The monoclonal antibody omalizumab seems to be effective at relieving symptoms for patients with chronic idiopathic urticaria who have not responded to H1-antihistamine therapy, report US researchers.
After 12 weeks of treatment, symptoms and signs of chronic idiopathic urticaria were diminished in patients who took the treatment during a phase III, multicenter, randomized study, say Karin Rosén (Genentech, San Francisco, California) and colleagues.
For the trial 323 individuals, who had suffered from chronic idiopathic urticaria for at least 6 months and had not responded to H1-antihistamine, were randomly allocated to receive an injection of omalizumab or placebo once every 4 weeks over a 12-week period and were observed for a further 16 weeks. Three different doses of omalizumab (75 mg, 150 mg, and 300 mg) were tested and the patients were assessed at weeks 4, 12, and 28.
As reported in The New England Journal of Medicine, the mean weekly itch-severity score was about 14 of a possible 21 points across all of the treatment groups at baseline
After 12 weeks, the mean reduction from baseline in this score was significantly greater in patients who received 150 mg and 300 mg omalizumab than in those who received placebo, at 8.1 and 9.8 compared with 5.1 points, respectively. The reduction in score observed with the 75 mg omalizumab group was nonsignificant (5.9).
The reductions from baseline in the mean weekly itch-severity scores, and in most of the prespecified secondary outcomes, were dose dependent and were consistently greater in the omalizumab versus placebo group before week 12. After week 12, the mean scores increased in all omalizumab groups and reached values similar to those in the placebo group by week 28.
"The observation that symptoms gradually recur after discontinuation… suggest that omalizumab administered as three doses at 4-week intervals did not substantially modify the basic underlying disease process in this population during this time period," say Rosen et al.
"Further work is needed before the exact role of omalizumab in the treatment of chronic idiopathic or spontaneous urticaria can be defined," concludes the team.
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