Cisplatin and S-1 With or Without Nimotuzumab in Untreated Advanced Gastric Adenocarcinoma

Inclusion Criteria: 1. provision of written informed consent; 2. male or female; and aged ≥ 18 years; 3. Histologically verified, untreated, metastatic or locally advanced inoperable adenocarcinoma or signet ring cell carcinoma of the stomach or gastroesophageal junction; 4. At least one radiographically documented measurable lesion according to Response Evaluation Criteria In Solid Tumors Version 1.1(RECIST1.1) Criteria; 5. An Eastern Cooperative Oncology Group (ECOG) performance status of 0-2; and a life expectancy ≥ 3months; 6. No previous palliative chemotherapy; 7. Adequate function of vital organs: white blood cells (WBC) ≥ 4.0×109/L, neutrophils (ANA) ≥ 1.5 × 109/L, platelets ≥ 100 × 109/L, hemoglobin ≥ 90g/L (blood transfusion is permitted if necessary), serum bilirubin ≤ 1 times the upper normal limit (UNL), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \< 2.5 times the UNL, alkaline phosphatase (AKP) ≤ 5 times the UNL, creatinine (Cr) ≤ 1 times the UNL, normal electrocardiography (ECG). Exclusion Criteria: 1. pregnant or lactating patients, or reproductive women without effective contraception; 2. Patients with only non-measurable disease: small lesions (longest diameter \< 10mm or pathological lymph nodes with ≥ 10 to \< 15mm short axis), Bone lesions, leptomeningeal disease, ascites, pleural or pericardial effusion, lymphangitic involvement of skin or lung; abdominal masses/abdominal organomegaly identified by physical exam that is not measurable by reproducible imaging techniques. 3. Symptomatic of brain metastasis; 4. Patients with clinically severe comorbidity including diabetes mellitus, hypertension, heart disease, or chronic active hepatitis (HBV carrier can be enrolled if circumstance permits ); 5. No previous radiotherapy for measurable lesions.