嵌合抗原受体（CAR）T细胞疗法在治疗血液癌方面显示出有希望的结果，但对表达表面膜抗原（MSLN）的固体肿瘤的疗效受限。其中一个原因是免疫抑制性肿瘤微环境，它由物理屏障、多种免疫逃逸机制和各种对肿瘤生长和存活有利的生化因子组成。这些因素降低了临床试验中针对MSLN的CAR T细胞的抗肿瘤活性。因此，需要新的治疗策略来提高针对MSLN的CAR T细胞疗法的有效性。 为了调查抗MSLN CAR-T细胞的抗肿瘤活性是否取决于它们识别的表位，我们生成了针对MSLN结合到不同区域（区域I、II、III和全长）的CAR T细胞。然后，在体外和体内评估了MSLN靶向CAR T细胞单独或与化疗药物依妥南或抗PD-1抗体的联合使用的抗肿瘤活性。 我们发现，MSLN靶向CAR T细胞可以有效杀死MSLN阳性肿瘤细胞（H9、H226和Panc-1），但对MSLN阴性细胞（A431）没有作用。在H9肿瘤异种移植小鼠模型中，所有CAR T细胞显示出类似的肿瘤抑制作用，但一个具有区域I表位（R47）的MSLN靶向scFv表现稍好。依妥南与CAR_R47 T细胞的联合使用在H9异种移植小鼠和患者源性异种移植小鼠中协同增强了肿瘤控制。 我们的结果表明，依妥南可以增强针对MSLN靶向CAR T细胞的抗肿瘤活性，并提供了一种针对MSLN阳性实体肿瘤的有希望的联合治疗策略。 ©2023. 作者（们）独家许可给Springer-Verlag GmbH Germany，Springer Nature的一部分。

Chimeric antigen receptor (CAR) T cell therapy has shown promising results in treating blood cancers, but it has limited efficacy against solid tumors that express mesothelin (MSLN). One of the reasons is the immunosuppressive tumor microenvironment, which consists of physical barriers, multiple mechanisms of immune evasion, and various biochemical factors that favor tumor growth and survival. These factors reduce the antitumor activity of MSLN-targeted CAR T cells in clinical trials. Therefore, new therapeutic strategies are needed to enhance the effectiveness of MSLN-targeted CAR T cell therapy.To investigate whether the antitumor efficacy of anti-MSLN CAR-T cells depends on the epitopes they recognize, we generated MSLN-targeted CAR T cells that bind to different regions of MSLN (Region I, II, III and Full length). We then evaluated the antitumor activity of MSLN-targeted CAR T cells alone or in combination with the chemotherapeutic drug irinotecan or an anti-PD-1 antibody in vitro and in vivo.We found that MSLN-targeted CAR T cells effectively killed MSLN-positive cancer cells (H9, H226 and Panc-1), but not MSLN-negative cells (A431) in vitro. In a mouse model of H9 tumor xenografts, all CAR T cells showed similar tumor suppression, but an MSLN-targeted scFv with Region I epitope, R47, performed slightly better. Combining irinotecan with CAR_R47 T cells enhanced tumor control synergistically in both H9 xenograft mice and patient-derived xenograft mice.Our results suggest that irinotecan can enhance the antitumor activity of MSLN-targeted CAR T cells, and offer a promising combination therapy strategy for MSLN-positive solid tumors.© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.