Inhibiting VTCN1 overcomes immunosuppression in colorectal cancer to activate T cells via galectin-3

Colorectal cancer (CRC) continues to be a major cause of cancer-related death globally, largely due to mechanisms of immune evasion that drive treatment resistance. Although multidisciplinary care has improved outcomes, how immune checkpoint molecules, particularly V-set domain-containing T-cell activation inhibitor 1 (VTCN1) and galectin-3, drive immunosuppression in CRC remains incompletely defined. In this study, we used an integrated multi-omics framework combining single-cell sequencing, transcriptomics, and proteomics to delineate the VTCN1-galectin-3 axis in CRC. We then validated its functional relevance using the VTCN1 inhibitor SGN-B7H4 in vitro and in vivo by assessing T cell function and tumor progression. Our results show that inhibiting VTCN1 markedly downregulates galectin-3 expression in T cells (P < 0.01), promoting T cell activation, as reflected by a 42% increase in CD25+CD69+ populations. Consequently, CRC cell proliferation was reduced by 58%, migration by 72% in scratch assays, and invasion by 65% in Transwell assays. In mouse models, SGN-B7H4 administration suppressed tumor growth by 63% relative to controls. These outcomes identify the VTCN1-galectin-3 axis as a pivotal mediator of immune suppression in CRC and highlight the therapeutic promise of targeting this pathway. Our work underscores the potential of VTCN1 inhibitors as part of combined treatment modalities, especially for immunotherapy-resistant CRC.NEW & NOTEWORTHY This study identifies the V-set domain-containing T-cell activation inhibitor 1 (VTCN1)-galectin-3 axis as a key immunosuppressive pathway in colorectal cancer (CRC). We show that inhibiting VTCN1 downregulates galectin-3 in T cells, reversing their dysfunction and reactivating antitumor immunity. Therapeutically, the VTCN1 inhibitor SGN-B7H4 restricted tumor progression by enhancing T-cell activity and impairing cancer cell proliferation, migration, and invasion. These findings reveal a novel immune checkpoint mechanism and establish VTCN1 as a promising target to overcome immunotherapy resistance in CRC.