分泌抗 PD-L1 单链可变片段的抗 CD19 CAR-T 细胞减弱 PD-L1 介导的 T 细胞抑制

Adoptive T cell therapy using second-generation anti-CD19 chimeric antigen receptor T cells (anti-CD19-CAR2-T) induced complete remission in many heavily pretreated patients with B cell acute lymphoblastic leukemia (B-ALL) or diffuse large B cell lymphoma (DLBCL).

However, poor clinical efficacy was observed in treating aggressive B cell lymphomas (BCL). The limited T cell function was reported by programmed cell death protein 1 ligand (PD-L1) expressed on BCL cells bound to the PD-1 receptor on T cells.

To overcome this problem, we generated anti-CD19-CAR4-T cells secreting anti-PD-L1 single-chain variable fragment (scFv), namely anti-CD19-CAR5-T cells, and evaluated their functions in vitro. Both anti-CD19-CAR-T cells contain an anti-CD19 scFv derived from a monoclonal antibody, FMC63, linked to CD28/4-1BB/CD27/CD3 . The secreting anti-PD-L1 scFv is derived from atezolizumab.

Our results showed that secreted anti-PD-L1 scFv could bind to PD-L1 and block the binding of anti-PD-L1 monoclonal antibodies on PD-L1 high tumor cells. Anti-CD19-CAR4-T and anti-CD19-CAR5-T cells efficiently killed CD19 + target tumor cells in two-dimensional (2D) and three-dimensional (3D) co-culture systems.

However, anti-CD19-CAR5-T cells demonstrated superior proliferative ability. Interestingly, at a low effector (E) to target (T) ratio of 0. 5:1, anti-CD19-CAR5-T cells showed higher cytotoxicity against CD19 + /PD-L1 high cells compared to that of anti-CD19-CAR4-T cells. The cytotoxicity of anti-CD19-CAR4-T cells against CD19 + /PD-L1 high could be restored by adding anti-PD-L1 scFv.

Our findings demonstrate the combination antitumor efficiency of anti-CD19-CAR4-T cells and anti-PD-L1 scFv against CD19 + /PD-L1 high tumors. As such, anti-CD19-CAR5-T cells should be further investigated in vivo antitumor efficiency and clinical trials as a treatment for aggressive B cell lymphoma.