背景:癌症中MET受体的异常激活是通过遗传改变或,更频繁地,通过转录上调。一部分MET扩增或突变的肿瘤对MET靶向剂敏感,但是他们的反应通常是短暂的,作为次级阻力最终发生。由于在没有遗传改变的情况下,MET通常不是肿瘤驱动因素,过表达MET的肿瘤对MET靶向治疗没有/反应差。因此,绝大多数显示MET激活的肿瘤仍代表未满足的医疗需求.
方法:在这里,我们提出了一种基于表达嵌合抗原受体(CAR)的T淋巴细胞的免疫治疗策略,该T淋巴细胞靶向不同组织型的MET过表达肿瘤。我们设计了两种不同的MET-CAR构建体,并针对不同的MET过表达模型测试了MET-CAR-T细胞的细胞毒活性,包括肿瘤细胞系,原发性癌细胞,类器官,和免疫缺陷小鼠的异种移植物。
结果:我们证明了MET-CAR-T对表达MET的细胞具有特异性细胞毒活性。细胞杀伤与细胞表面表达的MET水平成正比。虽然CAR-T细胞毒性在生理水平上与携带MET的细胞相比是最小的,基本上保留正常细胞,与MET过度表达的肿瘤相比,活性是强劲的,显着控制肿瘤细胞在体外和体内的生长。值得注意的是,MET-CAR-T细胞还能够在下游信号转导中携带次级突变的MET扩增的癌细胞中制动对MET靶向剂的获得性抗性。
结论:我们在临床前水平设定并验证了一种MET-CAR免疫治疗策略,该策略可能有益于不适合使用抑制分子进行MET靶向治疗的癌症,包括那些表现出主要或次要阻力的。
BACKGROUND: Aberrant activation of the MET receptor in cancer is sustained by genetic alterations or, more frequently, by transcriptional upregulations. A fraction of MET-amplified or mutated tumors are sensible to MET targeting agents, but their responsiveness is typically short-lasting, as secondary resistance eventually occurs. Since in the absence of genetic alterations MET is usually not a tumor driver, MET overexpressing tumors are not/poorly responsive to MET targeted therapies. Consequently, the vast majority of tumors exhibiting MET activation still represent an unmet medical need.
METHODS: Here we propose an immunotherapy strategy based on T lymphocytes expressing a Chimeric Antigen Receptor (CAR) targeting MET overexpressing tumors of different histotypes. We engineered two different MET-CAR constructs and tested MET-CAR-T cell cytotoxic activity against different MET overexpressing models, including tumor cell lines, primary cancer cells, organoids, and xenografts in immune-deficient mice.
RESULTS: We proved that MET-CAR-T exerted a specific cytotoxic activity against MET expressing cells. Cell killing was proportional to the level of MET expressed on the cell surface. While CAR-T cytotoxicity was minimal versus cells carrying MET at physiological levels, essentially sparing normal cells, the activity versus MET overexpressing tumors was robust, significantly controlling tumor cell growth in vitro and in vivo. Notably, MET-CAR-T cells were also able to brake acquired resistance to MET targeting agents in MET amplified cancer cells carrying secondary mutations in downstream signal transducers.
CONCLUSIONS: We set and validated at the pre-clinical level a MET-CAR immunotherapy strategy potentially beneficial for cancers not eligible for MET targeted therapy with inhibitory molecules, including those exhibiting primary or secondary resistance.