Sintilimab in Combination with Chemotherapy ± Local Treatment for Om-G/GEJ

Inclusion criteria

• Pathologically confirmed esophagogastric junction (EGJ)/gastric adenocarcinoma.
• Oligometastatic disease diagnosed via CT, MRI, or PET/CT:≤3 extracranial organs involved, ≤5 total metastatic lesions, each ≤5 cm in diameter,Regional lymph nodes count as one station; distant nodes counted per station.
• No progression after two cycles of immunochemotherapy.
• Primary and metastatic lesions at diagnosis eligible for local treatment.
• All metastatic lesions measurable per RECIST 1.1.
• Adequate hematological function: Neutrophil count ≥ 1.5 × 109/L, Platelets ≥ 100 × 109/L and Hemoglobin ≥90g/L.
• Adequate liver function: Total bilirubin ≤ 1.5 × upper limit of normal (ULN); AST (SGOT) and ALT (SGPT) < 2.5 × ULN in the absence of liver metastases, or < 5 × ULN in case of liver metastases. ALP ≤ 2.5 × upper limit of normal (ULN); ALB ≥30g/L.
• Adequate renal function: Serum creatinine ≤ 1.5 x ULN, and creatinine clearance ≥ 60 ml/min.
• Adequate coagulation function: INR/PT≤ 1.5 x ULN, aPTT≤ 1.5 x ULN.
• No serious concomitant disease that will threaten the survival of patients to less than 5 years.
• Male or female. Age ≥ 18 years and ≤80 years.
• Written (signed) informed consent.
• Good compliance with the study procedures, including lab and auxiliary examination and treatment.
• Female patients should not be pregnant or breast feeding.

Exclusion criteria

• Non-adenocarcinoma histology of gastric/esophagogastric junction tumors, such as squamous cell carcinoma or neuroendocrine carcinoma.
• Esophagogastric junction/gastric adenocarcinoma with positive Her-2 status requiring anti-Her-2 treatment.
• Uncontrolled meningeal or peritoneal metastasis.
• Peripheral neuropathy of grade ≥2.
• Poor nutritional status, BMI <18.5 kg/m², or PG-SGA score ≥9.
• Underwent major surgery or suffered a severe injury within 4 weeks prior to the first dose of the investigational drug.
• Presence of uncontrolled pleural effusion, pericardial effusion, or ascites requiring repeated drainage.
• Received any investigational drug within 4 weeks prior to the first dose of the study drug.
• Required systemic treatment with corticosteroids (daily >10 mg prednisone equivalent) or other immunosuppressive agents within 2 weeks prior to the first dose of the investigational drug.
• Received an anti-tumor vaccine or live vaccine within 4 weeks before the first dose of the study drug.
• Diagnosed with any active autoimmune disease or a history of autoimmune diseases.
• History of immunodeficiency, including a positive HIV test, any acquired or congenital immunodeficiency diseases, or a history of organ transplantation or allogeneic bone marrow transplantation.
• Any condition within 14 days prior to treatment requiring systemic corticosteroid therapy (dose>10mg/day of prednisone or equivalent) or other immunosuppressive treatments.
• Presence of uncontrolled cardiac symptoms or conditions, such as:

• NYHA Class II or higher heart failure
• Unstable angina
• Myocardial infarction within the past year
• Clinically significant supraventricular or ventricular arrhythmias requiring clinical intervention.
• Severe infection within 4 weeks prior to the first dose, including pneumonia requiring hospitalization, bacteremia, or infectious complications.
• History of interstitial lung disease, non-infectious pneumonia, pulmonary fibrosis, or other uncontrolled acute pulmonary diseases.
• Active pulmonary tuberculosis infection diagnosed by history or CT scan, or a history of active tuberculosis infection within the past year, or a history of untreated active tuberculosis infection more than one year ago.
• Active hepatitis B or hepatitis C.
• Laboratory abnormalities of sodium, potassium, or calcium greater than Grade 1 within 2 weeks before enrollment that cannot be corrected with treatment.
• Known allergy to monoclonal antibodies, any PD-1 components, paclitaxel, capecitabine, or any components used in their formulations.
• Pregnant or breastfeeding women, or women of childbearing potential who are unwilling or unable to use effective contraception.