Sintilimab and Nab-paclitaxel in Second-line Treatment of Advanced Gastric or Gastro-oesophageal Junction Adenocarcinoma

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.