Despite study bust, Vistagen still hopes to file anxiety drug
Vistagen has chalked up another trial failure for fasedienol, its drug candidate for social anxiety disorder (SAD), cratering its share price, despite the company's assertions that there may be a way forward for the programme.
The readout of the PALISADE-4 trial of the intranasal therapy suggests a bust for the drug, with no statistically significant improvement on either its primary or secondary endpoints, but the company said it will nevertheless seek a meeting with the FDA to talk about a possible regulatory route forward based on a single pivotal trial.
PALISADE-4's result follows a similarly unimpressive performance for fasedienol (PH94B) in the PALISADE-3 trial reported last December, as well as the earlier readout from the PALISADE-1 in 2022, all of which have used the self-reported Subjective Units of Distress Scale (SUDS) as the primary endpoint.
The one success in the programme comes from the PALISADE-2 study in 2023, which showed that a single dose of the drug administered prior to a stressful public speaking challenge yielded a significant improvement in SUDS scores.
Now, Vistagen reckons it can chart a course forward for the drug using a different outcome measure – the Liebowitz Social Anxiety Scale (LSAS) – based on a subgroup analysis from PALISADE-4, which found a "nominally statistically significant" improvement on this measure in a group of patients with very severe social anxiety at enrolment.
Assuming the FDA comes on board with the idea, it would also pivot away from the development of the drug as a single-dose, acute treatment for SAD, and look at the use of multiple doses for "overall treatment of social anxiety disorder over time."
That plan, based on an update to the FDA's 'substantial evidence' guidance published earlier this month, would see one new trial run with the LSAS endpoint, backed up by results from PALISADE-2, other placebo control clinical trials of fasedienol, and aggregated safety data.
Judging by the reaction of investors in Vistagen, that could be seen as a long shot, given that shares in the Nasdaq-listed company were down nearly 73% at the time of writing.
"The results of the primary analysis of PALISADE-4 were not what we had hoped for. However, we are encouraged by the safety and tolerability data and our post-hoc analysis," said the company's chief medical officer, Dr Angel Angelov.
"As we look at the totality of data across the fasedienol development program, we believe there is evidence of fasedienol's therapeutic potential for patients with social anxiety disorder," he added.
Vistagen also said that its current cash reserves should be sufficient to support operations into 2027.
In 2019, Vistagen reported that its ketamine-like drug AV-101B failed a phase 2 trial in major depressive disorder (MDD), sending the programme back into early-stage clinical development and leading to another rout of its shares.
