DMDG-GMP-SPS Joint Meeting 2026

GalNAc-conjugated siRNAs have emerged as a promising class of therapeutics with potential across various disease areas. Assessing metabolic stability and biotransformation plays a critical role in the development of these therapies, necessitating the selection of suitable in vitro models. However, many existing in vitro systems fail to accurately predict in vivo metabolic behavior.

Our objective was to systematically identify the optimal models and conditions to simulate in vivo metabolism. We selected Inclisiran, a representative GalNAc-conjugated siRNA, as the model compound. We conducted a thorough comparison of in vitro metabolism across various matrices—including serum, plasma, plated hepatocytes, liver homogenate, S9 fractions, tritosomes, lysosomes, and cytosol—to reflect Inclisiran’s trajectory from injection to the RNA-induced silencing complex (RISC) in hepatocytes.

Our findings demonstrate that rat serum and heparinized plasma closely mirror the in vivo metabolism of Inclisiran by blood nucleases. Furthermore, we optimized several effective hepatic systems to accurately simulate intracellular liver metabolism. To ensure translational relevance, ongoing research focuses on validating these models across different species, particularly human systems. Comparative analyses between human and animal models will help refine species-specific metabolic predictions and reduce discrepancies in drug development.

This research offers valuable insights into the metabolic pathways of Inclisiran, establishing a critical foundation for selecting appropriate in vitro systems. Ultimately, these validated models will facilitate the design and screening of future oligonucleotide therapeutics, thereby advancing the field of RNA-based drug development.