FDA approved zolbetuximab-clzb (Vyloy) for first-line treatment of CLDN18.2-positive, HER2-negative, locally advanced unresectable or metastatic gastric or GEJ adenocarcinoma, supported by phase 3 trials SPOTLIGHT and GLOW, showing improved PFS and OS. Zolbetuximab targets CLDN18.2, leading to tumor cell destruction, and synergizes with chemotherapy, offering a new biomarker-driven therapy for gastric and GEJ cancers.