Background: Immunotherapy utilizing T cells genetically modified to express chimeric antigen receptors (CARs) is rapidly emerging as a promising novel treatment for hematological and nonhematological malignancies. In order to target the TKI-insensitive leukemia stem cells (LSCs) in chronic myeloid leukemia (CML) by CAR T cells, we chose CD26 as a cell surface tumor-associated antigen due to preferentially expression on LSCs. Additionally, CD26 has also been suggested to be a multipurpose therapeutic target for other cancer. Therefore, developing the CD26-targeting CAR T cells may be a promising therapy for not only LSCs but also other CD26+ cancer cells. Methods: We designed the second-generation CD26-targeting CAR utilizing 4-1BB (CD137) as costimulatory domain, and transduced T cells with CD26-CAR containing lentiviral. Then we evaluated the transduction efficiency and expansion ability, and demonstrated the existence of self-antigen-driven fratricide by cytokine assay and cytotoxicity assay. Results: Anti-CD26-4-1BB-CAR T cells exhibited poor viability, multiple cytokine secretion, down-regulation of CD26 and direct cytotoxicity against themselves, indicating self-antigen-driven fratricide. Conclusion: Eradicating CML-LSCs via anti-CD26-4-1BB-CAR T cells is not applicable, and optimized design or alternative target is needed.

中文翻译：

---

表达CD26特异性嵌合抗原受体的T细胞表现出广泛的自身抗原驱动的杀伤分子。

背景：利用经过基因修饰的T细胞表达嵌合抗原受体（CARs）的免疫疗法正在迅速出现，作为血液学和非血液学恶性肿瘤的一种有希望的新疗法。为了通过CAR T细胞靶向慢性髓样白血病（CML）中的TKI不敏感白血病干细胞（LSCs），我们选择CD26作为细胞表面肿瘤相关抗原，因为它在LSCs上优先表达。另外，还已经提出CD26是其他癌症的多用途治疗靶标。因此，开发针对CD26的CAR T细胞可能不仅对LSC，而且对其他CD26 +癌细胞都是有前途的疗法。方法：我们设计了以4-1BB（CD137）为共刺激域的第二代CD26靶向CAR，并用含有慢病毒的CD26-CAR转导了T细胞。然后，我们评估了转导效率和扩增能力，并通过细胞因子测定法和细胞毒性测定法证明了自身抗原驱动的杀幼虫剂的存在。结果：抗CD26-4-1BB-CAR T细胞表现出较差的生存力，多种细胞因子分泌，CD26的下调和对自身的直接细胞毒性，表明自身抗原驱动的杀人分子。结论：通过抗CD26-4-1BB-CAR T细胞消除CML-LSC是不适用的，需要优化设计或替代靶标。指示自身抗原驱动的杀人剂。结论：通过抗CD26-4-1BB-CAR T细胞消除CML-LSC是不适用的，需要优化设计或替代靶标。指示自身抗原驱动的杀人剂。结论：通过抗CD26-4-1BB-CAR T细胞消除CML-LSC是不适用的，需要优化设计或替代靶标。