Biologics as Treatment Alternative for Hypereosinophilic Syndrome

Biologics may be safter than immunomodulators for treating hypereosinophilic syndrome (HES), according to the results of a retrospective international data analysis.

To evaluate the safety and results of using biologics to treat HES, researchers retrospectively analyzed data collected from 13 medical centers worldwide.

To have their data included in the analysis, patients needed a peripheral eosinophil count of 1500/mm3, and clinical signs and symptoms of eosinophilia. They also needed to have received treatment with a biologic without being enrolled in a placebo-controlled trial. These biologics included alemtuzumab, benralizumab, dupilumab, mepolizumab, omalizumab, and reslizumab.

After analyzing the data repository, the researchers determined that 151 courses of these agents had been prescribed for 121 patients with HES. Of these courses, 59% produced an improvement in HES symptoms, and 77% allowed other HES medications to be tapered. For instance, in the 105 patients taking systemic glucocorticoids daily when biologic therapy was started, the glucocorticoid dose could be reduced by a mean of 10 mg of daily prednisone equivalents.

Results of the analysis also revealed that biologics were generally safe and well-tolerated, except for infusion reactions to alemtuzumab.

After switching biologics, 13 of 24 patients experienced clinical improvement, and 9 patients who did not respond initially to lower-dose mepolizumab later responded to an increased dose.

“Biologics may offer a safer treatment alternative to existing therapies for HES, although the optimal dosing and choice [of biologic] for each subtype of HES remain to be determined,” the researchers noted.


—Ellen Kurek



Chen MM, Roufosse F, Wang SA, et al. An international, retrospective study of off-label biologic use in the treatment of hypereosinophilic syndromes. J Allergy Clin Immunol Pract. 2022;S2213-2198(22)00132-00135. Published February 15, 2022. doi:10.1016/j.jaip.2022.02.006