Stoke Therapeutics Nominates Next Preclinical Target in Genetic Eye Disease

Stoke Therapeutics announced the nomination of OPA1 as its second preclinical candidate.

“Based on new preclinical data, we are announcing today the expansion of our pipeline with the nomination of OPA1 as our next preclinical target,”  Edward M. Kaye, MD, Chief Executive Officer of Stoke Therapeutics, said in a company news release. “Consistent with our strategy, we believe our approach has the potential to be a first-in-class, disease modifying treatment for autosomal dominant optic atrophy, the most common inherited optic nerve disorder. There are currently no treatments available for this disease, which causes progressive and irreversible vision loss in both eyes starting in the first decade of life.”

The nomination of OPA1 as the company’s next preclinical target is supported by preclinical data that demonstrated in vitro and in vivo target engagement and protein upregulation in OPA1 protein-deficient cells. In these studies, TANGO antisense oligonucleotides (ASOs) demonstrated:

• Dose-dependent decreases in non-productive OPA1 mRNA and increases in OPA1 protein expression in vitro and in vivo.
• An increase in OPA1 protein expression to approximately 75% of wild-type levels in an OPA1 haploinsufficient (OPA1 +/-) cell line.
• In vivo increases in OPA1 protein levels in the retina of wild-type rabbits that correlated with increases in the level of the test ASO.
• The test ASO was well tolerated for up to 29 days (maximum days evaluated) after intravitreal injection.

Recently completed preclinical studies have now demonstrated the ability of TANGO ASOs targeting the OPA1 gene to upregulate adenosine triphosphate production (ATP) levels in the mitochondria. These new data showed that in haploinsufficient cells where half the amount of OPA1 is present and mitochondrial function is impaired, our ASOs demonstrated an ability to increase OPA1 protein levels and also partially restore mitochondrial function as measured by an increase in ATP production. OPA1 expression is essential to retinal ganglion cell survival and visual signal transmission. Retinal ganglion cells have high energy needs making them particularly susceptible to losses in ATP production due to OPA1 haploinsufficiency.

“The ATP finding is significant because in patients with autosomal dominant optic atrophy (ADOA), the retinal ganglion cells are not producing enough ATP and have defective mitochondrial function, which leads to cell death and progressive vision loss. These new data suggest that our ASO approach can restore mitochondrial function to potentially address the underlying cause of autosomal dominant optic atrophy,” said Gene Liau, PhD, Executive Vice President, Head of Research and Preclinical Development of Stoke Therapeutics. “Our goal is to advance an ASO that would delay, or potentially even prevent, vision loss for people living with ADOA. We aim to complete our lead optimization studies by the end of 2021 so that we can advance the most promising potential new medicine into human studies.”

OPA1 protein deficiency is the primary cause of ADOA, the most common inherited optic nerve disorder. ADOA typically presents in the first decade of life and affects approximately one in 30,000 people globally with a higher incidence in Denmark of one in 10,000 due to a founder effect. An estimated 65% to 90% of cases are caused by loss of function mutations in one allele (haploinsufficiency) in the OPA1 gene. There are over 400 different mutations reported to date in ADOA patients. Similar to Stoke’s Dravet syndrome program, Stoke’s approach for ADOA leverages upregulation of the wild-type allele and can potentially be used to treat ADOA due to loss of OPA1 activity in a mutation-independent manner.