Pramipexole Shows Significant Anhedonia Reduction in Nature Medicine Trial — Alto Neuroscience, Inc.

Event summary

Nature Medicine published PRIME-PRAXOL trial results showing pramipexole significantly reduced anhedonia in mood disorder patients compared to placebo.
Pramipexole demonstrated a mean difference of -4.04 on the Snaith–Hamilton Pleasure Scale (p=0.006) and maintained improvements through a six-month open-label extension.
Post-hoc analysis revealed greater efficacy in MDD patients (Hedges’ g=0.99 on SHAPS) compared to dysthymia patients.
ALTO-207, Alto’s pramipexole-ondansetron combination, aims to address pramipexole’s tolerability issues, including high nausea rates (60% in the trial).
Alto is advancing ALTO-207 in a potentially pivotal Phase 2b trial for treatment-resistant depression.

The big picture

The PRIME-PRAXOL trial results reinforce the potential of dopaminergic mechanisms in treating anhedonia, a poorly addressed dimension of depression. Alto’s ALTO-207 aims to capitalize on this by improving pramipexole’s tolerability, addressing a significant unmet need in treatment-resistant depression. The findings align with broader industry trends toward mechanism-led approaches in psychiatry, where precision treatments are increasingly prioritized.

What we're watching

Trial Execution: Whether Alto can replicate these results in its Phase 2b trial for treatment-resistant depression.
Tolerability Advantage: The pace at which ALTO-207 can demonstrate superior tolerability over pramipexole alone.
Market Differentiation: How Alto positions ALTO-207 against existing and emerging treatments for anhedonia in depression.