Icatibant, a new bradykinin-receptor antagonist, in hereditary angioedema.

BACKGROUND: Hereditary angioedema is characterized by recurrent attacks of angioedema of the skin, larynx, and gastrointestinal tract. Bradykinin is the key mediator of symptoms. Icatibant is a selective bradykinin B2 receptor antagonist. METHODS: In two double-blind, randomized, multicenter trials, we evaluated the effect of icatibant in patients with hereditary angioedema presenting with cutaneous or abdominal attacks. In the For Angioedema Subcutaneous Treatment (FAST) 1 trial, patients received either icatibant or placebo; in FAST-2, patients received either icatibant or oral tranexamic acid, at a dose of 3 g daily for 2 days. Icatibant was given once, subcutaneously, at a dose of 30 mg. The primary end point was the median time to clinically significant relief of symptoms. RESULTS: A total of 56 and 74 patients underwent randomization in the FAST-1 and FAST-2 trials, respectively. The primary end point was reached in 2.5 hours with icatibant versus 4.6 hours with placebo in the FAST-1 trial (P=0.14) and in 2.0 hours with icatibant versus 12.0 hours with tranexamic acid in the FAST-2 trial (P<0.001). In the FAST-1 study, 3 recipients of icatibant and 13 recipients of placebo needed treatment with rescue medication. The median time to first improvement of symptoms, as assessed by patients and by investigators, was significantly shorter with icatibant in both trials. No icatibant-related serious adverse events were reported. CONCLUSIONS: In patients with hereditary angioedema having acute attacks, we found a significant benefit of icatibant as compared with tranexamic acid in one trial and a nonsignificant benefit of icatibant as compared with placebo in the other trial with regard to the primary end point. The early use of rescue medication may have obscured the benefit of icatibant in the placebo trial. (Funded by Jerini; ClinicalTrials.gov numbers, NCT00097695 and NCT00500656.)

Hereditary angioedema.

PURPOSE OF REVIEW: Hereditary angioedema is an autosomal-dominant deficiency of C1 inhibitor--a serpin inhibitor of kallikrein, C1r, C1s, factor XII, and plasmin. Quantitative or qualitative deficiency of C1 inhibitor leads to the generation of vasoactive mediators, most likely bradykinin. The clinical syndrome is repeated bouts of nonpruritic, nonpitting edema of the face, larynx, extermities, and intestinal viscera. Recently, investigators, physicians, and industry have demonstrated a renewed interest in the biology and treatment of hereditary angioedema. RECENT FINDINGS: Investigators have generated a C1INH-/- mouse model that has demonstrated the importance of the contact activation system for hereditary angioedema-related vascular permeability. An interactive database of mutations is available electronically. Investigators have continued exploration into mRNA/protein levels. The proceedings of a recent workshop have been impressive in the scope and depth. Clinicians have produced consensus documents and expert reviews. The pharmaceutical industry has initiated clinical trails with novel agents. SUMMARY: Hereditary angioedema is often misdiagnosed and poorly treated. Diagnosis requires careful medical and family history and the measurement of functional C1 inhibitor and C4 levels. Attenuated androgens, anti-fibrinolytics, and C1 inhibitor concentrates are used for long-term and preprocedure prophylaxis, but have significant drawbacks. C1 inhibitor concentrates and fresh frozen plasma are available for acute intervention. The mainstays of supportive care are airway monitoring, pain relief, hydration, and control of nausea. New agents such as recombinant C1 inhibitor, kallikrein inhibitors, and bradykinin inhibitors may offer safer and more tolerable treatments.