A Study of Anti-PD-1 and LAG-3 Bispecific Antibody(AK129) Combined With Chemotherapy With or Without Cadonilimab in the First-line Treatment of Unresectable Locally Advanced or Metastatic G/ GEJ Adenocarcinoma

Inclusion criteria

• The subject must sign the written informed consent form(ICF) voluntarily.
• Aged ≥ 18 to ≤ 75 years,male and female at the time of signing the ICF.
• Histologically confirmed adenocarcinoma of the gastric or gastroesophageal junction (GEJ).
• Inoperable locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma.
• Participants had not previously received systemic therapy for locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma.
• According to RECIST v1.1 criteria, subjects had at least one measurable tumor target.

Exclusion criteria

• Subjects with known HER2 positive gastric or gastroesophageal junction adenocarcinoma.
• Histopathological examination confirmed other pathological types.
• Had received palliative local therapy for non-target lesions within 2 weeks before the first administration.
• Past treatment with immune checkpoint inhibitors,immune checkpoint agonists,immune cell therapy and any treatment targeting the immune mechanism of tumor action.
• History of gastrointestinal perforation and fistula within 6 months before the first dose.
• Active or previously documented inflammatory bowel disease,inability to swallow, malabsorption syndrome.
• Active malignancy within the last 3 years.
• Active or untreated brain metastases, meningeal metastases, spinal cord compression, or pia meningeal disease are known to exist.
• The presence of clinical symptoms of pleural effusion, pericardial effusion, or abdominal effusion, or the need for frequent drainage.
• There was an active autoimmune disease that required systemic treatment within 2 years prior to the start of the study.