ERBB2 and neoplasm: In mice harboring HER2-low HT-55 xenografts, equimolar doses of HER2-XPAT protein (5.1 mg kg−1) and unmasked HER2-TCE (0.9 mg kg−1) led to significant tumor growth inhibition (TGI) (P = 0.013 versus vehicle control for both) (Fig. 3b).