ATRX/DAXX in EUS-FNB Specimens of Pan-NETs

Condition(s) studied

Investigational drug(s) / intervention(s)

ATRX/DAXX immunohistochemistry: Immunohistochemistry will be performed using an Autostainer Leica (Leica Biosystems) according to the manufacturer's instructions. Four μm formalin-fixed paraffin-embedded sections will be immunostained with antibodies for Cytokeratin AE1/AE3 (AE1-AE3, 1:100 dilution, Novocastra/United Kingdom) Chromogranin A (DAK-A3, 1:2500, Dako/Denmark), and Synaptophysin (27G12, 1:100, Novocastra), Ki67 (MIB1, 1:100, Dako/Denmark), ATRX (1:400, Sigma-Aldrich), DAXX (1:200, Sigma-Aldrich). After antigen retrieval, immunostaining will be performed in an automated Bond instrument (Vision-Biosystem, Leica, Milan, Italy) using a sensitive peroxidase-based 'Bond polymer Refine' detection system.

Study summary

P-NENs are classified as functional (F-) or non-functional (NF-) depending on the presence or absence of a clinical hormonal hypersecretion syndrome. Moreover, the WHO 2017 classification of pNENs distinguishes between well-differentiated pancreatic neuroendocrine tumors (pNETs) and poorly differentiated pancreatic neuroendocrine carcinomas (pNECs). pNETs are then divided according to a grading scheme based on Ki67 index in pNETs-G1 (Ki67 index ≤3%) and pNETs-G2 (Ki67 index between 4% and 20%). pNECs are all G3, with a Ki67 index \>20%. Endoscopic ultrasound with fine-needle biopsy (EUS-FNB) demonstrated safe and effective preoperative grading based on the Ki-67 proliferative index. However, downstaging rate is not neglectable, reaching 15% in a recent metanalysis. Moreover, recent whole-exome and whole genome sequencing studies revealed that the mutually exclusive inactivating mutations in death domain-associated protein (DAXX) and/or in α-thalassemia/mental retardation X-linked (ATRX) chromatin remodeling genes are associated with more aggressive disease. In a retrospective study, the investigators recently evaluated the correspondence of DAXX/ATRX expression on 41 EUS-FNB samples with corresponding surgical specimens demonstrating a 95.1% (almost perfect agreement, κ = 0.828; p \< 0.001) and 92.7% (substantial agreement, κ = 0.626; p \< 0.001) concordance for DAXX and ATRX expression, respectively. This study aims to evaluate the potential clinical/prognostic role of DAXX/ATRX expression as implementation of the currently used Ki67-based grading, evaluated on EUS-FNB samples in a prospective cohort of patients with NF-pNETs

Eligibility

Primary outcome measure(s)

• ATRX/DAXX loss-tumor aggressiveness association — 18 months
  To assess the association between ATRX/DAXX loss of expression assessed on endoscopic ultrasound biopsy specimens and pathological features indicative of tumor aggressiveness evaluated on surgical pathology

Trial sites (1)

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