LGALS9 and gastric cancer: Mechanistically, VISTA<sup>+</sup> monocyte-macrophage (MoMac) populations promoted T cell exhaustion via the LGALS9-PTPRC signalling axis and exhibited enhanced antigen-presenting capacity.<h4>Conclusions</h4>Our findings establish VISTA as a central immunoregulatory checkpoint in gastric cancer, suggesting its potential as a promising therapeutic target for combination immunotherapeutic approaches.