Longboard Commences $150 Million Public Offering as It Reports Positive Results in DEEs

Rare Daily Staff

Longboard Pharmaceuticals said it has commenced a $150 million public offering as it reported positive topline results of its PACIFIC Study evaluating its experimental therapy bexicaserin to treat a broad range of developmental and epileptic encephalopathies.

The PACIFIC study is a phase 1b/2a study. It enrolled 52 participants ages 12-65 years old with developmental and epileptic encephalopathies (DEE) diagnosis at 34 study sites across the United States and Australia to evaluate the safety, tolerability, efficacy, and pharmacokinetics of oral bexicaserin at three different doses three times daily versus placebo.

Participant DEE diagnoses included Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS), and other qualifying DEEs. Following a five-week screening period and baseline evaluations, study participants initiated a dose titration over a 15-day period and subsequently continued on the highest tolerated dose throughout the maintenance period of 60 days.

Of the 52 participants enrolled in the study, 43 participants were randomized to bexicaserin (DS=4, LGS=24, DEE Other=15) and 9 to placebo (DS=0, LGS=5, DEE Other=4). The median number of countable motor seizures per 28-day period at baseline was 38.8 in the bexicaserin group compared to 20.8 in the placebo group. Participants were able to remain on a contemporary, stable polytherapy regimen of up to four anti-seizure medications (ASMs) throughout the study, with the most common ASMs being clobazam, cannabidiol, lamotrigine and levetiracetam.

The median change in countable motor seizure frequency (primary efficacy endpoint) from baseline for the evaluable participants treated with bexicaserin was a decrease of 53.3 percent, compared to a 20.8 percent decrease for those receiving placebo. Overall, this represents a placebo-adjusted reduction in seizure frequency of 32.5 percent. The median change in countable motor seizure frequency from baseline was a decrease of 72.1 percent in DS, 48.1 percent LGS, and 61.2 percent in DEE. This represents a placebo-adjusted reduction in seizure frequency of 27.3 percent in LGS and 28.6 percent in DEE.

Bexicaserin exhibited favorable safety and tolerability results. Most participants (85.7 percent) in the bexicaserin treated group that started the maintenance period tolerated the highest dose. The most common adverse events (AEs) observed were somnolence, decreased appetite, constipation, diarrhea, and lethargy.

There were three participants that reported a serious adverse event (SAE) (ankle fracture, constipation, increased seizures) and no deaths were reported in the study. Overall, nine participants in the bexicaserin group discontinued due to an AE. Of note, two of these participants discontinued during the maintenance period (seven participants discontinued during the titration period). No participants in the placebo group discontinued or experienced an SAE.

All of the participants who completed the PACIFIC study elected to enroll in the ongoing 52-week open-label extension study.

Additional data from the PACIFIC Study are intended to be presented at future medical meetings.

“Given the groundbreaking design of the PACIFIC Study and the broad efficacy of bexicaserin observed across DEEs in this study, we believe that bexicaserin provides us with the cornerstone to build a world-class epilepsy franchise and to explore development paths forward that may offer novel options to DEE patients that are vastly underserved,” said Kevin Lind, Longboard’s president and CEO. “We are continuing our phase 3 preparations as we evaluate the broader dataset.”