摘要
Pleural and peritoneal metastasis accompanied by malignant pleural effusion(MPE)or malignant ascites(MA)is frequent in patients with advanced solid tumors that originate from the lung,breast,gastrointestinal tract and ovary.Regional delivery of CAR-T cells represents a new strategy to control tumor dissemination in serous cavities.However,malignant effusions constitute an immune-suppressive environment that potentially induces CAR-T cell dysfunction.Here,we demonstrated that the anti-tumor cytotoxicity of conventional 2nd-generation CAR-T cells was significantly inhibited by both the cellular and non-cellular components of MPE/MA,which was primarily attributed to impaired CAR-T cell proliferation and cytokine production in MPE/MA environment.Interestingly,we found that PD-L1 was widely expressed on freshly-isolated MPE/MA cells.Based on this feature,a novel PD-L1-targeting chimeric switch receptor(PD-L1.BB CSR)was designed,which can bind to PD-L1,switching the inhibitory signal into an additional 4-1BB signal.When co-expressed with a 2nd-generation CAR,PD-L1.BB CSR-modified CAR-T cells displayed superior fitness and enhanced functions in both culture medium and MPE/MA environment,causing rapid and durable eradication of pleural and peritoneal metastatic tumors in xenograft models.Further investigations revealed elevated expressions of T-cell activation,proliferation,and cytotoxicity-related genes,and we confirmed that PD-L1 scFv and 4-1BB intracellular domain,the two important components of PD-L1.BB CSR,were both necessary for the functional improvements of CAR-T cells.Overall,our study shed light on the clinical application of PD-L1.BB CSR-modified dual-targeting CAR-T cells.Based on this study,a phase I clinical trial was initiated in patients with pleural or peritoneal metastasis(NCT04684459).
基金
National Science and Technology Major Project(2018ZX09733001-003-004)
National Natural Science Foundation of China(81673001 and 81872489).