QLS31905 in Combination With CAPOX Versus Sintilimab in Combination With CAPOX as First-line Treatment in Patients With GC/GEJ

Inclusion Criteria: * Subjects voluntarily participate in the study and sign the informed consent form; * Eastern Cooperative Oncology Group (ECOG) performance status score of 0-1; * Expected survival time ≥ 12 weeks; * Histologically or cytologically confirmed diagnosis of gastric or gastroesophageal junction adenocarcinoma; * No prior systemic anti-tumor treatment for unresectable locally advanced or metastatic disease; * Has measurable or non-measurable (but assessable) disease; * Patients with adequate cardiac, liver, renal function, etc. Exclusion Criteria: * Known history of allergy to any component of the study drug; * Other second primary malignant neoplasm within 5 years; * Significant cardiovascular and cerebrovascular disorders within 6 months before randomization; * Haemorrhage requiring haemostatic treatment within 3 months prior to randomisation; * Previous or current interstitial pneumonia, pulmonary fibrosis, pneumoconiosis, etc; * Previous treatment targeting CLDN18.2; * Patients with added risks associated with the study or may interfere with the interpretation of study results as determined by the investigator, or deemed unsuitable by the investigator.