Alto Neuroscience Pushes Back Against Investor Claims Over Depression Drug Trial

Alto Neuroscience is seeking to dismiss an investor lawsuit accusing the psychiatric biotech company of overstating the prospects of its lead depression drug candidate, Alto-100.

In a filing submitted to a California federal court, Alto argued that the proposed class action relies on “fraud by hindsight,” claiming investors are attempting to reinterpret the company’s earlier statements after disappointing Phase 2b trial results emerged.

The lawsuit centres on Alto-100, a treatment candidate for major depressive disorder that was highlighted around the time of Alto’s $120 million IPO in February 2024. Investors allege the company failed to disclose risks tied to patient compliance and trial execution, later revealed after the study failed to perform strongly against a placebo.

According to investors, the trial was negatively affected by patients who falsely reported taking the medication, raising questions about the reliability of the results and the company’s earlier public statements about the drug’s prospects.

Alto, however, argues there is no evidence executives knew at the time that the trial design created a heightened risk of noncompliance or failure. The company also challenged claims tied to remote trial sites, patient recruitment practices and compensation structures, arguing the complaint relies on vague statements from former employees that have been taken out of context.

The company further stated that operational changes made after the trial reflected “lessons learned” rather than evidence of concealed risks.

The dispute highlights growing investor scrutiny around biotech trial disclosures, particularly as companies seek funding and public market support based on early-stage clinical data.