Assessing the expression of Nectin-4 in solid tumors by immunohistochemistry - what do we know?

Antibody-Drug Conjugates (ADCs) represent a promising class of anti-cancer substances that combine the specificity of monoclonal antibodies with the potency of cytotoxic drugs, hence they enable a new approach of targeted therapy. The use of the ADC Entfortumab Vedotin (EV), which targets the viral receptor Nectin-4, showed an impressive clinical response in metastatic urothelial carcinoma. In this review, we present what is known about the expression of Nectin-4 in various tumor entities, focusing on immunohistochemistry as a diagnostic venue to detect positive expression, as this inexpensive technique is readily available in pathology laboratories. Various studies demonstrated expression of Nectin-4 in many solid tumor entities with the highest expression rates in urothelial carcinomas and breast cancer. To date, the relevance of the subcellular compartment of immunoreactivity (membranous vs. cytoplasmic) is still unclear in respect of its predictive value for EV therapy, which ought to be clarified in further studies.