Targeting Truncated O-Glycan Elicits Dual T Cell Immunity and Overcomes MHC-I Heterogeneity to Design Effective Cancer Vaccine

Aberrant O-glycosylation is a hallmark of cancer, but its contribution to immune evasion is unclear. Using CRISPR-Cas9 to delete GalNAc-transferases, particularly GalnT7, in tumor cells, we reduced mucin-type O-glycan truncation, thus promoting activated dendritic cell- and T cell-dependent immunity, eradicating established tumors, preventing metastasis, and generating durable memory. It enhanced clearance of MHC class I-positive tumors via coordinated CD8+ and CD4+ T cell responses, and uniquely enabled CD4+ T cell-mediated elimination of MHC class I-deficient tumors, which evade cytotoxic T lymphocyte surveillance. Tumor cells with reduced O-glycan truncation served as potent whole-cell vaccines, with efficacy further improved by radiotherapy. These findings establish glycosylation as a central regulator of tumor immune evasion and define a broadly applicable vaccine platform that bypasses the limitations of neoantigen-based approaches for low-immunogenicity cancers.