TACSTD2 encodes TROP-2 (trophoblast cell-surface antigen 2), a glycoprotein that serves as a cell surface marker with significant roles in cancer biology and therapeutic targeting 1. TROP-2 is overexpressed in a wide range of human epithelial cancers including breast, colorectal, pancreatic, hepatocellular, and urothelial carcinomas, while showing lower expression in normal tissues 12. The protein regulates cancer growth, invasion, and metastasis through multiple signaling pathways and has roles in stem cell biology 1. In liver tissue, TROP2 expression identifies a heterogeneous EPCAM+ progenitor population with strong potential to form bipotent liver organoids 3. Clinically, TROP2 has emerged as an important therapeutic target, particularly through antibody-drug conjugates (ADCs) like sacituzumab govitecan and datopotamab deruxtecan, which have demonstrated significant efficacy in treating metastatic triple-negative breast cancer and other solid tumors 456. High TACSTD2 expression is associated with specific genomic alterations including TP53 and KRAS mutations, increased immune cell infiltration, and generally correlates with poorer overall survival in several cancer types 2. TROP2 expression can be assessed non-invasively using PET imaging with 68Ga-MY6349, facilitating patient selection for targeted therapies 7.