Expression of Nectin-4 in Bladder Urothelial Carcinoma, in Morphologic Variants, and Nonurothelial Histotypes

Abstract

The antibody-drug conjugate enfortumab-vedotin acts by targeting nectin-4, a protein that is nearly ubiquitously expressed in conventional urothelial cancer. However, expression of nectin-4 in morphologic variants of urothelial carcinoma and nonurothelial histotypes was unknown. Immunohistochemistry for nectin-4 using was performed on 169 patients including 83 with nonmuscle invasive bladder cancer and 86 patients with muscle invasive bladder cancer. Staining was scored for intensity (0 to 3) and extent (% positive cells) using the histological score system, where >15 was considered positive. Overall, 72/83 (87%) samples of nonmuscle invasive urothelial carcinoma were positive, including 29/30 (97%) noninvasive papillary urothelial carcinomas, 7/8 (87.5%) carcinomas in situ, 36/45 (80%) papillary urothelial carcinomas invading the lamina propria. Overall, 50/86 muscle invasive tumors were positive, including 15/22 (68.2%) urothelial carcinomas, 7/10 (70%) squamous cell carcinomas, 3/11 (28%) micropapillary tumors, 4/6 (66%) adenocarcinomas, 2/4 (50%) nested carcinomas, 5/8 (63%) plasmacytoid, 1/10 (10%) sarcomatoid carcinomas, and 0/15 (0%) small cell carcinomas. Whole transcriptome RNA sequencing revealed that compared with conventional urothelial carcinomas, most sarcomatoid carcinomas and all but 2 small cell carcinomas expressed very low levels of nectin-4 mRNA but expressed significant levels of either trop2 or ERBB2, which are the molecular targets of 2 other antibody-drug conjugates-sacituzumab gavitecan (trop2) or trastuzumab deruxtecan (ERBB2/HER2). In summary, our study demonstrates that there is heterogeneity of expression of nectin-4 in morphologic variants of urothelial cancer and nonurothelial histotypes, and suggests that testing expression of nectin-4 should be considered in morphologic variants or nonurothelial histotypes found to have lower expression.

Figure 1.. Immunohistochemistry for nectin-4 in conventional urothelial carcinoma, urothelial carcinoma with squamous differentiation, and plasmacytoid urothelial carcinoma.

A. Hematoxylin and eosin (H&E) stained section of conventional urothelial carcinoma. B. Immunohistochemistry for nectin-4 in conventional urothelial carcinoma (same tumor as in “A”) showing strong membranous staining in the majority of tumor cells. C. H&E stained section of urothelial carcinoma with squamous differentiation. D. Immunohistochemistry for nectin-4 in same tumor as in “C” demonstrating strong cytoplasmic staining. E. H&E stained section of plasmacytoid variant of urothelial carcinoma. F. Immunohistochemistry for nectin-4 in same tumor as in “E” demonstrating weak staining in a subset of tumor cells.

Figure 2.. Immunohistochemistry for nectin-4 in micropapillary urothelial carcinoma, urothelial carcinoma with glandular differentiation, and nested urothelial carcinoma.

A. Hematoxylin and eosin (H&E) stained section of micropapillary urothelial carcinoma. B. Immunohistochemistry for nectin-4 in same tumor as in “A” showing strong membranous staining in a subset of tumor cells. C. H&E stained section of urothelial carcinoma with glandular differentiation. D. Immunohistochemistry for nectin-4 in same tumor as in “C” demonstrating weak cytoplasmic staining. E. H&E stained section of nested variant of urothelial carcinoma. F. Immunohistochemistry for nectin-4 in same tumor as in “E” demonstrating moderate staining in a subset of tumor cells.

Figure 3.. Immunohistochemistry and mRNA expression for nectin-4 in small cell carcinoma of the bladder and sarcomatoid urothelial carcinoma.

A. H&E section of conventional urothelial carcinoma with small cell carcinoma. B. Immunohistochemistry with nectin-4 in same tumor as in “A” showing strong staining in the conventional urothelial carcinoma (left, brown stain) while small cell carcinoma is negative. C. H&E stained section of sarcomatoid urothelial carcinoma. D. Immunohistochemistry for nectin-4 in same tumor as in “C” demonstrating complete absence of staining in tumor cells. E. Heat-map of next generation RNA sequencing of conventional urothelial carcinoma, small cell carcinoma of the bladder and sarcomatoid urothelial carcinoma. Red colors indicate overexpression. SC: sarcomatoid carcinoma; SCBC: small cell bladder cancer; UC: Urothelial carcinoma.