ERBB2 and gastric cancer: Pivotal Phase III trials, such as KEYNOTE-859 (7), CheckMate-649 (8), and ORIENT-16 (9), have established the combination of chemotherapy and a PD-1 inhibitor as the standard of care for first-line treatment of HER2-negative advanced GC (with mPFS of 6.9–7.7 months), a recommendation endorsed by major clinical guidelines including NCCN, CSCO, and ESMO.