Treatment with RNA-Targeting Gene Therapy Reverses Molecular and Functional Features of Myotonic Dystrophy Type 1 in Mice

Preclinical data published today in Nature Biomedical Engineering shows reversal of disease phenotypes indicating potential of RNA-targeting systems as treatments for DM1 and other RNA mediated diseases

SAN DIEGO, CA, USA I September 14, 2020 I Locanabio, Inc., a leader in RNA-targeted gene therapy, today announced that results from a preclinical study of the company's therapeutic systems for the potential treatment of myotonic dystrophy type 1 (DM1) were published in Nature Biomedical Engineering. For the full article, titled "The sustained expression of Cas9 targeting toxic RNAs reverses disease phenotypes in mouse models of myotonic dystrophy," please visit: https://www.nature.com/articles/s41551-020-00607-7

Scientists at Locanabio, working with academic collaborators at UC San Diego School of Medicine and the University of Florida, assessed whether an RNA-targeting CRISPR Cas9 system (RCas9) could provide molecular and functional rescue of dysfunctional RNA processing in a DM1 mouse model. The RCas9 system was administered with one dose of an AAV gene therapy vector. Results in both adult and neonatal mice and using both intramuscular and systemic delivery showed prolonged RCas9 expression even at three months post-injection with efficient reversal of molecular (elimination of toxic RNA foci, MBNL1 redistribution, reversal of splicing biomarkers) and physiological (myotonia) features of DM1. Importantly, there were no significant adverse responses to the treatment.

"These results are consistent with earlier findings from several in vitro studies in muscle cells derived from DM1 patients published by Locanabio's scientific co-founder Dr. Gene Yeo of UC San Diego and further indicate the significant potential of our RNA-targeting gene therapy as a DM1 treatment," said Jim Burns, Ph.D., Chief Executive Officer at Locanabio. "Data show that our RNA-targeting system is able to destroy the toxic RNA at the core of this devastating genetic disease and thereby correct the downstream molecular and biochemical changes that result in myotonia, which is a hallmark symptom of DM1. We are pleased that Nature Biomedical Engineering recognizes the value of these preclinical data and we look forward to further advancing this developmental program to the benefit of DM1 patients."

"Currently available treatments for DM1 can improve specific symptoms but do not target the underlying biology and cause of the disease. These data demonstrate that RNA-targeting systems may efficiently and specifically eliminate toxic RNA repeats that cause DM1 and potentially lead to a more effective treatment option for patients," said Dr. Yeo. "The results also indicate that RNA-targeting gene therapy has potential applications in the treatment of other diseases, such as Huntington's disease and certain genetic forms of ALS, which are also caused by a buildup of toxic RNA repeats."

These studies were funded in part by the Muscular Dystrophy Association (MDA). "We are delighted to support Locanabio's recent work in myotonic dystrophy. These preclinical results represent a promising advance and a novel scientific approach for a group of patients who represent a major unmet medical need," said Sharon Hesterlee, Ph.D., Chief Research Officer, MDA.         

About Locanabio, Inc.

Locanabio is the global leader in developing a new class of genetic medicines. Our unique and multi-dimensional approach uses gene therapy to deliver RNA binding protein-based systems to correct the message of disease-causing RNA and thereby change the lives of patients with devastating genetic diseases. These broad capabilities delivered via gene therapy enable Locanabio to potentially address a wide range of severe diseases with a single administration. The company is currently advancing programs in neuromuscular, neurodegenerative and retinal diseases. For more information, visit www.locanabio.com.

About Myotonic Dystrophy

Myotonic dystrophy type 1 (DM1) is an autosomal dominant genetic disorder affecting skeletal muscle, cardiac muscle, the gastrointestinal tract, and the central nervous system. DM1 is caused by a mutation in the myotonic dystrophy protein kinase (DMPK) gene. This mutation leads to a repeat expansion of the CTG (cytosine-thymine-guanine) trinucleotide. The expanded CTG is transcribed into toxic CUG (cytosine-uracil-guanine) repeats in the DMPK messenger RNA (mRNA). These toxic mRNA repeats lead to disease symptoms including progressive muscle wasting, weakness and myotonia (delayed relaxation of skeletal muscle), a hallmark of DM1. The incidence of myotonic dystrophy has historically been estimated at one in 8,000 individuals worldwide or approximately 40,000 people in the United States.

SOURCE: Locanabio

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