Multimeric Conjugates Using Engineered Peptide Scaffolds for Efficient siRNA Delivery.

Oligonucleotide therapeutics (ONT) traditionally involve a single targeting moiety per oligonucleotide when conjugated for organ delivery. Multimerization represents a novel approach by connecting multiple ONTs to a single scaffold, thereby influencing the drug's activity and biophysical properties in vivo. Recently, others have demonstrated the efficacy of this strategy, showing enhanced tissue retention and extended silencing with the capability to target multiple genes simultaneously. The investigation of diverse multimeric designs is thus an exciting opportunity to explore the delivery of the ONT. In this study, we engineered a versatile peptide branching unit able to link up to four small interfering RNAs together. We conjugated a GalNAc targeting moiety to these scaffolds for liver hepatocyte delivery and assessed their silencing activity. Our approach was further expanded to explore different peptide architectures (linear versus cyclized) and additional functionalities, including endosomal escape domains and dual target silencing. We then evaluated the constructs via subcutaneous and intravenous (i.v.) administration in mice. Notably, the intravenous administration of multimeric siRNA GalNAc demonstrated potent silencing in the liver and significantly affected liver-to-kidney biodistribution. Our findings suggest that peptides as branching units offer a promising pathway for ONT multimerization, advancing the challenges of drug delivery.