肿瘤细胞治疗研究
英文原题：Effective CAR T-cell targeting of an MUC1 cleavage product.
这些结果支持，靶向 MUC1*（MUC1 的生长因子受体形式）与携带 CD3 中 1XX 突变的 CAR-T 联合，具有治疗实体瘤癌症的潜力。
背景：我们开发了靶向黏蛋白1（MUC1）*（MUC1*）的嵌合抗原受体（CAR）T细胞；MUC1*是MUC1的一种肿瘤相关生长因子受体形式。我们的抗体MNC2可特异性结合癌细胞上的MUC1*，但不结合所有正常上皮细胞均表达的全长MUC1。我们检测了CD3中的酪氨酸转苯丙氨酸突变（称为“1XX”）能否增强体内持久性，并使CAR识别和杀伤低抗原表达的癌细胞。方法：我们开展体内实验，比较带有4-1BB或CD28共刺激结构域、并分别带有或不带有CD3信号结构域第2和第3免疫受体酪氨酸活化基序（ITAM）中“1XX”酪氨酸转苯丙氨酸突变的CAR。所有CAR均采用相同的huMNC2单链可变片段靶向肿瘤。为评估不同CAR的敏感性，我们移植了由不同比例高MUC1*表达癌细胞组成的肿瘤。此外，将野生型低MUC1*表达细胞改造为红色荧光，而高表达MUC1*的工程化细胞标记为绿色荧光，从而比较不同CAR对低、高抗原表达癌细胞的敏感性。结果：高剂量时，所有CAR-T细胞均能在短期内有效杀伤高抗原表达肿瘤。然而，只有携带1XX突变的CAR能在长期实验中抑制肿瘤复发。有趣的是，接受野生型CD3 CAR治疗的动物，其肿瘤复发由低抗原表达细胞驱动。即使以低剂量给药，也只有携带1XX突变的CAR能杀伤低抗原表达肿瘤。处死后分析显示，携带1XX突变的CAR-T细胞在体内的持久性长于CD3为野生型的4-1BB或CD28 CAR-T细胞。结论：这些结果支持靶向MUC1*（即MUC1的生长因子受体形式）并结合CD3含1XX突变CAR-T的策略具有治疗实体瘤的潜力。
BACKGROUND: We developed Chimeric antigen receptor (CAR) T cells targeting mucin 1 (MUC1)* (muk * (muk 1 star)), which is the tumor-associated growth factor receptor form of MUC1. Our antibody, MNC2, uniquely binds to MUC1* on cancer cells but does not bind to full-length MUC1, which is expressed on all normal epithelial cells. We tested the ability of the Tyr to Phe mutations in CD3 , known as "1XX", to increase in vivo persistence and enable the recognition and killing of low antigen-expressing cancer cells. METHODS: We performed in vivo experiments comparing CARs with either 4-1BB or CD28 co-stimulatory domains, with or without the "1XX" Tyr to Phe mutations in ITAMs 2 and 3 of the CD3 signaling domain. All CARs were targeted to the tumor using the same huMNC2-scFv. To explore the sensitivity of each CAR, tumors comprising varying percentages of high MUC1* expressing cancer cells were xenografted. Further, wild-type low MUC1* expressing cells were engineered to fluoresce red while the cells engineered to express more MUC1* were made to fluoresce green. This experimental design allowed us to compare the sensitivity limits of the CARs against low versus high antigen-expressing cancer cells. RESULTS: At high dose, all the CAR T cells effectively killed high antigen-expressing tumors in the short term. However, only the CAR bearing the 1XX mutations inhibited tumor recurrence in long-term experiments. Interestingly, in animals treated with CARs bearing wild-type CD3 , tumor recurrence was driven by the low antigen-expressing cells. Only the CAR bearing 1XX mutations demonstrated the ability to kill low antigen-expressing tumors, even when administered at low dose. Post-sacrifice analysis showed that the CAR T cells with 1XX mutations persisted longer in vivo than either 4-1BB or CD28 CAR T cells with wild-type CD3 . CONCLUSIONS: These results support that the combination of targeting MUC1*, the growth factor receptor form of MUC1, with a CAR T bearing the 1XX mutations in CD3 has therapeutic potential for the treatment of solid tumor cancers.
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