Enhancing the efficacy of siRNA Antibody Oligonucleotide Conjugates (AOCs) through chemical design
- 1Karolinska Institutet
Abstract
Antibody-oligonucleotide conjugates (AOCs) offer a promising solution to delivery challenges of therapeutic oligonucleotides. However, the relationship between their complex chemical architectures and biological activity remains poorly understood, limiting the development of important structure-function relationships. For siRNA-containing AOCs, increasing the siRNA-to-antibody ratio beyond one (drug-to-antibody ratio, DAR>1) reduces potency, attributed to altered pharmacokinetics arising from increased negative charge density. Here, we investigated whether simple chemical modifications could improve AOC efficacy and mitigate limitations associated with higher DAR. Introduction of a single C16 lipid modification to the siRNA significantly enhanced target gene silencing compared to the unmodified AOC. Extending this modification to a DAR2 architecture, in which two siRNAs are conjugated per antibody, restored the loss of activity associated with increasing DAR from 1 to 2. Notably, at an equivalent siRNA dose (1 mg/kg), the DAR2-C16 AOC requires half the amount of antibody while achieving knockdown comparable to the DAR1-C16 AOC. We also developed a charge-balancing ionizable linker (CBIL) designed to partially compensate for the negative charge of siRNA. Incorporation of the CBIL enhanced target gene silencing in heart and skeletal muscle without a corresponding increase in hepatic activity, resulting in a shift toward greater extrahepatic activity relative to liver. Together, these findings demonstrate that chemical modification of both the siRNA payload and antibody-siRNA linker can be used to tune AOC potency and tissue activity, while enabling higher payload loading without compromising efficacy. These results establish chemical design as an important strategy for expanding the architecture and therapeutic potential of AOCs.
Related
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BibTeX
@misc{hayes2026enhancing,
title = {{Enhancing the efficacy of siRNA Antibody Oligonucleotide Conjugates (AOCs) through chemical design}},
author = {O. G. Hayes and J. A. Rädler and E. Filipiak and T. Czapik and S. Roudi and M. Ojansivu and H. Saranya Ilamathi and A. Marquant and Y. Huang and O. P. Wiklander and R. Zain and M. Honcharenko and S. EL Andaloussi},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.23.753708},
url = {https://www.biorxiv.org/content/10.64898/2026.09.23.753708v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Enhancing the efficacy of siRNA Antibody Oligonucleotide Conjugates (AOCs) through chemical design
AU - O. G. Hayes
AU - J. A. Rädler
AU - E. Filipiak
AU - T. Czapik
AU - S. Roudi
AU - M. Ojansivu
AU - H. Saranya Ilamathi
AU - A. Marquant
AU - Y. Huang
AU - O. P. Wiklander
AU - R. Zain
AU - M. Honcharenko
AU - S. EL Andaloussi
PY - 2026
DA - 2026/09/23
PB - bioRxiv
DO - 10.64898/2026.09.23.753708
UR - https://www.biorxiv.org/content/10.64898/2026.09.23.753708v1
AB - Antibody-oligonucleotide conjugates (AOCs) offer a promising solution to delivery challenges of therapeutic oligonucleotides. However, the relationship between their complex chemical architectures and biological activity remains poorly understood, limiting the development of important structure-function relationships. For siRNA-containing AOCs, increasing the siRNA-to-antibody ratio beyond one (drug-to-antibody ratio, DAR>1) reduces potency, attributed to altered pharmacokinetics arising from increased negative charge density. Here, we investigated whether simple chemical modifications could improve AOC efficacy and mitigate limitations associated with higher DAR. Introduction of a single C16 lipid modification to the siRNA significantly enhanced target gene silencing compared to the unmodified AOC. Extending this modification to a DAR2 architecture, in which two siRNAs are conjugated per antibody, restored the loss of activity associated with increasing DAR from 1 to 2. Notably, at an equivalent siRNA dose (1 mg/kg), the DAR2-C16 AOC requires half the amount of antibody while achieving knockdown comparable to the DAR1-C16 AOC. We also developed a charge-balancing ionizable linker (CBIL) designed to partially compensate for the negative charge of siRNA. Incorporation of the CBIL enhanced target gene silencing in heart and skeletal muscle without a corresponding increase in hepatic activity, resulting in a shift toward greater extrahepatic activity relative to liver. Together, these findings demonstrate that chemical modification of both the siRNA payload and antibody-siRNA linker can be used to tune AOC potency and tissue activity, while enabling higher payload loading without compromising efficacy. These results establish chemical design as an important strategy for expanding the architecture and therapeutic potential of AOCs.
ER -