Fenfluramine treatment for Dravet syndrome: Long term real-world analysis demonstrates safety and reduced health care burden.

OBJECTIVE

Fenfluramine (FFA), stiripentol (STP), and cannabidiol (CBD) are approved add-on therapies for seizures in Dravet syndrome (DS). We report on the long-term safety and health care resource utilization (HCRU) of patients with DS treated with FFA under an expanded access program (EAP).

METHODS

A cohort of 124 patients received FFA for a median of 2.8 years (34.4 months). We compared data on safety and HCRU during FFA treatment with those from a same pre-treatment period. Echocardiography was conducted every 6 months. Information collected included gender, age, and auxological parameters (height, weight, and body mass index [BMI]) at the start (T0) and follow-up (T1); FFA treatment details (start, withdrawal, dosage); adverse events (AEs); and HCRU data including hospital admissions, status epilepticus (SE) episodes, and rescue medication use. We grouped patients by weight: ≤37.4 kg (n = 68, 54.8%) and ≥37.5 kg (n = 56; 45.1%), with FFA dosing adjusted accordingly. Statistical analyses included paired t test, Wilcoxon signed-rank test, Kaplan-Meier analysis, and Bonferroni correction to adjust for multiple testing.

RESULTS

Mean age was 47 months at clinical diagnosis and 81 months at T0. The last follow-up average FFA dose was .5 mg/kg/day, with a median of .4 mg/kg/day. FFA led to a 9.5% reduction in prior treatment load. At last follow-up, 118 of 124 (91.5%) remained on FFA. Rescue medication use decreased significantly from 4.5 to 1, hospitalizations from 1 to 0, and SE episodes from 0-240 to 0-180 (p < .001 for all). Seizure freedom was achieved in 9 of 118 patients (7.6%). AEs occurred in 39 of 124 patients (31.5%), with no cardiac issues or deaths. There was an overall mean reduction in BMI, with no statistical significance, and never requiring FFA withdrawal.

SIGNIFICANCE

FFA is well tolerated, without cardiac toxicity, and reduces treatment load and HCRU, suggesting improved patient management. BMI reduction in young children highlights the need for growth and nutritional monitoring.