Surufatinib and Serplulimab Combined With AG Regimen Compare With AG Regimen as Conversion Therapy for Patients With Locally Advanced Pancreatic Cancer (SAGE)

Inclusion Criteria: 1. Written informed consent obtained from the patient prior to treatment. 2. Pathologically confirmed unresectable locally advanced pancreatic cancer, received no surgical therapy. 3. Age between 18 and 75 years at the time of study entry. 4. Eastern Cooperative Oncology Group (ECOG) performance status ≤ 1. 5. Measurable or evaluable lesions according to RECIST v1.1 criteria. 6. Life expectancy ≥ 12 weeks. 7. There are no serious organic diseases of the heart, lungs, brain and other organs. 8. Adequate functioning of the bone marrow and major organs function meeting the following criteria: 1. White blood cell count ≥ 4 × 109/L, Neutrophil count ≥ 1.5 × 109/L, Platelets count ≥ 100 × 109/L,Hemoglobin ≥ 90 g/L. 2. Normal coagulation function, without active bleeding or thrombotic diseases: INR ≤ 1.5 × ULN, APTT ≤ 1.5 × ULN. 3. Liver function: Total serum bilirubin ≤ 1.5 ×ULN, Serum aspartate aminotransferase (AST) and serum alanine aminotransferase (ALT) ≤ 3 × ULN, Obstructive Jaundice with total serum bilirub ≤ 1.5 x ULN after internal/ external drainage. 4. Kidney function: Serum creatinine ≤ 1.5 × upper limit of normal (ULN) or creatinine clearance ≥ 60 mL/min. 5. Cardiac function:left ventricular ejection fraction (LVEF) of 50%≥ on 2D cardiac ultrasound. 9. Male or female patients of potential for childbearing who voluntarily used effective contraceptive methods such as double-barrier contraception, condoms, oral or injection avoidance or pregnancy medications, IUDs, etc during the study period and within 6 months of the last study medication . All female patients will be considered fertile unless the female patient is naturally menopausal. Exclusion Criteria: 1. Participants diagnosed pancreatic cancer with distant metastases. 2. Participation in other antineoplastic drug clinical trials within 4 weeks prior to enrollment; 3. Previous systemic antitumor therapy (chemotherapy, radiation, targeted or immunoth, etc.). 4. Diagnosis of any second malignancy, except for adequately treated basal cell skin cancer or in situ carcinoma of the cervix uteri. 5. Known allergy or hypersensitivity to any of the study drugs or any of the study drug excipients. 6. Active or prior documented autoimmune or inflammatory disorders. 7. Participants are being treated with immunosuppressants, or systemic or absorbable topical hormones for immunosuppressive purposes (dose\> 10 mg/day prednisone or other equivalent hormones) , and the use is still continued within 2 weeks before enrollment. 8. Have undergone any surgery (other than biopsy) or invasive treatment or manipulation within 4 weeks prior to enrollment and the surgical incision has not healed completely (except intravenous catheterization, puncture drainage, internal or external drainage of obstructive jaundice, etc.) 9. Participants with abnormal thyroid function who were unable to maintain thyroid function within the normal range with medical treatment. 10. Hypertension that cannot be controlled in the presence of optimal treatment is defined as systolic blood pressure ≥ 150 mmHg and/or diastolic blood pressure ≥ 100 mmHg. 11. Urinary routine showed that urinary protein ≥2+, and 24-hour urinary protein\>1.0g. 12. Participantst currently has any disease or condition that affects the absorption of the drug, or the participants cannot take sulfatinib orally 13. participants with evidence or history of significant bleeding tendency within 3 months prior to enrollment (bleeding\>30 mL within 3 months with hematemesis, melena, hematochezia), hemoptysis (fresh blood\>5 mL within 4 weeks); Patients with history of hereditary or acquired bleeding or coagulation dysfunction, with clinically significant bleeding symptoms or definite bleeding tendency within 3 months, such as gastrointestinal bleeding and hemorrhagic gastric ulcer. 14. Cardiovascular disease of significant clinical significance, including but not limited to acute myocardial infarction, severe/unstable angina, or coronary bypass grafting within 6 months prior to enrollment; New York Heart Association (NYHA) grade \> 2 for congestive heart failure; ventricular arrhythmias requiring drug therapy; Electrocardiogram (ECG) showing QT interval ≥480 ms; 15. Severe infection that is active or uncontrolled: 1. Inherited or acquired immunodeficiency disease, 2. Known clinically significant history of liver disease, including viral hepatitis \[known hepatitis B virus (HBV) carriers must exclude active HBV infection , HBV DNA positive (\>1×104 copies/mL or \>2000 IU/ml)\]; 3. known hepatitis C virus infection (HCV) and positive HCV RNA (\>1×103 copies/ml) or other hepatitis, cirrhosis. 16. Pregnant or lactating women or participants with family planning during the trial period. 17. Participants have a known history of psychotropic substance abuse, alcoholism, or drug abuse. 18. The investigator believes that the participant has any clinical or laboratory abnormalities or other reasons that are unsuitable for this clinical study.