Praxis Precision Medicines Reports FDA Alignment On Ulixacaltamide NDA; Reports EMBOLD Results For Relutrigine With 53% Seizure Reduction, And Vormatrigine RADIANT Study Shows Up To 100% Weekly Seizure Reduction In Focal Onset Seizures; Monotherapy Study, POWER3, Is On Track To Begin In First Half Of 2026

Ulixacaltamide

On December 4, 2025, Praxis Precision Medicines, Inc. (the "Company") announced the successful completion of its pre-New Drug Application ("NDA") meeting with the U.S. Food and Drug Administration (the "FDA"), including receipt of written feedback and an in-person meeting. The Company has gained alignment from the FDA on the content of the NDA and expects to complete its NDA submission in early 2026.

Relutrigine

On December 4, 2025, the Company announced positive results from the registrational cohort of the EMBOLD study evaluating relutrigine for the treatment of patients with SCN2A and SCN8A developmental and epileptic encephalopathies ("DEEs"), following a recommendation by the Data Monitoring Committee to stop the study early for efficacy.

On December 6, 2025, the Company shared the results of the EMBOLD study, demonstrating relutrigine was well-tolerated with rapid, significant and increasing seizure reduction over time with broad functional improvements across behavior, alertness, communication and overall status. The Company will meet with the FDA in the coming weeks to discuss next steps. The Company will make a determination of the timing for filing the NDA after the meeting.

The topline results for the EMBOLD study were as follows:

•Patients receiving relutrigine (n=51) experienced a 53% placebo-adjusted reduction in seizures over 16-weeks (p<0.0002).

•Patients achieved a 66% increase in motor seizure-free days (p=0.034).

•Both clinician and caregiver global impression scores showed statistically significant improvements, with most patients improving across both scales in alertness, communication, and seizure severity.

•There were no drug-related serious adverse events and treatment-related adverse events were predominantly mild and moderate.

Vormatrigine

On December 6, 2025, the Company shared the full results of the RADIANT study evaluating vormatrigine in patients with focal onset seizures ("FOS") or generalized epilepsy. The key results were as follows:

Focal Onset Seizures (n=62)

•Patients taking vormatrigine for 8 weeks on background anti-seizure medications saw a 54% median reduction in seizures.

•In week 1, 58% of patients achieved at least a 50% reduction in seizures, which increased to 61% by week 8.

•Increasing and sustained effect was observed, with FOS patients reaching 100% median weekly seizure reduction after 8 weeks and maintained through 16 weeks.

•Over 11% of patients experienced seizure freedom for the entire 8-week period and roughly one third of patients experienced seizure freedom for a consecutive 28-day period.

Generalized Epilepsy (n=3)

•Three patients with generalized epilepsy included in the cohort experienced a similar treatment effect as FOS patients, with rapid, durable seizure reduction.

The Company has completed recruiting for the POWER1 pivotal study in FOS and is on track to complete the POWER2 study in the second half of 2026. The monotherapy study, POWER3, is on track to begin in the first half of 2026.