CURE Discovery: Using Patient-Specific Cardiac Cells to Predict SUDEP Risk

CURE-funded researchers are using a novel technique to discover ways to predict patients at an increased risk of Sudden Unexpected Death in Epilepsy (SUDEP). Dr. Lori Isom, her team, and co-investigator Dr. Jack Parent at the University of Michigan are transforming skin cells from patients with developmental and epileptic encephalopathy (DEE) syndromes into induced pluripotent stem cells (iPSCs). The team then generates cardiac cells from the iPSCs which retain the patients’ exact genetic information. These unique, patient-specific cardiac cells are used as models to understand if DEE-associated genes play a role in causing heart abnormalities which may lead to SUDEP. The team also hopes to develop measurable indicators, known as biomarkers, of SUDEP risk.

Severe DEE syndromes, such as Dravet syndrome, are associated with a high incidence of SUDEP. It is estimated that up to 20% of patients with Dravet syndrome die from SUDEP.1 There is still much to be understood about the mechanisms of SUDEP and how to predict who is at risk for it.

Dravet syndrome and other DEEs are often associated with variants in genes, such as SCN1A, SCN1B, and SCN8A. These genes provide instructions to make sodium ion channels, which are very important proteins that help brain cells transmit electrical signals. The same genes are also expressed in the heart; thus, the team hypothesizes that any variants in these genes that disrupt electrical signaling in the brain would affect normal electrical function of the heart as well. In support of this hypothesis, the investigators’ previous work in mouse models of Dravet syndrome and DEEs showed that these mice exhibited irregular heartbeat, which in some cases preceded SUDEP-like events.2-4

In this CURE-funded project, the investigators expanded upon their previous work by testing their hypothesis in heart muscle cells called cardiac myocytes, generated in the laboratory from skin cells of patients with Dravet syndrome or other DEEs using iPSC technology. This Nobel Prize-winning technology involves obtaining skin or blood cells from patients and converting them to iPSCs. These are stem cells that can be converted into almost any specialized cell type in the body, such as heart, muscle, pancreatic, or neuronal cells. The cells are patient-specific, meaning they retain the unique genetic make-up of the patient they originated from, allowing investigators to study cell types which would otherwise be very difficult or impossible to obtain from a living patient.

Dr. Isom, Dr. Parent, and their colleagues previously used iPSC technology to generate heart muscle cells from four patients with variants in the SCN1A gene and found increased sodium currents and spontaneous contraction rates in these cells, suggesting cardiac electrical dysfunction.5 Cardiac abnormalities were subsequently found in the patient with the highest increase in sodium current.5 These data suggest that iPSC-cardiac cells may be useful models for identifying and developing biomarkers, such as increased sodium current, as indicators of SUDEP risk.

The investigators used the same technique to study variants in the SCN1B and SCN8A genes. The team observed that iPSC-cardiac myocytes derived from a patient with SCN1B Dravet syndrome had increased sodium currents similar to those seen in iPSC-cardiac myocytes from the patient with SCN1A Dravet syndrome, suggesting that variants in these two different genes could cause heart abnormalities through similar mechanisms. Preliminary data in iPSC-cardiac myocytes from patients with DEE caused by variants in SCN8A, suggest that these cells have altered beating rates but no change in sodium current, which is aligned with their observations in a mouse model with a variant in SCN8A.

Taken together, these results reveal mechanisms by which different epilepsy-related genes can affect heart function and SUDEP. Future research will investigate the impact of variants of a specific non-ion channel gene to see if it causes altered cardiac beating. Patient-specific iPSC cardiac myocytes are a very useful model to study SUDEP mechanisms and could be developed as diagnostic biomarkers to identify SUDEP risk in patients.

1 Cooper MS et al. Mortality in Dravet Syndrome. Epilepsy Res. 2016 Dec; 128:43-47.
2 Auerbach DS et al. Altered Cardiac Electrophysiology and SUDEP in a Model of Dravet Syndrome. PLoS One. 2013;8(10).
3 Lopez-Santiago LF et al. Sodium channel Scn1b null mice exhibit prolonged QT and RR intervals. J Mol Cell Cardiol. 2007;43(5):636-47.
4 Frasier CR et al. Cardiac arrhythmia in a mouse model of SCN8A Epileptic Encephalopathy. Proc Natl Acad Sci U S A. 2016; in press.
5 Frasier CR et al. Channelopathy as a SUDEP Biomarker in Dravet Syndrome Patient Derived Cardiac Myocytes. Stem Cell Reports. 2018 Sep 11;11(3):626-634.

