Asthma has multiple phenotypes which stand to benefit from precision medicine
Breath Biopsy has been used to differentiate asthma patients from health controls
Breath Biopsy could be used to identify uncontrolled asthma
Asthma is a chronic inflammatory condition affecting close to 350 million people worldwide1. Although all asthma patients experience a common set of symptoms, the underlying disease mechanisms vary between patients and this impacts treatment. Understanding the phenotypes responsible for asthma in each patient is key to improving treatment.
Currently treatment focuses on symptom management, and finding the right treatment can be a lengthy process of trial and error. A reliable test for different asthma phenotypes could improve the speed and efficiency of diagnosis and enable more widespread use of precision medicine. Research examining VOCs as a tool for precision medicine in adult asthma has been reviewed previously4,5.
Recent years have seen the approval of biological drugs such as XOLAIR®, NUCALA®, CINQAIR®, FASENRA®, and DUPIXENT® targeted at specific pathways relevant to inflammatory subtypes, yet their approval for clinical use has been delayed due to the high cost of the treatment, combined with the difficulty of identifying patients with the correct asthma phenotype who would benefit from the drug.
Studies have demonstrated that volatile organic compounds (VOCs) in exhaled breath can outperform existing measures, such as fractional exhaled nitric oxide (FENO) and lung function tests, as biomarkers when discriminating between asthmatics and healthy controls6. Van der Schee et al. found that VOCs in breath are able to predict responsiveness to steroid treatment in steroid-naïve, mild to moderate asthma patients7. With an area under the curve of 0.88, VOCs outperformed both FENO and measurements of eosinophil cells from sputum samples.
Discrimination of Asthmatic vs. Non-Asthmatic Patients with Breath Biopsy®
We’ve examined the ability of VOCs analyzed using Breath Biopsy to discriminate between asthmatic and non-asthmatic patients (Figure 2). As you can see, even in a heterogeneous clinical trial population, which included individuals with a wide variety of pulmonary conditions, the VOC profile discriminates well between patients with and without an asthma diagnosis.
Figure 2. Breath VOCs analyzed using Breath Biopsy were used to build a classifier which could discriminate between patients with or without a diagnosis of asthma. The Receiver Operator Characteristics (ROC) curve shows an area under the curve of 0.92. The ROC evaluates the ability of a test to discriminate between states with 1.0 indicating a perfect test. The patient population included individuals with a wide variety of pulmonary conditions, participating in a larger clinical trial.
Breath Biopsy for Distinguishing Controlled vs. Uncontrolled Asthma
Reliable biomarkers to identify patients with uncontrolled asthma, or to predict exacerbations, would inform treatment decisions and facilitate disease management. The profile of VOCs in exhaled breath can be used to distinguish between patients with controlled and uncontrolled asthma (Figure 3), which is an important aspect of a patient’s asthma phenotype.
Figure 3. Breath VOCs analyzed using Breath were used to build a classifier which could identify individuals with self-reported uncontrolled asthma with 85% sensitivity and 98% specificity. ROC curve shows an area under the curve of 0.88. A subpopulation of individuals participating in a larger clinical trial were included in this analysis.
It has also been reported that breath VOCs analysed using our FAIMS technology can potentially predict loss of control in asthma8. In this study the Lonestar® VOC Analyzer, was shown to outperform sensor array type eNoses and gas chromatography-mass spectrometry (GC-MS).