Sequential AG and mFOLFOX Combined With Serplulimab Injection and Bevacizumab Injection in Untreated Advanced Pancreatic Cancer

Nab-paclitaxel:125 mg/m2, ivgtt, D1, 8 and 15,every 6 weeks for a treatment cycle Gemcitabine hydrochloride: 1g/m2, ivgtt, D1, 8 and 15,every 6 weeks for a treatment cycle 5-FU: 2400 mg/m2 ,ivgtt over 46h, D29-30, every 6 weeks for a treatment cycle Oxaliplatin: 85 mg/m2 ,ivgtt, D29, every 6 weeks for a treatment cycle LV: 400 mg/m2 ,ivgtt over 2h, D29, every 6 weeks for a treatment cycle Serplulimab Injection: 3mg/kg,ivgtt,D1, every 2 weeks for a treatment cycle. Bevacizumab Injection: 5mg/kg,ivgtt,D1, every 2 weeks for a treatment cycle.