1. Patients have good compliance, can understand the research process of this study, and sign a written informed consent
2. Patients with pathologically confirmed pancreatic adenocarcinoma.
3. Patients who have not received prior chemotherapy, radiotherapy or other systematic treatment for pancreatic cancer;
4. Patients with locally advanced pancreatic cancer ( NCCN Version 1，2019 criteria).
5. ECOG PS 0-1;
6. Tumor size is measurable according to RECIST1.1 criteria
7. Expected survival over 3 months;
8. Bone marrow function: neutrophils≥1.5x109/L, platelets ≥100x109/L, hemoglobin≥ 90g/L;
9. Liver and kidney function: serum creatinine≤1.5ULT; AST and ALT≤ 2.5 ULT; total bilirubin ≤ 1.5 ULT;
10. No contraindications to the use of S-1 and nab-paclitaxel.
You may not be if
1. ≥ Grade 2 existing peripheral neuropathy;
2. Any other malignancy within 5 years prior to enrollment, with the exception of adequately treated in-situ carcinoma of the cervix, uteri, bladder, or nonmelanomatous skin cancer.
3. Active, uncontrolled infection(s) requiring systemic therapy, defined as ongoing signs/symptoms related to the infection without improvement despite appropriate treatment.
4. Severe, active co-morbidity, defined as follows:
Unstable angina and/or congestive heart failure requiring hospitalization within the last 6 months Transmural myocardial infarction within the 6 months of study registration Uncontrolled hypertension, diabetes or arrhythmia. Chronic obstructive pulmonary disease exacerbation or other respiratory illness requiring hospitalization.
5. Not able to take medicine orally.
6. Pregnancy or lactation, and women of childbearing age who refused to take appropriate contraceptive measures during the course of this study;
7. Participation in other clinical trial within 30 days before the first dose of the drug;
