Context: Seasonal allergic rhinitis is a common IgE-mediated disorder that produces troublesome symptoms. A recombinant humanized monoclonal anti-IgE antibody (omalizumab) forms complexes with free IgE, blocking its interaction with mast cells and basophils and lowering free IgE levels in the circulation.
Objective: To assess the efficacy and safety of omalizumab for prophylaxis of symptoms in patients with seasonal allergic rhinitis.
Design: Randomized, double-blind, dose-ranging, placebo-controlled trial conducted from July 25 through November 21, 1997.
Setting: Twenty-five outpatient centers throughout the United States.
Patients: Five hundred thirty-six patients aged 12 to 75 years with at least a 2-year history of moderate to severe ragweed-induced seasonal allergic rhinitis and a baseline IgE level between 30 and 700 IU/mL.
Interventions: Patients were randomly assigned to receive omalizumab, 50 mg (n = 137), 150 mg (n = 134), or 300 mg (n = 129), or placebo (n = 136) subcutaneously just prior to ragweed season and repeated during the pollen season every 3 weeks in patients with baseline IgE levels of 151 to 700 IU/mL (4 total treatments) and every 4 weeks in patients with baseline IgE levels of 30 to 150 IU/mL (3 total treatments).
Main outcome measures: Self-assessed daily nasal symptom severity scores (range, 0-3), rescue antihistamine use, and rhinitis-specific quality of life during the 12 weeks from the start of treatment.
Results: Nasal symptom severity scores were significantly lower in patients who received 300 mg of omalizumab than in those who received placebo (least squares means, 0.75 vs 0.98, respectively; P =.002). A significant association was observed between IgE reduction and nasal symptoms and rescue antihistamine use. Rhinitis-specific quality of life scores were consistently better in patients who received 300 mg of omalizumab than in those who received lower dosages or placebo and did not decline during peak season. The frequency of adverse events was not significantly different among the omalizumab and placebo groups.
Conclusion: Omalizumab decreased serum free IgE levels and provided clinical benefit in a dose-dependent fashion in patients with seasonal allergic rhinitis.