BC001 in Combination with Sintilimab and XELOX in the Treatment of HER-2 Negative Advanced or Metastatic Gastric Cancer or Gastroesophageal Junction Adenocarcinoma.

Inclusion Criteria:

1. Subjects must be able to understand and voluntarily sign the written informedconsent.

2. Subjects must be willing and able to complete the study procedures and follow-upexaminations.

3. Male or female subjects aged between 18 and 75 years old (including 18 and 75 yearsold).

4. HER-2 negative patients with advanced or metastatic gastric cancer orgastroesophageal junction adenocarcinoma (GC/GEJ) (according to the 8th edition ofAJCC/UICC TNM staging) confirmed by histopathology or cytopathology, who have neverreceived systemic treatment before (the time interval from the end of previousneoadjuvant treatment/adjuvant treatment to the recurrence of the disease > 6 monthswill be regarded as untreated).

5. According to RECIST version 1.1, there must be at least one measurable tumor lesionshown by CT or MRI examination.

6. Subjects with normal oral intake.

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

8. Expected survival period is greater than 3 months.

9. There is no serious hematological, hepatic or renal function abnormality, meetingthe following laboratory test results: the absolute neutrophil count (ANC) should be ≥1.5×10⁹/L, platelet (PLT) ≥100×10⁹/L, and hemoglobin (HGB) ≥90g/L; Serum creatinine (Cr) ≤1.5× the upper limit of normal range (ULN). When Cr > 1.5×ULN, , andcreatinine clearance rate (Ccr)≥ 60mL/min(calculated according to the Cockcroft -Gault formula); the qualitative urine protein should be ≤1 +, or if the qualitativeurine protein ≥2 +, the 24-hour urine protein < 1g; total bilirubin (TBIL) ≤1.5×ULNor ≤3×ULN (for patients with liver cancer or liver metastases), alanineaminotransferase (AST) and aspartate aminotransferase (ALT) ≤3.0×ULN or ≤5×ULN (forpatients with liver cancer or liver metastases), alkaline phosphatase (ALP) ≤2.5×ULNor ≤5×ULN (for patients with liver cancer or liver metastases); the internationalnormalized ratio (INR) or prothrombin time T (PT) ≤1.5×ULN, and the activatedpartial thromboplastin time (APTT) ≤1.5×ULN.

10. Male or female subjects should take effective contraceptive measures during thetreatment period and within 6 months after the last dose administration.

Exclusion Criteria:

1. Subjects who have undergone major organ surgical operations (excluding needlebiopsy) or had significant trauma within 4 weeks prior to the first use of the studydrug, or who need to undergo elective surgeries during the trial period.

2. Subjects whose original lesions have invaded the central nervous system (CNS) withsymptoms, are unstable or require high-dose steroids (≥10mg dexamethasone orequivalent dose) to achieve control.

3. Subjects suffering from other primary malignancies, except for malignancies with lowmetastasis risk and low death risk (5-year survival rate > 90%), such asmalignancies that have been cured and have not relapsed within 3 years beforeenrollment in the study; completely resected basal cell and squamous cell skincancers; completely resected carcinomas in situ of any type.

4. Subjects with active infections (such as viral, bacterial or fungal infections) thatrequire systemic treatment.

5. Subjects currently suffering from interstitial lung disease (except forradiation-induced pulmonary fibrosis that does not require hormone treatment).

6. Subjects with a history of active bleeding within the past 4 weeks or at risk ofgastrointestinal perforation, or with a history of recent surgeries that have nothealed or with a history of wound complications caused by surgical operations.

7. Subjects who had gastrointestinal bleeding within 3 months prior to the use of thestudy drug and without evidence verified by endoscopy or colonoscopy that they haverecovered; subjects with severe gastrointestinal diseases within 2 weeks prior tothe use of the study drug.

