Omalizumab: A useful tool for inducing tolerance to bee venom immunotherapy

Insect venom anaphylaxis occurs in about 3% of adults and venom immunotherapy (VIT) is an established treatment of sting anaphylaxis.1 The protective effect of VIT is quite convincing, as it is associated with a success rate of 98% with wasp VIT and 75–85% with bee venom immunotherapy (BVIT). Adverse reactions may occur, especially with BVIT,2 and systemic adverse reactions to BVIT are reported to occur in about 14% of patients.3 Omalizumab is a recombinant humanized monoclonal anti-IgE antibody approved in Europe as add-on therapy for allergic severe asthma not controlled by standard therapy and as add-on therapy for chronic spontaneous urticaria. Pre-treatment with omalizumab has demonstrated a role in preventing severe allergic anaphylaxis following VIT administration, as shown in several published case reports.4–7 This efficacy is likely to be explained with the established omalizumab mechanism of action of binding free IgE and subsequent downregulation of FcεRI on mastcells, basophils, and eosinophils.8 The efficacy of omalizumab pre-treatment in a case where the presence of venom specific IgE was not detected has also been reported,9 suggesting an additional mechanism of action, such as mast cell apoptosis due to lack of IgE binding.5 We describe the case of two cousins at high risk of bee stings, where treatment with omalizumab allowed a successful BVIT.