Many patients with chronic idiopathic urticaria ( also called chronic spontaneous urticaria ) do not have a response to therapy with H1-antihistamines, even at high doses.
In phase 2 trials, Omalizumab ( Xolair ), an anti-IgE monoclonal antibody that targets IgE and affects mast-cell and basophil function, has shown efficacy in such patients.
In this phase 3, multicenter, randomized, double-blind study, researchers have evaluated the efficacy and safety of Omalizumab in patients with moderate-to-severe chronic idiopathic urticaria who remained symptomatic despite H1-antihistamine therapy.
323 patients were randomly assigned 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 ).
The baseline weekly itch-severity score was approximately 14 in all four study groups.
At week 12, the mean 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 less than 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 ).
In conclusion, Omalizumab diminished clinical symptoms and signs of chronic idiopathic urticaria in patients who had remained symptomatic despite the use of approved doses of H1-antihistamines. ( Xagena )
Maurer M et al, N Engl J Med 2013; 368:924-935