This study will evaluate the efficacy and safety of adjuvant therapy with liposomal irinotecan in combination with oxaliplatin, and S-1 compared with capecitabine combined with capecitabine in participants with pancreatic ductal adenocarcinoma after radical surgery.

Inclusion Criteria:

1. Patients able and willing to provide a written informed consent aged 18-75 years.
2. Histologically confirmed resected ductal pancreatic adenocarcinoma (including adenosquamous carcinoma).
3. Undergone radical resection and confirmed macroscopic complete resection (R0 and R1).
4. Full recovery after surgery; able to start adjuvant treatment within 12 weeks after surgery.
5. Eastern Cooperative Oncology Group (ECOG) performance status 0-1.
6. The main organs function well.

Exclusion Criteria:

1. Patients with other types of non-ductal tumor of the pancreas, including endocrine tumors or acinar cell adenocarcinoma, pancreatoblastoma, and solid-pseudopapillary tumor.
2. Macroscopic incomplete tumor removal (R2 resection).
3. Prior neo-adjuvant treatment, radiation therapy, or systemic therapy for pancreatic adenocarcinoma.
4. Presence or history of metastatic or locally recurrent pancreatic adenocarcinoma.
5. CA 19-9> 180 U / ml within 21 days before randomization.
6. The toxicity of previous therapy has not recovered to Grade 1 or below.
7. Known peripheral neuropathy (CTCAE ≥ Grade 2).
8. Known deficiency of dihydropyrimidine dehydrogenase (DPD)
9. Subjects with a confirmed diagnosis of Gilbert's syndrome