• Voluntarily participate and sign the informed consent form;

• Male or female, ≥18 years;

• Patients with gastric or gastroesophageal junction adenocarcinoma confirmed by histopathology;

• Clinical stage cT3-4aN+, no distant metastasis (M0);

• According to the baseline imaging and medical history data evaluated by the Investigators, radical surgery for gastric cancer and R0 resection is expected; Subjects had not previously received any antitumor therapy for gastric or gastroesophageal junction adenocarcinoma;

• HER2- expression: IHC 1+, 2+, 3+;

• ECOG performance status score of 0 or 1;

• Cardiac function: left ventricular ejection fraction ≥50%;

• The following criteria should be met within 7 days prior to study dosing (normal values are based on the clinical trial center):

‣ 1Bone marrow function:

‣ absolute neutrophil count (ANC) ≥1.5×109/L (no treatment with granulocyte colony-stimulating factor within 1 week prior to examination);

‣ Platelets ≥100×109/L (platelets should not be transfused within 1 week before the examination, and recombinant human thrombopoietin therapy should not be used within 2 weeks)

‣ hemoglobin ≥9g/dL (blood transfusion and erythropoietin treatment are not allowed within 2 weeks prior to the examination);

‣ 2Liver function:

‣ Serum total bilirubin ≤1.5 times the upper limit of normal (ULN);

‣ alanine amino transferase (ALT) and aspartate amino transferase (AST) ≤2.5 × ULN;

‣ 3 Kidney function:

• a.Blood creatinine ≤1.5×ULN or creatinine clearance (CrCl) ≥50 mL/min according to Cockcroft-Gault formula method; Female: CrCl= (140-age) × weight (kg) × 0.85 72 × serum creatinine (mg/dL) Male: CrCl= (140-age) × weight (kg) × 1.00 72 × serum creatinine (mg/dL)

‣ 4 Coagulation function:

‣ prothrombin time (PT) ≤1.5×ULN;

‣ thrombin time (TT) ≤ 1.5×ULN;

‣ activated partial thromboplastin time (APTT) ≤ 1.5×ULN.

⁃ Female subjects should be surgically sterilized, postmenopausal, or agree to use at least one medically acceptable method of contraception (e.g., intrauterine device, contraceptives, or condoms) for 7 days before the first dose and for 6 months after the end of the study treatment period, and not breastfeed. Blood pregnancy tests must be negative within 7 days prior to study enrollment. Male subjects should agree to use at least one medically approved contraceptive method (e.g., condoms, abstinence, etc.) for 7 days prior to initial dosing and up to 6 months after the end of the study treatment period;

⁃ Able to understand trial requirements, willing and able to follow trial and follow-up procedures.