contains NECTIN4 that encodes for a membrane protein, and amplification may result in increased NECTIN4 expression. Enfortumab vedotin (EV), an antibody drug conjugate, targets NECTIN4. The objective of this study was to determine the frequency of NECTIN4 amplification by fluorescence in situ hybridization (FISH) and protein expression by immunohistochemistry (IHC) in primary UC and subtypes. Tissue microarrays (TMA) were constructed from 841 patients who underwent cystectomy between 2000 and 2020. In 218 patients, TMAs were constructed from a concurrent pelvic lymph node metastasis. NECTIN4 amplification varied by subtype and was present in 18% of UCs, 13% of UCs with squamous differentiation, 25% of micropapillary, 19% of plasmacytoid, 17% high-grade neuroendocrine carcinoma, 8% of pure squamous cell carcinoma, 6% of nested and 6% of sarcomatoid carcinomas. Tumors with NECTIN4 amplification had significantly higher H scores compared to non-amplified tumors (p<0.0001), and H scores increased with increasing copy number in amplified tumors. NECTIN4 amplification was identified in 17% of lymph node metastases, and 70% of amplified primary tumors had an amplified metastasis which increased to over 90% when whole section FISH was performed in discordant TMA cases. There was a moderate agreement between IHC staining of primary and lymph node metastasis (kappa 0.41). NECTIN4 amplifications vary in frequency amongst UC and subtypes and amplifications result in higher protein expression. Bladder cancer with NECTIN4 amplification may have limited protein expression while non-amplified tumors may show high expression. There was concordance of NECTIN4 amplification and protein expression between primary and lymph node metastases, but there were a small number of cases with amplified primary tumors and unamplified metastases, and primary tumors with high protein expression, and metastasis with low expression.
Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc. 2025 Oct 29 [Epub ahead of print]
John C Cheville, Jacob J Orme, Sounak Gupta, Fabrice Lucien-Matteoni, R Jeffrey Karnes, Prabin Thapa, Abhinav Khanna, Shruthi Naik, Vidit Sharma, Igor Frank, Lance Pagliaro, Fernando Quevedo, Burak Tekin, Ryan Knudson, Patricia Greipp, Carrie Brandt, Justin Koepplin, Brian Costello, Elisabeth Heath, George Vasmatzis, Angelo Florio, Stephen A Boorjian, Paras H Shah
Division of Anatomic Pathology. Electronic address: ., Department of Medical Oncology., Division of Anatomic Pathology., Department of Urology., Department of Health Sciences Research., Department of Molecular Medicine, Mayo Clinic, Rochester, MN.