Second-Line Adjuvant Therapy With Nab-Paclitaxel Plus Gemcitabine Versus Oxaliplatin Plus Folinic Acid and Fluorouracil for Gemcitabine-Refractory Pancreatic Cancer After Curative Resection

Inclusion Criteria:

* Signed informed content obtained prior to treatment
* Age ≥ 18 years and ≤ 75 years
* Eastern Cooperative Oncology Group (ECOG) performance status 0-2
* Patients must have histologically confirmed pancreatic adenocarcinoma (or any mixed pathology if adenocarcinoma is predominant) after R0 or R1 resection. The pathological staging does not exceed the stage ⅡB. And the patients have received gemcitabine as adjuvant chemotherapy after curative resection.
* There is progression or recurrence of tumor during the course of adjuvant chemotherapy with gemcitabine, or within 6 months after the whole courses of treatment.
* No severe defects in hematological system, immune system, cardiac function and pulmonary function.
* White blood cell (WBC) ≥ 4 × 10\^9/L; Absolute neutrophil count (ANC) ≥ 1.5 × 10\^9/L; Platelets (PLT) ≥ 100 × 10\^9/L; Hemoglobin (Hgb) ≥ 9 g/dL
* Aspartate aminotransferase (AST) (serum glutamate oxaloacetate transaminase (SGOT)）/ alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase (SGPT)) ≤ 2.5 × institutional upper limit of normal (ULN); Total bilirubin (TBIL) ≤ ULN; Creatinine (CRE) ≤ 1.5 × ULN
* Prothrombin time (PT) and international normalized ratio (INR) ≤ 1.5 × ULN
* The patients are willing to comply to the study plan and other requirements.

Exclusion Criteria:

* There is another malignant tumor with the patient.
* Patients who have received any form of anti-tumor therapy within 4 weeks prior to the enrollment, including chemotherapy, radiotherapy, interventional chemoembolization, radiofrequency ablation, and molecular targeted therapy
* Use of any other investigational agents within 4 weeks prior to the enrollment.
* The progression or recurrence of tumor occurs after 6 months of the course of the adjuvant chemotherapy with gemcitabine.
* Patients with uncontrolled intercurrent illness including, but not limited to ongoing or active infection, internal hemorrhage, pancreatic leakage, bile leakage, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.
* History of allergic reactions attributed to compounds of similar chemical or biological composition to the drugs.
* Metabolic acidosis, acute or chronic, including ketoacidosis
* Pregnant or nursing women
* Any event or condition that is possible to harm the safety of the patients or the integrities of data, including severe medical risk factors, medical conditions, and laboratory disorders.
* Patients who are unwilling or unable to comply with study procedures, or may be absent from the observation for more than 7 days.