Characterization of six clinical drugs and dietary intervention in the nonobese CDAA-HFD mouse model of MASH and progressive fibrosis.

The choline-deficient l-amino acid defined-high-fat diet (CDAA-HFD) mouse model is widely used in preclinical metabolic dysfunction-associated steatohepatitis (MASH) research. To validate the CDAA-HFD mouse, we evaluated disease progression and responsiveness to dietary and pharmacological interventions with semaglutide, lanifibranor, elafibranor, obeticholic acid (OCA), firsocostat, and resmetirom. Disease phenotyping was performed in C57BL/6J mice fed CDAA-HFD for 3-20 wk and ranked using the MASLD Human Proximity Score (MHPS). Semaglutide, lanifibranor, elafibranor, OCA, firsocostat, or resmetirom were profiled as treatment intervention for 8 wk, starting after 6 wk of CDAA-HFD feeding. Semaglutide and lanifibranor were further evaluated as early (preventive) therapy for 9 wk, starting 3 wk after CDAA-HFD diet feeding. In addition, benefits of dietary intervention (chow reversal) for 8 wk were characterized following 6 wk of CDAA-HFD feeding. CDAA-HFD mice demonstrated a nonobese phenotype with fast onset and progression of MASH and fibrosis, high similarity to human MASH-fibrosis, and tumor development after 20 wk of diet-induction. Semaglutide and lanifibranor partially reversed fibrosis when administered as prevention but not as treatment intervention. Elafibranor was the only interventional drug therapy to improve fibrosis. In comparison, chow-reversal resulted in complete regression of steatosis with improved liver inflammation and fibrosis in CDAA-HFD mice. CDAA-HFD mice recapitulate histological hallmarks of advanced MASH with progressive severe fibrosis, however, in the absence of a clinical translational obese dysmetabolic phenotype. CDAA-HFD mice are suitable for profiling drug candidates directly targeting hepatic lipid metabolism, inflammation, and fibrosis. The timing of pharmacological intervention is critical for determining antifibrotic drug efficacy in the model. The CDAA-HFD mouse model is widely used in preclinical MASH research, but validation of the model is lacking. This study presents the longitudinal characterization of disease progression. Furthermore, late-stage clinical compounds and dietary intervention (chow reversal) display distinct hepatoprotective effects in the model. Collectively, the study provides critical information guiding the use of the CDAA-HFD mouse model in preclinical drug discovery for MASH and fibrosis.