Development of an Antiseizure Drug Screening Platform for Dravet Syndrome at the NINDS Contract Site for the Epilepsy Therapy Screening Program

Abstract, originally published in Epilepsia

Objective: Dravet syndrome (DS) is a rare but catastrophic genetic epilepsy, with 80% of patients carrying a mutation in the SCN1A gene. Currently, no antiseizure drug (ASD) exists that adequately controls seizures. In the clinic, individuals with DS often present first with a febrile seizure and, subsequently, generalized tonic-clonic seizures that can continue throughout life. To facilitate the development of ASDs for DS, the contract site of the National Institute of Neurological Disorders and Stroke (NINDS) Epilepsy Therapy Screening Program (ETSP) has evaluated a mouse model of DS using the conditional knock-in Scn1aA1783V/WT mouse.

Methods: Survival rates and temperature thresholds for Scn1aA1783V/WT were determined. Prototype ASDs were administered via intraperitoneal injections at the time-to-peak effect, which was previously determined, prior to the induction of hyperthermia-induced seizures. ASDs were considered effective if they significantly increased the temperature at which Scn1aA1783V/WT mice had seizures.

Results: Approximately 50% of Scn1aA1783V/WT survive to adulthood and all have hyperthermia-induced seizures. The results suggest that hyperthermia-induced seizures in this model of DS are highly refractory to a battery of ASDs. Exceptions were clobazam, tiagabine, levetiracetam, and the combination of clobazam and valproic acid with add-on stiripentol, which elevated seizure thresholds.

Significance: Overall, the data demonstrate that the proposed model for Dravet syndrome is suitable for screening novel compounds for the ability to block hyperthermia-induced seizures and that heterozygous mice can be evaluated repeatedly over the course of several weeks, allowing for higher throughput screening.

Researchers Identify Potential Approach to Controlling Epileptic Seizures

Summary, originally published on medicalxpress.com

Researchers from Case Western Reserve University have identified a potential new approach to better controlling epileptic seizures. Lin Mei, professor and chair of the Department of Neurosciences at the Case Western Reserve School of Medicine, who led the new study in mouse models, said the team found a new chemical reaction that could help control epileptic seizures.

Their findings were recently published in The Journal of Clinical Investigation.

In Dravet syndrome, a genetic type of epilepsy that is among the more severe forms of the condition, the sodium channel—a membrane pore critical for inhibiting neuron activation—is mutated and allows excitatory neurons to misfire, causing seizures.

“It would be great if you could find a mechanism to make the sodium channels more stable,” Mei said.

He and his colleagues found that a chemical reaction in the brain, called neddylation, stabilizes the sodium channel in mouse models. When the researchers produced a mouse that lacked the protein required for neddylation in inhibitory neurons, it developed epilepsy. The surprising emergence of the condition inspired the team to explore the neddylation process in more depth; eventually they discovered that neddylation plays a critical role for the sodium channel.

The next step in their research, he said, is to identify drugs or approaches that can manipulate this chemical reaction to stabilize the sodium channel. The researchers are also conducting further experiments to determine whether this applies to patients with other types of epilepsy, not just Dravet patients.

Envision Will Study Dravet Natural History in Children to Learn Impact

Summary, originally published in Dravet Syndrome News

The first participant has been enrolled in Envision, a natural history study that will follow children with Dravet syndrome for more than two years as it seeks to shed light on how this severe type of epilepsy affects motor and neurological development, seizures, and behavior.

Envision also will assess Dravet’s impact on parents and caregivers, in addition to examining health care resource use among patients.

“Natural history studies are incredibly important to understanding and developing treatments for disease,” the Dravet Syndrome Foundation notes on its website in an informational page about Envision.

“The information collected from a natural history study can then be used as a reference to inform health care decisions, including preventative interventions,” the website said.

Envision, conducted by Encoded Therapeutics, is recruiting about 50 children, ages 6 months to 5 years (60 months) for the two-year study. To be eligible, children must have a clinical diagnosis of Dravet and a confirmed mutation in the SCN1A gene — the most common underlying cause of the syndrome, which leads to overactivation of the nervous system and the development of seizures. For more information on locations and contacts, go here.

Foundation Promoting New Dravet ICD-10 Codes

The Dravet Syndrome Foundation (DSF) is promoting awareness of the new global health statistics codes now in effect for Dravet syndrome. Known as “ICD-10” codes, the designations could bring about improved patient outcomes and scientific knowledge of this severe type of epilepsy.

The DSF is encouraging those living with the disorder to help spread word of the designations by informing their providers. In coming weeks, the DSF will be mailing Dravet community members packages that will include business cards with the new codes.