8. Subjects with a history of severe cardiovascular and cerebrovascular diseases,including but not limited to: Having severe cardiac rhythm or conductionabnormalities, such as ventricular arrhythmias requiring clinical intervention,grade II - III atrioventricular block, etc.; Having suffered from acute coronarysyndrome, congestive heart failure, aortic dissection, stroke/TIA or other grade 3or above cardiovascular and cerebrovascular events within 6 months prior to thefirst dose administration; Having heart failure of New York Heart Association (NYHA)class > II or left ventricular ejection fraction (LVEF) < 50%; Having a baselineQTcF interval corrected for heart rate calculated by the Fridericia formula > 450msec (for males) and > 470 msec (for females); Having any factors that increase therisk of QTc prolongation or arrhythmia, such as heart failure, hypokalemia,congenital long QT syndrome, a family history of long QT syndrome or using anyconcomitant drugs known to prolong the QT interval. Having a diastolic blood pressure ≥ 100 mmHg or a systolic blood pressure ≥ 160 mmHgafter standardized treatment.

9. Subjects who have received treatments such as colony-stimulating factors anderythropoietin within 2 weeks prior to the use of the study drug.

10. Subjects who have been vaccinated with live vaccines within 4 weeks prior to the useof the study drug. Live vaccines include but are not limited to the following:measles, mumps, rubella, varicella/zoster (chickenpox), yellow fever, rabies,Bacillus Calmette-Guérin (BCG) and typhoid vaccines. Seasonal influenza vaccines forinjection are usually inactivated virus vaccines, so their use is permitted;intranasal influenza vaccines (e.g., FluMist) are attenuated live vaccines and arenot permitted for use.

11. Subjects who are currently receiving long-term treatment with non-steroidalanti-inflammatory drugs (such as indomethacin, ibuprofen, etc.) or antiplateletdrugs (such as clopidogrel, ticlopidine, dipyridamole, etc.) (the use of aspirin ispermitted with a maximum daily dose of 325mg).

12. Subjects with a known history of liver diseases of significant clinicalsignificance, including active hepatitis (hepatitis B surface antigen positive andthe copy number of HBV DNA > the normal value of the testing unit; hepatitis C virusantibody positive and the copy number of HCV RNA > the normal value of the testingunit), hepatic encephalopathy, hepatorenal syndrome, liver function at Child-Pughgrade B or more severe cirrhosis.

13. Subjects with a history of human immunodeficiency virus infection or suffering fromother acquired or congenital immunodeficiency diseases.

14. Subjects who are preparing for or have previously received tissue/organtransplantation.

15. Subjects known to be allergic to the study drugs, monoclonal antibodies and othertherapeutic protein preparations (fresh or frozen plasma, human serum albumin,cytokines, interleukins, etc.).

16. Subjects known to have alcohol and/or drug dependence.

17. Female subjects with a positive blood pregnancy test or those who are breastfeeding.

18. Subjects with known signs of active bleeding in the lesions.

19. Subjects with pleural effusion, pericardial effusion or ascites that areuncontrollable and require repeated drainage or medical intervention. Only thosewith a small amount of ascites shown by imaging but without symptoms can beenrolled.

20. Subjects known to have dihydropyrimidine dehydrogenase (DPD) deficiency (or thosewho have experienced grade 3 or above mucosal toxicity during previousfluorouracil-containing treatments).

21. Subjects with cardiac obstruction, pyloric obstruction or persistent and repeatedvomiting (defined as vomiting ≥ 3 times within 24 hours).

22. Subjects who had intestinal obstruction or the following diseases within 3 monthsprior to the first use of the study drug: inflammatory bowel disease or extensivebowel resection (partial colectomy or extensive small bowel resection accompanied bychronic diarrhea), Crohn's disease, ulcerative colitis.

23. Subjects with a history of deep vein thrombosis, pulmonary embolism or any otherserious thromboembolism within 3 months before enrollment; subjects who need to usevitamin K antagonists for anticoagulation or need to use heparin at a therapeuticdose (prophylactic dose is acceptable) during the study period.

24. Subjects who need to use systemic immunosuppressive therapy within 14 days prior tothe first use of the study drug or during the study period, except for the followingsituations: intranasal, inhaled, topical steroids or local steroid injections (suchas intra-articular injection); physiological doses of systemic corticosteroids (≤10mg/day prednisone or equivalent dose); short-term (≤7 days) use of steroids forthe prevention or treatment of non-autoimmune allergic diseases.

25. Subjects judged by the researcher as being unsuitable for participating in thisstudy for other reasons.