Omalizumab (Xolair) may elicit more of a response in patients with chronic idiopathic urticaria than do H1-antihistamines, study results indicate.
A monoclonal antibody, omalizumab is a treatment for severe asthma. It targets immunoglobulin E and affects mast-cell and basophil function. The agent has shown efficacy in urticaria patients in phase 2 trials.
Recently, a phase 3 randomized, double-blind New England Journal of Medicine study evaluated the efficacy and safety of omalizumab in 323 persons, aged 12 to 75 years, with moderate-to-severe chronic idiopathic urticaria who remained symptomatic despite H1-antihistamine therapy.
The patients received three injections of omalizumab 75 mg, 150 mg, or 300 mg, or placebo. Each injection was spaced four weeks apart, and treatment was followed by 16 weeks of observation. The primary efficacy outcome was the change from baseline in a weekly itch-severity score. The scale ranged 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 changes in the weekly itch-severity score from baseline fell by 9.8 points in the 300-mg group, 8.1 points in the 150 mg group, 5.9 points in the 75-mg group, and 5.1 points in the placebo group. Also at 12 weeks, hives were totally eliminated in 53% of the omalizumab users, and 44% experienced no further hives or itch.
Adverse events occurred with similar frequency in all four groups, and frequency of serious adverse effects was low, but higher in the 300-mg group (6%) than in the placebo (3%), 150-mg (1%), or 75-mg (1%) groups.