Longboard Pharmaceuticals, Inc. announced positive interim results from its ongoing 52-week open-label extension of the PACIFIC Study evaluating bexicaserin (LP352) in participants ages 12-65 years old with Developmental and Epileptic Encephalopathies. The PACIFIC OLE Study is a 52-week Phase 2, open-label, long-term safety study of bexicaserin in participants with a range of DEEs, including Dravet syndrome (n=3), Lennox-Gastaut syndrome (n=20). and DEE Other (n=18), who completed the PACIFIC Study (n=41).

The study objectives are to investigate the safety and tolerability of multiple doses of bexicaserin in participants with DEEs, and to analyze the effect of bexicaserin on the frequency of observed countable motor seizures and other seizure types. The interim analysis was conducted when participants reached the approximate 6-month point in the OLE Study. Summary of Efficacy Results: The median change in countable motor seizure frequency for participants in the OLE Study over an approximate 6-month treatment period was a decrease of 56.1% (n=40) from their baseline entering the PACIFIC Study.

The median change in countable motor seizure frequency from baseline for: participants randomized to the bexicaserin-treated group in the PACIFIC Study was a decrease of 54.9% (n=31); ?participants randomized to the placebo group in the PACIFIC Study that transitioned to bexicaserin in the OLE was a decrease of 57.3% (n=9); Summary of Safety and Tolerability Results: Favorable safety and tolerability results were observed in this study. 100% of PACIFIC Study completers elected to enroll in the OLE with 95.1% (39 out of 41) remaining in the ongoing open-label study. One participant discontinued due to the adverse event (AE) of lethargy and one participant discontinued by withdrawal of consent.

The most common treatment emergent AEs in the overall group (n=41) occurring in >5% of patients were upper respiratory tract infections, COVID-19, pneumonia, sinusitis, seizures, and decreased appetite.