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Transcriptomic analysis in liver spheroids identifies a dog-specific mechanism of hepatotoxicity for amcenestrant
Piyush Bajaj1, Richard J Brennan1, Sébastien Laurent2
1Global Investigative Toxicology, Preclinical Safety, Sanofi, Cambridge, MA 02141, United States.
Abstract:
Therapeutic drugs can sometimes cause adverse effects in a nonclinical species that do not translate to other species, including human. Species-specific (rat, dog, and human) in vitro liver spheroids were employed to understand the human relevance of cholestatic liver injury observed with a selective estrogen receptor degrader (amcenestrant) in dog, but not in rat, during preclinical development. Amcenestrant showed comparable cytotoxicity in liver spheroids from all 3 species; however, its M5 metabolite (RA15400562) showed dog preferential cytotoxicity after 7 days of treatment. Whole genome transcript profiles generated from liver spheroids revealed downregulation of genes related to bile acid synthesis and transport indicative of strong farnesoid X receptor (FXR) antagonism following treatment with both amcenestrant and its M5 metabolite in the dog but not in rat or human. In human spheroids, upregulation of genes for detoxification enzymes indicative of pregnane X receptor (PXR) agonism was observed following amcenestrant treatment, whereas in the dog these genes were downregulated. The M5 metabolite showed gene dysregulation indicating PXR agonism in both rat and human, and antagonism in dog. Analysis of liver samples from a 3-mo dog toxicity study conducted with amcenestrant showed downregulation of several genes associated with PXR and FXR, corroborating the in vitro results. These results support the hypothesis that dogs are uniquely susceptible to cholestatic hepatotoxicity following administration of amcenestrant due to species-specific antagonism of FXR and highlight the value of in vitro liver spheroids to investigating mechanisms of toxicity and possible species differences.
Insights
Dogs exhibit unique susceptibility to cholestatic hepatotoxicity from amcenestrant due to species-specific farnesoid X receptor (FXR) antagonism. In vitro liver spheroids revealed key mechanisms driving these adverse drug reactions.
Area of Science:
- Drug metabolism and pharmacokinetics
- Hepatotoxicity mechanisms
- In vitro toxicology models
Background:
- Adverse drug reactions can be species-specific, complicating preclinical safety assessments.
- Cholestatic liver injury was observed in dogs treated with amcenestrant, a selective estrogen receptor degrader, but not in rats or humans.
- Understanding species differences in drug-induced liver injury is crucial for accurate human risk assessment.
Purpose of the Study:
- To investigate the species-specific mechanisms underlying cholestatic liver injury induced by amcenestrant.
- To evaluate the relevance of dog-specific toxicity to human safety using in vitro liver models.
- To explore the role of farnesoid X receptor (FXR) and pregnane X receptor (PXR) in amcenestrant-induced hepatotoxicity.
Main Methods:
- Utilized species-specific (rat, dog, human) in vitro liver spheroids for toxicity and gene expression analysis.
- Assessed cytotoxicity of amcenestrant and its M5 metabolite (RA15400562) in liver spheroids.
- Performed whole genome transcript profiling to analyze gene expression changes related to FXR and PXR signaling pathways.
- Corroborated in vitro findings with gene expression analysis from liver samples of a dog toxicity study.
Main Results:
- Amcenestrant and its M5 metabolite exhibited dog-preferential cytotoxicity in vitro.
- FXR antagonism was observed in dog liver spheroids treated with amcenestrant and its M5 metabolite, but not in rat or human spheroids.
- Species-specific pregnane X receptor (PXR) activity was noted: agonism in human and rat spheroids, antagonism in dog spheroids for the M5 metabolite.
- In vivo dog study data confirmed downregulation of PXR and FXR genes, supporting in vitro findings.
Conclusions:
- Dogs are uniquely susceptible to amcenestrant-induced cholestatic hepatotoxicity due to species-specific FXR antagonism.
- In vitro liver spheroids are valuable tools for elucidating mechanisms of drug-induced toxicity and identifying species-specific differences.
- The study highlights the importance of considering species-specific receptor interactions in drug development and safety evaluation.
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