Recombinant and Plasma-Purified Human C1 Inhibitor for the Treatment of Hereditary Angioedema

BACKGROUND: Agents for prophylaxis of hereditary angioedema (HAE) have been available in the United States for several decades, but their usefulness is limited by side effects and they cannot be used at all in some patients. No agents have been available in the United States to specifically treat acute attacks. HAE types I and II are associated with low functional levels of C1 inhibitor, and evidence accumulated over decades suggests that intravenous infusion of C1 inhibitor is useful for terminating angioedema attacks and for prophylaxis. KEY POINTS: C1 inhibitor derived from pooled human plasma has been available for decades in Europe, and 2 preparations have been recently introduced into the United States. Both have been efficacious in carefully controlled double-blind studies. One preparation, Cinryze, was approved by the U.S. Food & Drug Administration (FDA) for prophylaxis of HAE attacks in October 2008, and the second, Berinert, was approved by the FDA for treatment of acute attacks in October 2009. A third preparation, the recombinant human C1 inhibitor Rhucin, is completing clinical trials. Although not yet approved by the FDA, preliminary results made available suggest that Rhucin, too, is effective in terminating attacks of HAE. CONCLUSIONS: Americans will now have access to effective acute and prophylactic treatments with C1 inhibitor for hereditary angioedema.