---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-25-101620"
form_type: "8-K"
ticker: "DYN"
cik: "0001818794"
company_name: "Dyne Therapeutics, Inc."
filed_at: "2025-08-04T23:59:59+00:00"
generated_at: "2026-05-17T21:33:15.396932+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# FDA Breakthrough Therapy Designation for DYNE-251 in Duchenne MD

## Summary
- FDA granted Breakthrough Therapy Designation to DYNE-251 for DMD amenable to exon 51 skipping.
- Designation based on DELIVER trial data showing sustained functional improvement over 18 months.
- DYNE-251 now joins DYNE-101 (DM1) as Dyne's second compound to receive this designation.
- Registrational expansion cohort data expected late 2025; BLA submission for accelerated approval anticipated early 2026.
- Benefits include rolling review, Priority Review eligibility, and enhanced FDA support.

## SEC filing metadata
- accession: 0000950170-25-101620
- form_type: 8-K
- ticker: DYN
- cik: 0001818794
- company_name: Dyne Therapeutics, Inc.
- filed_at: 2025-08-04T23:59:59+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1818794/000095017025101620/0000950170-25-101620-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1818794/000095017025101620/dyn-20250804.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-25-101620
- JSON: https://secwatch.observer/filing/0000950170-25-101620.json
- Plain text: https://secwatch.observer/filing/0000950170-25-101620.txt

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