Exhibit 99.1 Dyne Therapeutics Reports Second Quarter 2025 Financial Results and Recent Business Highlights WALTHAM, Mass., July 28, 2025 – Dyne Therapeutics, Inc. (Nasdaq: DYN), a clinical-stage company focused on delivering functional improvement for people living with genetically driven neuromuscular diseases, today reported financial results for the second quarter of 2025 and recent business highlights. "This quarter we made significant progress on our clinical and regulatory plans for our DM1 and DMD i ...