Omalizumab for the Treatment of Chronic Idiopathic or Spontaneous Urticaria

BACKGROUND Many patients with chronic idiopathic urticaria (also called chronic spontaneous urticaria) do not have a response to therapy with H-1-antihistamines, even at high doses. In phase 2 trials, omalizumab, an IgE monoclonal antibody that targets IgE and affects mast-cell and basophil function, has shown efficacy in such patients. METHODS In this phase 3, multicenter, randomized, double-blind study, we evaluated the efficacy and safety of omalizumab in patients with moderate-to-severe chronic idiopathic urticaria who remained symptomatic despite H-1-antihistamine therapy (licensed doses). We randomly assigned 323 patients to receive three subcutaneous injections, spaced 4 weeks apart, of omalizumab at doses of 75 mg, 150 mg, or 300 mg or placebo, followed by a 16-week observation period. The primary efficacy outcome was the change from baseline in a weekly itch-severity score (ranging from 0 to 21, with higher scores indicating more severe itching). RESULTS The baseline weekly itch-severity score was approximately 14 in all four study groups. At week 12, the mean (+/- SD) change from baseline in the weekly itch-severity score was -5.1 +/- 5.6 in the placebo group, -5.9 +/- 6.5 in the 75-mg group (P = 0.46), -8.1 +/- 6.4 in the 150-mg group (P = 0.001), and -9.8 +/- 6.0 in the 300-mg group (P<0.001). Most prespecified secondary outcomes at week 12 showed similar dose-dependent effects. The frequency of adverse events was similar across groups. The frequency of serious adverse events was low, although the rate was higher in the 300-mg group (6%) than in the placebo group (3%) or in either the 75-mg or 150-mg group (1% for each). CONCLUSIONS Omalizumab diminished clinical symptoms and signs of chronic idiopathic urticaria in patients who had remained symptomatic despite the use of approved doses of H-1-antihistamines. (Funded by Genentech and Novartis Pharma; ClinicalTrials.gov number, NCT01292473.)