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

Environmental exposure to cat allergen is common, and sensitization to cat allergens is strongly associated with asthma.

We sought to examine the efficacy of omalizumab in preventing acute bronchoconstriction induced by environmental exposure to cat allergen.

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 FEV(1) at week 16 for omalizumab-treated versus placebo-treated patients. FEV(1) 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.

The area under the curve for percentage decrease in FEV(1) 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).

The severity of acute airway reactions and symptoms caused by controlled cat room exposure to allergens was significantly reduced by treatment with omalizumab.