Combination of Anti-PD-1 Antibody and Chemotherapy in Pancreatic Cancer

Inclusion Criteria: * Pathologically (histologically or cytologically) confirmed pancreatic ductal adenocarcinoma (PDAC). * No evidence of distant metastasis (such as liver, peritoneum, lung) evaluated by abdominal contrast-enhanced CT, MRI, and chest CT. PET/CT or other imaging examinations would be used if necessary. * Initial assessment for definitive borderline resectable or locally advanced tumors (resectability judgment is based on CT enhanced scan or magnetic resonance imaging, NCCN2019 first edition standard). * ECOG score 0 or 1. * Serum creatinine level is normal, and serum total bilirubin level is less than 1.5 x ULN. * ALT and AST are less than 2 x ULN. * If biliary obstruction is observed, biliary decompression should be performed when the patient is randomly assigned to receive neoadjuvant chemotherapy. * Leukocyte count (\> 3.5 x 10\^6 /mL), neutrophil count (\> 1.5 x 10\^6 /mL), platelet count (\> 80 x 10\^6 /mL), hemoglobin (\> 9 g/dL). * Signed informed consent. Exclusion Criteria: * History of malignance treatment in the past, excluding basal and cutaneous squamous cell carcinoma, cervical carcinoma in situ, papillary thyroid carcinoma * History of participation of other clinical trails within 4 weeks * History of immunotherapy within 4 weeks * History of receiving chemotherapy, radiotherapy and molecular target therapy within 2 weeks * Tumor is a local recurrent lesion. * Imaging confirmed severe portal hypertension / cavernous transformation. * Ascites * Gastric outlet obstruction * Respiratory failure requires supplementation of oxygen. * Immune deficiency syndrome, such as active tuberculosis and HIV infection. * Hematological precancerous diseases, such as myelodysplastic syndromes. * Major cardiovascular diseases (including myocardial infarction, unstable angina, congestive heart failure, severe uncontrolled arrhythmia) during the past six months of enrollment. * Evidence of clinical-related or previous interstitial lung disease, such as noninfectious pneumonia or pulmonary fibrosis, or baseline chest CT scan or chest X-ray findings * Previous or physical findings of central nervous system disease, except for adequately treated (e.g. primary brain tumors, uncontrolled seizures or strokes with standard medications) * Preexisting neuropathy \> 1 (NCI CTCAE). * Allograft requires immunosuppressive therapy or other major immunosuppressive therapies. * Severe serious wounds, ulcers or fractures. * Confirmed coagulant disease. * Clinical evaluation is unacceptable.