Effect of fenfluramine on convulsive seizures in CDKL5 deficiency disorder.

CDKL5 deficiency disorder (CDD) is an X-linked pharmacoresistant neurogenetic disorder characterized by global developmental delays and uncontrolled seizures. Fenfluramine (FFA), an antiseizure medication (ASM) indicated for treating convulsive seizures in Dravet syndrome, was assessed in six patients (five female; 83%) with CDD whose seizures had failed 5-12 ASMs or therapies. Median age at enrollment was 6.5 years (range: 2-26 years). Mean FFA treatment duration was 5.3 months (range: 2-9 months) at 0.4 mg/kg/day (n = 2) or 0.7 mg/kg/day (n = 4; maximum: 26 mg/day). One patient had valproate added for myoclonic seizures. The ASM regimens of all other patients were stable. Among five patients with tonic-clonic seizures, FFA treatment resulted in a median 90% reduction in frequency (range: 86%-100%). Tonic seizure frequency was reduced by 50%-60% in two patients with this seizure type. One patient experienced fewer myoclonic seizures; one patient first developed myoclonic seizures on FFA, which were controlled with valproate. Adverse events were reported in two patients. The patient with added valproate experienced lethargy; one patient had decreased appetite and flatus. No patient developed valvular heart disease or pulmonary arterial hypertension. Our preliminary results suggest that FFA may be a promising ASM for CDD. Randomized clinical trials are warranted.

Ataluren for drug-resistant epilepsy in nonsense variant-mediated Dravet syndrome and CDKL5 deficiency disorder.

OBJECTIVE: Ataluren is a compound that reads through premature stop codons and increases protein expression by increasing translation without modifying transcription or mRNA stability. We investigated the safety and efficacy of ataluren in children with nonsense variants causing Dravet Syndrome (DS) and CDKL5 Deficiency Syndrome (CDD). METHODS: This single-center double-blind, placebo-controlled crossover trial randomized subjects to receive ataluren or placebo for 12 weeks (period 1), a 4-week washout, then another 12-week treatment (period 2). The primary outcome was ataluren's safety profile. The secondary outcome measures were (1) changes in convulsive and/or drop seizure frequency and (2) changes in minor seizure types during ataluren treatment compared to placebo. Exploratory objectives assessed changes in cognitive, motor, and behavioral function as well as quality of life during ataluren therapy. RESULTS: We enrolled seven subjects with DS and eight subjects with CDD. Three treatment-related adverse events (AE) occurred during the blinded phases. Two subjects withdrew due to AE. Ataluren was not effective in reducing seizure frequency or improving cognitive, motor, or behavioral function or quality of life in subjects with either DS or CDD due to nonsense variants. Limitations included a small sample size and 12-week treatment phase, possibly too short to identify a disease-modifying effect. SIGNIFICANCE: There was no difference between ataluren and placebo; ataluren is not an effective therapy for seizures or other disorders in children with DS or CDD due to nonsense variants. There were no drug-related serious AE during the double-blind period, consistent with ataluren's favorable safety profile in larger studies. (Funded by Epilepsy Foundation, Dravet Syndrome Foundation, Finding A Cure for Seizures and Epilepsy and PTC Therapeutics, Inc.; ClinicalTrials.gov number, NCT02758626).