Clinical Study of SHR-1701 Plus Chemotherapy as Perioperative Treatment in Subjects With Gastric Cancer

Inclusion Criteria:

1. Pathologically diagnosed with GC or GEJC, histologically confirmed to beadenocarcinoma, and have no previous anti-tumor treatments for GC or GEJC.

2. Aged 18 or above, male or female.

3. Be suitable for (investigator's assessment) and planning to undergo neoadjuvanttherapy + radical surgery with curative intent before entering into the study.

4. locally advanced Gastric Cancer or Gastroesophageal Junction Cancer confirmed byinvestigator.

5. Be able to provide tumor tissue blocks.

6. Eastern Cooperative Oncology Group (ECOG) performance status score of 0-1.

7. Life expectancy of ≥ 6 months.

8. Have adequate organ and bone marrow functions.

9. Women without childbearing potential refer to post-menopausal women, or women whounderwent bilateral oophorectomy with medical records. Male subjects and femalesubjects of childbearing potential must agree to take a medically approvedcontraceptive measure (refer to Appendix 4) during the study, within 3 months afterthe last dose of investigational product (SHR-1701), and within 9 months after thelast dose of chemotherapy agents (S-1 and oxaliplatin); have a negative serumpregnancy test result within 3 days prior to the start of study treatment and not bebreastfeeding.

10. Subjects must agree and have signed the informed consent form, be willing and ableto follow the scheduled visits, study treatment, laboratory tests, and other studyprocedures.

Exclusion Criteria:

1. Have known squamous cell carcinoma, undifferentiated carcinoma, or otherhistological types of gastric cancer, or adenocarcinoma mixed with gastric cancer ofother histological types.

2. Have unresectable factors, including unresectable tumors or contraindications tosurgery or refusal of surgery.

3. Have more than 20% weight loss within 2 months prior to enrollment or randomization.

4. Have previously received some treatments or medications including anti-tumortreatments.

5. Diagnosed with other malignant tumors within 5 years prior to enrollment.

6. Have any active, known, or suspected autoimmune disease.

7. Have clinically significant bleeding symptoms or clear bleeding tendency within 3months prior to enrollment or randomization; have gastrointestinal perforationand/or gastrointestinal fistula within 6 months prior to enrollment orrandomization; have arterial/venous thrombotic events within 6 months prior toenrollment or randomization.

8. Have major vascular disease within 6 months prior to enrollment or randomization.

9. Have severe, unhealed, or dehisced wounds and active ulcers or untreated fractures.

10. Have intestinal obstruction and/or clinical signs or symptoms of gastrointestinalobstruction within 6 months prior to enrollment or randomization.

11. Have interstitial lung disease, non-infectious pneumonitis, or uncontrolled systemicdisease.

12. Have known allergies to the study drug or their excipients; have severe allergicreactions to other monoclonal antibodies.

13. Have HIV infection or known AIDS, active untreated hepatitis or co-infection withhepatitis B and C.

14. Have uncontrolled cardiac symptoms or disease:

15. Have received systemic antibiotics for ≥ 7 days within 4 weeks prior to enrollmentor randomization, or have unexplained fever > 38.5 °C during screening or before thefirst dose.

16. Have known history of allogeneic organ transplantation or allogeneic hematopoieticstem cell transplantation.

17. Have been screened for other clinical studies but failed the screening because PD-L1expression did not meet the inclusion criteria or met the exclusion criteria; haveparticipated in clinical studies of any other drugs, less than 4 weeks or 5half-lives of the drug between the last dose of these study treatments andenrollment/randomization for this study (whichever is longer).

18. Have a known history of psychotropic substance abuse or drug abuse.

19. Have other severe physical or psychiatric disorders or laboratory abnormalities,which may increase the risk of participation in this study or interfere with thestudy results, or deemed unsuitable by the investigator.