1. Age ≥ 18 years but ≤ 75 years
2. Being able to follow the protocol requirements as per investigator's evaluation.
3. Provide written informed consent before any protocol-related procedure (that is not a
part of subject's routine care) is carried out.
4. Unresectable locally advanced or metastatic gastric carcinoma (GC) or
gastro-esophageal junction (GEJ) carcinoma, and have histologically confirmed
5. The subject may have at least a measurable lesion or an evaluable lesion, if not
measurable; the investigator will carry out evaluation according to Response
Evaluation Criteria in Solid Tumors (RECIST) v1.1 within 28 days prior to
6. Eastern Cooperative Oncology Group performance status (ECOG PS) 0 or 1.
7. Expected survival ≥ 3 months.
8. Subject must not have received systemic treatment (including HER2 inhibitor) for
advanced or metastatic gastric carcinoma.
9. Subject must provide tumor tissue samples for biomarker analysis in order to determine
the expression of PD-L1.
10. Permitted prior treatment: Subjects with GC or GEJ carcinoma priorly treated with
adjuvant or neoadjuvant therapy, who experience clinical progression of disease at
least 6 months during treatment or after treatment are allowed to be enrolled.
11. Subjects must have adequate organ function as assessed in the laboratory tests
12. Subjects with active hepatitis B or active hepatitis C must receive antiviral
treatment for at least 14 days prior to the first dose of study treatment and pass the
hepatitis B virus (HBV) DNA titer test (≤ 500 IU/mL or 2500 copies/mL) and hepatitis C
virus (HCV) RNA test (≤ lower limit of detection) before being enrolled. The subject
should be willing to continue effective anti-viral treatment during the study.
13. Female subject with childbearing potential must have negative serum pregnancy test
result at screening, except for those with available sterilization operation record or
post-menopausal subjects. Female subject with childbearing potential or male subjects
and their partners must agree to take effective contraceptive measures from the day of
signing ICF till at least 6 months after the last dosing of investigational product.
1. Known HER-2 positivity.
2. A known additional primary malignancy that occurred within 5 years prior to the first
dose of investigational treatment, except for locally curable cancers that have been
apparently cured, such as basal or squamous cell skin cancer, superficial bladder
cancer, or carcinoma in situ of the prostate, cervix, or breast.
3. Known primary central nerve system (CNS) tumor or meningeal metastasis, or unstable
CNS metastasis (symptomatic within 4 weeks before first dose of investigational
product, requiring corticosteroid treatment, or without radiologic evidence supporting
stable status for over 4 weeks prior to the first dose of investigational product).
4. Any severe or uncontrolled systemic disease, for example diabetes mellitus or
hypertension, that may increase the risk associated with participation or
investigational product administration, or compromise subject's ability to receive
investigational product, as per investigator's judgment.
5. Known positive human immunodeficiency virus (HIV) or acquired immunodeficiency
6. Has had prior chemotherapy, immune therapy, biological therapy (including cancer
vaccine, cytokine therapy or growth factors to control cancer) used as systemic
treatment for cancer, within 14 days before the first dose of investigational product.
7. Any prior treatment of antibody/drug that targets at T-cell coregulatory proteins or
immune checkpoints pathways(including anti-PD-1, anti-PD-L1, anti-CTLA4, anti-TIM3,
anti-LAG3 antibody, etc.).
8. Subjects with conditions that in the investigator's opinion are not suitable for
participating in this trial.