Cadonilimab Combined With S-1 or Capecitabine as Second-line Treatment for Advanced Pancreatic Cancer

Eligible patients will receive Cadonilimab (6mg/k, iv, D1,Q3W)combined with S-1 (40-60mg po BID Q3W D1-14）or Capecitabine (1250mg/m2, po BID Q3W D1-14）until disease progression or unacceptable toxicity. Patients who had used S-1 in the first line should choose capecitabine; patients who had used capecitabine in the first line should choose S-1; otherwise decided by investigator's choice.