YMN-136 Vaccine for Patients With Advanced Hepatobiliary and Pancreatic Malignancies

Inclusion Criteria: 1. Voluntarily sign the informed consent form, and be able to understand and agree to comply with the study procedures and visits as specified in the protocol. 2. Age: 18 to 75 years old, male or female. 3. Patients with pathologically or histologically confirmed, unresectable advanced hepatobiliary and pancreatic malignancies who must have experienced disease progression after receiving standard anti-tumor therapy, or who are unable to receive or tolerate standard therapy, or who refuse standard therapy: (1) Patients with advanced hepatocellular carcinoma who have failed standard therapy, defined as disease progression after prior treatment with PD-(L)1 and mTKI systemic therapy (either separately or in combination), or discontinuation of treatment due to intolerance to toxicity; (2) Patients with advanced biliary tract cancer who have failed standard therapy, defined as disease progression after prior treatment with gemcitabine-containing systemic therapy and non-cytotoxic therapy (i.e., targeted therapy or immunotherapy), or discontinuation of treatment due to intolerance to toxicity; (3) Patients with advanced pancreatic cancer who have failed standard therapy, defined as disease progression after prior treatment with at least two systemic therapies (must include fluoropyrimidines and gemcitabine), or discontinuation of treatment due to intolerance to toxicity. 4\. Positive IMP3 expression. 5. At least one evaluable lesion according to RECIST v1.1. 6. Eastern Cooperative Oncology Group (ECOG) performance status: 0 or 1. 7. Life expectancy ≥ 12 weeks. 8. Organ function levels at screening must meet the following requirements: 1. Absolute neutrophil count (ANC) ≥ 1.5 × 10⁹/L; 2. Platelet count (PLT) ≥ 75 × 10⁹/L; 3. Hemoglobin (Hb) ≥ 90 g/L; 4. Total bilirubin (TBIL) ≤ 1.5 × ULN; 5. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 × ULN, or ≤ 5 × ULN in patients with liver metastases; 6. Serum creatinine (Cr) ≤ 1.5 × ULN, or creatinine clearance (Cockcroft-Gault formula) ≥ 45 mL/min; 7. International normalized ratio (INR) and prothrombin time (PT) ≤ 1.5 × ULN; 8. QTc interval calculated by Fridericia's formula ≤ 450 ms for males and ≤ 470 ms for females; 9. Urinalysis/24-hour urine protein quantification: urine protein qualitative ≤ 1+ (if urine protein qualitative ≥ 2+, 24-hour urine protein \< 1 g is acceptable for enrollment); 10. Cardiac function: left ventricular ejection fraction ≥ 50%. 9. Eligible patients (male or female) with childbearing potential must agree to use a medically accepted physical contraceptive method (e.g., intrauterine device, condom, tubal or vas deferens ligation, etc.) during the study period and for 6 months after the last dose. Female patients of childbearing potential must have a negative serum or urine HCG test at screening. Exclusion Criteria: 1. Presence of extensive peritoneal metastasis or intestinal obstruction. 2. Presence of uncontrolled pleural effusion, pericardial effusion, or ascites requiring repeated drainage. 3. Known allergy to any component of the investigational drug (e.g., lipid nanoparticles, RNA carrier) or to drugs of the same class. 4. Prior receipt of vaccine therapy. 5. Received chemotherapy, targeted therapy, or immunotherapy within 4 weeks prior to the first dose. 6. In the dose-escalation and dose-expansion phases: received anti-tumor therapy (including chemotherapy, radiotherapy, targeted therapy, immunotherapy, biological therapy, or other investigational drug therapy for target lesions) within 4 weeks or 5 drug half-lives (whichever is shorter, but at least 14 days) prior to the first dose; or received traditional Chinese medicine or Chinese patent medicine with anti-tumor indications within 14 days prior to the first dose. 7. Use of immunosuppressive drugs within 4 weeks prior to the first dose or expected use during the study period, except for corticosteroid nasal sprays, inhalers, or systemic prednisone ≤ 10 mg/day (or equivalent doses of similar drugs). 8. History of organ transplantation, bone marrow transplantation, or hematopoietic stem cell transplantation. 9. Receipt of a live attenuated vaccine within 28 days prior to the first dose. 10. In the dose-escalation and dose-expansion phases: presence of symptomatic, untreated, or central nervous system (CNS) metastases requiring ongoing treatment (including corticosteroids and antiepileptics). Patients with previously treated CNS metastases may be enrolled if they have been clinically stable for at least 4 weeks prior to enrollment, have no evidence of new or enlarging metastases, and have discontinued corticosteroid therapy. Patients with asymptomatic CNS metastases not requiring treatment may be enrolled. 11. In the dose-escalation and dose-expansion phases: toxicity from prior anti-tumor therapy that has not recovered to baseline or to Grade 0-1 per NCI-CTCAE v5.0 (except for alopecia and hyperpigmentation). Irreversible toxicities that are reasonably not expected to be exacerbated by the study drug may be enrolled after confirmation with the investigator. 12. History of autoimmune diseases, such as systemic lupus erythematosus, psoriasis requiring systemic therapy, rheumatoid arthritis, inflammatory bowel disease, etc. Patients with type I diabetes mellitus, hypothyroidism controlled with replacement therapy only, or skin diseases not requiring systemic therapy (e.g., vitiligo, psoriasis) may be enrolled. 13. History of immediate hypersensitivity reactions, eczema, or asthma that cannot be controlled with topical corticosteroids. 14. History of other malignancies, except for curatively treated curable tumors, such as basal or squamous cell skin cancer, superficial bladder cancer, carcinoma in situ of the cervix, or carcinoma in situ of the breast. 15. Presence of uncontrolled comorbid conditions, including but not limited to: unexplained fever \> 38.5°C (patients with tumor-related fever to be enrolled at the inv