Nectin‐4 expression in a subset of cutaneous adnexal carcinomas: A potential target for therapy with enfortumab vedotin

Background Enfortumab vedotin (EV) is an antibody‐drug conjugate directed against Nectin‐4 that is used to treat urothelial carcinoma. Nectin‐4 is inherently expressed in the skin and adnexal structures. Since therapeutic options for cutaneous adnexal carcinomas are limited, we sought to evaluate Nectin‐4 expression in adnexal carcinomas and benign adnexal neoplasms to identify tumors that are potentially targetable with EV. Methods Eight sebaceous carcinomas (seven periocular and one lymph node metastasis), eight digital papillary adenocarcinomas, seven squamoid eccrine ductal carcinomas, eight poromas, eight trichilemmomas, and seven sebaceous adenomas were subjected to immunohistochemical staining for anti‐Nectin‐4 antibody. H‐scores for Nectin‐4 expression were calculated. Results Benign adnexal neoplasms had a significantly lower mean (±SD) Nectin‐4 H‐score (142.6 ± 39.1) than did the adnexal carcinomas (198 ± 90.8; p = 0.006). Nectin‐4 was expressed in 91% (21/23) of adnexal carcinomas. Sebaceous carcinomas frequently exhibited high expression of Nectin‐4 (88% [7/8]), with a mean (±SD) H‐score (258.1 ± 58.4) significantly higher than those for digital papillary adenocarcinomas (197.5 ± 52.5; p = 0.035) and squamoid eccrine ductal carcinomas (131.4 ± 114.1; p = 0.031). Sebaceous carcinomas also had significantly higher H‐scores than did sebaceous adenomas (186.4 ± 25.0; p = 0.013). Conclusions Increased Nectin‐4 expression in a subset of cutaneous adnexal carcinomas, particularly sebaceous carcinomas, reveals that EV is a potential therapeutic option for these tumors.