First-line Treatment of Gastric or Gastroesophageal Junction Adenocarcinoma With Dual Immunotherapy Combined With Chemotherapy

Inclusion Criteria: * 1\. The participant voluntarily agrees to participate in this study, signs the informed consent form, and strictly adheres to the requirements of the study protocol. * 2\. Age ≥18 years and ≤75 years at enrollment, regardless of gender. * 3\. Histologically confirmed unresectable locally advanced or metastatic G/GEJ adenocarcinoma, with inclusion criteria specifying HER2- status (HER2+ status defined as IHC3+ or IHC2+ and FISH+). * 4\. No prior systemic treatment for unresectable locally advanced or metastatic G/GEJ adenocarcinoma; previous neoadjuvant and/or adjuvant therapy is acceptable, but all systemic treatments must have been completed at least 12 months prior to the diagnosis of unresectable or metastatic disease. * 5\. At least one measurable tumor lesion according to RECIST 1.1 criteria. * 6\. ECOG PS of 0 or 1. * 7\. Life expectancy ≥3 months. * 8\. Fully recovered from any toxicities related to prior treatments prior to enrollment in the study. * 9\. BMI \>18. * 10\. Adequate function of major organs * 11\. Fertile subjects must use appropriate contraception during the study and for 120 days after the end of the study. They must have a negative serum pregnancy test within 7 days prior to enrollment and must not be breastfeeding. Exclusion Criteria: * 1\. Any unstable systemic disease: including active infection, uncontrolled hypertension, unstable angina, angina that started within the last 3 months, congestive heart failure (New York Hear…