A bump in blood eosinophils raises concerns and red flags because these changes may signal a loss of asthma control, an increased risk for exacerbations, or an emergence of systemic inflammation such as vasculitis in eosinophilic granulomatosis polyarthritis (EGPA).¹ In contrast, a rise in blood eosinophils may simply reflect inherent variabilities of blood eosinophils and not indicate any impending risk.² In the care of patients with severe asthma, assessments of blood eosinophils are an essential component of patient biomarker evaluations to determine whether type 2 (T2) inflammation exists, select T2 biologics, or if greater than 1,500 eosinophils/μL, indicate underlying EGPA. Blood eosinophils also change with biologic treatment. With anti-interleukin-5 (IL-5)/IL-5R monoclonal treatment, blood eosinophils are dramatically reduced.³ These reductions in blood eosinophils do not, however, reflect or predict clinical efficacy. Dupilumab blocks the IL-4/IL-13 pathway and has been approved for the treatment of severe asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), atopic dermatitis (AD), and most recently, eosinophilic esophagitis (EoE). In asthma and CRSwNP, especially, increases in peripheral blood eosinophils occur with dupilumab. Although limited reports note that increases in blood eosinophils with dupilumab are associated with untoward effects,^4,⁵ the scope of this interaction is not fully defined, leaving clinicians with a lack of evidence-based guidance.

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