PREVAIL: investigating ctDNA for the diagnosis of pancreatic and biliary duct cancer

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07/01/23

Justin Mencel, MBBS, The Royal Marsden NHS Foundation Trust, London, UK, provides an overview of the PREVAIL ctDNA pilot study (NCT04566614), which evaluated the use of ctDNA to support the diagnostic pathway for patients with suspected pancreatic and biliary tract cancers (BTC). Dr. Mencel explains how BTCs and pancreatic tumors are fairly difficult to diagnose due to their deep location within the tumor, often requiring invasive diagnostic techniques to diagnose such as endoscopies. This became more of an issue during the COVID-19 pandemic when there was a global reduction in invasive diagnostic procedures. Circulating tumor DNA (ctDNA) is DNA that has been released from the tumor into the bloodstream of patients and can be analyzed through a liquid biopsy, thereby offering a non-invasive method of diagnoses. 16 patients with suspected BTC and 16 patients with suspected pancreatic cancer were recruited onto the PREVAIL pilot study, from which ctDNA was collected and analyzed via a custom 59 gene panel at the Institute of Cancer Research. The detection rate of ctDNA was 69% and 56% for patients with suspected pancreatic cancer and BTC, respectively. A sensitivity and specificity analysis was carried out in 23 patients across the two cohorts. The sensitivity and specificity of ctDNA to detect pancreatic cancer were 80% and 100%, respectively for pancreatic cancer and for BTC 100% and 75%, respectively. A false-positive was detected in the BTC cohort, however, the patient was subsequently diagnosed with esophageal cancer, explaining the detection of ctDNA. It was therefore concluded that ctDNA may be used reliably for diagnosis in patients who are unable to undergo biopsies or for difficult to access tumors, as well as to accelerate diagnosis in those requiring repeated biopsies, which can ultimately improve diagnostic efficiencies. This interview took place at the American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium.