DAXX, ATRX, and MSI in PanNET and Their Metastases: Correlation with Histopathological Data and Prognosis

Area of Science:

• Oncology
• Molecular Pathology
• Cancer Biomarkers

Background:

• Pancreatic neuroendocrine tumors (PanNETs) research on ATRX, DAXX loss, and microsatellite instability (MSI) yields inconclusive results.
• Data on these markers in PanNET metastases remains unpublished.

Purpose of the Study:

• To investigate the role of ATRX and DAXX protein expression and microsatellite instability (MSI) in PanNETs and their metastases.
• To evaluate the prognostic significance of ATRX and DAXX loss in PanNETs.

Main Methods:

• Immunohistochemistry (IHC) for ATRX, DAXX, MSH2, MSH6, MLH1, and PMS2 on 74 PanNETs and 19 metastases.
• Mutation analysis via sequencing for ATRX- and DAXX-negative tumors.
• Polymerase chain reaction (PCR) for MSI in cases with IHC marker loss.

Main Results:

• DAXX loss observed in 11% and ATRX loss in 8% of PanNETs.
• DAXX loss correlated with higher tumor grade and tended toward decreased overall survival.
• MSI identified in 4% of tumors, associated with poor prognosis.
• DAXX and ATRX expression differed in 17% of lymph node metastases compared to primary tumors.

Conclusions:

• Loss of DAXX immunoreactivity reliably identifies a more aggressive PanNET subtype.
• DAXX immunolabeling is a valuable prognostic marker for PanNETs.
• ATRX loss is a weaker indicator and less suitable as a surrogate for genetic sequencing.
• IHC for DAXX and ATRX can identify PanNET subtypes for targeted aggressive therapy.