Efficacy and Safety Profile of Tricyclo-DNA Antisense Oligonucleotides in Duchenne Muscular Dystrophy Mouse Model

Abstract

Antisense oligonucleotides (AONs) hold promise for therapeutic splice-switching correction in many genetic diseases. However, despite advances in AON chemistry and design, systemic use of AONs is limited due to poor tissue uptake and sufficient therapeutic efficacy is still difficult to achieve. A novel class of AONs made of tricyclo-DNA (tcDNA) is considered very promising for the treatment of Duchenne muscular dystrophy (DMD), a neuromuscular disease typically caused by frameshifting deletions or nonsense mutations in the gene-encoding dystrophin and characterized by progressive muscle weakness, cardiomyopathy, and respiratory failure in addition to cognitive impairment. Herein, we report the efficacy and toxicology profile of a 13-mer tcDNA in mdx mice. We show that systemic delivery of 13-mer tcDNA allows restoration of dystrophin in skeletal muscles and to a lower extent in the brain, leading to muscle function improvement and correction of behavioral features linked to the emotional/cognitive deficiency. More importantly, tcDNA treatment was generally limited to minimal glomerular changes and few cell necroses in proximal tubules, with only slight variation in serum and urinary kidney toxicity biomarker levels. These results demonstrate an encouraging safety profile for tcDNA, albeit typical of phosphorothiate AONs, and confirm its therapeutic potential for the systemic treatment of DMD patients.

Employment of Microencapsulated Sertoli Cells as a New Tool to Treat Duchenne Muscular Dystrophy

“…However, the use of AONs have some aspects to be improved, such as the poor tissue uptake and the relative low rescue of dystrophin expression. Recently, tricyclo-DNA (tcDNA) has been tested in two different DMD mouse models inducing the restoration of dystrophin expression in several tissues, and improvement of respiratory and cardiac functions [37,38].…”

Targeting Alternative Splicing as a Potential Therapy for Episodic Ataxia Type 2

“…These are conformationally constrained AONs specially designed to limit torsional flexibility of the sugar backbone in order to stabilize tcDNA/RNA heteroduplexes [115]. Their efficacy has recently been demonstrated in mouse models of DMD, where they induced consistently higher levels of exon skipping and rescue of dystrophin protein levels than 2 OMePSs and PMOs [116,117]. Toxicological and tolerance studies are currently being conducted to evaluate the possibility of clinical applications.…”

The Use of Tricyclo-DNA Oligomers for the Treatment of Genetic Disorders

“…Recently, we demonstrated the therapeutic potential of tcDNA (15-mers or 13-mers) in DMD mouse models following 12 weeks of systemic treatment [ 43 , 44 ]. TcDNA-ASOs were detected in all skeletal tissues as well as in the heart and the brain after intravenous injection and their long-lasting effect was measured as long as 12 weeks after the end of the treatment.…”

“…Evaluation of toxicology is particularly important when developing new generation of ASOs to avoid subsequent failure of a new drug in further toxicological studies. We have recently evaluated the toxicological profile of tcDNA-ASOs in DMD mouse model and shown that high dose tcDNA treatment (200 mg/kg/wk for 12 weeks) was well-tolerated in all mice [ 44 ]. Because of the well-known immunostimulatory effects of PS ASOs [ 92 , 93 ], complement activation and cytokines levels were evaluated.…”