Following a string of clinical setbacks, Vistagen’s nasal spray for social anxiety has now failed to top placebo even when given as a double dose. But just like with prior disappointing readouts, the biotech has set its sights on a subpopulation it says may provide a path to FDA approval.
The phase 2 trial enrolled 61 patients with social anxiety disorder and subjected them to a public speaking challenge. Some patients took two puffs of Vistagen’s experimental drug, fasedienol, before the challenge, while others took one puff of fasedienol followed by placebo, or two puffs of placebo.
On the study’s primary endpoint, reduction in anxiety severity as measured by the subjective units of distress scale (SUDS), there was no difference between the single-dose or double-dose arms and placebo, Vistagen announced Thursday. But the Bay Area biotech also caveated that the trial was not powered to find a statistically significant difference between groups, and in terms of raw numbers fasedienol outperformed placebo.
A double dose of fasedienol reduced SUDS by 15.4 points, compared to a drop of 14.7 for the single dose and 6.8 for the placebo arm.
But just like with a phase 3 fail back in June, Vistagen highlighted its beleaguered drug candidate’s superior performance in a subpopulation of patients who suffer from very severe social anxiety disorder. In these patients, the placebo response was blunted to just a 1.6 drop in SUDS, while a double dose produced a 17.5-point reduction and the single dose 15.3.
While these results were closer to statistical significance, they ultimately did not garner p-values below 0.05.
“Although not designed to show statistical significance, the study showed consistent findings across multiple efficacy measures and contributes to our growing understanding of how patients may benefit from fasedienol,” Vistagen Chief Medical Officer Angel Angelov, M.D., said in the company’s release. “These results will help inform our discussions with the FDA regarding a potential registrational pathway for fasedienol.”
The new results “add incremental evidence supporting the efficacy of fasedienol,” analysts from William Blair wrote in a note to investors. “Though we note it is hard to gain conviction around the data," the analysts cautioned, "given the exploratory nature of the study, small sample sizes, and the fact that larger phase 3 studies have shown mixed data.”
There is high unmet need in social anxiety disorder, the analysts added, which may make the FDA “amenable to a path forward here.”
Vistagen’s June trial failure followed a similar phase 3 miss last December, after which the biotech laid off around 20% of its employees. The company’s recent run of clinical struggles is a far cry from fasedienol’s phase 3 win that sent Vistagen’s stock soaring over 1000% back in 2023.
Editor's note: This story was updated at 11:40am E.T. with analyst comment.