– Financing led by Commodore Capital with participation from new and existing biotech focused investors –

–  Alto expects to use the proceeds of the financing to support the development of ALTO-207 in Treatment Resistant Depression through a planned Phase 3 study and to a potential NDA submission –

Alto Neuroscience, Inc. ("Alto") (NYSE:ANRO), a clinical-stage biopharmaceutical company focused on the development of novel precision medicines for neuropsychiatric disorders, announced today that it has entered into a securities purchase agreement with institutional and accredited investors to sell securities in a private placement financing (the "PIPE") for gross proceeds of approximately $120 million, before deducting offering expenses. The financing is being led by Commodore Capital, with participation from new and existing institutional investors, including Dellora Investments, Driehaus Capital Management, Perceptive Advisors, Spruce Street Capital, Venrock Healthcare Capital Partners, Vestal Point Capital, and a large biotech dedicated investor.

Alto intends to use the proceeds from the PIPE to fund the development of ALTO-207, a fixed-dose combination of pramipexole (a dopamine D3-preferring D3/D2 agonist) and ondansetron, through a planned Phase 3 clinical trial in treatment resistant depression ("TRD"), as well as for working capital and general corporate purposes. Alto expects to initiate a Phase 2b study of ALTO-207 in TRD in the first half of 2026 and to initiate a Phase 3 study in early 2027. With the funding from the PIPE, the Company expects to have capital to support the planned Phase 3 study of ALTO-207 in TRD patients through completion, and if the study is positive, to an NDA submission. After giving effect to the anticipated net proceeds from the PIPE, the Company estimates its cash and cash equivalents would have been approximately $275 million as of February 28, 2026.