---
schema_version: "secwatch.filing_event.v1"
accession: "0001664710-26-000024"
form_type: "8-K"
ticker: "KROS"
cik: "0001664710"
company_name: "Keros Therapeutics, Inc."
filed_at: "2026-03-09T23:59:59+00:00"
generated_at: "2026-05-15T17:54:29.293103+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# Keros collaborates with Mass General on Phase 2 ALS trial of rinvatercept; presents new Phase 1 data at MDA Conf.

## Summary
- Entered agreement with Massachusetts General Hospital for Phase 2 ALS trial within HEALEY ALS MyMatch program.
- Additional Phase 1 data presented at 2026 MDA Conference: rinvatercept generally well-tolerated with no serious adverse events.
- Phase 1 data showed increased muscle mass, decreased fat mass, and increased bone mineral density in healthy volunteers.
- Proteomic analysis confirmed target engagement and anti-fibrotic/anti-inflammatory effects consistent with activin inhibition.
- Keros plans two Phase 2 trials: one in Duchenne muscular dystrophy (DMD) and one in ALS.

## SEC filing metadata
- accession: 0001664710-26-000024
- form_type: 8-K
- ticker: KROS
- cik: 0001664710
- company_name: Keros Therapeutics, Inc.
- filed_at: 2026-03-09T23:59:59+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/1664710/000166471026000024/0001664710-26-000024-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1664710/000166471026000024/kros-20260309.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001664710-26-000024
- JSON: https://secwatch.observer/filing/0001664710-26-000024.json
- Plain text: https://secwatch.observer/filing/0001664710-26-000024.txt

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