A Randomized Double-Blinded, Placebo-Controlled Study of Omalizumab for Idiopathic Anaphylaxis

Background: Idiopathic anaphylaxis (IA) is a diagnosis of exclusion, thus taking away the option of therapeutic management focused on eliminating the inciting agent. Epinephrine and antihistamines followed by systemic corticosteroids are the mainstays of therapy for acute events. There is no prophylactic therapy that reliably prevents anaphylaxis. Objective: We sought to determine the efficacy of omalizumab in the management of patients with frequent episodes of IA in a DBPC trial. Methods: We prospectively enrolled 19 patients with frequent IA (=6 episodes/yr) and who then underwent a medical evaluation that included a serum tryptase determination, mutational analysis for KIT D816V and bone marrow evaluation to rule out a clonal mast cell disorder. Computer-generated random numbers were provided by the study pharmacist. The primary endpoint was anaphylactic events in the 6 months after baseline. Sixteen patients completed the primary trial. Results: No statistically significant difference was demonstrated between the placebo and treated groups. There was a trend for efficacy in the treatment group, particularly after 60 days. Overall, the safety profile was favorable without long-term side effects. Conclusion: Omalizumab was safely administered to a difficult to treat patient population with IA. The efficacy results trended modestly in favor of the treatment group, but no statistically significant differences were detected. Clinical trials number: NCT00890162. Copyright © 2020. Published by Elsevier Inc.

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