Biologic Agents Are Changing the Landscape of Severe Asthma

While corticosteroids are effective in most patients with severe asthma, 10%-20% of patients with severe or very severe asthma continue to have acute exacerbations despite optimal doses of corticosteroids. Decades ago, it was recognized that some patients with steroid-resistant asthma had elevated blood eosinophil levels. In addition, eosinophilia was associated with elevated cytokines, specifically interleukin (IL)-4 or IL-5. With the advent of biological therapeutics, it has become possible to address eosinophilia in those "steroid-resistant" patients with asthma with the administration of IL-4 or IL-5 antagonists or receptor antagonists. We now have three such agents that are approved for asthma by the US Food and Drug Administration (FDA): mepolizumab, reslizumab, and benralizumab. Dupilumab is currently under review by the FDA. The relative efficacy of these agents will not be known until head-to-head clinical trials are performed, but at present, they are generally considered equally effective.^[1]

In which patients would administration of one of the above agents be appropriate? Authoritative reports suggest that patients with severe or very severe asthma and who have blood eosinophil counts of ≥ 300 cells/μL should be considered.^[2] In general, the higher the eosinophil count, the greater the response to an anti-eosinophil agent. Other markers for appropriate administration of a biologic remain to be discovered and validated.

What effects can be expected when a biologic has been administered? Available data suggest that lung function, typically the FEV₁, should increase by at least 100 mL or more. Symptoms should improve, and acute exacerbations should decrease in frequency and severity. The need for corticosteroids decreased by at least 50%, according to one study of dupilumab.^[3]

It is also appropriate to consider the costs of long-term treatment with a biologic as well as the inconvenience of long-term administration.

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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.

Cite this: Nicholas J. Gross. Biologic Agents Are Changing the Landscape of Severe Asthma - Medscape - Aug 17, 2018.

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