The code designation specifically for Dravet, which was created last fall, was due to efforts by the DSF and its medical advisory board, comprised of Dravet specialists. Before that, the disease was lumped in with a broad group of epileptic conditions with different causes and treatment strategies.

The dedicated codes are expected to make it easier for specialists in the field to conduct research, determine prevalence, morbidity and mortality rates, and recruit patients for clinical trials. They also will help scientists and clinicians track treatment outcomes and establish protocols for standard care.

 

Study Shows Genetic Testing Program Lowered Age of Molecular Diagnosis in Children

Summary, originally published in Dravet Syndrome News

By implementing a free-of-charge epilepsy genetic testing program, it is possible to lower the average age of molecular diagnosis of children with epileptic disorders caused by mutations in the SCN1A gene, such as Dravet syndrome, from more than 6 to less than 2 years of age.

The study with that finding, “Reducing the Time to Diagnosis and Increasing the Detection of Individuals With SCN1A-Related Disease Through a No Cost, Sponsored Epilepsy Genetic Testing Program,” was presented during the American Epilepsy Society (AES) 2020 Virtual Annual Meeting.

Genetic mutations in the SCN1A gene have been associated with a wide spectrum of epileptic disorders, including Dravet syndrome, generalized epilepsy with febrile seizures plus (GEFS+), and early infantile epileptic encephalopathy (EIEE).

According to a previous study, from 2011 to 2015, the average age of molecular diagnosis of patients with forms of epilepsy associated with SCN1A mutations was 6.2 years.

“As precision medicine therapies emerge, it is becoming increasingly important to diagnose SCN1A-related disorders before disease progression,” the researchers wrote.

Inflammation in Genetic Epilepsy

Summary, originally published in Epilepsia

Brain inflammation plays a role in human epilepsy, but most studies have focused on acquired epilepsies, such as those due to head trauma, viral infection or other insults. Neuroinflammation has never been reported in genetic epilepsy associated with ion channel gene mutations.

Jing-Qiong (Katty) Kang, MD, PhD, and colleagues previously characterized how mutations in the gene encoding a GABA-A receptor subunit — part of an ion channel that blunts excitatory signaling — contribute to epileptogenesis in mouse models.

They now report in the journal Epilepsia that mice with a particular GABA-A receptor subunit mutation (a model for the genetic epilepsy Dravet syndrome) have increased levels of proinflammatory factors in the brain, but not in the plasma. They found increased neuroinflammation in multiple brain regions and throughout different developmental stages and showed that it was independent of seizure occurrence.

This research was supported by grants from Citizens United for Research in EpilepsyDravet Syndrome Foundation, Vanderbilt Brain Institute, and National Institutes of Health (NS082635, TR002243). 

Impact of the COVID-19 Lockdown on Patients and Families with Dravet Syndrome

Summary, originally published in Epilepsia Open

We explored the impact of coronavirus virus 2019 (COVID-19) pandemic on patients with Dravet Syndrome (DS) and their family. With European patient advocacy groups (PAGs), we developed an online survey in 10 languages to question health status, behavior, personal protection, and health services before and after lockdown.

Approximately 538 European PAG members received electronic invitations. Survey ran from 14 April to 17 May 2020 with 219 answers; median age 9 y 10 m. Protection against infection were highly used prior to COVID-19, but 88% added facemask-use according to pandemic recommendations. Only one patient was tested positive for COVID?19. Most had stable epilepsy during lockdown and few families (4%) needed emergency care during lockdown. However, behavior disorder worsened in over one-third of patients, regardless of epilepsy changes. Half of appointments scheduled prior to lockdown were postponed; 12 patients (11%) had appointments fulfilled; 39 (36%) had remote consultations. Responders welcomed remote consultations. Half of responders were unsatisfied with psychological remote support as only few (21 families) received this support. None of the five of patient in clinical trials stopped investigational treatment. Prior adoption of protective measures against general infection might have contributed to avoiding COVID-19 infections. Protocols for the favored remote contact ought to now be prepared.

Specific ICD-10 Codes for Dravet Ultimately Could Improve Patient Outcomes

Article, originally published by Dravet Syndrome News

Dravet syndrome now has its own global health statistics codes — known as “ICD-10” codes — that potentially could result in improved patient outcomes and enhanced clinical and scientific knowledge of the genetic disorder.

The National Center for Health Statistics has designated what are known as International Statistical Classification of Diseases and Related Health Problems (ICD) codes specifically for Dravet. Before, the disease was lumped in with a broad group of epileptic conditions with different causes and treatment strategies, under the code G40.8.

The dedicated Dravet syndrome codes, which took effect Oct. 1, are expected to make it easier for those in the field to conduct research, determine prevalence and morbidity and mortality rates, and recruit patients for clinical trials. The codes also will help researchers and clinicians to track treatment outcomes and develop protocols for a standard of care.