This clinical trial is to evaluate the safety and impact on prognosis of personalized neoantigen peptide-based vaccines, which are based on next-generation sequencing and major histocompatibility complex affinity prediction algorithm, in patients with pancreatic ductal adenocarcinoma. The hypothesis of this study is that personalized neoantigen vaccines will be safe and can systemically elicit measurable neoantigen-specific immunologic responses in patients. Participants will receive complete macroscopic resection of primary tumor, standard adjuvant chemotherapy and subsequently personalized neoantigen vaccines.

This is a single-center, open-label Phase Ib clinical trial. In this trial, adult subjects with pancreatic ductal adenocarcinoma who have completed resection of the primary tumor and who have not undergone preoperative chemotherapy will be enrolled in the study. Eligible enrolled patients all will undergo tumor resection and all receive adjuvant chemotherapy prior to preparation of the personalized neoantigen vaccine. After the chemotherapy finish, subsequently patients will receive a priming immunization with five doses of the personalized neoantigen vaccine over one month and a boosting immunization with two doses three months later. This clinical trial will examine the safety and effect of the personalized neoantigen vaccine when given at several different time points and will examine the participant's peripheral blood cells for signs that the vaccine induces immunologic responses. Finally we will establish the typical flow to assess efficiency and safety of vaccines according to the different reactivity of patients, as a result, to explore the most suitable practical approaches for applying personalized pancreatic tumor vaccines.

Inclusion Criteria:

1. Pathologic diagnosis of pancreatic ductal adenocarcinoma
2. Aged ≥20 and ≤75
3. Male or not pregnant women
4. Undergone radical resection (R0 status of resection margins [no cancer cells within 1 mm of all resection margins])
5. No serious underlying disease, Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
6. No chemotherapy or radiotherapy before resection surgery
7. No significant cardiac, lung, liver, kidney, and bone marrow insufficiency
8. No HIV or syphilis infection
9. Signing informed consent

Exclusion Criteria:

1. Poor postoperative situation
2. Obvious organ dysfunction
3. Radiographically confirmed recurrence or metastasis within 180 days after the surgery
4. Unstable angina pectoris, symptomatic congestive heart failure, severe arrhythmias, Myocardial infarction in the past 6 months, and prolonged QT interval (> 450ms)
5. Previous malignant tumors other than pancreatic cancer
6. Cannot be follow up
7. Participating in other clinical trials
8. Without chemotherapy after resection surgery

Exit criteria:

1. Missed within one month after surgery or not follow-up as required
2. Patient's own willingness to withdraw
3. Concurrent disease or severe adverse events
4. Protocol violations
5. Administrative reasons