Histo-molecular characterization of pancreatic cancer with microsatellite instability: intra-tumor heterogeneity, B2M inactivation, and the importance of metastatic sites

Claudio Luchini, Andrea Mafficini, Deyali Chatterjee, Maria L Piredda, Concetta Sciammarella, Pooja Navale, Giuseppe Malleo, Paola Mattiolo, Giovanni Marchegiani, Antonio Pea, Roberto Salvia, Lodewijk A Brosens, Gaetano Paolino, Maria G Mastrosimini, Nicola Silvestris, Michele Milella, Liang Cheng, Volkan N Adsay, Rita T Lawlor, Aldo Scarpa

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Pancreatic ductal adenocarcinoma (PDAC) with microsatellite instability (MSI)/defective mismatch repair (dMMR) is the only subtype of pancreatic cancer with potential response to immunotherapy. Here, we report the histo-molecular characterization of MSI/dMMR PDAC with immunohistochemistry, MSI-based PCR, and next-generation sequencing. Five paradigmatic cases have been identified. The main results include the first report in pancreatic cancer of MSI/dMMR intra-tumor heterogeneity, the presence of microsatellite-stable metastases from MSI/dMMR primary and recurrent B2M gene inactivation, which may confer resistance to immunotherapy. In addition to the classic PDAC drivers, ARID1A was the most common mutated gene in the cohort. Intra-tumor heterogeneity, B2M inactivation, and metastatic sites should be carefully considered in MSI/dMMR PDAC, which should also be investigated in routine diagnostic practice with specific molecular analysis. The chromatin remodeler ARID1A represents another potential driver gene in this context.

Original languageEnglish
Pages (from-to)1261-1268
Number of pages8
JournalVirchows Archives
Volume480
Issue number6
Early online date6 Oct 2021
DOIs
Publication statusPublished - Jun 2022

Keywords

  • Pancreatic cancer
  • Pancreatic ductal adenocarcinoma
  • Immunotherapy
  • Microsatellite
  • B2M

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