TROP-2 Is Not a Therapeutic Target in Melanoma: a Morphological Study

Introduction: Cutaneous malignant melanoma represents only 1% of all skin cancers, but it has become a leading cause of cancer death, especially in young adults, owing to the high number of patients with disease progression and recurrence. In fact, disease progression and recurrence is still an important issue in treatment of this disease. Trophoblast surface antigen-2 (TROP-2) is a type I transmembrane glycoprotein belonging to the epithelial cell adhesion molecule (EpCAM) family, a group of proteins involved in cell adhesion and anti-TROP-2 antibody–drug conjugate, and showed important beneficial effects in cancers. We hypothesized that if TROP-2 was expressed in melanomas, it could represent a therapeutic target. Methods: In total, 50 primary melanomas at different stages and ten melanocytic nevi (used as control group) were analyzed for TROP-2 protein expression by immunohistochemistry and confocal microscopy. Results: TROP-2 was expressed on the cell membranes of epidermal melanocytes and keratinocytes, while melanocytic nevi and melanoma tissues (at any stage) did not show TROP-2 expression. Conclusions: Our findings suggest that TROP-2 could not be considered a therapeutic target for melanoma treatment because of the absence of detectable expression in the analyzed cohort.