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Published on: October 4, 2022
Molecular Characterization and Clinical Relevance of MGMT-Silenced Pancreatic Cancer
Federico Nichetti1,2, Marco Silvestri3, Luca Agnelli3
1Medical Oncology Department, Fondazione IRCCS Istituto Nazionale dei Tumori di Milano, Milan, Italy.
Background:
The identification of actionable molecular targets of pancreatic cancer (PAC) is key to improving patient outcomes. We hypothesized O6-methylguanine-DNA methyltransferase (MGMT) silencing may occur in a subset of PAC tumors, with unexplored clinical and molecular correlates.
Experimental Design:
We leveraged sequencing data from The Cancer Genome Atlas (TCGA), the Clinical Proteomic Tumor Analysis Consortium 3 (CPTAC-3), and the (Australian Pancreatic Cancer Genome Initiative) PACA-AU cohorts to characterize MGMT-silenced PAC. Genomic, transcriptomic, methylation, and clinical data were investigated, and findings were validated in silico using methylation, transcriptomic and drug sensitivity data from Cancer Cell Line Encyclopedia (CCLE) project, and in a real-world cohort of PAC patients profiled for MGMT status at Istituto Nazionale Tumori of Milan (INT).
Results:
On the basis of Human Methylation 450k data, MGMT silencing was identified in ~6% of PAC cases and was enriched in tumors with non-ductal histology, with a trend toward longer overall survival. MGMT-silenced tumors were associated with a lower frequency of KRAS mutations and showed features of immune exclusion. In the INT cohort, MGMT-silencing was confirmed in ~7% of cases and prevalent in KRAS wild type tumors, with a favorable prognostic impact. In silico analysis suggested a higher sensitivity to alkylating and DNA damaging agents in MGMT-silenced PAC cell lines.
Conclusions:
MGMT silencing occurs in a small subgroup of PACs and is enriched in KRAS wild type cases, with a favorable prognostic impact. Our findings provide the rationale to explore combinations of alkylating with DNA damaging agents in MGMT-silenced PAC.
Insights
O6-methylguanine-DNA methyltransferase (MGMT) silencing occurs in a small subset of pancreatic cancer (PAC) patients, particularly those with KRAS wild type tumors. This silencing is linked to improved survival and suggests potential sensitivity to DNA damaging agents.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Identifying actionable molecular targets is crucial for improving pancreatic cancer (PAC) patient outcomes.
- The study investigates O6-methylguanine-DNA methyltransferase (MGMT) silencing in PAC, hypothesizing unexplored clinical and molecular correlations.
Purpose of the Study:
- To characterize MGMT-silenced pancreatic cancer (PAC) by analyzing genomic, transcriptomic, methylation, and clinical data.
- To explore the clinical and molecular correlates of MGMT silencing in PAC.
Main Methods:
- Leveraged The Cancer Genome Atlas (TCGA), CPTAC-3, and PACA-AU cohort data for genomic, transcriptomic, and methylation analysis.
- Validated findings using CCLE and a real-world cohort (INT) with MGMT status profiling.
- Investigated associations between MGMT silencing, histology, KRAS mutation status, and survival.
Main Results:
- MGMT silencing identified in ~6-7% of PAC cases, enriched in non-ductal histology and KRAS wild type tumors.
- MGMT-silenced tumors showed a trend toward longer overall survival and were associated with immune exclusion.
- In silico analysis indicated higher sensitivity to alkylating and DNA damaging agents in MGMT-silenced PAC cell lines.
Conclusions:
- MGMT silencing is a distinct molecular subtype in a small PAC subgroup, associated with KRAS wild type status and a favorable prognosis.
- Findings support exploring combinations of alkylating and DNA damaging agents for MGMT-silenced PAC treatment.
