Inclusion Criteria:  Age from 18 to 70 years old, no gender limit The primary tumor is diagnosed as gastric adenocarcinoma (papillary, tubular, signet ring cell, poorly differentiated and mucinous adenocarcinoma) by endoscopic biopsy sampling and follow-up histopathological staining The pre-operative staging includes: a) Stage IVa（cT4bNanyM0），resectable; b) Stage II-III（cT1-2N1-3M0、cT3-4aN0-3M0）, gastro-oesophageal junction (GEJ) cancer；c) Stage III（cT3-4aN1-3M0）, non-GEJ cancer, appropriate for neoadjuvant therapy Stage IVb or locally unresectable late-stage gastric or GEJ cancer, previously never received chemotherapy Eastern Cooperative Oncology Group (ECOG) performance score 0 or 1 The function of major organs is normal, meeting the following criteria: a) routine blood tests (no blood transfusion in the past 14 days): HB≥90g/L；ANC ≥1.5×109/L；PLT ≥80×109/L；b）blood biochemical parameters: BIL <1.5-fold upper limit of normal (ULN)；ALT<2.5×ULN; AST<2.5×ULN；Crea≤1×ULN Fresh tumor tissue biopsies are obtainable and the clinical information of the patients is complete Patients have been informed and consented  Exclusion Criteria:  Previously received neoadjuvant therapy Previously had other types of malignancy and received chemotherapy or radiotherapy Previously had chicken pox, herpes zoster or other severe contagious diseases Have severe active ulcer (gastrointestinal tract, skin, etc.) or have developed a high fever Have a medical history of myocardial infarction, cerebral infarction, or pulmonary embolism Have complications of gastric cancer (bleeding, perforation and obstruction etc.) and need emergency operation Pregnant or lactating women Have severe mental diseases Allergic to chemotherapy drugs Have metastatic brain cancer Refuse to cooperate and to complete a treatment