title: Activated protein C in sepsis: emerging insights regarding its mechanism of action and clinical effectiveness.
abstract: OBJECTIVE
  Dysregulation of endogenous coagulant and anticoagulant systems is now believed to play an important role in the pathogenesis of sepsis and septic shock. Reductions in host activated protein C levels and resultant microvascular thrombosis provided a basis for the use of recombinant human activated protein C in sepsis. Although controversial, the findings from an initial phase III trial testing this agent resulted in its approval for use in patients with severe sepsis and high risk of death. This review highlights emerging insights into the biology of protein C and activated protein C in sepsis, summarizes additional analysis growing out of the phase III trial testing recombinant human activated protein C, and assesses the cost-effectiveness that the clinical use of the agent has had thus far.
  
  
  RESULTS
  Binding of activated protein C to the endothelial cell protein C receptor is recognized to result in a growing number of actions including increased activity of activated protein C itself and inhibition of both nuclear factor-kappaB, a central regulator in the host inflammatory response, and apoptosis. Additional analysis of the original phase III trial testing recombinant human activated protein C appears to emphasize one of the US Food and Drug Administration's original concerns regarding an association between severity of sepsis and this agent's effects. Postmarketing analysis and growing experience with other anticoagulant agents and corticosteroids in sepsis raise questions regarding the ultimate cost-effectiveness of activated protein C.
  
  
  CONCLUSIONS
  The protein C pathway is important both to coagulant and inflammatory pathways during sepsis. Based on emerging investigations, its actions appear to be increasingly complex ones. Despite potentially promising results in an initial phase III trial, the role of recombinant human activated protein C in the treatment of septic patients must continue to be evaluated.
authors.affiliation: Critical Care Medicine Department, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland 20892, USA. MHaley@cc.nih.gov
authors.forename: Michael
authors.initials: M
authors.lastname: Haley
authors.forename: Xizhong
authors.initials: X
authors.lastname: Cui
authors.forename: Peter C
authors.initials: PC
authors.lastname: Minneci
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Deans
authors.forename: Charles
authors.initials: C
authors.lastname: Natanson
authors.forename: Peter Q
authors.initials: PQ
authors.lastname: Eichacker
mesh_terms: D001777:Blood Coagulation / Q000187:drug effects; D017326:Clinical Trials, Phase III as Topic; D006801:Humans; D007249:Inflammation / Q000188:drug therapy; D011486:Protein C / Q000191:economics / Q000494:pharmacology / Q000627:therapeutic use*; D011994:Recombinant Proteins / Q000494:pharmacology / Q000627:therapeutic use; D018805:Sepsis / Q000188:drug therapy* / Q000401:mortality; D016896:Treatment Outcome
chemical_list: D011486:Protein C; D011994:Recombinant Proteins