Persistence of exon 2 skipping and dystrophin expression at 18 months after U7snRNA-mediated therapy in the Dup2 mouse model

Liubov V Gushchina; Adrienne J Bradley; Tatyana A Vetter; Jacob W Lay; Natalie L Rohan; Emma C Frair; Nicolas Wein; Kevin M Flanigan

doi:10.1016/j.omtm.2023.101144

Persistence of exon 2 skipping and dystrophin expression at 18 months after U7snRNA-mediated therapy in the Dup2 mouse model

Mol Ther Methods Clin Dev. 2023 Oct 26:31:101144. doi: 10.1016/j.omtm.2023.101144. eCollection 2023 Dec 14.

Authors

Liubov V Gushchina^{1

2}, Adrienne J Bradley¹, Tatyana A Vetter^{1

2}, Jacob W Lay¹, Natalie L Rohan¹, Emma C Frair¹, Nicolas Wein^{1

2}, Kevin M Flanigan^{1

2

3}

Affiliations

¹ The Center for Gene Therapy, Nationwide Children's Hospital and The Ohio State University, Columbus, OH, USA.
² Department of Pediatrics, The Ohio State University, Columbus, OH, USA.
³ Department of Neurology, The Ohio State University, Columbus, OH, USA.

Abstract

Duchenne muscular dystrophy (DMD) is a progressive X-linked disease caused by mutations in the DMD gene that prevent the expression of a functional dystrophin protein. Exon duplications represent 6%-11% of mutations, and duplications of exon 2 (Dup2) are the most common (∼11%) of duplication mutations. An exon-skipping strategy for Dup2 mutations presents a large therapeutic window. Skipping one exon copy results in full-length dystrophin expression, whereas skipping of both copies (Del2) activates an internal ribosomal entry site (IRES) in exon 5, inducing the expression of a highly functional truncated dystrophin isoform. We have previously confirmed the therapeutic efficacy of AAV9.U7snRNA-mediated skipping in the Dup2 mouse model and showed the absence of off-target splicing effects and lack of toxicity in mice and nonhuman primates. Here, we report long-term dystrophin expression data following the treatment of 3-month-old Dup2 mice with the scAAV9.U7.ACCA vector. Significant exon 2 skipping and robust dystrophin expression in the muscles and hearts of treated mice persist at 18 months after treatment, along with the partial rescue of muscle function. These data extend our previous findings and show that scAAV9.U7.ACCA provides long-term protection by restoring the disrupted dystrophin reading frame in the context of exon 2 duplications.

Keywords: Becker muscular dystrophy; Duchenne muscular dystrophy; U7snRNA; dystrophin; exon skipping; gene therapy; scAAV9.U7.ACCA.

Grants and funding

P50 AR070604/AR/NIAMS NIH HHS/United States