Data Show Progress in Developing Breath Biopsy Tests for Liver Cirrhosis, NASH

Owlstone Medical is sharing new data on the development of liver disease detection tests. Results serving as proof of principle towards the deployment of tests for liver cirrhosis and Non-Alcoholic Steatohepatitis (NASH) were presented earlier this summer at EASL Congress 2023, the annual meeting of the European Association for Study of the Liver. 
 
A poster titled, “Dynamic Limonene Breath Testing Maximizes Classification Performance for Subjects with Cirrhosis” described Owlstone’s research efforts to establish limonene as a non-invasive EVOC Probe for liver disease through a cross-sectional study run at the Facultad de Medicina Clínica Alemana Universidad del Desarrollo and Hospital Padre Hurtado, Santiago, Chile. 
 
The study enrolled 29 ultrasound-confirmed cirrhosis cases and 29 healthy controls to assess the performance of Owlstone’s limonene breath test in cirrhosis detection, to determine the optimal time for collection of a breath sample after ingesting the EVOC probe, and to explore the correlation between limonene bioavailability and disease severity. 
 
As previously reported,¹ subjects with cirrhosis show significantly higher levels of limonene when compared with healthy controls, even from dietary sources alone, and this study demonstrated further elevated limonene levels on breath after administering the EVOC probe. Optimal test performance for cirrhosis detection was seen at 60 minutes after EVOC administration (83% sensitivity, 90% specificity, 89% PPV, 84% NPV, 0.91 AUC). Furthermore, the study results correlated closely with disease severity, opening a path for using this approach for early disease detection. 

“These results have further increased confidence that our liver disease tests have the potential to become powerful clinical tools in both primary and secondary care settings. With this stage of our development complete, we plan to evaluate the impact of additional EVOC probes on test performance when administered alongside limonene, in particular to confirm the ability to reliably detect earlier stages of liver disease,” Owlstone Medical Co-Founder/CEO Billy Boyle stated.
 
Owlstone is developing non-invasive, easy-to-use, breath tests that can be taken in primary care settings for detecting liver cirrhosis; and for earlier liver disease detection at NASH, where the potential for liver recovery is much greater, providing clinicians with a way to efficiently screen patients to identify those most likely to benefit from upcoming NASH therapeutics. The tests will be based on using both dietary limonene and a panel of orally administered EVOC probes including limonene. 
 
“Through this study, we have demonstrated that altered levels of limonene in exhaled breath following ingestion of an EVOC probe can effectively identify subjects with cirrhosis compared to controls,” said Dr. Luis Méndez Alcaman, primary investigator, Facultad de Medicina Clínica Alemana Universidad del Desarrollo and Hospital Padre Hurtado. “Notably, most of the patients in the study were early-stage cirrhosis cases and not decompensated, adding validity to our reported conclusions. The potential value of Owlstone’s approach was reinforced during the study through two clinical cases that had been misallocated through initial ultrasound scans but were correctly identified by the breath test, one healthy control that actually had cirrhosis, and one cirrhotic patient whose disease had resolved.”
 
Deaths from liver cirrhosis continue to increase globally, in part due to its late diagnosis in secondary care. Non-alcoholic fatty liver disease (NAFLD) and NASH are leading global causes of chronic liver disease. Approximately 24% of U.S. adults have NAFLD, which has advanced to NASH in between 1.5% to 6.5% of the population.² Liver biopsy has long been the gold standard to stage disease, however it is costly, invasive, and can have serious complications, and so is unsuited for broad use. Liver disease therefore is often diagnosed late, at the stage of cirrhosis with decompensation, when prognosis is poor.³ 

This diagnostic gap is increasingly being recognized in clinical care, by payors, and by governments. At a U.K. parliamentary debate coinciding with International NASH day,⁴ liver disease was declared a silent killer and a public health emergency,⁵ and there was a call for expanding liver testing in at-risk individuals, including a commitment to drive earlier liver disease diagnosis.
 
Breath Biopsy represents a new way to determine the chemical makeup of breath by measuring volatile organic compounds (VOCs), gaseous molecules that can be sampled quickly and non-invasively. VOCs originate from all body parts as the end product of metabolic processes, making Breath Biopsy applicable to numerous diseases including lung cancer, liver disease, and digestive disease. Breath also contains microscopic aerosol particles from the lungs and airways, which can contain a wide range of biomarkers including for infectious disease. The nature of Breath Biopsy therefore makes it suited to addressing two major healthcare challenges: early disease detection and precision medicine.
 
Exogenous VOC (EVOC) Probes are a reliable and highly sensitive alternative to the detection of endogenous biomarkers, as is standard in liquid biopsy, which are often found at very low levels and so are difficult to detect in early disease. EVOC Probes instead are engineered to release a volatile reporter on breath after cleavage by a specific target pathway. This approach offers the advantage that compounds not normally found at significant levels in breath can be introduced into the body (individually or as a cocktail) to explore the ways in which they are absorbed, metabolized or excreted. Further, high levels can be administered, substantially improving signal-to-noise ratios compared to signals from endogenous sources and thus greatly improving reliability of detection.
 
Owlstone Medical is developing breath-based diagnostics through its Breath Biopsy, a platform capable of both biomarker discovery and use in routine clinical testing. The platform includes ReCIVA, a proprietary sample collection device that can take stable breath samples anywhere, the world’s only commercial Breath Biopsy Laboratory located in Cambridge, U.K., and the Breath Biopsy VOC Atlas, the most extensive catalogue of identified volatile organic compounds (VOCs) commonly found on breath.  The company’s technology is protected by more than 120 granted and pending patents and has been used in over 100 research papers. Owlstone Medical has an active portfolio of Breath Biopsy tests in development for early lung cancer and liver disease detection. In digestive health, clinical tests for small intestinal bacterial overgrowth and carbohydrate malabsorption are already on market, and breath testing is emerging as an effective way for patients to monitor and manage symptoms.

References
¹ https://www.owlstonemedical.com/about/news/2020/sep/22/announcing-key-liver-study-results/ 
² https://www.niddk.nih.gov/health-information/liver-disease/nafld-nash/definition-facts   
³ https://pubmed.ncbi.nlm.nih.gov/35472313/  
⁴ https://www.international-nash-day.com/ 
⁵ https://www.medscape.co.uk/viewarticle/liver-disease-public-health-emergency-mps-2023a1000cll