Omalizumab (administered subcutaneously every 2 or 4 weeks per serum IgE levels and body weight) has been assessed in randomized controlled trials in patients with moderate-to-severe asthma who remain symptomatic despite receiving ICS therapy. The ICS dose remained constant during the first 16 weeks and was tapered over the next 8 to 12 weeks. Adding omalizumab to therapy significantly reduced exacerbations vs adding placebo during the steroid-stable and steroid-tapering phases, and allowed greater reductions in ICS dose requirements (all p < 0.01). Symptom management improved after adding omalizumab to therapy and was maintained at the lower ICS doses. 

In pooled analyses of clinical trials, omalizumab significantly reduced asthma exacerbations by 38% (p < 0.0001), emergency department visits by 61% (p = 0.013), hospital admissions by 52% (p = 0.041), and unscheduled doctor visits by 47% (p = 0.0003) vs control subjects, and provided clinically meaningful improvements in asthma-related quality of life. The benefits of adding omalizumab were particularly evident in patients receiving high-dose ICS therapy, those with frequent asthma exacerbations, and those with poor lung function.

Patients treated with high-dose ICSs plus a LABA who had reduced lung function and a recent history of clinically significant exacerbation were evaluated in a separate trial. Adding omalizumab to therapy significantly reduced severe exacerbations by 50% (p = 0.002) and emergency department visits by 44% (p = 0.038) vs placebo, and improved lung function (p < 0.05), asthma symptoms (p < 0.05), and asthma-related quality of life (p < 0.001).

The patients recruited to participate in these clinical trials had a broad range of asthma symptoms and prior therapy, but the spectrum is even broader in actual clinical practice. The cost-effectiveness of the use of omalizumab in the treatment of all patient subpopulations has been questioned and may be greatest in patients whose asthma is poorly controlled despite maximal ICS therapy, providing savings in the cost of hospitalization. Identifying those patients who are most likely to benefit from omalizumab therapy is likely to have a positive impact on the cost-effective use of this drug.