Xolair (omalizumab) is now licensed as add-on therapy for the treatment of chronic spontaneous urticaria (CSU) in adults and children over 12 years of age with an inadequate response to antihistamines.1
The approved dose of omalizumab in this setting is 300mg by subcutaneous injection every four weeks. The need for continued therapy should be reassessed periodically. Only the 150mg prefilled syringe is currently licensed for this indication.1
Omalizumab binds to IgE, lowers free IgE levels and leads to downregulation of IgE receptors. It is not entirely understood how this results in an improvement of CSU symptoms.1
The safety and efficacy of omalizumab were assessed in two phase III studies in patients with CSU who remained symptomatic despite treatment with H1 antihistamines at licensed doses.1
In the first study at week 12, omalizumab 300mg reduced weekly itch score (primary endpoint) by 9.4 compared with a reduction of 3.6 in the placebo group.1
Consistent observations were made for omalizumab 300mg in the second study, with a reduction in weekly itch-severity score of 9.8 +/6.0 compared with 5.1 +/5.6 in the placebo group (p<0.001).2
Results were similar in a third study, which examined the safety of omalizumab in patients with CSU who remained symptomatic despite treatment with H1 antihistamines at up to four times the approved dose plus an H2 antihistamine and/or leukotriene receptor antagonist.3
The most common side-effects were sinusitis, headache, arthralgia and injection site reactions.1
Both presentations of omalizumab are also indicated as add-on therapy in patients with severe persistent allergic IgE-mediated asthma.1
1. Xolair Summary of Product Characteristics, February 2014.
2. Maurer M et al. N Engl J Med 2013; 368: 924-35.
3. Kaplan A et al. J Allergy Clin Immunol 2013; 132: 101-9.