Asthma Biomarkers: Using Eosinophils, FeNO, and IgE to Guide Therapy

In "Asthma Biomarkers: Using Eosinophils, FeNO, and IgE to Guide Therapy," the panel gets specific about the three biomarkers in routine use.

Dr. Chupp asks Dr. Wechsler how he uses biomarkers when a patient shows several at once. Dr. Wechsler names the three currently in use: eosinophils in blood or sputum, exhaled nitric oxide, and IgE. Each can serve as a predictive biomarker, a response biomarker, or both. He draws the distinction concretely. Eosinophils fall when anti-IL-5 therapy is given, while IgE levels may not fall with anti-IgE therapy, making IgE a poor response marker.

His approach is to check all of them and build a full picture, alongside asthma severity judged by exacerbation frequency and decrement in lung function. More than one biomarker is elevated at least two thirds of the time, he says; isolated elevation is rare. So he looks for a dominant marker, one wildly out of proportion to the others, such as an eosinophil count of 1,000 or a nitric oxide level of 200. That happens occasionally and can guide therapy directly.

When no marker dominates, he turns to phenotypic features and comorbidities. Atopic dermatitis might steer him toward anti-IL-4 therapy, chronic sinusitis with nasal polyps toward another agent, and an eosinophilic granulomatosis with polyangiitis phenotype toward a different one again. Beyond that, he integrates patient-centered factors: dosing frequency, where the drug is administered, and what insurance will cover.

Dr. Ross agrees the tools are limited and says she would welcome gene-related options. Her population skews allergic, so an eosinophil count of 1,000 with atopic dermatitis, or an IgE of 3,000, does not necessarily implicate asthma. She asks how many conditions she can treat at once. For the purely asthmatic patient with no comorbidities, biomarkers carry far more weight.

Our next episode, " Navigating Severe Asthma Management Without Direct TSLP Biomarkers," puts the harder question to Dr. Hanania: what do you do when the marker you need does not exist?