613 HER2-XPAT, a novel protease-activatable prodrug T cell engager (TCE), with potent T-cell activation and efficacy in solid tumors and large predicted safety margins in non-human... by Fiore Cattaruzza, Ayesha Nazeer, Zachary Lange, Caitlin Koski, Mikhail Hammond, Trang Dao-Pick, Angela Henkensiefken, Mika Derynck, Volker Schellenberger, Bryan Irving