---
schema_version: "secwatch.filing_event.v1"
accession: "0001999480-25-000053"
form_type: "8-K"
ticker: "ANRO"
cik: "0001999480"
company_name: "Alto Neuroscience, Inc."
filed_at: "2025-06-26T23:59:59+00:00"
generated_at: "2026-05-18T18:30:31.498176+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# Alto Neuroscience identifies EEG biomarker and positive Phase 2 results for ALTO-203 in MDD

## Summary
- ALTO-203 showed pro-cognitive and wake-promoting effects; EEG theta/beta ratio confirmed as key biomarker (25µg: p<0.05).
- Improvements in sustained attention replicated Phase 1 findings; greatest in patients with high baseline theta/beta ratio (25µg: p<0.01; 75µg: p<0.05).
- Objective sleep measures from wearables confirmed wake-promotion; both doses significant (25µg: p<0.05; 75µg: p<0.001 vs placebo).
- MADRS improvements were small (25µg: -2 points at week 3 vs placebo) but trial not powered for significance.
- Safety profile: well tolerated, insomnia most common adverse event; predictable PK.

## SEC filing metadata
- accession: 0001999480-25-000053
- form_type: 8-K
- ticker: ANRO
- cik: 0001999480
- company_name: Alto Neuroscience, Inc.
- filed_at: 2025-06-26T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.65
- calibrated_materiality_score: 0.65
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1999480/000199948025000053/0001999480-25-000053-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1999480/000199948025000053/alto-20250626.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001999480-25-000053
- JSON: https://secwatch.observer/filing/0001999480-25-000053.json
- Plain text: https://secwatch.observer/filing/0001999480-25-000053.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.