BALTIMORE – according to data presented at the annual meeting of the American Epilepsy Society. Large reductions in convulsive seizure frequency for prolonged periods may improve everyday deficits in executive function in these patients, according to the investigators.
Dravet syndrome often entails cognitive impairment, including deficits in executive function. The frequency and severity of convulsive seizures are believed to worsen cognitive impairment over time, but few researchers have conducted long-term studies to test this hypothesis. Adjunctive fenfluramine significantly reduced the frequency of convulsive seizures and improved executive function after 14 weeks in a phase 3 study of patients with Dravet syndrome.
An open-label extension of a phase 3 study
In an open-label extension of this study, Joseph Sullivan, MD, director of the pediatric epilepsy center at the University of California, San Francisco, Benioff Children’s Hospital, and colleagues analyzed the relationship between changes in convulsive seizure frequency and executive function. The investigators also examined the effect of reducing convulsive seizure frequency by comparing patients with profound reductions (greater than 75%) versus patients with minimal reductions (less than 25%).
Patients aged 2-18 years entered the open-label study and received adjunctive fenfluramine for 1 year. At the beginning of the open-label phase, the dose was titrated to effect. The dose ranged from 0.2 mg/kg per day to 0.7 mg/kg per day and was administered as 2.5 mg/mL of fenfluramine. The maximum dose was 17 mg with stiripentol or 26 mg without.
The investigators calculated the percent difference in convulsive seizure frequency per 28 days from baseline to the end of the open-label study. They evaluated executive function using the Behavior Rating Inventory of Executive Function (BRIEF), which caregivers completed at baseline and year 1 for patients aged 5-18 years. Scores on the BRIEF were updated to the newer version: BRIEF2. Dr. Sullivan and colleagues calculated Spearman’s rho correlation coefficients to evaluate the association between BRIEF2 Behavior Regulation Index, Emotion Regulation Index, Cognitive Regulation Index, and Global Executive Composite scores. Lower scores on the BRIEF2 indexes and composite indicate better executive functioning. In addition, the researchers compared clinically meaningful change in BRIEF2 indexes and composite scores from baseline to year 1 between patients with minimal and profound reductions in convulsive seizure frequency using Fisher’s exact test. They defined a clinically meaningful change as an improvement in the Reliable Change Index of greater than 95%.
Profound reduction in seizure frequency was common
At the time of analysis, 53 patients had completed at least 1 year of open-label fenfluramine and had baseline and year 1 BRIEF2 data. Patients’ median age was 10 years, and 57% of patients were male. The median reduction from prerandomization baseline in convulsive seizure frequency was 71%. The reduction ranged from 99.7% to 55.0%.
Twenty-four (45%) patients had a reduction in convulsive seizure frequency of greater than 75%, and 11 (21%) had a reduction of less than 25%. Change in convulsive seizure frequency correlated significantly with Emotion Regulation Index and Global Executive Composite. Change in seizure frequency tended to correlate with Cognitive Regulation Index, but the result was not statistically significant. Change in convulsive seizure frequency was not significantly associated with Behavior Regulation Index. A significantly higher percentage of patients in the profound responder group had significant, clinically meaningful improvements on Emotion Regulation Index and Global Executive Composite, compared with minimal responders.
Zogenix, the company that is developing fenfluramine as a treatment for Dravet syndrome, funded the study. Several investigators are employees of Zogenix.
SOURCE: Bishop KI et al. AES 2019, Abstract 2.438.
