Introduction

Biliary strictures are usually caused by malignancies such as Cholangiocarcinoma (CCA) or Pancreatic Ductal Adenocarcinoma (PDAC). 70% of these neoplasms are diagnosed at advanced stages due to late-onset symptoms, lack of biomarkers, and challenges in obtaining histological samples. Curative surgical resection with adjuvant therapy is the first-line treatment, but 20% of cases are resectable at diagnosis and 80% relapse within 3 years^1,2. The impact of systemic therapies on overall survival remains limited, however new targeted therapies have shown remarkable efficacy in patients with actionable mutations based on tumor genetic profiling. Clinical guidelines advocate multigene panel analysis of tumor tissue prior to or during first-line treatment^3,4, considering that 40% of CCA patients and around 25% of PDAC patients harbor actionable genetic mutations^5,6. When tumor tissue is insufficient, liquid biopsies using cfDNA can be considered³. Liquid biopsy of bile, collected during an Endoscopic Retrograde Cholangiopancreatography (ERCP) in malignant biliary stricture cases, could potentially detect therapeutic targets.

Aims & Methods

This prospective proof-of-concept pilot study aims to assess NGS-based cfDNA analysis in bile as a novel liquid biopsy for detecting genetic mutations, and specifically actionable mutations, compared to tissue NGS.
19 CCA and 9 PDAC patients with malignant biliary stenosis undergoing ERCP in a tertiary hospital (2017-2020) were included. Bile samples were collected during the first ERCP and the Pathological Anatomy department selected tissue samples with ≥40% tumor content. Massive sequencing of DNA libraries was performed using the Pan-Cancer Panel^TM (52-genes) for bile samples, and the Oncomine^TM Comprehensive Assay Panel v3 (161 genes) for tissue.

Results

Concerning CCA patients, bile NGS identified all patients with mutations (19/19) opposite to 84.3% (16/19) of patients in tissue. Bile NGS identified 7 patients (37%) with actionable mutations, none was detected in tissue. We detected 47/49 mutations in bile NGS vs. 22/49 in tissue. High concordance was observed: 91% (20/22) of tissue mutations were also in bile. Regarding actionable mutations considered in ESMO guidelines³; 7 were detected in bile NGS, none detected in tissue. The actionable mutations identified were ERBB2 (5), IDH2 (1), and KRAS^G12C(1).
In the PDAC group, bile NGS identified 89% (8/9) of patients with mutations, compared to 66.6% (6/9) of patients in tissue. Bile NGS identified 5 patients (55%) with actionable mutations vs. 4 (44%) in tissue. Bile NGS detected 16/18 mutations in bile in contrast to 12/18 in tissue. High concordance was observed: 83.3% (10/12) of tissue mutations were also in bile. NGS in bile detected 6 actionable mutations considered in ESMO guidelines^4,; KRAS^G12D (5) and ERBB3, compared to 4 in tissue; KRAS^G12D.

Conclusion

These results highlight the potential of bile liquid biopsy in detecting actionable mutations; bile NGS increased the diagnosis sensibility and the number of mutations detected, compared with tissue NGS, which could allow more patients to be considered for targeted therapies. This approach does not require histological material consumption and collecting bile during an ERCP is simple and secure. In addition, NGS technology is available in all molecular laboratories. We consider that the application of liquid biopsy in bile can be accessible and an effective tool, with direct and immediate clinical implementation, improving precision medicine strategies and the therapeutic management of CCA and PDAC patients with biliary stenosis.

References

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2.Park W, Chawla A, O’Reilly EM. Pancreatic Cancer: A Review. JAMA. 2021 Sep 7;326(9):851–62.3.
3.Vogel A, Ducreux M; ESMO Guidelines Committee. ESMO Clinical Practice Guideline interim update on the management of biliary tract cancer. ESMO Open. 2025 Jan;10(1):104003. Epub 2024 Dec 17.
4.Conroy T, Pfeiffer P, Vilgrain V, Lamarca A, Seufferlein T, O’Reilly EM, et al. Pancreatic cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up. Ann Oncol. 2023 Nov;34(11):987–1002.
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