FeNO testing can help with the selection of a personalised, targeted therapy by identifying appropriate patients for biologic treatments.1
Key highlights:
Type 2 asthma, driven by eosinophilic inflammation and often marked by elevated FeNO levels, accounts for up to 70% of all asthma cases.
FeNO can be used as a biomarker to highlight which biologics will be most effective based on patient response and monitoring inflammatory changes.
The addition of monoclonal antibodies has allowed for more effective control of asthma and significant improvements in their quality of life.
Severe asthma
Often associated with persistent type 2 inflammation, severe asthma affects up to 13% of all asthma patients, but contributes towards a disproportionate share of hospitalisations, emergency room visits and morbidity rates.2-4
In many of these patients, asthma can remain uncontrolled despite high doses of inhaled corticosteroids and on-going treatment – highlighting the need for more personalised and targeted approaches.5
In these cases, stepping-up treatment with biologics can offer significant benefits, such as reducing exacerbations, as well as improving lung function, symptoms and overall asthma control.2,4,6
“FeNO is essential and critical in the evaluation of severe asthma and biologic assessment.”
– Leonard B. Bacharier, Professor of Pediatric and Director of the Center for Pediatric Asthma Research.7
What are biologics?
In asthma care, biologics are largely monoclonal antibodies that target key inflammatory cytokines involved in the immune response, offering new treatment options for patients with moderate-to-severe asthma.8
The role of FeNO in selecting candidates for biologics
Studies have shown that biologic initiation can reduce the risk of exacerbations by 72.9%.9 However, biologic treatments are not suitable for everyone.10
Selecting which patients will most likely benefit from biologic treatment, and the most appropriate biologic for these patients depend on multiple factors, including exacerbation history, medication adherence and levels of biomarkers like FeNO and blood eosinophils.2,11
“Focus on giving precision-based medicine to give the right drugs to the right patient based on their biomarkers.”
– Dr Michael Wechsler, Professor of Medicine and critical care specialist.12
The use of biomarkers in predicting response to biologic treatment is crucial for effective management. Type 2 asthma, driven by eosinophilic inflammation and often marked by elevated FeNO levels, accounts for up to 70% of all asthma cases.13
However, in patients with severe asthma, Type 2 inflammation is present in as many as 93% of cases.14 This is significant as FeNO testing allows clinicians to identify and monitor this inflammation, offering a more individualised approach to treatment strategies and in guiding biologics.15
This also aligns with recommendations in the updated 2025 GINA Guidelines, which support the use of biomarkers like FeNO to guide clinical decisions around biologic add-on therapies.16 The guidelines recommend confirming that a patient has severe disease before progressing to biologic treatment, with FeNO included as one of the key biomarkers in this assessment.16
The role of FeNO in selecting the right biologic
FeNO plays an important role in guiding biologic selection and should be used alongside blood eosinophils and IgE when assessing a patient’s inflammatory pathway, or phenotype.17 When considering whether to start or switch a biologic, FeNO can highlight a patient’s phenotype, and therefore guide which biologics will likely be most effective based on patient response and inflammatory pathway.1,18 This approach supports a more tailored choice of therapy to suit individual patient profiles.
In cases where higher baseline FeNO levels were noted prior to biologic treatment, this was generally associated with reduced exacerbation rates and improved asthma control – particularly in patients treated with omalizumab, dupilumab or Tezepelumab.1 FeNO is particularly valuable in identifying patients who are likely to respond to IL-4/IL-13 targeted therapies.
For many patients with asthma, the addition of monoclonal antibodies has allowed for more effective control of their disease and significant improvements in their quality of life. 8
Ready for FeNO by NIOX®?
NIOX® is the gold standard for FeNO testing, widely trusted by clinicians and used in thousands of clinical trials worldwide – including pivotal studies for asthma biologics. Its accuracy and reliability make it the preferred choice for both everyday practice and cutting-edge research.19
Unlock accurate and repeatable FeNO measurements with NIOX® and transform your asthma care.20 Get started today by requesting a quote for a quote to see how fast and reliable FeNO testing is with NIOX®.21
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References:
1. Pianigiani T et al. Exploring the interaction between fractional exhaled nitric oxide and biologic treatment in severe asthma: A systematic review. Antioxidants. 2023;12(2):400. 2.Chandrasekara, S., Wark P. Biologic therapies for severe asthma with persistent type 2 inflammation. Aust Prescr 2024;47:36-42. Available at; https://doi.org/10.18773/austprescr.2024.015. 3.Jin, H.J., Biological treatments for severe asthma. Yeungnam University journal of medicine, 2020:37(4), 262–268. Available at; https://doi.org/10.12701/yujm.2020.00647. 4.McGregor, M. C., Krings, J. G., Nair, P., & Castro, M. Role of Biologics in Asthma. American journal of respiratory and critical care medicine, 2019:199(4), 433–445. Available at; https://doi.org/10.1164/rccm.201810-1944CI. 5.Dreher, M. and Müller, T. Add-on Therapy for Symptomatic Asthma despite Long-Acting Beta-Agonists/Inhaled Corticosteroid. Tuberculosis and respiratory diseases, 2018:81(1), 1–5. Available at; https://doi.org/10.4046/trd.2017.0102. 6.Gyawali, B., Georas, S. N., and Khurana, S. Biologics in severe asthma: a state-of-the-art review. European respiratory review: an official journal of the European Respiratory Society, 2025:34(175), 240088. Available at; https://doi.org/10.1183/16000617.0088-2024. 7.Davis, M.D., The role of fractional exhaled nitric oxide and oscillometry in pediatric asthma. Respir Care. 2025;70(6):632–639. Available at; https://doi.org/10.1089/respcare.12674. 8.Kardas, G., et al. Monoclonal antibodies in the management of asthma: Dead ends, current status and future perspectives. Frontiers in immunology, 2022:13, 983852. Available at; https://doi.org/10.3389/fimmu.2022.983852. 9.Chen, W., et al. Impact of initiating biologics in patients with severe asthma on long‑term oral corticosteroids or frequent rescue steroids (GLITTER): data from the International Severe Asthma Registry. J Allergy Clin Immunol Pract. 2023;11(9):2732–7. Available at; https://doi.org/10.1016/j.jaip.2023.05.044. 10.Barry LE et al. Cost-Effectiveness of Fractional Exhaled Nitric Oxide Suppression Testing as an Adherence Screening Tool Among Patients With Difficult-to-Control Asthma. The Journal of Allergy and Clinical Immunology: In Practice. 2023. 11.Couillard, S., Jackson, D. J., Pavord, I. D., and Wechsler, M. E. Choosing the right biologic for the right patient with severe asthma. Chest, 2025:167(2), 330–342. 12.NIOX®. Digital Webinar; MKT-PRM-US-0160. 13.Kaya T et al. The Fractional exhaled Nitric Oxide (FeNO)-test as add-on test in the diagnostic work-up of asthma: a study protocol. BMC Pulmonary Medicine. 2024;24(1):178. 14.Heaney LG et al. Eosinophilic and noneosinophilic asthma: an expert consensus framework to characterize phenotypes in a global real-life severe asthma cohort. Chest. 2021;160(3):814-830. 15.Loewenthal L et al. FeNO in asthma. Semin Respir Crit Care Med. 2022;43:635-645. 16.Global Initiative for Asthma (GINA). 2025 GINA Strategy Report; Global strategy for asthma management and prevention. Available at; https://ginasthma.org/2025-gina-strategy-report/. 17.Menzies-Gow A et al. Clinical utility of fractional exhaled nitric oxide in severe asthma management. Eur Respir J. 2020;55(3):1901633. 18.Dragonieri, S., Portacci, A., Quaranta, V. N., and Carpagnano, G. E. Advancing Care in Severe Asthma: The Art of Switching Biologics. Advances in respiratory medicine, 2024:92(2), 110–122. Available at; https://doi.org/10.3390/arm92020014. 19.NIOX®. Data on File; MKT-DOF-014. 20.Gao J et al. Association between fractional exhaled nitric oxide, sputum induction and peripheral blood eosinophil in uncontrolled asthma. Allergy, Asthma & Clinical Immunology. 2018;1. 21.Alving K et al. Validation of a new portable exhaled nitric oxide analyzer, NIOX VERO®: randomized studies in asthma. Pulm Ther. 2017;3:207-18.