Manufacturing and electrostatic surface optimization of CAR-T cells improve therapeutic efficacy in liver malignancies.

BACKGROUND

Chimeric antigen receptor T-cell (CAR-T) therapy has achieved remarkable success in hematologic malignancies, yet demonstrates limited efficacy in solid tumors, including hepatic cancers. T-cell exhaustion and insufficient persistence represent major obstacles. We hypothesized that optimizing both manufacturing processes and CAR structural design could reduce exhaustion and enhance therapeutic outcomes in immunocompetent mouse models of primary and metastatic liver malignancies.

METHODS

We systematically compared antibody-based versus bead-based activation methods, evaluating their effects on T-cell exhaustion phenotypes. Retroviral vector (RVV) production was optimized for murine T-cell transduction, assessing vector stability and T-cell phenotypes. Different cytokine conditions were tested for their impact on T-cell expansion, memory phenotypes, and anti-tumor efficacy using GPC3-targeted CAR-T cells in hepatocellular carcinoma models. Through structural prediction and electrostatic field simulation, we identified that high positive charge patches (PCP) in the EpCAM-targeting G8.8 scFv caused CAR clustering and tonic signaling. We generated charge-optimized variants and evaluated their therapeutic efficacy in an immunocompetent colorectal cancer liver metastasis model.

RESULTS

Antibody activation showed superior homogeneity and expansion despite initially higher exhaustion markers, which equilibrated by day 10 without affecting viability. RVV harvested at 72 hours post-transfection yielded optimal titers. RVV remained stable through freeze-thaw cycles. IL-7 supplementation to IL-2 significantly enhanced memory phenotypes, reduced exhaustion, and improved tumor control in GPC3-CAR-T therapy. Electrostatic optimization of G8.8 scFv substantially reduced tonic signaling, decreased T-cell exhaustion, and enhanced anti-tumor efficacy in the MC38-EpCAM model.

CONCLUSIONS

Systematic optimization of manufacturing conditions and structure-based charge engineering of CAR constructs synergistically enhance therapeutic efficacy against liver malignancies, providing a translatable framework for improving solid tumor CAR-T therapy.