Human epidermal growth factor receptor 2 (HER2) is overexpressed in some breast and gastric cancer patients. As the first HER2-targeteed therpeutic antibody, trastuzumab could significantly improve the prognosis of HER2-positive cancer patients. However, even responding patients inevitably get worse due to acquired resistance to trastuzumab after a period of treatment. Many HER2-targeted antibody drugs used wild-type tumor cells to conduct their corresponding preclinical experiments in vitro and in vivo. However, it is impossible to determine whether these newly developed drugs have antitumor effective to trastuzumab-resistant tumor cells. In the study, two trastuzumab-resistant HER2-positive tumor cell populations NCI-N87-TR and BT474-TR were generated. Then, we examined the anti-tumor effects of newly constructed immunotoxins with low immunogenicity and off-target toxicity based on the trastuzumab-resistant tumor cells both in vitro and in vivo. Results demonstrated that the immunotoxin IHP25-BT could not only effectively inhibit tumor growth but also inhibit liver metastasis of tumor cells in a mouse xenograft model. Furthermore, tumor tissue transcriptome sequencing was performed to clarify the potential mechanisms of inhibiting tumor cell distant metastasis by immunotoxin. In conclusion, this work describes a series of attractive therapeutic immunotoxins, the low immunogenicity and off-target toxicity making them promising for trastuzumab-resistant cancer therapy.

人表皮生长因子受体 2 (HER2) 在一些乳腺癌和胃癌患者中过度表达。作为首个靶向 HER2 的治疗性抗体，曲妥珠单抗可显着改善 HER2 阳性癌症患者的预后。然而，即使是有反应的患者，在经过一段时间的治疗后，也会由于对曲妥珠单抗的获得性耐药而不可避免地变得更糟。许多HER2靶向抗体药物使用野生型肿瘤细胞进行相应的体外和体内临床前实验. 然而，无法确定这些新开发的药物是否对曲妥珠单抗耐药的肿瘤细胞具有抗肿瘤作用。在该研究中，产生了两种曲妥珠单抗耐药的 HER2 阳性肿瘤细胞群 NCI-N87-TR 和 BT474-TR。然后，我们在体外和体内研究了基于曲妥珠单抗耐药肿瘤细胞的新构建的免疫原性和脱靶毒性的免疫毒素的抗肿瘤作用. 结果表明，免疫毒素 IHP25-BT 不仅可以有效抑制肿瘤生长，而且可以抑制小鼠异种移植模型中肿瘤细胞的肝转移。此外，进行肿瘤组织转录组测序以阐明免疫毒素抑制肿瘤细胞远处转移的潜在机制。总之，这项工作描述了一系列有吸引力的治疗性免疫毒素，低免疫原性和脱靶毒性使它们有望用于抗曲妥珠单抗的癌症治疗。