Positive Interim Results for ALTO-300

Based on the results of the interim analysis, the Phase IIb trial will continue with an increase of approximately 50 biomarker positive patients in the final analysis sample. Topline results are expected in mid-2026.

“The outcome of this interim analysis marks an important milestone for the ALTO 300 program,” said Amit Etkin, M.D., Ph.D., founder and chief executive officer of Alto Neuroscience. “The interim analysis was an opportunity to leverage valuable insight from the completed ALTO 100 Phase IIb trial, and we are encouraged by these results. We look forward to reporting topline data in mid-2026.”

Prior to the interim analysis, a blinded committee conducted an in-depth site and patient eligibility review that resulted in the prospective exclusion of sites and patients from the analysis population. Following the eligibility review, the biomarker positive population in the interim analysis consisted of 87 patients.

The double-blind, placebo-controlled study (NCT05922878) is enrolling patients characterized by an electroencephalogram (EEG) biomarker signature. The company expects to enroll approximately 200 biomarker positive patients in the final analysis sample. Patients are randomized to receive ALTO 300 or placebo in addition to a background antidepressant, to which they have had inadequate response, over a six-week treatment period. The primary outcome is the change from baseline on the Montgomery-Åsberg Depression Rating Scale, or MADRS, score.

ALTO 300, an oral, small molecule designed to act as a melatonin agonist and 5-HT2C antagonist, is being developed as an adjunctive treatment in the United States for patients with MDD, characterized by an EEG biomarker.