RAPP · Rapport Therapeutics, Inc. Common Stock

Rapport Therapeutics reported positive topline results from the 8-week follow-up period of its Phase 2a trial evaluating RAP-219 in focal onset seizures (FOS). The data indicates that the drug candidate provides sustained efficacy even after treatment cessation, a significant finding driven by RAP-219's pharmacokinetic profile. The company updated the estimated half-life of RAP-219 to approximately 22 days, a notable increase from the previously reported 14 days. This longer half-life allowed therapeutic plasma concentrations to be maintained throughout the follow-up period, supporting continued clinical benefit.

Efficacy metrics were robust during the follow-up phase. In the first four weeks post-treatment (weeks 9-12), patients experienced a 90% median reduction in clinical seizures and an 80% median reduction in Long Episodes (LEs), an objective biomarker. While efficacy showed some attenuation in the second four weeks (weeks 13-16), clinically meaningful improvements persisted with a 59% median reduction in clinical seizures. Consolidated results over the 16-week observation window demonstrated a 68% median reduction in clinical seizures and a 12% seizure freedom rate.

The safety profile remained favorable, with no serious adverse events attributed to the drug during the follow-up period. These results were presented at the 2026 American Academy of Neurology Annual Meeting. The sustained efficacy and updated half-life data may support less frequent dosing regimens in future development, potentially enhancing patient compliance and competitive positioning in the epilepsy market.