Efficacy and safety of a SOD1-targeting artificial miRNA delivered by AAV9 in mice are impacted by miRNA scaffold selection

• Published in: Molecular therapy. Nucleic acids Vol. 34; p. 102057
• Main Authors: Lau, Shukkwan K., Hawley, Zachary C.E., Zavodszky, Maria I., Hana, Sam, Ferretti, Daniel, Grubor, Branka, Hawes, Michael, Xu, Shanqin, Hamann, Stefan, Marsh, Galina, Cullen, Patrick, Challa, Ravi, Carlile, Thomas M., Zhang, Hang, Lee, Wan-Hung, Peralta, Andrea, Clarner, Pete, Wei, Cong, Koszka, Kathryn, Gao, Feng, Lo, Shih-Ching
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 12.12.2023; American Society of Gene & Cell Therapy; Elsevier
• Subjects: adeno-associated virus; ALS; artificial miRNA; gene therapy; MT: oligonucleotides: therapies; Original; preclinical; primary miRNA scaffold; RNAi; SOD1; vector design; artificial miRNA; RNAi; MT: oligonucleotides: therapies; primary miRNA scaffold; preclinical; ALS; gene therapy; adeno-associated virus; vector design; SOD1
• ISSN: 2162-2531; 2162-2531
• DOI: 10.1016/j.omtn.2023.102057

Toxic gain-of-function mutations in superoxide dismutase 1 (SOD1) contribute to approximately 2%–3% of all amyotrophic lateral sclerosis (ALS) cases. Artificial microRNAs (amiRs) delivered by adeno-associated virus (AAV) have been proposed as a potential treatment option to silence SOD1 expression and mitigate disease progression. Primary microRNA (pri-miRNA) scaffolds are used in amiRs to shuttle a hairpin RNA into the endogenous miRNA pathway, but it is unclear whether different primary miRNA (pri-miRNA) scaffolds impact the potency and safety profile of the expressed amiR in vivo. In our process to develop an AAV amiR targeting SOD1, we performed a preclinical characterization of two pri-miRNA scaffolds, miR155 and miR30a, sharing the same guide strand sequence. We report that, while the miR155-based vector, compared with the miR30a-based vector, leads to a higher level of the amiR and more robust suppression of SOD1 in vitro and in vivo, it also presents significantly greater risks for CNS-related toxicities in vivo. Despite miR30a-based vector showing relatively lower potency, it can significantly delay the development of ALS-like phenotypes in SOD1-G93A mice and increase survival in a dose-dependent manner. These data highlight the importance of scaffold selection in the pursuit of highly efficacious and safe amiRs for RNA interference gene therapy. [Display omitted] Lo and colleagues examined AAV-based artificial miRNAs that suppress SOD1 and determined different miRNA scaffolds can impact molecular processing, safety, and efficacy of these drugs in mice. This demonstrates the importance of miRNA scaffolds in artificial miRNA design as one considers developing this class of therapeutics for treatment of SOD1-ALS.