Avidity Biosciences LLC has developed a strategy for delivering siRNA and antisense therapies to tissues outside the liver and has preclinical proof-of-concept for two molecules that target muscle. The company has set its next sights on lymphocyte delivery.
Avidity is creating a new class of antibody-drug conjugate (ADC) it calls antibody-siRNA conjugates (ASCs), using the highly specific targeting of antibodies to deliver the nucleic acids to tissue-specific cell markers, and relying on endocytosis to internalize the active agent (see “Muscling Up”).
According to EVP of R&D Arthur Levin, who was previously SVP at Ionis Pharmaceuticals Inc., Avidity is the first company to extend the ADC modality from small molecules to biopolymers like siRNA.
The idea is that the conjugates will avoid the lipid-based toxicities of nanoparticles, the most common delivery vehicle for nucleic acids, and the need for highly cytotoxic payloads that can compromise standard ADCs that carry small molecules.
Levin believes the approach will