New approach methodologies (NAMs) for preclinical and translational evaluation of mRNA-lipid nanoparticle (LNP) therapeutics.

Messenger RNA-lipid nanoparticle (mRNA-LNP) therapeutics have emerged as a versatile drug modality, enabling in vivo protein expression for vaccines, cancer immunotherapy, and the treatment of genetic and metabolic diseases. Although mRNA-LNP platforms achieved rapid clinical success during the COVID-19 pandemic, most candidates fail to progress beyond preclinical development, largely due to the limited capacity of conventional animal models to predict human-relevant efficacy, safety, inflammation, biodistribution, and population heterogeneity. New approach methodologies (NAMs), encompassing advanced in vitro and ex vivo human systems and in silico computational models, offer a promising strategy to address these translational gaps while reducing reliance on animal testing. In this review, we evaluate commonly used animal models for mRNA-LNP development and highlight key areas where animal findings have shown poor concordance with human clinical outcomes. We then provide a comprehensive overview of emerging NAM technologies, including in vitro and ex vivo-based platforms such as two-dimensional and three-dimensional cell culture systems and microphysiological platforms; as well as in silico tools, including physiologically based pharmacokinetic (PBPK), quantitative systems pharmacology (QSP), and artificial intelligence (AI) models for formulation design and delivery optimization. Collectively, this review highlights how systematic adoption of NAMs can improve human predictivity, accelerate development timelines, and support more efficient, ethical, and translational robust mRNA-LNP drug development.