Capeox Regimen Combined With Sintilimab and Bevacizumab for Gastric Cancer

Inclusion Criteria: 1. Histological or cytological diagnosis confirmed adenocarcinoma of stomach and gastroesophageal junction (including signet ring cell carcinoma, mucinous adenocarcinoma, hepatoid adenocarcinoma) 2. Imaging and surgical evaluation of unresectable recurrent or metastatic patients 3. The expected survival time was more than 3 months 4. The age is between 18 and 70 years old, both male and female 5. No systematic treatment has been given to patients with advanced or metastatic gastric and esophagogastric junction adenocarcinoma.If the patients who have received adjuvant or neoadjuvant therapy (including chemotherapy, radiotherapy and chemotherapy), the last treatment must be completed at least 6 months before randomization, and there is no recurrence or disease progression at the time of treatment.Palliative radiotherapy was allowed, but it must be completed at least 2 weeks before the first study treatment.Subjects were allowed to receive anti-tumor traditional Chinese medicine preparations in the past, but they must be discontinued at least 2 weeks before randomization 6. Eastern Cooperative Oncology Group(ECoG) - 1 physical status 7. At least one lesion can be evaluated according to RECIST 1.1 criteria 8. It can provide pathological tissues or fresh pathological tissues that are filed within 6 months after the signature of informed consent for screening, and can obtain the test results. For the slices filed within 6 months before randomization, it should be confirmed that no systematic treatment (including adjuvant / neoadjuvant therapy) has been received after obtaining the samples 9. The function of the main organs is normal, that is to say, it meets the following standards: 1. Blood routine examination (no blood transfusion within 14 days before screening) 2. Hemoglobin ≥ 90 g / L; 3. Absolute neutrophil count (ANC) ≥ 1.5×109/L; 4. Platelet count ≥ 75×109/L; Blood biochemical test (albumin was not used within 14 days before screening) 5. Albumin ≥ 28 g / L; 6. Total bilirubin ≤ 1.5×Upper limit of normal value (ULN); 7. Aspartate aminotransferase (AST), alanine aminotransferase (ALT) ≤ 3×ULN; If there is liver metastasis, aspartate aminotransferase (AST), alanine aminotransferase (ALT) ≤ 5×ULN 8. Creatinine ≤ 1.5×ULN;Coagulation function: 9. International normalized ratio (INR) or prothrombin time (PT) ≤ 1.5×ULN; 10. Activated partial thromboplastin time (APTT) ≤ 1.5×ULN 10. For sections filed in the first 6 months of randomization, it should be confirmed that no systematic treatment (including adjuvant / neoadjuvant therapy) has been received since sample acquisition 11. Acute toxicity caused by previous anti-tumor treatment or surgery was relieved to grade 0-1 (according to ncictcae 5.0) or to the level specified in the inclusion / exclusion criteria 12. Female subjects of childbearing age were required to conduct a serum pregnancy test within 3 days before the start of the study, and the results were negative, and they were willing to use a medically recognized high-efficiency contraceptive method (such as intrauterine device, contraceptive or condom) during the study period and within 3 months after the last administration of the study drug;For male subjects whose partners are women of childbearing age, they should be sterilized by surgery or agree to use effective contraceptive methods during the study and within 3 months after the last study administration 13. With my consent and signed the letter of understanding, I am willing and able to follow the planned visit, research treatment, laboratory examination and other test procedures Exclusion Criteria: 1. HER2 + (or HER2 +) is known to be positive 2. Gastric cancer known as squamous cell carcinoma, undifferentiated or other tissue types, or adenocarcinoma mixed with other tissue types 3. There are uncontrolled or symptomatic active central nervous system (CNS) metastases, which can be characterized by clinical symptoms, brain edema, spinal cord compression, cancer metastasis, malignant meningitis, leptomeningeal disease, and / or progressive growth.Patients with CNS metastases can be enrolled in the study if they are adequately treated and their psychiatric symptoms can return to baseline level at least 2 weeks before randomization (except for residual signs or symptoms related to CNS treatment).In addition, subjects were required to discontinue corticosteroids or receive prednisone (or equivalent other corticosteroids) at least 2 weeks before randomization, or to receive a stable or gradually reduced dose of prednisone (or equivalent) at least 2 weeks before randomization 4. There were hydrothorax and ascites which could not be controlled by puncture and drainage within 14 days before the random;Pericardial effusion with clinical symptoms or moderate or above 5. The weight of the subjects decreased by more than 20% in the first two months of randomization 6. The following treatments or drugs were received before randomization: a) major surgery was performed within 28 days before randomization (tissue biopsy and peripherally inserted central catheter operation peripherally inserted central venous catheter （PICC） for diagnosis are allowed; b) immunosuppressive drugs were used within 7 days before randomization,Does not include nasal and inhaled corticosteroids or physiological doses of systemic hormones (i.e. no more than 10 mg / D of nisone or other corticosteroids with equivalent physiologic doses);c) Live attenuated vaccine was administered within 28 days before randomization or within 60 days after the end of drug treatment;d) Antineoplastic therapy (including chemotherapy, radiotherapy, immunotherapy, endocrine therapy, targeted therapy, biotherapy or tumor embolization) within 28 days before randomization 7. Any other malignant tumor was diagnosed within 3 years before entering the study, except basal cell carcinoma of skin or squamous or superficial bladder cancer, carci