Soticlestat (TAK-935) is a medication being studied for its potential to help people with certain types of epilepsy, which are conditions that cause frequent seizures. In this trial, soticlestat is used alongside other treatments that patients are already taking for their epilepsy. The goal is to see if soticlestat can be safely used over a long period and if it is well-tolerated by patients. This means researchers want to know if patients can take it without experiencing too many side effects. Soticlestat is being tested in people with specific rare forms of epilepsy, such as Dravet Syndrome and Lennox Gastaut Syndrome, to see if it can help reduce their seizures when used with their current treatments.

Dravet Syndrome – Dravet Syndrome is a severe form of epilepsy that begins in infancy. It is characterized by prolonged seizures that are often triggered by fever or hot temperatures. As the child grows, other types of seizures may develop, including myoclonic and absence seizures. The condition can lead to developmental delays and cognitive impairment. Over time, individuals may experience difficulties with balance and coordination. Behavioral issues and sleep disturbances are also common as the disease progresses.

Lennox-Gastaut Syndrome – Lennox-Gastaut Syndrome is a complex, rare form of epilepsy that typically appears in early childhood. It is marked by multiple types of seizures, including tonic and atonic seizures, which can lead to sudden falls. Cognitive dysfunction and developmental delays are common, often worsening over time. The condition is also associated with behavioral problems and learning difficulties. Seizures in Lennox-Gastaut Syndrome are often resistant to treatment and can be frequent and severe. The syndrome can significantly impact daily life and development.

CDKL5 Deficiency Disorder – CDKL5 Deficiency Disorder is a rare genetic condition that causes severe neurodevelopmental impairment. It is characterized by early-onset seizures, often beginning in infancy. The disorder leads to significant developmental delays, affecting motor skills, communication, and cognitive abilities. Individuals may experience difficulties with feeding and have poor muscle tone. As the disorder progresses, it can result in scoliosis and other orthopedic issues. Behavioral challenges, such as irritability and sleep disturbances, are also common.

Chromosome 15 Duplication Syndrome – Chromosome 15 Duplication Syndrome is a genetic disorder caused by an extra copy of a segment of chromosome 15. It is associated with developmental delays, intellectual disability, and autism spectrum disorder. Seizures are common and can vary in type and severity. The condition often leads to hypotonia, or reduced muscle tone, and may affect motor skills. Individuals may also experience behavioral issues, such as anxiety and hyperactivity. The syndrome can impact communication and social interaction abilities.

Developmental and Epileptic Encephalopathies (DEEs) – Developmental and Epileptic Encephalopathies are a group of severe epilepsy disorders that begin in infancy or early childhood. They are characterized by frequent and severe seizures that can lead to developmental regression or delays. The condition affects cognitive, motor, and behavioral development, often resulting in significant impairment. Seizures in DEEs are typically resistant to treatment and can vary widely in type. Over time, individuals may experience a decline in skills they previously acquired. The condition can also lead to sleep disturbances and other neurological issues.