Stoke Therapeutics to Present Encore Data at the 15th European Epilepsy Congress that Demonstrate the Potential for Zorevunersen to be the First Disease-Modifying Medicine for the Treatment of Dravet Syndrome

– First presentation of landmark data from Phase 1/2a and OLE studies of zorevunersen that showed substantial reductions in seizures and continued improvements in multiple measures of cognition and behavior –

BEDFORD, Mass.--(BUSINESS WIRE)-- Stoke Therapeutics, Inc. (Nasdaq: STOK), a biotechnology company dedicated to restoring protein expression by harnessing the body’s potential with RNA medicine, today announced it will present data from its Dravet syndrome clinical program at the 15th European Epilepsy Congress (EEC) taking place September 7 – 11, in Rome, Italy.

The Company is advancing zorevunersen (STK-001), a proprietary antisense oligonucleotide (ASO), as the first potential medicine to address the genetic cause of Dravet syndrome. Presentations include a platform session as well as two poster presentations showcasing a comprehensive dataset from the Company’s Dravet syndrome studies.

“Our natural history study makes a compelling case that current treatments are insufficient to address the needs of patients with Dravet syndrome because patients still have high seizure rates and plateau in their neurodevelopment,” said Barry Ticho, M.D., Ph.D., Chief Medical Officer of Stoke Therapeutics. “In this context, and based on the data we have seen from our clinical studies of zorevunersen, we believe we have the potential to change the way this disease is treated by addressing the root cause of the disease, not just the symptoms. We look forward to continuing to work with Dravet syndrome leaders around the world to prepare for a Phase 3 registrational study of zorevunersen.”

Details for the Company’s presentations at EEC are as follows:

• Title: MONARCH and ADMIRAL: Open-label, Phase 1/2a studies in USA and UK investigating safety, drug exposure, and clinical effect of zorevunersen, an antisense oligonucleotide (ASO), in children and adolescents with Dravet syndrome Session: Platform Session – Paediatric Epileptology Event Type: Platform Session Presentation Date & Time: Tuesday, September 10, 12:22 – 12:30 PM CEST Presenter: Helen Cross, MB ChB, Ph.D., Professor, The Prince of Wales’s Chair of Childhood Epilepsy and Head of the Developmental Neuroscience Programme at University College London Great Ormond Street Institute of Child Health, Honorary Consultant in Paediatric Neurology, President of the International League Against Epilepsy
• Title: 24-month analysis of BUTTERFLY: A prospective, observational study to investigate seizures and comorbidities in children and adolescents with Dravet syndrome (DS) Event Type: In-Person Posters Presentation Date & Time: Sunday, September 8, 2:30 PM - 2:33 PM CEST Presenter: Joseph Sullivan, M.D., FAES, Professor of Neurology and Pediatrics and Director of the Pediatric Epilepsy Center of Excellence at the University of California San Francisco Poster Number: P788
• Title: SWALLOWTAIL and LONGWING: Open-Label Extension (OLE) studies for children and adolescents with Dravet syndrome who previously participated in a study of Antisense Oligonucleotide zorevunersen Event Type: In-Person Posters Presentation Date & Time: Sunday, September 8 - Tuesday, September 10; Q&A from 1:30 - 3:00 PM CEST each day Presenter: Andreas Brunklaus, MD, Consultant Paediatric Neurologist at the Royal Hospital for Children, Glasgow, Honorary Professor at the University of Glasgow, member of Dravet Syndrome UK's Medical Advisory Board Poster Number: P875

About Dravet Syndrome

Dravet syndrome is a severe and progressive genetic epilepsy characterized by frequent, prolonged and refractory seizures, beginning within the first year of life. Dravet syndrome is difficult to treat and has a poor long-term prognosis. Complications of the disease often contribute to a poor quality of life for patients and their caregivers. The effects of the disease go beyond seizures and often include intellectual disability, developmental delays, movement and balance issues, language and speech disturbances, growth defects, sleep abnormalities, disruptions of the autonomic nervous system and mood disorders. The disease is classified as a developmental and epileptic encephalopathy due to the developmental delays and cognitive impairment associated with the disease. Compared with the general epilepsy population, people living with Dravet syndrome have a higher risk of sudden unexpected death in epilepsy, or SUDEP. There are no approved disease-modifying therapies for people living with Dravet syndrome. One out of 16,000 babies are born with Dravet syndrome, which is not concentrated in a particular geographic area or ethnic group.

About Zorevunersen (STK-001)

Zorevunersen is an investigational new medicine for the treatment of Dravet syndrome currently being evaluated in ongoing clinical trials. Stoke believes that zorevunersen, a proprietary antisense oligonucleotide (ASO), has the potential to be the first disease-modifying therapy to address the genetic cause of Dravet syndrome. Zorevunersen is designed to upregulate NaV1.1 protein expression by leveraging the non-mutant (wild-type) copy of the SCN1A gene to restore physiological NaV1.1 levels, thereby reducing both occurrence of seizures and significant non-seizure comorbidities. Zorevunersen has been granted orphan drug designation by the FDA and the EMA, and rare pediatric disease designation by the FDA as a potential new treatment for Dravet syndrome.

About the U.S. Studies: MONARCH (Phase 1/2a) and SWALLOWTAIL (OLE)

The MONARCH study was a Phase 1/2a open-label study of children and adolescents ages 2 to 18 who have an established diagnosis of Dravet syndrome and have evidence of a genetic mutation in the SCN1A gene. The primary objectives for the study were to assess the safety and tolerability of zorevunersen (STK-001), as well as to determine the pharmacokinetics in plasma and exposure in cerebrospinal fluid. A secondary objective was to assess the efficacy as an adjunctive antiepileptic treatment with respect to the percentage change from baseline in convulsive seizure frequency.

Following completion of MONARCH, patients who met study entry criteria were eligible to continue treatment in SWALLOWTAIL, an open-label extension (OLE) study designed to evaluate the long-term safety and tolerability of repeat doses of zorevunersen. The study is also evaluating the long-term effects of zorevunersen on convulsive seizure frequency and on behavior, cognition and overall quality of life. Dosing in SWALLOWTAIL is ongoing.

About the UK Studies: ADMIRAL (Phase 1/2a) and LONGWING (OLE)

The ADMIRAL study was a Phase 1/2a open-label study of children and adolescents ages 2 to