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…