Of the constantly expanding spectrum of cell-surface targets in oncology, delta-like ligand 3 (DLL3), carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), and trophoblast cell-surface antigen 2 (TROP2) have been a focus for pre-clinical and clinical drug development efforts for advanced PC 23–28. This evidence concerns the gene TACSTD2 and pachyonychia congenita.