We have recently described a novel EGFR-targeted Fc-less 4-1BB agonistic trimerbody (1D8N/CEGa1), which is a potent costimulator in vitro and exhibits enhanced tumor penetration and powerful anti-tumor activity in immunocompetent mice bearing gene-modified CT26 colorectal carcinoma cells expressing human EGFR (10). Here, EGFR is linked to colorectal carcinoma.