ERBB2 and colonic neoplasm: Further examples of on-target, off-tumor toxicity include carboxyanhydrase-IX-specific CAR T-cell therapy for renal cell carcinoma that resulted in the development of cholestasis due to expression of this antigen on bile duct epithelium (203), and unfortunately, the infusion of HER-2/neu CAR T-cells in a patient with advanced colonic cancer that led to respiratory distress and cardiac arrest which was attributed to putative low levels of HER-2/neu expression on lung epithelial cells (204).