Another limitation in the choice of targets and antibodies arises with immunotoxins, which require internalization in order to hae a cytotoxic effect on tumour cells.

• 由于需要细胞内化的过程以使肿瘤细胞内部产生细胞毒效应，免疫毒素还面临在治疗对象和单抗选择方面的局限。