Mutational signature profiling classifies subtypes of clinically different mismatch-repair-deficient tumours with a differential immunogenic response potential.
Br J Cancer 2022;
126:1595-1603. [PMID:
35197584 PMCID:
PMC9130322 DOI:
10.1038/s41416-022-01754-1]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 01/24/2022] [Accepted: 02/10/2022] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND
Mismatch repair (MMR) deficiency is the hallmark of tumours from Lynch syndrome (LS), sporadic MLH1 hypermethylated and Lynch-like syndrome (LLS), but there is a lack of understanding of the variability in their mutational profiles based on clinical phenotypes. The aim of this study was to perform a molecular characterisation to identify novel features that can impact tumour behaviour and clinical management.
METHODS
We tested 105 MMR-deficient colorectal cancer tumours (25 LS, 35 LLS and 45 sporadic) for global exome microsatellite instability, cancer mutational signatures, mutational spectrum and neoepitope load.
RESULTS
Fifty-three percent of tumours showed high contribution of MMR-deficient mutational signatures, high level of global exome microsatellite instability, loss of MLH1/PMS2 protein expression and included sporadic tumours. Thirty-one percent of tumours showed weaker features of MMR deficiency, 62% lost MSH2/MSH6 expression and included 60% of LS and 44% of LLS tumours. Remarkably, 9% of all tumours lacked global exome microsatellite instability. Lastly, HLA-B07:02 could be triggering the neoantigen presentation in tumours that show the strongest contribution of MMR-deficient tumours.
CONCLUSIONS
Next-generation sequencing approaches allow for a granular molecular characterisation of MMR-deficient tumours, which can be essential to properly diagnose and treat patients with these tumours in the setting of personalised medicine.
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