Stoke Therapeutics is gearing up to initiate a Phase 3 trial for its investigational drug, zorevunersen, a novel RNA-based therapy targeting Dravet syndrome, a severe form of epilepsy primarily affecting children. This move follows encouraging outcomes from a mid-stage study that demonstrated the drug's potential and helped the company address earlier safety concerns.
RNA-Based Approach to Dravet Syndrome
Zorevunersen works by instructing a patient’s cells to produce more of a specific protein, differing from other RNA therapies that typically focus on gene silencing. This approach is particularly relevant for dominant genetic diseases where there is a deficiency of 50% of the protein. According to Stoke CEO Dr. Ed Kaye, the drug aims to up-regulate RNA splicing within the cells, thereby increasing protein levels back to 100%.
"What we’ve learned is that RNA medicines are very effective in up-regulating splicing, and what we try to do is fine-tune the amount of protein we need in those cells," Kaye said.
One of the significant unmet needs in Dravet syndrome is addressing not only seizures but also improving cognition and behavior. Stoke's approach has shown promise in these areas, even in patients aged 18 and older. This is particularly notable as, historically, such improvements were not anticipated in older patients with developmental abnormalities.
Addressing Safety and Manufacturing Challenges
Earlier in its development, zorevunersen faced safety issues, including temporary paralysis in juvenile monkeys. These challenges led to a partial clinical hold in 2020. However, Stoke has since worked closely with the FDA, implementing a slow dose escalation strategy to mitigate risks. The company reports that 81 patients have now been treated with a favorable safety profile.
Stoke is also proactively addressing manufacturing and patient access challenges. Drawing from past experiences, particularly Kaye's time at Genzyme, the company is focused on establishing a commercial-grade manufacturing process and ensuring adequate drug supply. They have already hired a head of commercial and are engaging with payers to secure reimbursement for the therapy.
Pipeline Expansion and Collaboration
Beyond zorevunersen, Stoke has several earlier-stage candidates in its pipeline, including treatments for rare genetic vision loss diseases and other neurological conditions. In 2022, Stoke partnered with Acadia Pharmaceuticals in a deal potentially worth over $900 million to jointly develop these earlier-stage candidates.
The Future of RNA Therapeutics
Stoke Therapeutics' advancements underscore the growing potential of RNA therapeutics in addressing difficult neurological diseases. By focusing on up-regulating protein production, Stoke is pioneering a unique approach that could offer new hope for patients with Dravet syndrome and other genetic disorders.
