This is a single arm, single cencer, phase II clinical trial. This study aims to evaluate the efficacy and safety of Cadonilimab combined with S-1 or capecitabine as a second-line treatment for advanced pancreatic cancer.

Main Inclusion Criteria:

• Signed written informed consent
• Age 18-80, female or male
• Histopathologically confirmed pancreatic ductal adenocarcinoma
• Patients with locally advanced pancreatic cancer who have previously received standard first-line anti-tumor treatment (radiotherapy, chemotherapy, targeted or immunotherapy, etc.)
• Locally advanced pancreatic cancer is defined as follows: a. The tumor has no distant metastasis; b. Pancreatic head/uncinate process: The tumor contacts the superior mesenteric artery >180˚; c. Pancreatic body and tail: The tumor contacts the superior mesenteric artery or celiac artery >180˚; The tumor contacts the celiac artery and infiltrates the abdominal aorta; d. The tumor invades the jejunal branch of the superior mesenteric artery. Portal vein-superior mesenteric vein cannot be safely reconstructed due to tumor invasion, vein occlusion, or involvement of a large range of jejunal branches of the superior mesenteric vein.
• At least one measurable lesion (RECIST1.1)
• ECOG PS 0-1
• Expected survival time>3 months
• Adequate organ function

Main Exclusion Criteria:

• Malignant diseases other than pancreatic cancer diagnosed within 5 years before the first dose (excluding radically resected basal cell carcinoma of the skin, squamous cell carcinoma of the skin, and/or radically resected carcinoma in situ)
• Currently participating in interventional clinical research treatment, or having received other research drugs or used research devices within 4 weeks before the first dose
• Active autoimmune disease
• Allogeneic organ transplantation or allogeneic hematopoietic stem cell transplantation
• Allergic to the active ingredients or excipients of this study drug, cadonilimab, S-1 or capecitabine
• Have not fully recovered from any toxicity and/or complications caused by the intervention before starting treatment
• History of HIV
• Active HBV or HCV
• Pregnant or breastfeeding women
• Any severe or uncontrolled systemic disease
• Active pulmonary tuberculosis
• People with mental disorders who are unable to cooperate with treatment
• Uncontrolled infection
• The investigators assess that the subjects are unable to complete the entire trial process or are otherwise unsuitable for participating in this trial