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. This remodeling 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.