This Phase IIa Randomized, Double-blind, Parallel Group, Placebo-controlled, multicenter Study to Evaluate Safety, Tolerability, Pharmacokinetics and Efficacy of Multiple Intravenous Injection of SY-005（recombinant human annexin A5） in Sepsis Subjects. 96 patients will be entered into the study and randomised in a 1:1:1:1 ratio to receive SY-005 2.5mg or SY-005 5mg or SY-005 10mg or placebo.

Key Inclusion Criteria:

• Patients are diagnosed with sepsis and receive study treatment within 48 hours
• Sepsis-related Organ Failure Assessment（SOFA）score range from 2 to 13
• The informed consent form signed by the patient or the patient's legally acceptable representative

Key Exclusion Criteria:

• Pregnant or breastfeeding women ; Women of childbearing potential (WOCBP) could not take effective method of contraception

• Moribund, and death is considered imminent within 24 hours or patient expected survival time is less than 6 months due to the underlying disease

• Absolute neutrophil count (ANC) <0.5 x 10^9/L

• New York Heart Association (NYHA) classification IV

• Patient with end-stage lung disease

• eGFR <60ml/min

• Alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) >3.0 times the upper limit of normal (ULN)

• Immunosuppressed patients with following situations:

  1. Human immunodeficiency virus (HIV) infection
  2. Patients undergoing active radiation or chemotherapy treatment within the past 3 months
  3. Any organ or bone marrow transplant and related immunosuppressive therapy
  4. High dose steroids (eg, > 0.5 mg/kg prednisone or a steroid with equivalent activity, daily for a month) within 3 months before provision of written informed consent for the study

• Patients with high bleeding risk:

  1. Recent surgery <72 hours, or a planned surgical procedure in the next 24h
  2. Severe thrombocytopenia (< 30 x 10^9/L, before platelet transfusion)
  3. Recent trauma <72 hours
  4. History of gastrointestinal bleeding or intracranial hemorrhage in the past 6 weeks.
  5. Stroke or head injury in the past 3 months
  6. On-going therapeutic anticoagulants that could not be interrupted (except prophylactic heparin treatment that can be continued）
  7. Any history of Chronic liver disease with a Child score B or C
  8. Any condition at risk of bleeding, as appreciated by the physician in charge of the patient

• Severe anemia (hemoglobin <5.9 g/dL)