Elsunersen (PRAX-222) - (EMBRAVE)

June 22, 2026: Praxis Precision Medicines, Inc. (NASDAQ: PRAX) announced the FDA granted Breakthrough Therapy Designation to elsunersen (PRAX-222), an antisense oligonucleotide for seizures associated with SCN2A Developmental and Epileptic Encephalopathy (SCN2A-DEE) caused by gain-of-function SCN2A variants.

The designation was supported by positive topline results from EMBRAVE Part A, a randomized, sham-controlled Phase 1/2 ascending-dose study in nine pediatric patients (ages 2–12). Elsunersen achieved a 77% sham-adjusted reduction in monthly seizures from baseline (p=0.015; 95% CI [33, 92]); 71% of treated patients had >50% seizure reduction and 57% had at least one 28-day seizure-free period during six months. Benefits were sustained in an open-label extension for up to one year. The company reported elsunersen was well-tolerated with no drug-related serious adverse events, discontinuations, or neuroinflammation signals (doses up to 8 mg).

Praxis said the pivotal EMBRAVE3 study, aligned with FDA (announced December 2025), is enrolling ~30 patients under a streamlined single-arm, baseline-controlled registrational pathway; primary analysis measures change from baseline in countable motor seizures over 24 weeks (plus a 24-week extension). Elsunersen also holds FDA Orphan Drug and Rare Pediatric Disease designations and EMA Orphan Drug and PRIME designations; the program is in collaboration with Ionis Pharmaceuticals and RogCon.