A Trial of Adebrelimab Plus (SHR-A1811/SHR-A1904 With Chemotherapy) or SHR-8068 as Treatment for Gastric/GEJ Cancer

Inclusion criteria

• Patients with histologically confirmed gastric or gastroesophageal junction adenocarcinoma who have not received prior anti-tumor therapy for gastric/gastroesophageal junction cancer.
• Age: ≥18 and ≤70 years, both male and female.
• Ability to provide fresh tumor tissue (preferred) or archival formalin-fixed paraffin-embedded (FFPE) tumor blocks/unstained slides obtained within 6 months before enrollment.
• Availability of biomarker testing results before enrollment.
• ECOG performance status of 0-1.
• Life expectancy ≥ 6 months.
• Adequate organ and bone marrow function.
• Female participants must be either non-childbearing potential or of childbearing potential with a negative serum pregnancy test within 3 days prior to treatment initiation and not lactating. Childbearing-potential participants and their partners must agree to avoid sperm/ovum donation and comply with contraception requirements from informed consent signing until 8 months after the last dose.
• Voluntarily signed informed consent form, with willingness and ability to comply with scheduled visits, treatments, laboratory tests, and study procedures.

Exclusion criteria

• Known squamous cell carcinoma, undifferentiated carcinoma, mixed adenocarcinoma with other histologic types, or other non-adenocarcinoma gastric cancers.
• 20% body weight loss within 2 months before enrollment.
• Prior treatments: Anti-tumor therapy for gastric/gastroesophageal junction cancer; Participation in other drug trials with last dose ≤4 weeks or ≤5 half-lives (whichever longer) before enrollment; Major surgery within 28 days before enrollment; Live attenuated vaccination within 28 days before enrollment or planned during/within 60 days after treatment.
• Known hypersensitivity to any study drug component (Adebrelimab, SHR-A1811, SHR-A1904, SHR-8068, fluorouracil, capecitabine, tegafur/gimeracil/oteracil) or humanized monoclonal antibodies.
• Other malignancies within 5 years, except curatively treated basal/squamous cell skin cancer, superficial bladder cancer, cervical carcinoma in situ, ductal breast carcinoma in situ, or papillary thyroid cancer.
• History of immunodeficiency, organ transplantation, or active autoimmune disease.
• Clinically significant bleeding within 3 months or bleeding predisposition at screening; Arterial/venous thromboembolism within 6 months or at screening.
• Non-healing wounds, active ulcers, or untreated fractures.
• Active severe gastrointestinal disorders.
• Interstitial pneumonia or lung disease.
• Severe cardiovascular/cerebrovascular diseases or metabolic disorders.
• Active HBV/HCV infection or HBV-HCV co-infection.
• Active tuberculosis (TB) within 1 year by history/CT, or prior untreated active TB >1 year ago.
• Severe infection within 4 weeks before first dose; CTCAE ≥Grade 2 active infection requiring systemic antibiotics within 2 weeks; Chronic infections potentially affecting treatment/surgery.
• History of drug abuse or illicit substance use.
• Other conditions that may increase study risk, confound results, or render the patient unsuitable per investigator judgment.