# Refined Design and Liquid-Phase Assembly of GalNAc-siRNA Conjugates: Comparative Efficiency Validation in PCSK9 Targeting

## TL;DR

This paper presents a new method for creating GalNAc-siRNA conjugates that efficiently target PCSK9, potentially improving the treatment of cardiovascular diseases.

## Contribution

The study introduces an optimized synthesis method and in silico algorithm for designing effective GalNAc-siRNA conjugates.

## Key findings

- An optimized siRNA sequence significantly enhanced the inhibitory effect of GalNAc-siRNA conjugates.
- The synthesis process was optimized to reduce manufacturing costs and enable scalability.
- The in vitro model confirmed the effectiveness of the conjugates in suppressing PCSK9 gene expression.

## Abstract

The development and application of therapeutic oligonucleotides, such as siRNA, miRNA, ASOs and aptamers, is a rapidly growing field in biomedicine. These molecules are undergoing extensive preclinical and clinical testing, and the market for synthetic RNA drugs is expanding. However, several challenges remain, including targeted delivery and high costs associated with development, screening and production. One significant advance has been the creation of GalNAc-conjugates, which selectively target ASGPR and deliver oligonucleotides to hepatocytes. Although these conjugates have shown promising results, their widespread use is limited by the lack of effective synthesis methods. Thus, the development of new methods for the synthesis of ligand-oligonucleotide conjugates is an important task to which this study is devoted. In this study, we created a library of siRNA conjugates with the GalNAc L-96 ligand to suppress the expression of the PCSK9 gene associated with elevated LDL and an increased risk of developing cardiovascular diseases. The selection of the most effective siRNA molecules was carried out using an algorithm previously developed by our research group, which considers thermodynamic stability, predicted specificity and effectiveness. To experimentally confirm the effectiveness of conjugates, an in vitro model based on the cultivation of hepatocyte cells was developed. Optimization of the conjugate synthesis process has significantly reduced the cost of manufacturing technology, which creates the potential for efficient scaling of synthesis for transfer and application in the pharmaceutical industry. The results of the study showed that the development of the siRNA sequence optimized in silico resulted in a significant increase in the inhibitory effect of the GalNAc-siRNA conjugate compared to a compound similar to a commercial drug.