Preclinical Obesity Models and Their Translational Limitations

Preclinical models are the foundation of obesity drug development, but the translation from rodent efficacy to human clinical outcomes remains imperfect. Several approved or investigational compounds that showed robust weight loss in mice have failed to replicate those results in human trials, while others have produced human results that diverged from preclinical predictions. Understanding the limitations of current models is essential for interpreting early-stage data.

Diet-Induced Obesity Models

The most common preclinical obesity model is the diet-induced obesity (DIO) mouse, typically maintained on a 45–60% high-fat diet. DIO mice develop hyperphagia, insulin resistance, and hepatic steatosis, broadly recapitulating features of human metabolic syndrome. However, the magnitude of weight loss in DIO mice treated with GLP-1 agonists often exceeds what is achievable in humans by a substantial margin, reflecting differences in energy metabolism, body composition, and regulatory set points.

Genetic Models

Monogenic obesity models such as ob/ob (leptin-deficient) and db/ob (leptin receptor-deficient) mice have been instrumental in identifying appetite-regulatory pathways, but their extreme phenotype does not reflect the polygenic aetiology of common human obesity. These models are most useful for mechanistic studies rather than efficacy prediction.

Emerging Approaches

Efforts to improve translational predictability include the use of aged and metabolically diverse mouse cohorts, non-human primate studies, and organ-on-chip platforms that model human gut-peptide interactions in vitro. The Jackson Laboratory's collaborative cross mouse population offers greater genetic diversity than traditional inbred strains, potentially improving the generalisability of preclinical findings.

For researchers interpreting preclinical obesity data, the key is to understand what each model can and cannot predict. Rodent studies remain indispensable for mechanistic insight and early safety screening, but the quantitative relationship between rodent and human weight loss is not linear, and cross-species extrapolation should be made with caution.

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