This study is a prospective, randomized ，multicencter, phase II clinical trial that aims to enroll patients with locally advanced gastric adenocarcinoma who have not received any prior treatment and are candidates for surgery. The purpose of this study is to assess the safety and efficacy of Mecapegfilgrastim Combined With Adebrelimab and 5- fluorouracil, leucovorin, oxaliplatin and docetaxel (FLOT)） as Neoadjuvant Therapy in Resectable gastric and gastroesophageal junction cancer
1.Subjects aged 18-75 years (including 18 and 75 years old);
2.Subjects who understand the study procedures and content, and voluntarily sign the written informed consent form;
3.Subjects with HER2-negative or HER2 status unknown gastric or gastroesophageal junction adenocarcinoma, clinically staged as T3-4a/N+M0 locally advanced gastric cancer by ultrasound gastroscopy, CT/MRI and other imaging evaluations.
4.Subjects who have not received prior systemic therapy.
1.Subjects with a history of or concurrent with other tumors malignant, except for cured early-stage tumors, including basal cell carcinoma of the skin and carcinoma in situ of the cervix, and early-stage tumors such as stage I lung cancer and stage I rectal cancer that have received radical treatment and are judged by the investigator not to affect the subject's life in the short term.
2.Subjects who have participated in other drug clinical studies within 4 weeks;
3.Subjects with a history of haemorrhage, the severity of any grade ≥ 3 haemorrhage event according to CTCAE 5.0 criteria within 4 weeks prior to screening;
4.Prior to screening, there were known highly suspected distant metastases, such as suspected peritoneal nodules, suspected cancerous ascites, and no laparoscopic confirmation;