To evaluate the efficacy and safety of Sintilimab (PD-1 inhibitor) and nab-paclitaxel in second line treatment of advanced gastric and gastro-esophageal junction adenocarcinoma. This is a prospective, multi-centers, single arm phase II trial with primary objective overall response rate and second objective of safety and other efficacy endpoints.

Inclusion Criteria:

• pathological confirmed advanced gastric and gastro-esophageal junction adenocarcinoma;
• progression after first-line treatment of fluoropyrimidine and platinum, allow patients progressed on/within 6 months of neoadjuvant/adjuvant treatment; allow local radiotherapy after 21days later;
• 18-75 years old;
• ECOG: 0 or 1;
• has adequate organ function
• writen ICF;

Exclusion Criteria:

• previous treated with taxanes (including paclitaxel, nab-PTX, lipo-PTX, and docetaxel etc..);
• Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-CTLA-4 antibody;
• has known active central nervous system metastatases;
• has received a live vaccine within 4 weeks prior to the first dose of study treatment with any acitve autoimmune disease or history of autoimmune disease, including but not limited to the following: hepatititis, 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), orventricular 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.

The baseline characteristics of patients could be shared to othter researchers per request.