Study of FMT Combined With Nivolumab in Gastric Cancer

Inclusion Criteria: * Voluntarily participate in this study and provide written informed consent * Age ≥ 18 years and ≤70 years, male or female * Pathological confirmed locally advanced, unresectable or metastatic gastric adenocarcinoma, esophagogastric junction adenocarcinoma and lower esophagus adenocarcinoma that are resistant to anti-PD-1/L1 antibodies * Able and willing to provide tumor tissue * At least one measurable extracranial target lesion according to iRECIST * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 * Life expectancy ≥3 months Exclusion Criteria: * History of other primary malignancies within 5 years except adequately treated in situ carcinoma of the cervix or non-melanoma carcinoma of the skin * Had systemic diseases that were difficult to control within 4 weeks prior to screening * History of anti-PD-1 antibodies related adverse reactions that led to the permanent withdrawal of anti-PD-1 therapy * History of coagulation disorders * Mechanical or paralytic obstruction of the gastrointestinal tract * Anticipated to receive a great number of antibiotics during study period