Sintilimab Combined With Modified FLOT Regimen in the Treatment of Metastatic Gastric Cancer

Inclusion Criteria:

1. Aged ≥18 years and men or women
2. With histologically confirmed adenocarcinoma of the stomach or gastroesophagealjunction, local lesions that cannot be radically resected, or metastatic gastriccancer
3. For treatment-naïve patients, or postoperative recurrence at least 6 months from thelast adjuvant chemotherapy
4. With Eastern Cooperative Oncology Group (ECOG) PS of 0-1
5. With a life expectancy of more than 3 months
6. Who obtain the following laboratory test data within 7 days (including the seventhday) prior to the study screening: neutrophil count of ≥1.5 × 10^9/L, platelet countof ≥100 × 10^9/L, hemoglobin level of ≥90 g/L, serum total bilirubin of ≤1.25 theupper limit of normal (ULN); ALT and AST levels of ≤2.5 × ULN (≤5 × ULN for patientswith liver metastasis); serum creatinine level of ≤1.0 × ULN and creatinine clearanceof ≥50 ml/min; International Normalized ratio (INR) or prothrombin time (PT) ≤1.5 ULN;If the subject is receiving anticoagulant therapy, PT should be within the prescribedanticoagulant range.
7. With at least one extragastric measurable lesion (Response Evaluation Criteria inSolid Tumors [RECIST] 1.1 criteria)
8. Patients (or their legal representative/guardian) must sign an informed consent formindicating that they understand the purpose of the study, understand the proceduresnecessary for the study, and are willing to participate in the study.

Exclusion Criteria:

1. Patients with history of other types of cancer in the last 3 years, except for curedcervical cancer or cutaneous basal cell carcinoma.
2. Patients with symptomatic brain or leptomeningeal metastases (unless the patient hasbeen treated for >2 months) who has a negative imaging result within 4 weeks beforeparticipating in the study and is stable disease at study entry.
3. Patients with clinically significant gastrointestinal obstruction, gastrointestinalbleeding (defecate occult blood + + + and above) or perforation.
4. Patients who have received PD-1, PD-L1 or PD- L2, CD137, CTLA-4 antibody therapy, orany other T cells stimulate or total checkpoint pathways for specific target antibodyor drugs.
5. Patients with active, or have a history and possible recurrence of autoimmune diseaseof the subjects (such as: Systemic lupus erythematosus, rheumatoid arthritis,inflammatory bowel disease, autoimmune thyroid disease, multiple sclerosis,vasculitis, glomerulonephritis, etc.), or those at high risk (such as those who havereceived an organ transplant requiring immunosuppressive therapy). However, patientswith vitiligo, psoriasis, alopecia, or Grave's disease who did not require systemictreatment within the last 2 years, or patients with hypothyroidism who required onlythyroid hormone replacement therapy, and patients with type 1 diabetes who requiredonly insulin replacement therapy could be enrolled.
6. Patients now with interstitial lung disease or pneumonia, pulmonary fibrosis, acutelung diseases, radiation pneumonia.
7. Patients who received any investigational drugs or antitumor drugs within 4 weeksprior to enrollment.
8. Patients who received immunosuppressive drugs within 4 weeks, which does not includenasal, inhalation or other routes of topical corticosteroids or physiological doses ofsystemic corticosteroids (i.e., not exceeding 10 mg/ day of prednisone or equivalentdoses of other corticosteroids), or short-term (not exceeding 7 days) use ofcorticosteroids for the prevention or treatment of non-autoimmune allergic diseases.
9. Patients who received the live attenuated vaccine within 4 weeks before the first doseof study treatment. Note: Inactivated virus vaccines for injectable seasonal influenzaare permitted for up to 4 weeks prior to initial administration; But live attenuatedinfluenza vaccines are not allowed;
10. Patients who received major surgery within 4 weeks before the first dose of studytreatment(open chest, craniotomy or laparotomy) or expected during the research andtreatment need to accept major surgery not associated with this study.
11. Patients who infected with human immunodeficiency virus (HIV) disease (HIV antibodypositive), or with other acquired, congenital immunodeficiency disease, or has ahistory of organ transplantation, or stem cell transplantation.
12. Patients who have chronic active hepatitis B or active active hepatitis C. Hepatitis Bvirus carriers, stable after drug treatment of hepatitis B (DNA drop degree is nothigher than 200 iu/mL or copy number < 1000 copies/mL) and has cured patients withhepatitis c (HCV RNA test negative) into the group.
13. Patients with known active tuberculosis.
14. Patients with severe infections before 4 weeks of fisrt dose of treatment, activeinfection which needs oral or intravenous antibiotic therapy before 4 weeks of fisrtdose of treatment.
15. Patients with symptomatic congestive heart failure (New York heart association gradeII - IV) or symptomatic or poorly controlled arrhythmia.
16. Patiemts with uncontrolled arterial blood pressure with specification treatment (systolic blood pressure of greater than 160mmHg or diastolic blood pressure ofgreater than 100 mmHg).
17. Patients who had any arterial thromboembolic events, including myocardial infarction,unstable angina, cerebrovascular accident, or transient ischemic attack within 6months before the screening.
18. Patinets with deep vein thrombosis, pulmonary embolism, or any other serious historyof thromboembolism within 3 months (implantable venous infusion port source sex orcatheter thrombosis, or superficial venous thrombosis were not regarded as a "severe"thromboembolism).
19. Patients who have a history of neurological or psychiatric disorders, such as memory,epilepsy, dementia, compliance, or the peripheral nervous system disorder.
20. alcohol dependence or 1-year history of drug or drug abuse.
21. Pregnancy or lactation women; Those who are fertile but do not take adequatecontraceptive measures;
22. may lead to the following results of other acute or chronic diseases, mental illnessor abnormal laboratory values: participated in or study drug dosage associated with anincreased risk, or interfere with the interpretation of results, and according to theresearcher's judgment does not conform the patient to participate in this study.