Nal-IRI/5-FU/LV Chemotherapy Combined With PD-L1 Inhibitor and Multi-target Anti-angiogenic Small Molecule±SBRT as Second-line Therapy in Metastatic Pancreatic Cancer Patients

Inclusion Criteria: 1. Age ≥ 18 years and ≤ 75 years, ECOG score of ≤2 points, expected survival time ≥ 3 months. 2. Patients with histologically or cytologically confirmed advanced metastatic pancreatic cancer. 3. Imaging suggests distant measurable lesions. 4. Failure of first-line therapy and no use of fluorouracil, irinotecan, or liposomal irinotecan drugs in the first-line therapy. Patients need to meet the following hematologic indicators e1. Neutrophil count ≥ 1.5×109/L e2. Hemoglobin ≥ 10 g/dL e3. Platelet count ≥ 100×109/L f. Patients need to meet the following biochemical parameters f1. Total bilirubin ≤ 1.5× upper limit of normal (ULN) f2. AST and ALT \<1.5×ULN f3. Creatinine clearance ≥ 60ml/min g. Patients of childbearing age need to take appropriate protective measures (contraception or other methods of birth control) before enrollment and during the trial. H. Has signed an informed consent form. i. Able to follow the study protocol and follow-up process. Exclusion Criteria: 1. Have received second-line or more anti-tumor therapy in the past. 2. First-line treatment with fluorouracil, irinotecan or liposomal irinotecan, etc. 3. Patient has a prior history of other tumors, unless it is cervical cancer in situ, treated squamous cell carcinoma or bladder epithelial tumors (Ta and TIS) or other malignancies that have received curative therapy (at least more than 5 years prior to enrollment). 4. Patient has an active bacterial or fungal infection (≥ 3rd edition NCI-CTC2 grade). Patient has HIV, HCV, HBV infection, uncontrolled coronary artery disease or asthma, uncontrolled cerebrovascular disease or other disease deemed non-enrollable by the investigator. f. Patients with autoimmune diseases or immunodeficiencies who should be treated with immunosuppressive drugs. g. Pregnant and lactating women. Women of childbearing potential must have a negative pregnancy test within 7 days prior to enrollment. h. Substance abuse, clinical or psychological, or social factors that compromise informed consent or study conduct. i. Those who may be allergic to treatment drugs.