Praxis Precision Medicines (PRAX) Study Result summary

Study background and disease overview

• Developmental and epileptic encephalopathies (DEEs) are severe, early-onset disorders with high seizure burden, developmental delays, and early mortality, often caused by SCN2A or SCN8A mutations.

• Estimated 5,000 US patients with SCN2A/SCN8A DEEs, characterized by refractory seizures and significant quality of life impact.

• Current treatments are sub-optimal, with frequent safety and tolerability issues.

Study design and patient population

• EMBOLD is a multicenter, double-blind, placebo-controlled, randomized study with an open-label extension, enrolling 16 patients aged 2–18 years with SCN2A or SCN8A DEE.

• Patients were randomized to relutrigine or placebo for 16 weeks, with dose adjustments allowed between 0.25 and 1.0 mg/kg/day; 13 entered the open-label extension.

• Baseline median motor seizures per 28 days was 53.5; most patients were on multiple anti-seizure medications.

Key study results and efficacy

• Relutrigine achieved a 46% placebo-adjusted reduction in motor seizures during the double-blind period, with over 30% of patients achieving seizure freedom for at least 28 days.

• In the long-term extension, a 75% median reduction in motor seizures was observed, with five patients remaining seizure-free for over 28 days, some exceeding 200 days.

• Over 2,000 fewer seizures were recorded since study start for EMBOLD participants.