NALIRIFOX+Adebrelimab+PULSAR for Advanced Pancreatic Cancer

Inclusion Criteria: * Age: 18-75 years, regardless of gender. * Histologically confirmed pancreatic ductal adenocarcinoma (PDAC). * Previously untreated, locally advanced unresectable or metastatic PDAC, with at least one measurable lesion (RECIST v1.1) not previously irradiated. * ECOG Performance Status (PS): 0-1. * Expected survival ≥ 3 months. * Willing and able to comply with study procedures, treatment, and follow-up. * No contraindications to radiotherapy. * Adequate organ function: WBC ≥ 2.5×10⁹/L, ANC ≥ 1.5×10⁹/L; Platelets ≥ 75×10⁹/L; Hemoglobin (HGB) ≥ 90 g/L (no transfusion or EPO dependence within 7 days); Total bilirubin (Tbil) ≤ 1.5×ULN; ALT/AST ≤ 5×ULN;Albumin ≥ 30 g/L; INR ≤ 1.5×ULN; Serum creatinine (Cr) ≤ 1.5×ULN Urine protein ≤ 1+ * HBsAg-positive patients must have HBV-DNA ≤ 1×10³ IU/mL (copies/mL). If HBV-DNA ≥ 1×10³ IU/mL, patients may still be eligible if chronic HBV is stable and not expected to increase risk, per investigator assessment. * Voluntary participation with signed informed consent form. Exclusion Criteria: * History of severe hypersensitivity to chimeric, human(ized) antibodies, or fusion proteins. * Pregnant or breastfeeding women, or men/women of childbearing potential unwilling/unable to use effective contraception during the study. * Other malignancies within 5 years, except: Malignancies treated with curative intent and no known active disease for ≥5 years with low recurrence risk; Adequately treated non-melanoma skin cancer or len…