靶向 IGHV4-34 B 细胞受体的 CAR-T 细胞特异性清除肿瘤性及自身免疫性 B 细胞

Current US Food and Drug Administration-approved chimeric antigen receptor (CAR) T cell therapies for B cell leukemias and lymphomas target CD19, which is widely expressed across the B cell lineage, often leading to on-target, off-tumor B cell depletion, prolonged immune suppression, and antigen-negative escape in a subset of patients.

In contrast, B cell receptor (BcR) signaling is essential for the survival of most mature B cell neoplasms, and BcRs carrying the immunoglobulin heavy variable gene IGHV4-34 are highly enriched in B cell malignancies compared with normal B cells.

Further, self-reactive IGHV4-34 + serum autoantibodies are enriched in aggressive systemic lupus erythematosus (SLE) and other autoimmune diseases.

Here, we developed CAR T cells targeting the BcR carrying IGHV4-34 (CART4-34).

We found that CART4-34 showed specific cytotoxicity and cytokine secretion toward IGHV4-34 + malignant B cells.

In addition, although CD19 was down-regulated upon relapse after treatment with CART19, IGHV4-34 + BcR levels remained intact upon relapse after treatment with CART4-34, suggesting reduced risk of antigen-negative escape. In IGHV4-34 + HBL1 cell line-derived xenograft mouse models, CART4-34 showed robust expansion and antitumor activity comparable to those of CART19. Optimized CAR:BcR binding using shorter CAR hinge domains improved immune synapse morphology and in vivo activity.

In addition, we showed that CART4-34 could target human IGHV4-34 + SLE B cells and deplete IGHV4-34 + autoantibodies ex vivo, without targeting healthy B cells or affecting total IgG titers.

In conclusion, we developed a CAR T cell product that specifically targets pathogenic B cells in lymphoid malignancies and SLE, offering potential for precision cell therapy for these indications.