Praxis Reports 77% Seizure Reduction with Elsunersen in Early-Seizure Onset SCN2A-DEE in EMBRAVE Part A

Praxis Precision Medicines announced positive topline results from the randomized, placebo-controlled EMBRAVE Part A trial evaluating elsunersen in pediatric patients with early-seizure onset SCN2A developmental and epileptic encephalopathy (DEE). The Phase 1/2 study showed substantial seizure reduction along with improvements in multiple disease-related functional domains, with treatment generally well tolerated.

Trial Design and Patient Population

EMBRAVE Part A (NCT05737784) is a randomized, placebo-controlled Phase 1/2 study assessing safety and efficacy of ascending doses of elsunersen in children with SCN2A-DEE. Nine patients aged 2–12 years were randomized in a 3:1 ratio to receive elsunersen or a sham procedure every four weeks for 24 weeks, followed by an open-label extension (OLE). All enrolled patients continued into the OLE phase. Treatment began at 1 mg, with optional dose escalation based on seizure response and tolerability.

Efficacy Results

Elsunersen treatment resulted in a 77% placebo-adjusted reduction in monthly seizures from baseline (p=0.015; 95% CI: 33–92). More than half of treated patients (57%) experienced at least one 28-day period of seizure freedom. The observed efficacy was sustained during the open-label extension for up to one year.

Functional improvements were also reported. All patients (100%) receiving elsunersen demonstrated improvements in at least one domain including sleep, motor function, muscle tone, attention, or neuropsychomotor development, while no improvements were observed in the placebo group.

Safety and Tolerability

Elsunersen was generally well tolerated. No drug-related serious adverse events were reported, and no patients discontinued treatment. No signals of neuroinflammation were observed at doses up to 8 mg. Most treatment-emergent adverse events were mild to moderate and consistent with findings from earlier EMBRAVE studies.

Company leadership stated that the EMBRAVE Part A results demonstrated consistent seizure reduction and disease-modifying improvements in children with early-seizure onset SCN2A-DEE. The company also noted that the pivotal EMBRAVE3 study is ongoing and that placebo-controlled data from EMBRAVE Part A will be shared with stakeholders.

About Elsunersen

Elsunersen (PRAX-222) is an antisense oligonucleotide designed to selectively reduce SCN2A gene expression, targeting the underlying cause of early-seizure onset SCN2A-DEE in patients with gain-of-function mutations. Preclinical studies demonstrated reductions in SCN2A gene and protein expression, along with dose-dependent seizure reduction, improved behavioral outcomes, and increased survival in SCN2A mouse models.

Elsunersen has received Orphan Drug Designation and Rare Pediatric Disease Designation from the FDA, and Orphan Drug and PRIME designations from the European Medicines Agency. The program is being developed in collaboration with Ionis Pharmaceuticals and RogCon. Additional data from EMBRAVE Part A are expected to be presented at upcoming scientific meetings.

Reference

Praxis Precision Medicines Announces Positive Results from the EMBRAVE Part A Trial of Elsunersen in Patients with SCN2A Early-Onset Developmental and Epileptic Encephalopathy, 06 April 2026, Praxis Precision Medicines Announces Positive Results from the EMBRAVE Part A Trial of Elsunersen in Patients with SCN2A Early-Onset Developmental and Epileptic Encephalopathy – Praxis Precision Medicines, Inc.

A Clinical Trial of PRAX-222 in Pediatric Participants with Early Onset SCN2A Developmental and Epileptic Encephalopathy, ClinicalTrials.gov ID NCT05737784, https://clinicaltrials.gov/study/NCT05737784