Pregabalin Effective in Reducing Seizure Frequency in Children with Focal Seizures: A Randomized Controlled Trial

In this investigation, researchers tested pregabalin as for safety and effectiveness as adjunctive treatment in children (aged 4-16 years) with partial-onset seizures, now called focal onset seizures. Criteria for inclusion was experiencing focal seizures and having a stable 1 to 3 antiepileptic drug regimen. Pregabalin 2.5 mg/kg/d, 10 mg/kg/d or placebo were used in the study, with doses increased to 3.5 or 14 mg/kg/d for subjects weighing <30 kg. Common adverse events included somnolence, increased weight and increased appetite.

According to this double-blind, randomized, placebo-controlled, international study, pregabalin 10 mg/kg/d showed effectiveness in reducing seizure frequency in children with focal seizures vs placebo; both doses of pregabalin were generally safe and well tolerated.

Levetiracetam Versus Carbamazepine in Treatment of Rolandic Epilepsy

PURPOSE: The aim of the current study was to systematically review the literature to compare the efficacy of levetiracetam (LEV) with that of carbamazepine (CBZ) to control seizures and reduce the burden of interictal epileptiform discharges in children with rolandic epilepsy (RE) and also to compare their tolerability.

METHODS: Researchers searched the electronic database PubMed on January 9, 2019 for original articles that included the following English-language search terms in the title: “Rolandic epilepsy” OR “benign childhood epilepsy with centrotemporal spikes” since 2000. They concentrated the review on three main areas: 1. Neuropsychological impairments in children with RE; 2. Influence of epileptic activity on cognitive performance in RE; 3. Effects of antiepileptic drug (AED) therapies in RE.

RESULTS: The primary search yielded 308 papers. The researchers reviewed the results and removed duplicate articles and all nonoriginal, non-English papers. Finally, after carefully reviewing the full texts, we included 44 original articles to achieve the aims of this review.

CONCLUSION: Physicians taking care of children with rolandic epilepsy (RE) should be aware of the risks for cognitive dysfunctions in these patients and screen their patients for any subtle dysfunction that may affect their academic performance and achievement. If and when the physician decides to prescribe an antiepileptic drug for their patients with RE, levetiracetam is probably a better option compared with carbamazepine to prescribe for these children.

AQB-565 Shows Promise in Preclinical Testing in the Model of Epileptic Spasms During Infancy: Head-to-Head Comparison with ACTH

Epileptic spasms during infancy (infantile spasms) represent a serious treatment and social problem despite their rare occurrence. Current treatments include hormonal therapy (adrenocorticotropin-ACTH or corticosteroids) or vigabatrin (per se or in the combination). These treatments are partially effective and with potentially significant adverse effects. Thus, the search for new effective drugs is warranted.

Researchers tested efficacy of a novel fusion peptide AQB-565 developed by Aequus Biopharma in a model of infantile spasms consisting of prenatal exposure to betamethasone and repeated postnatal trigger of spasms with N-methyl-d-aspartic acid (NMDA). AQB-565 molecule includes the first 24 amino acids of ACTH, a ten amino acid linker and a modified melanocyte-stimulating hormone molecule. In contrast to ACTH with almost uniform activity over all peripheral and central melanocortin receptor isoforms, AQB is preferentially active on central melanocortin receptors MC3 and MC4. Here, we used equivalent doses of rat ACTH (full molecule) and AQB-565 and compared their efficacy in a prospective randomized test against of repeated bouts of spasms on postnatal days (P)12, P13 and P15 in the rat model.

All doses of ACTH (range 0.02-1.0 mg/kg s.c.) and all doses but one of AQB-565 in the same range suppressed spasms in P15 rats (treatment stopped on P14). There was no dose-dependent effect and both compounds had all-or-none effect that is similar to clinical outcome of hormonal treatment of infantile spasms in children. Thus, AQB-565 may represent a novel treatment of infantile spasms similarly effective as ACTH but with potentially limited side effects.

Marinus Pharmaceuticals Initiates Phase 3 Study in Children with PCDH19-Related Epilepsy

Marinus Pharmaceuticals announced it is initiating a single global pivotal Phase 3 clinical study (Violet Study) evaluating oral ganaxolone in children with PCDH19-related epilepsy (PCDH19-RE), a rare genetic epilepsy. If successful, the Violet Study is intended to support the regulatory filings for approval of ganaxolone in this underserved and refractory patient population.

The Violet Study is a global, double-blind, randomized, placebo-controlled pivotal Phase 3 clinical study evaluating ganaxolone in children with PCDH19-RE. The study will enroll up to 70 patients between the age of 1 and 17 with a confirmed PCDH19 mutation. All patients that meet eligibility will be stratified into one of two biomarker groups and randomized (ganaxolone or placebo) within each stratum. The trial will consist of an 8-week prospective baseline period to collect seizure data, followed by a 17-week double-blind treatment phase.

