Alto Neuroscience Inc. has announced the upcoming initiation of a Phase 2b clinical trial for their drug ALTO-207, expected to start by mid-2026. ALTO-207 is a fixed-dose combination of pramipexole and ondansetron, designed to achieve rapid antidepressant effects in patients with treatment-resistant depression $(TRD.UK)$ while mitigating adverse events associated with pramipexole alone. This trial follows the publication of results from the PAX-D study in The Lancet Psychiatry, which demonstrated significant symptom reduction in TRD patients using pramipexole, though accompanied by a high rate of adverse effects. Alto plans to collaborate with the National Health Service and PAX-D clinical sites for the trial. The study results have already been presented during an investor conference call by Alto Neuroscience.