Abstract
It is stated that benefit of omalizumab treatment in severe IgE-dependent asthma requires serum free IgE concentrations below 50 ng/ml. It is unclear if monitoring free serum IgE is clinically meaningful once omalizumab treatment is initiated.
Free IgE and omalizumab serum concentrations were quantified in 22 patients with severe asthma (68% female, 47±11 yrs., mean (±SD) pre-bronchodilator FEV1 62±13%, baseline mean (±SEM) free serum IgE 652±136 ng/ml) treated with omalizumab for 4 months using a Recovery-ELISA.
Omalizumab treatment reduced free serum IgE prior to the second omalizumab injection by 73%, after 16 weeks by 81% to 58±12 ng/ml (p<0.001 vs. baseline). 17 patients responded to anti-IgE therapy as judged by physician-rated global evaluation of treatment effectiveness. There was no relation between free serum IgE concentrations and treatment response. 41% of responders had free IgE levels above 50 ng/ml and 40% of non-responders below 50 ng/ml. There was no significant or clinically relevant difference regarding changes in lung function, exhaled NO, asthma control, and quality of life between patients with free IgE below or above 50 ng/ml.
Monitoring free IgE and omalizumab serum concentrations in patients treated with omalizumab does not predict clinical response or add to the decision to continue or stop treatment. The relevance of free IgE measurements is limited to demonstrating an adequate reduction in non-responders. These results question the free IgE target range postulated to be necessary for a treatment response.
- © 2011 ERS