Ph1b/2 Study of the Safety and Efficacy of SHR-A1811 Combinations in Advanced HER2+ Gastric Cancer

Inclusion Criteria: Age from 18 to 75 , Male and female participants Local advanced unresectable or metastatic disease Pathologically documented adenocarcinoma of gastric or gastroesophageal junction; HER2 positive; Phase Ib: progression at least one prior Regimen or could not tolerate the standard treatment，pevious anti-HER2 therapy was included Phase II: previously untreated patients ; ECOG 0-1; The expected survival ≥3 months; Sufficient bone marrow and organ functions; Exclusion Criteria: There were ascites, pleural effusion and pericardial effusion that needed to be treated; Major surgery was performed within 4 weeks; Have active autoimmune disease or history of autoimmune disease; Patients with interstitial pneumonia; There was severe infection within 4 weeks before starting the study treatment; Patients with active pulmonary tuberculosis infection history within 1 year before enrollment; Serious cardiovascular and cerebrovascular diseases; Gastrointestinal perforation and/or gastrointestinal fistula occurred within 6 months before enrollment;