Patients randomized to ganaxolone will titrate over four weeks to a dose of up to 600 mg of ganaxolone oral liquid suspension three times a day and maintain that dose for the following 13-weeks. After the double-blind period, all patients who meet certain eligibility requirements will have the opportunity to receive ganaxolone in an open label phase of the study. The company expects to begin screening patients for enrollment into the study in the second quarter of 2019 and data from the study are estimated to be available in 2021.

How Often is Antiseizure Drug-Free Ketogenic Diet Therapy Achieved?

The ketogenic diet (KD) is often started not only for seizure reduction but also to potentially wean antiseizure drugs (ASDs) in children with epilepsy. Although there have been several publications regarding ASD reduction on the KD, it is unknown how often complete medication withdrawal occurs.

Researchers reviewed the charts of all children started on the KD at Johns Hopkins Hospital and Johns Hopkins All Children’s Hospital from 1/11 to 4/18. Children were defined as achieving drug-free diet (DFD) status if they started the KD on at least 1 ASD and achieved a period of time where they were on the KD alone.

Over the time period, 232 children were evaluated; drug-free diet status occurred in 43 (18.5%), of which 32 (13.8% of the full cohort) remained off antiseizure drugs for the remainder of their ketogenic diet treatment course. Eleven children restarted antiseizure drugs after a mean of 7 months. Children achieving drug-free diet therapy were more likely to be younger, have fewer antiseizure drugs at ketogenic diet onset, have Glut1 deficiency or epilepsy with myoclonic-atonic seizures, but were less likely to have Lennox-Gastaut syndrome or a gastrostomy tube.

NeuroCycle Therapeutics Awarded NIH SBIR Grant to Study Next-Generation Treatment of Dravet Syndrome

NeuroCycle Therapeutics, Inc. announced it had been awarded a $0.5M Small Business Innovation Research grant from the National institute of Neurological Disorders and Stroke (NINDS) to evaluate its advanced subtype-selective GABAA receptor modulators, NCT10004 and NCT10015, in models of Dravet Syndrome (Award Number R43NS107051).

This grant builds upon the company’s strategy to develop a portfolio of small molecule drug candidates that maximize efficacy and minimize side effects through selective targeting of the central nervous system.

Latest Genetic Sequencing Techniques Reveal New Disease Mutations Associated With Epilepsy and Dravet Syndrome

Next-generation sequencing techniques have revealed that genetic mutations in the KCND3 gene may be responsible for more types of epilepsy than previously thought, and new candidate genes associated with Dravet syndrome have been identified, a new study reports.

The study, “Gene mutational analysis in a cohort of Chinese children with unexplained epilepsy: identification of a new KCND3 phenotype and novel genes causing Dravet syndrome,” was published in the journal Seizure.

1 in 5 Pediatric Epilepsy Readmissions Preventable

While 1 in 5 pediatric epilepsy readmissions were scheduled, an additional 20% were judged to be preventable, according to a new report.

An interdisciplinary team from the Cincinnati Children’s Hospital Medical Center was established to review and characterize 30-day readmissions from patients admitted for epilepsy between May 2014 and October 2016. The team was made up of inpatient and outpatient neuroscience nurses, care managers, a quality outcomes manager, and child neurology physicians who individually reviewed the data.

“There was no prior data of this sort, so we were not sure what we were going to find when we started the study,” study author Marissa Vawter-Lee, MD told MD Magazine®. Other studies had found that pediatric epilepsy readmission rates hovered around 6-10% but they did not describe the readmitted patients.

The investigators classified 21.5% of the readmissions as “preventable” and 64.9% as not preventable. The most common preventable causes for readmissions were problems with the discharge care plan or medication management, the study authors said.

A Neuropsychological Model for the Pre-Surgical Evaluation of Children with Focal-Onset Epilepsy: An Integrated Approach

This review explores the complexities of pre-surgical neuropsychological assessment for children with focal-onset epilepsy. A model is proposed outlining a range of factors that potentially influence the neuropsychological formulation. These factors include a developmental, epilepsy, psychological and cognitive dimension, together with family and social context and intrinsic factors. This model is child-centered and recognizes that these factors will be weighted differently for each individual. In some instances the neuropsychological profile might suggest localized and lateralized function, but there are significant limitations to this approach in the context of the contemporary view of epilepsy as a network disorder.

This review recognizes that a range of issues impact on neuropsychological function in children with focal-onset epilepsy, including the connectivity between neural systems and the dynamic nature of development. The aim of this review is to provide a neuropsychological framework to enhance and support clinical decision-making in the pre-surgical evaluation of children with focal-onset epilepsy.