Drotrecogin alfa (activated), a recombinant form of human activated protein C, is the first therapeutic intervention shown to reduce all-cause mortality in severe sepsis. In the Phase 3 study (F1K-MC-EVAD; PROWESS), 1690 patients were randomly assigned to receive a 96-hour intravenous infusion of drotrecogin alfa (activated) 24 micrograms/kg/h or placebo (850 patients and 840 patients, respectively). Overall, administration of drotrecogin alfa (activated) yielded a clinically significant reduction in 28-day all-cause mortality: 24.7% of drotrecogin alfa (activated) patients died versus 30.8% of placebo patients (19.4% relative risk reduction; p=0.005; Bernard et al. 2001). The only safety concern noted in the Phase 3 trial was an increased risk of serious bleeding among drotrecogin alfa (activated) patients (3.5% versus 2.0% of placebo patients). The difference between the two treatment groups in the number of patients who experienced a serious bleeding event was due to the greater number of drotrecogin alfa (activated) patients who experienced a serious bleeding event that was related to a procedure (for example, bleeding that resulted from the placement of a catheter or nephrostomy tube). The number of patients who experienced spontaneous serious bleeding events was similar between the two treatment groups.

The Regulatory authorities have approved the use of drotrecogin alfa (activated) in severe sepsis patients with a high level of disease severity and risk of death. Thus, the regulatory authorities have requested a study evaluating drotrecogin alfa (activated) in a specific subpopulation of patients with severe sepsis and at lower risk of death.