Patients treated with Longboard Pharmaceuticals’ bexicaserin saw a 32.5% drop in the frequency of countable motor seizures relative to placebo in a Phase 1b/IIa study. The company’s shares soared 316% Tuesday on the news.
Pictured: Bar graph and a trendline showing an increasing trend in stock value/iStock, Think_About_Life
Longboard Pharmaceuticals on Tuesday posted positive top-line data from the Phase Ib/IIa PACIFIC study, showing that its investigational 5-HT2C receptor superagonist bexicaserin can strongly reduce seizures in patients with developmental and epileptic encephalopathies.
After 28 days, patients in the PACIFIC trial treated with Longboard’s bexicaserin saw a 53.3% drop in countable motor seizures, the study’s primary efficacy endpoint. In addition, seizure frequency decreased by 20.8% compared to placebo, resulting in a placebo-adjusted seizure reduction of 32.5% in favor of bexicaserin.
Longboard CMO Randall Kaye in a statement called the early findings from PACIFIC “exciting,” setting bexicaserin up to become a “clinically and commercially best-in-class product” with the “potential to redefine the standard of care” in developmental and epileptic encephalopathies (DEE).
The biopharma’s stock soared 316% on Tuesday in response to the readout, according to Seeking Alpha.
Longboard will present additional data from PACIFIC at upcoming medical meetings and will push the development of bexicaserin into Phase III, the company said.
Designed to be orally available, bexicaserin is a superagonist of the 5-HT2C receptor, which binds to the neurotransmitter serotonin and plays a role in the modulation of mood, appetite and motor behaviors. Bexicaserin works by regulating GABA, another neurotransmitter, reducing the central hyperexcitability that is a key characteristic of seizures.
According to Longboard’s website, bexicaserin does not act on the 5-HT2A or 5-HT2B receptor subtypes, which have typically been associated with toxicities and side effects.
In terms of safety, the most common side effects in the PACIFIC study were diarrhea, lethargy, constipation, somnolence and decreased appetite. Three participants experienced serious adverse events, including constipation, an ankle fracture and a higher frequency of seizures.
There were no deaths but nine patients in the bexicaserin arm dropped out of the study due to treatment toxicities. None of the placebo participants discontinued participation or developed a serious adverse event.
PACIFIC was designed to test the safety, tolerability, pharmacokinetics and efficacy of this mechanism of action when given at 6-mg, 9-mg or 12-mg doses thrice daily. After an initial five-week screening period, patients started dose titrating bexicaserin for 15 days, eventually settling on their highest tolerated dose, which was maintained for 60 days.
Participants were allowed to retain stable anti-seizure regimens consisting of up to four medications throughout the study period.
On the heels of the PACIFIC data drop, Longboard on Tuesday also launched an underwritten public offering, seeking to issue and sell $150 million of shares of its voting common stock. Cantor and Citigroup will serve as joint lead book-running managers for the offering, while Wedbush PacGrow and H.C. Wainwright & Co. will act as lead managers.
Tristan Manalac is an independent science writer based in Metro Manila, Philippines. He can be reached at tristan@tristanmanalac.com or tristan.manalac@biospace.com.
