medwireNews: An electronic nose (eNose) can predict if patients with advanced non-small-cell lung cancer (NSCLC) will respond to immune checkpoint inhibitor therapy by analyzing the composition of volatile organic compounds (VOCs) in patients’ exhaled breath, say researchers.
They explain in the Annals of Oncology that the composition of VOCs is determined by normal physiological processes, and is influenced by metabolites produced by tumor cells, and subsequent host inflammatory responses, with previous research showing high accuracy for the VOC-based detection of lung cancer and the presence of EGFR mutations.
In the current study, a training set of 92 individuals with advanced NSCLC had their exhaled breath profiles collected and analyzed using the eNose (SpiroNose®, Breathomix, Reeuwijk, the Netherlands) within 2 weeks of starting treatment with the PD-1 inhibitors nivolumab or pembrolizumab.
The eNose correctly distinguished between patients who did and did not respond to anti-PD-1 therapy after 3 months on 89% of occasions, whereby patients with a partial response or stable disease were classed as responders, and patients with progressive disease were classed as nonresponders.
The findings were validated in an additional 51 patients, in whom the eNose accurately predicted a patient’s response to PD-1 inhibitor therapy on 85% of occasions.
These results suggest that “susceptibility to anti-PD-1 therapy is reflected by a distinct exhaled molecular fingerprint,” and confirm the efficacy of the eNose “in the noninvasive prediction of individual patient responses to immunotherapy,” say the researchers.
By contrast, immunohistochemistry analysis of PD-L1 expression levels in 40 of these 51 individuals showed that the biomarker correctly distinguished responders from nonresponders with an accuracy of 66%.
Rianne de Vries (University of Amsterdam, the Netherlands) and co-authors say that “[a]n ideal biomarker is minimally invasive, easy to collect, reliable, inexpensive and can be used to accurately identify a treatment response phenotype, to measure changes in disease activity or to confirm a diagnosis,” adding that “[i]n comparison with the currently used biomarker the eNose outperforms PD-L1 [immunohistochemistry] in all areas.”
The team concludes: “These results show that breath analysis by eNose can potentially avoid application of ineffective treatment in identified probable nonresponders. This way individual patients might be saved from unnecessary delays and start treatment with a better alternative.”
By Hannah Kitt
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