The purpose of this trial is to estimate overall response rate (ORR) of SHR-1210 combined with capecitabine and oxaliplatin or with apatinib as first-line treatment in subjects with locally advanced or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma.

Approximately 110 participants will be assigned to SHR-1210 + capecitabine + oxaliplatin combination therapy (Cohort 1), or SHR-1210 + apatinib combination therapy (Cohort 2).

Inclusion Criteria:

• Has histologically- or cytologically-confirmed diagnosis of locally advanced unresectable or metastatic adenocarcinoma of stomach or the esophagogastric junction (GEJ).
• Age ≥ 18 years old, male or female.
• NO previous therapy for advanced/metastatic disease of GC/GEJ (including HER2 inhibitor). Subjects with previous adjuvant/neo-adjuvant therapy completed more than 6 months can be enrolled.
• Has measurable disease per RECIST 1.1.
• Life expectancy ≥ 12 weeks.
• Eastern Cooperative Group (ECOG) performance status of 0 to 1.
• Has adequate organ function.
• Females of childbearing potential (FOCBP), who are not surgically sterile or postmenopausal, must conduct pregnancy test (serum or urine) within 7 days before enrollment, and must not be pregnant or breast-feeding women. If the result is negative, she must agree to use adequate contraception during the experiment and 3 months after the last administration of the test drugs. And non-sterilized males who are sexually active must agree to use adequate contraception during the experiment and 3 months after the last administration of the test drugs.

Exclusion Criteria:

• Has known HER2-positive status.
• Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-CTLA-4 antibody, or a VEGFR inhibitor.
• Has known active central nervous system metastases.
• Has received a live vaccine within 4 weeks prior to the first dose of study treatment.
• With any active autoimmune disease or history of autoimmune disease, including but not limited to the following: hepatitis, pneumonitis, uveitis, colitis (inflammatory bowel disease), hypophysitis, vasculitis, nephritis, hyperthyroidism, and hypothyroidism, except for subjects with vitiligo or resolved childhood asthma/atopy. Asthma that requires intermittent use of bronchodilators or other medical intervention should also be excluded.
• Clinically significant cardiovascular and cerebrovascular diseases, including but not 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), or ventricular arrhythmia which need medical intervention.
• Hypertension and unable to be controlled within normal level following treatment of anti-hypertension agents(within 3 months): systolic blood pressure > 140 mmHg, diastolic blood pressure > 90 mmHg.
• Coagulation abnormalities (INR > 1.5 or APTT > 1.5×ULN), with bleeding tendency or are receiving thrombolytic or anticoagulant therapy.

32 months

Same event may appear as both an adverse event (AE) and serious adverse event (SAE). However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another, or a participant may have experienced both a serious and non-serious event.