BRAF抑制剂上调肿瘤抗原MUC1表达提升MUC-1 CAR-T肿瘤杀伤效果的机制和转化研究

嵌合抗原受体修饰T细胞治疗（CAR-T）是肿瘤免疫治疗的重要方法，靶向MUC1的CAR-T是目前抗实体肿瘤中研究最广泛和最有希望的选择之一，但其临床疗效仍有待提高。我们前期通过敲除CAR-T的PD-1表达提高了治疗效果。为进一步提升疗效，我们通过药物库筛选发现BRAF抑制剂达拉非尼可提高肿瘤MUC1的表达。初步研究发现BRAF抑制剂可通过降低MUC1基因DNA甲基化及MUC1蛋白糖基化，上调肿瘤特异性低糖基化MUC1表达，提升MUC1 CAR-T的杀伤效果；而血清CA153水平与肿瘤细胞MUC1表达量正相关，提示CA153上调可作为指示BRAF抑制剂有效的指标。本课题拟在乳腺癌等实体瘤中，阐明BRAF抑制剂上调肿瘤特异性低糖基化MUC1表达的机制；明确能实时反映肿瘤MUC1表达水平的标志物；探索临床BRAF抑制剂和CAR-T联合应用的最佳模式，为提高CAR-T抗肿瘤疗效提供新策略。

Chimeric antigen receptor-modified T cell therapy (CAR-T) is an important method of tumor immunotherapy. CAR-T targeting MUC1 is one of the most widely studied and promising options in anti-solid tumors, but its clinical efficacy still needs to be improved. We have previously improved the therapeutic effect by knocking out the PD-1 expression of CAR-T. In order to further improve the therapeutic effect, we found that the BRAF inhibitor dabrafenib can increase the expression of MUC1 through drug library screening. The preliminary study found that BRAF inhibitor can up-regulate the expression of tumor-specific low glycosylated MUC1 and enhance the killing effect of MUC1 CAR-T by reducing the DNA methylation of MUC1 gene and the glycosylation of MUC1 protein; and the serum CA153 level is positively correlated with the expression of MUC1 in tumor cells, suggesting that the up-regulation of CA153 can be used as an indicator of the effectiveness of BRAF inhibitor. This project aims to clarify the mechanism of BRAF inhibitor up-regulating the expression of tumor-specific low glycosylated MUC1 in breast cancer and other solid tumors; identify the markers that can reflect the expression level of tumor MUC1 in real-time; explore the best mode of clinical BRAF inhibitor combined with CAR-T, and provide new strategies for improving the anti-tumor efficacy of CAR-T.