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Published on: May 27, 2021
Toxicogenomic module associations with pathogenesis: a network-based approach to understanding drug toxicity
J J Sutherland1, Y W Webster1, J A Willy1
1Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis IN, USA.
Abstract:
Despite investment in toxicogenomics, nonclinical safety studies are still used to predict clinical liabilities for new drug candidates. Network-based approaches for genomic analysis help overcome challenges with whole-genome transcriptional profiling using limited numbers of treatments for phenotypes of interest. Herein, we apply co-expression network analysis to safety assessment using rat liver gene expression data to define 415 modules, exhibiting unique transcriptional control, organized in a visual representation of the transcriptome (the 'TXG-MAP'). Accounting for the overall transcriptional activity resulting from treatment, we explain mechanisms of toxicity and predict distinct toxicity phenotypes using module associations. We demonstrate that early network responses complement traditional histology-based assessment in predicting outcomes for longer studies and identify a novel mechanism of hepatotoxicity involving endoplasmic reticulum stress and Nrf2 activation. Module-based molecular subtypes of cholestatic injury derived using rat translate to human. Moreover, compared to gene-level analysis alone, combining module and gene-level analysis performed in sequence identifies significantly more phenotype-gene associations, including established and novel biomarkers of liver injury.
Insights
Network-based genomic analysis aids drug safety by predicting toxicity. This approach identifies early toxicity signals and novel mechanisms, improving prediction of clinical liabilities.
Area of Science:
- Toxicogenomics
- Systems Biology
- Computational Biology
Background:
- Nonclinical safety studies are crucial for predicting drug clinical liabilities.
- Whole-genome transcriptional profiling faces challenges with limited treatment data.
- Network-based genomic analysis offers a solution for complex safety assessments.
Purpose of the Study:
- To apply co-expression network analysis to rat liver gene expression data for safety assessment.
- To develop a visual representation of the transcriptome (TXG-MAP) organizing gene modules.
- To predict toxicity mechanisms and phenotypes using network analysis.
Main Methods:
- Co-expression network analysis of rat liver gene expression data.
- Definition and organization of 415 gene modules into the TXG-MAP.
- Integration of module associations with transcriptional activity to explain toxicity.
- Comparison of network-based analysis with traditional histology and gene-level analysis.
Main Results:
- Identified 415 gene modules with unique transcriptional control within the TXG-MAP.
- Demonstrated that early network responses predict outcomes in longer studies.
- Discovered a novel hepatotoxicity mechanism involving endoplasmic reticulum stress and Nrf2 activation.
- Showcased translation of rat-derived cholestatic injury subtypes to human data.
- Found that combined module and gene-level analysis significantly enhances phenotype-gene association identification.
Conclusions:
- Network-based genomic analysis, specifically co-expression networks and the TXG-MAP, improves nonclinical safety assessment.
- Early network responses provide valuable predictive information complementing traditional methods.
- The approach identifies novel toxicity mechanisms and biomarkers, with translatable findings between species.
- Combining module and gene-level analysis is superior to gene-level analysis alone for identifying phenotype-gene associations.
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