Mountain View, California-based Alto Neuroscience, Inc. (NYSE: ANRO) announced the pricing of an underwritten registered direct offering of common stock, raising USD 100 million in gross proceeds to fund an additional Phase III trial of its lead psychiatric asset ALTO-207 in treatment-resistant depression — a condition where existing therapies leave a substantial portion of patients without adequate relief.
The offering comprises 3,776,436 shares priced at USD 26.48 per share. EcoR1 Capital led the financing, with participation from new and existing healthcare-focused institutional investors. Alto intends to deploy the proceeds alongside existing cash to accelerate ALTO-207's clinical program and support general working capital.
ALTO-207 is a fixed-dose oral combination of pramipexole, a dopamine D3/D2 agonist, and ondansetron, a 5-HT3 receptor antagonist added to mitigate nausea and enable dose escalation to antidepressant-effective levels. The asset was acquired from Chase Therapeutics Corporation in May 2025 for USD 1.75 million upfront plus up to USD 71.5 million in milestones, with prior Phase IIa data demonstrating antidepressant effects and favorable tolerability. Alto initiated a Phase IIb trial of ALTO-207 in April 2026, with topline data expected in the second half of 2027. The company has indicated that the Phase IIb is designed to resemble a registrational study, potentially enabling a single Phase III to support an NDA submission. The USD 100 million raise is intended to fund a separate, additional Phase III monotherapy trial, extending the program's development optionality.
Alto's broader pipeline includes six other clinical-stage assets. ALTO-300, a melatonergic agonist and 5-HT2C antagonist being evaluated in major depressive disorder using an EEG-derived biomarker strategy, is in Phase IIb with topline results expected mid-2026. ALTO-100, a BDNF modulator targeting bipolar depression, is also in Phase IIb with data anticipated in the second half of 2026. Both programs are supported by Alto's Precision Psychiatry Platform, which uses brain-based biomarkers to stratify patients by likelihood of response — a strategy designed to improve signal detection in notoriously noisy psychiatric trials. ALTO-101, a transdermal PDE4 inhibitor for cognitive impairment associated with schizophrenia, was discontinued from independent development following a Phase II failure in April 2026, with Alto indicating it may seek a partner for that asset.