Fenfluramine works in paediatric, adult patients with developmental/epileptic encephalopathies

In children and adults with developmental and epileptic encephalopathies (DEEs), treatment with fenfluramine appears to be effective with predictable tolerability, as shown in a real-world study.

Researchers used data from the Spanish Epilepsy Society’s DEEs registry and identified patients who initiated fenfluramine treatment at least 12 months before database closure. They reviewed medical records at 3, 6, and 12 months to assess the efficacy and safety of treatment.

Efficacy endpoints included seizure reductions of 100 percent, ≥75 percent, and ≥50 percent (responder), median percent seizure reduction, and seizure worsening. Adverse events (AEs) were evaluated as safety endpoints.

A total of 166 patients (mean age 16.6 years)—including 111 children (median age 10.1 years) and 55 adults (median age 26.5 years)—were included in the analysis. Of these, 84 had Lennox–Gastaut syndrome (LGS), 42 had Dravet syndrome (DS), and 40 had other DEEs. These patients had a median of three prior failed antiseizure medications (ASMs).

The median fenfluramine dose at 12 months was 0.49 mg/kg/day, with 77.1 percent treatment retention. Mean seizure frequency decreased by 68.8 percent over 12 months (p<0.001), with significant reductions across all diagnostic groups (p<0.001 for LGS, p<0.001 for DS, and p=0.004 for other DEEs).

The 12-month ≥50-percent responder rate was 61 percent, and the rates were similar in the paediatric and adult patient groups. Significant reductions were also noted in the mean number of concomitant ASMs used (p=0.004), and the proportion of patients requiring rescue medication (p<0.001).

Meaningful improvements in Clinical Global Impression scores for cognition, behaviour, sleep, and caregiver domains were documented in 59.3 percent, 40.9 percent, 24.3 percent, and 44.8 percent, respectively.

AEs occurred in 68.1 percent of patients, with most AEs being mild-to-moderate in severity. AEs led to treatment discontinuation in 12 percent, with no significant differences according to age.