CD80 and gastric cancer: This dual action significantly inhibits GC cell proliferation, migration, and invasion while promoting DC maturation (evidenced by elevated CD80/CD86 expression) and CD8+ T‐cell activation. In vivo, iRGD modification boosts tumor accumulation of NPs, and NP‐mediated PDT synergized with SOX9 silencing to suppress tumor growth in GC xenografts.