A Study to Evaluate SHR-1210 in Combination With Capecitabine + Oxaliplatin Sequenced by SHR-1210 + Apatinib as First-line Therapy in Treatment of Advanced Gastric Cancer

Inclusion Criteria:

• Has histologically- or cytologically-confirmed diagnosis of locally advancedunresectable or mestastatic adenocarcinoma of stomach or the esophagogastricjunction (GEJ)

• Age ≥ 18 years old, male or female

• NO previous therapy for advanced/metastatic disease of GC/GEJ (including HER-2inhibitor). Subjects with previous adjuvant/neo-adjuvant therapy completed more than 6 months can be enrolled.

• Has measurable disease per RECIST 1.1

• Eastern Cooperative Group (ECOG) performance status of 0 to 1

• Has adequate organ function

• Females of childbearing potential (FOCBP), who are not surgically sterile orpostmenopausal, must conduct pregnancy test (serum or urine) within 7 days beforeenrollment, and must not be pregnant or breast-feeding women. If the result isnegative, she must agree to use adequate contraception during the experiment and 3months after the last administration of the test drugs. And non-sterilized males whoare sexually active must agree to use adequate contraception during the experimentand 3 months after the last administration of the test drugs.

Exclusion Criteria:

• Has known HER2-positive status

• Has known active central nervous system metastatases

• Has received a live vaccine within 4 weeks prior to the first dose of studytreatment

• With any acitve autoimmune disease or history of autoimmune disease, including butnot limited to the following: hepatititis, pneumonitis, uveitis, colitis (inflammatory bowel disease), hypophysitis, vasculitis, nephritis, hyperthyroidism,and hypothyroidism, except for subjects with vitiligo or resolved childhoodasthma/atopy. Asthma that requires intermittent use of bronchodilators or othermedical intervention should also be excluded.

• Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-CTLA-4 antibody,or a VEGFR inhibitor.

• Clinically significant cardiovascular and cerebrovascular diseases, including butnot limited to severe acute myocardial infarction within 6 months before enrollment,unstable or severe angina, Congestive heart failure (New York heart association (NYHA) class > 2), orventricular arrhythmia which need medical intervention.

• Hypertension and unable to be controlled within normal level following treatment ofanti-hypertension agents: systolic blood pressure > 140 mmHg, diastolic bloodpressure > 90 mmHg.