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Updated: Jun 15, 2025

Genetic Encoding of a Non-Canonical Amino Acid for the Generation of Antibody-Drug Conjugates Through a Fast Bioorthogonal Reaction
Published on: September 14, 2018
Structure-Activity Relationship of Antibody-Oligonucleotide Conjugates: Evaluating Bioconjugation Strategies for
Michael Cochran1, Danny Arias1, Rob Burke1
1Avidity Biosciences, Inc., 10578 Science Center Drive Suite 125. San Diego, California 92121, United States.
Abstract:
Antibody-oligonucleotide conjugates are a promising class of therapeutics for extrahepatic delivery of small interfering ribonucleic acids (siRNAs). These conjugates can be optimized for improved delivery and mRNA knockdown (KD) through understanding of structure-activity relationships. In this study, we systematically examined factors including antibody isotype, siRNA chemistry, linkers, conjugation chemistry, PEGylation, and drug-to-antibody ratios (DARs) for their impact on bioconjugation, pharmacokinetics (PK), siRNA delivery, and bioactivity. Conjugation site (cysteine, lysine, and Asn297 glycan) and DAR proved critical for optimal conjugate PK and siRNA delivery. SiRNA chemistry including 2' sugar modifications and positioning of phosphorothioates were found to be critical for delivery and duration of action. By utilizing cleavable and noncleavable linkers, we demonstrated the impact of linkers on PK and mRNA KD. To achieve optimal properties of antibody-siRNA conjugates, a careful selection of siRNA chemistry, DAR, conjugation sites, linkers, and antibody isotype is necessary.
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