Cohort 4 will evaluate the combination of first-line zolbetuximab, mFOLFOX6, and nivolumab in intermediate-to-high CLDN18.2 positivity (2+/3+ IHC in ≥75% of tumor cells [high] or ≥50% but <75% of tumor cells [intermediate]), HER2-negative metastatic GAC/GEJ patients. The gene discussed is ERBB2; the disease is neoplasm.