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Utility of mismatch repair protein expression screening via an endoscopic ultrasound assessment of treatment-naive pancreas ductal adenocarcinoma
  1. Ana Garcia Garcia de Paredes1,2,
  2. Rondell P Graham3,
  3. Michael J Levy1,
  4. Robert R McWilliams4,
  5. Elizabeth Rajan1,
  6. Lizhi Zhang3,
  7. Ferga C Gleeson1
  1. 1 Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
  2. 2 Gastroenterology and Hepatology Department, Hospital Universitario Ramon y Cajal, Universidad de Alcala. IRYCIS, Madrid, Spain
  3. 3 Division of Anatomic Pathology, Mayo Clinic, Rochester, Minnesota, USA
  4. 4 Division of Medical Oncology, Mayo Clinic, Rochester, Minnesota, USA
  1. Correspondence to Dr Ferga C Gleeson, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55901, USA; gleeson.ferga{at}

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We read with great interest the recent articles by Luchini et al 1 2 and Grant et al 3 highlighting the low prevalence (1%–2%) of mismatch repair deficient pancreatic ductal adenocarcinoma (dMMR PDAC) and offering further knowledge pertaining to the molecular spectrum of this disease subtype. A plea was raised to augment translational and clinical research efforts to improve our understanding of dMMR PDAC.

However, from a practical perspective, only 20% of patients with PDAC reach surgical oncologic resection.4 These resection specimens have served as the source of prior dMMR PDAC analysis. Following the United States Food and Drug Administration approval of pembrolizumab as the first cancer therapy targeting a specific molecular signature, we identified a dMMR prevalence of 3% in a small retrospective cohort of archived pancreas endoscopic ultrasound fine-needle biopsy (EUS FNB) specimens.5 We recently completed an 18-month prospective evaluation of 218 consecutive treatment-naive PDAC patients diagnosed by EUS (fine-needle aspiration: 112 (51.4%), FNB: 91 (41.7%) or both: 15 (6.9%)) for MMR screening as a companion diagnostic test (table 1). A specimen adequate for ancillary studies was acquired in 193 (88.5%) …

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  • Contributors All authors: have made substantial contributions and satisfy the criteria for authorship, conception and design, analysis and interpretation of the data, drafting of the article, critical revision of the article for important intellectual content, final approval of the article, collection of samples and clinical data, generation of experimental data and revision of the manuscript and approval of the final version. FCG and AGGdP: study design, analysis and interpretation of data and drafting of the manuscript. All authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. FCG is the sole contact for the editorial process.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; internally peer reviewed.