Alto Neuroscience Presents Data at the 2025 American Society of Clinical Psychopharmacology Annual Meeting Reinforcing Safety and Tolerability Profile for ALTO-300 in Major Depressive Disorder

Business Wire

29-05-2025

MOUNTAIN VIEW, Calif.--(BUSINESS WIRE)--Alto Neuroscience, Inc. ('Alto') (NYSE: ANRO) a clinical-stage biopharmaceutical company focused on the development of novel precision medicines for neuropsychiatric disorders, today announced a presentation at the American Society of Clinical Psychopharmacology (ASCP) Annual Meeting, in Scottsdale, Arizona, held May 27-30, 2025.
ALTO-300, also known as agomelatine, is an oral, small molecule designed to act as a melatonin agonist and 5-HT2C antagonist being developed at 25mg as an adjunctive treatment in the United States for patients with MDD, characterized by an EEG biomarker. Agomelatine is an approved antidepressant medication at both 25mg and 50mg in Europe and Australia but has not been approved in the United States. In clinical studies, the 50mg dose of agomelatine was associated with low levels of reversible liver enzyme elevations, which were not associated with liver failure. In comparison to the 50mg dose of agomelatine, the 25mg dose has been shown to have similar antidepressant activity while avoiding the rates of liver function test (LFT) elevations associated with the 50mg dose.
'Our ASCP presentation continues to support the unique biomarker opportunity for patient stratification and reinforces the well-established safety and tolerability profile for ALTO-300,' said Amit Etkin, M.D., Ph.D., founder and chief executive officer of Alto Neuroscience. 'Agomelatine has been studied in thousands of patients globally and evidence from meta-analyses and real-world clinical care demonstrates the 25mg dose achieves an optimal balance of antidepressant activity without the concern of LFT elevation. These data are consistent with the positive results from our completed Phase 2a trial, and we are encouraged by the safety and tolerability profile of ALTO-300 in our ongoing Phase 2b trial in patients with major depressive disorder. Taken together, we believe the selected 25mg dose of ALTO-300 is well positioned to demonstrate clinical effects while avoiding the low LFT elevation rates associated with the 50mg dose, which typically occur early, are non-cumulative, resolve quickly, and are not associated with liver failure.'
Summary of Data Presented
ALTO-300 Safety and Tolerability Profile
The most common adverse event observed in the completed Phase 2a trial of ALTO-300 was headache. Additionally, the Phase 2a and Phase 2b trials have involved monitoring for elevated liver enzymes (≥ 3 times the upper limit of normal), with the Phase 2b trial including a stopping rule for elevated liver enzymes. No LFT elevations ≥ 3 times the upper limit of normal were observed in the Company's 239-patient completed Phase 2a trial, and no patients have been stopped in the ongoing Phase 2b trial due to liver enzyme elevation, which remains blinded.
ALTO-300 EEG Biomarker
The ALTO-300 biomarker signal likely reflects increased neural noise due to elevated 5-HT2C tone and reduced dopaminergic activity. Increasing 5-HT2C activity in a preclinical rodent model or directly depleting dopamine in a healthy human volunteer study—both the oppositive mechanistic effect of ALTO-300—resulted in greater EEG irregularity, consistent with a biomarker positive profile. These data reinforce the direct link between ALTO-300 and the EEG biomarker used to identify MDD patients who are more likely to be responders to treatment.
The following poster presented at ASCP 2025 is available under ' Publications ' in the platform section of Alto's website:
ALTO-300 as Adjunctive Treatment for Major Depressive Disorder Supported by Mechanistic Validation of Patient Selection Biomarker and Well-Established Safety and Tolerability Profile
Poster First Author: Michael Avissar, Ph.D.
About Alto Neuroscience
Alto Neuroscience is a clinical-stage biopharmaceutical company with a mission to redefine psychiatry by leveraging neurobiology to develop personalized and highly effective treatment options. Alto's Precision Psychiatry Platform™ measures brain biomarkers by analyzing EEG activity, neurocognitive assessments, wearable data, and other factors to better identify which patients are more likely to respond to Alto product candidates. Alto's clinical-stage pipeline includes novel drug candidates in bipolar depression, major depressive disorder, schizophrenia, and other mental health conditions. For more information, visit www.altoneuroscience.com or follow Alto on X.
Forward-Looking Statements
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Availability of Information on Alto's Website
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