Improving CAR-T cell function through a targeted cytokine delivery system utilizing car target-modified extracellular vesicles

Chimeric antigen receptor (CAR)-T-cell therapy has achieved remarkable clinical success in the treatment of B-cell malignancies; however, its efficacy can be limited by poor T-cell persistence and insufficient antitumor activity in certain cases. Moreover, interleukin-12 (IL-12) is a prominent agent in cancer immunotherapy, but its clinical application is constrained by severe toxicity associated with systemic exposure. In this study, we developed a novel cytokine delivery platform based on CAR target-modified cell-derived extracellular vesicles (EVs) that preferentially bind CAR-T cells to improve CAR-T-cell function. EVs with surface-displayed CD19 and/or IL-12 were successfully generated from HEK-293T cells. Compared with an equivalent concentration of rhIL-12, IL-12 EVs significantly enhanced the effector function of anti-CD19 CAR-T cells in vitro, resulting in increased Interferon-γ (IFN-γ) and TNF-α secretion, cytolytic activity, and T-cell expansion. Additionally, compared with EVs expressing IL-12 alone, EVs co-expressing IL-12 and CD19 (CD19/IL-12 EVs) exhibited superior binding efficiency to CAR-T cells but not to T cells, as indicated by flow cytometry. In xenograft model mice bearing CD19 + Raji tumors, intratumoral injection of CD19/IL-12 EVs resulted in durable antitumor responses and enhanced the in vivo expansion of CAR-T cells, outperforming CD19 EVs, IL-12 EVs and control EVs, without causing systemic toxicity. RNA sequencing (RNA-seq) analysis of CAR-T cells stimulated with EVs suggested that the increased efficacy was driven by IL-12 signaling. These data demonstrate that CAR-targeted modified EVs may serve as targeted cytokine delivery systems for CAR-T cells, offering a safe and effective strategy to augment CAR-T-cell function.