PE and its derived domains have been fused to anti-GPC3 (41, 42), anti-GPC2 (43), anti-VEGFR2 (44), anti-CD7 (45, 46), anti-HER2 (47), and anti-CD38 (48) nanobodies to improve their cytotoxic activities in several tumor models. This evidence concerns the gene ERBB2 and neoplasm.