Electronic Nose Could Track Action of Anti-PD-1 Therapy in Lung Cancer

By David Douglas

August 20, 2021

NEW YORK (Reuters Health) - In patients with non-small-cell lung cancer (NSCLC), exhaled-breath analysis with an "electronic nose" (eNose) may be able to monitor response to immune-checkpoint inhibitors as treatment progresses, according to a proof-of-concept study by Dutch researchers.

Dr. Michel M. van den Heuvel told Reuters Health by email that the outlook for lung cancer "has improved tremendously with the arrival of immunotherapy but still more than 50% of patients do not benefit. Early detection of treatment efficacy will help both the patient and the physician with decision making and might provide time for alternative trajectories."

In a paper in Lung Cancer, Dr. van den Heuvel of the Netherlands Cancer Institute, in Amsterdam, and colleagues treatment continuation is currently based on tumor dynamics evaluated by radiological imaging.

In earlier work it was established that at baseline, "the non-invasive eNose technology can help determine those patients who are likely not to respond," said Dr. van den Heuvel.

To examine whether ongoing monitoring was feasible, the researchers conducted a prospective observational study. Of the 94 patients the researchers followed, 62 were randomly assigned to a training cohort and the remaining 32 to a validation cohort.

They assessed the efficacy of treatment by the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 at three-month follow-up. The hypothesis was that gas-mixture patterns from volatile organic compounds as analyzed by eNose would be informative. It was expected that patients with a partial response (PR) would show greater metabolic/biochemical changes compared to patients with stable disease (SD) or progressive disease (PD).

After six weeks of treatment, the team found that "patients classified as PR showed a distinct clustering of prediction scores towards higher probabilities of an objective response, while patients classified as PD showed a distinct clustering towards lower probabilities of an objective response."

Patients categorized as SD showed an increased spread in prediction scores, with most falling back to low probabilities of an objective response.

In the training cohort, using measurements obtained both at baseline and at six weeks, a specificity of 73% at 100% sensitivity was achieved, The area under the curve (AUC) was 0.95. The results were confirmed in the validation cohort with an AUC of 0.97.

"Exhaled breath analysis by eNose early during treatment allows for a highly accurate, non-invasive and low-cost identification of advanced NSCLC patients who benefit from anti-PD-1 therapy," the researchers conclude.

"We currently are performing a large nationwide study in the Netherlands . . . where we hope to validate these findings," added Dr. van den Heuvel.

The study did not receive specific funding. Three authors report financial ties to a start-up company making eNoses.

SOURCE: https://bit.ly/3spo822 Lung Cancer, online August 2, 2021.