---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-24-241092"
form_type: "8-K"
ticker: "ANRO"
cik: "0001999480"
company_name: "Alto Neuroscience, Inc."
filed_at: "2024-10-22T23:59:59+00:00"
generated_at: "2026-05-30T11:52:12.504715+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Alto Neuroscience Phase 2b trial of ALTO-100 for MDD fails primary endpoint

## Summary
- ALTO-100 did not show statistically significant improvement on MADRS vs placebo in biomarker-defined MDD patients.
- Favorable safety and tolerability; no new signals; common AEs headache, nausea, abnormal dreams at rates similar to placebo.
- ALTO-100 also in Phase 2b for bipolar depression; cash expected to fund operations into 2027 with other readouts in H1 2025.
- Company will analyze full dataset to determine next steps for ALTO-100 in MDD.

## SEC filing metadata
- accession: 0001193125-24-241092
- form_type: 8-K
- ticker: ANRO
- cik: 0001999480
- company_name: Alto Neuroscience, Inc.
- filed_at: 2024-10-22T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1999480/000119312524241092/0001193125-24-241092-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1999480/000119312524241092/d876702d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-24-241092
- JSON: https://secwatch.observer/filing/0001193125-24-241092.json
- Plain text: https://secwatch.observer/filing/0001193125-24-241092.txt

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