Effects of omalizumab on changes in pulmonary function induced by controlled cat room challenge

Background: Environmental exposure to cat allergen is common, and sensitization to cat allergens is strongly associated with asthma. Objective: We sought to examine the efficacy of omalizumab in preventing acute bronchoconstriction induced by environmental exposure to cat allergen. Methods: Patients with a history of cat allergen-induced asthma were randomized to treatment with omalizumab or placebo and exposed to cat allergen in a controlled chamber for up to 1 hour at baseline and after 16 weeks of treatment. The primary efficacy outcome was area under the curve for percentage decrease from prechallenge FEV₁ at week 16 for omalizumab-treated versus placebo-treated patients. FEV₁ was recorded before and every 10 minutes during the 1-hour challenge. Chest, nasal, and ocular symptoms were also monitored during cat chamber exposure as secondary end points. Results: The area under the curve for percentage decrease in FEV₁ was 15.2% per hour for omalizumab-treated patients (n = 32) and 27.3% per hour for placebo-treated patients (n = 33), reflecting 44% less reduction in FEV ₁ and a treatment difference of -12.1% per hour (P = .0009; 95% CI, -19.0 to -5.2). Compared with placebo-treated patients, omalizumab-treated patients were also able to tolerate longer allergen exposure (P = .0006) and demonstrated significant reductions from prechallenge values in their chest symptom score (P < .0001) and nasal-ocular symptom score (P = .0002). Conclusions: The severity of acute airway reactions and symptoms caused by controlled cat room exposure to allergens was significantly reduced by treatment with omalizumab.