Biologic Eases Subset of Severe Asthma

For severe eosinophilic asthma, the novel monoclonal antibody mepolizumab cut exacerbations whether given as an injection or infusion and reduced steroid use in patients dependent on them, two trials showed.

The drug, which targets interleukin-5 (IL-5) to inhibit eosinophilic inflammation,cut exacerbations by 47% with intravenous dosing and by 53% with subcutaneous dosing when compared with placebo (0.93 and 0.81 versus 1.75 per year, both P<0.001), Hector G. Ortega, MD, ScD, of GlaxoSmithKline, found in the MENSA trial.

Mepolizumab injections more than doubled the likelihood of glucocorticoid dose strata reduction compared with placebo, with a median 50% dose reduction from baseline versus none with placebo (P=0.007), Elisabeth H. Bel, MD, PhD, of the University of Amsterdam, and colleagues found in a second study, dubbed SIRIUS. Investigators in both trials said that safety issues with the drug were no different from placebo.

Both trials were reported online in the New England Journal of Medicine in conjunction with presentation at the European Respiratory Society meeting in Munich.

Three prior trials had already shown that anti-IL-5 drugs helped in asthma cases targeted by sputum eosinophil levels, Parameswaran Nair, MD, PhD, of McMaster University in Hamilton, Ontario, noted in an accompanying editorial.

The two new trials provided some clinical observations with "important practical applications," though, he wrote.

"First, the subcutaneous administration of a lower dose of the drug (100 mg) than was previously reported was shown to be efficacious," he noted.

"Second, characterization of the eosinophilic phenotype on the basis of a blood eosinophil count of more than 300 cells per microliter despite concurrent treatment with high doses of glucocorticoids was sufficient to select patients who were likely to have a response to this therapy.

"Both these observations make it potentially simple and easy for practitioners to identify patients who are likely to benefit and administer the drug to them."

Some previous studies that had tried to identify candidates for treatment based on clinical characteristics alone had failed.

Sputum eosinophil counts have been used since, but their greater sensitivity to change than blood eosinophil levels comes at a cost in convenience.

"Although persistent blood eosinophilia may be sufficient to identify patients who are likely to have a response to this treatment, whether this biomarker is sufficient or is as effective as airway eosinophilia in monitoring the response to treatment remains to be seen," Nair pointed out.

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