This study primarily aims to assess the safety and tolerability of XP-004 personalized mRNA vaccines encoding tumor neoantigens combined with PD-1 inhibitor as adjuvant therapy for chemotherapy-intolerant patients following radical pancreatic cancer resection.

Secondary objectives focus on evaluating preliminary efficacy through three parameters: 1) XP-004-induced antigen-specific CD4+/CD8+ T cell activation levels, 2) recurrence-free survival (RFS), and 3) overall survival (OS) in post-operative pancreatic cancer patients receiving this combination therapy.

Inclusion Criteria:

1. Subjects voluntarily signed written informed consent files,Able to comply with the study protocol, in the investigator's judgment
2. Subjects must be >/= 18 years of age at time of informed consent, regardless of gender
3. Patients who have been confirmed by pathology to have pancreatic malignant tumors and have undergone radical surgery for pancreatic malignant tumors for 1-3 months
4. No copy number variations (CNVs) or loss of heterozygosity (Loss-of heterozygosity, LOH) were found in HLA-related genes and chromosomal regions by gene sequencing
5. Histologically confirmed pancreatic cancer samples underwent WES and RNA-seq analyses. Bioinformatics prediction identified at least one neoantigen effectively presented by the patient's HLA type, including those derived from KRAS or TP53 mutations.
6. According to the investigator's assessment, the patient is unable to tolerate chemotherapy, such as the score of the Eastern Cooperative Oncology Group (ECOG) Performance Scale ≥ 2 points

Exclusion Criteria:

1. Has had chemotherapy, traditional Chinese medicine with antitumor indications, or other antitumor therapies deemed to conflict with the current treatment by the investigator within 4 weeks prior to the first administration of the study drug
2. History of interstitial lung disease (ILD), pulmonary fibrosis
3. Other serious and/or uncontrollable diseases, which may affect the subject's participation in this study, include but not limited to a) a history of severe drug allergy, or is known to be allergic to any tumor vaccine and PD-1 inhibitor formulation components or has had severe allergic reactions to other monoclonal antibodies in the past, b) A history of immunodeficiency, including HIV positive or other acquired or congenital immunodeficiency diseases
4. Researchers believe that there are other reasons that are not suitable for participating in clinical trials