Antibody-drug conjugates (ADCs) such as enfortumab vedotin are currently revolutionizing the treatment of advanced urothelial carcinoma. Nevertheless, the development of therapy resistance remains a clinically relevant problem whose molecular basis is poorly understood.

This project develops a three-dimensional assembloid platform that combines patient-derived tumor organoids together with cancer-associated fibroblasts and endothelial cells. This physiologically representative model of the tumor microenvironment enables investigation of both the initial therapy response and the stepwise emergence of resistance under selective pressure. Three key resistance mechanisms are at the center of investigation: loss of target antigen expression, altered subcellular antigen localization, and the active role of the tumor microenvironment — in particular cancer-associated fibroblasts — in driving resistance development. Using single-cell RNA sequencing and multiplex immunohistology, cellular trajectories, cell-cell communication networks, and potentially actionable therapeutic targets are identified.