Page 1

EX - 99.1 2 dyn - ex99_1.htm EX - 99.1 YDyne THERAPEUTICS Exhibit 99.1 Dyne Therapeutics Reports Third Quarter 2021 Financial Results and Business Highlights - Robust In Vivo Data Presented at Scientific Meetings Support Advancement of Dyne's Co - lead Candidates into the Clinic - - Investigational New Drug ( IND ) Submissions Anticipated for DYNE - 251 in DMD During the Fourth Quarter of 2021 and for DYNE - 101 in DM1 During the First Quarter of 2022 - WALTHAM , Mass . , November 4 , 2021- Dyne Therapeutics , Inc. ( Nasdaq : DYN ) , a muscle disease company focused on advancing innovative life - transforming therapeutics for people living with genetically driven diseases , today reported financial results for the third quarter of 2021 and business highlights . " We made tremendous progress during the third quarter and are now preparing to advance Dyne's two co - lead programs into the clinic , with the IND submission for DYNE - 251 in DMD anticipated during the fourth quarter of 2021 , followed by the IND submission for DYNE - 101 in DM1 expected in the first quarter of 2022 , " said Joshua Brumm , president and chief executive officer of Dyne . " As we highlighted at our recent R & D Day and presentations at the World Muscle Society and Muscle Study Group meetings , we have generated robust in vivo data for these programs . The team has also done extensive work to engage with multiple stakeholders , including thought leaders , regulators , advocacy groups and patients to prepare to move both candidates into the clinic . The FORCE ™ platform is exhibiting powerful potential to address these rare muscle diseases where patients have few or no therapeutic options , and I'm proud that the Dyne team remains fully focused on urgently delivering on our mission . " Recent Highlights ☐ ☐ Dyne presented new in vivo data during the World Muscle Society 2021 Virtual Congress in September 2021 demonstrating the ability of DYNE - 101 in myotonic dystrophy type 1 ( DM1 ) to target the nucleus and achieve knockdown of toxic DMPKRNA , foci reduction and correction of splicing in muscle tissues in the novel hTfR1 / DMSXL mouse model . DYNE - 101 was also well tolerated in a non - GLP toxicology dose - range finding study in non - human primates ( NHPs ) . The Company presented new in vivo data on October 1 , 2021 during the 2021 Muscle Study Group Annual Scientific Meeting for its Duchenne muscular dystrophy ( DMD ) program , showing dystrophin restoration of 90 % of wild - type levels in the diaphragm and 78 % in the heart with approximately 80 % dystrophin - positive fibers following a single dose of FORCE in the mdx mouse model . Its candidate , DYNE - 251 , also achieved exon 51 skipping of 52 % in the diaphragm and 43 % in the heart in NHPs and was well tolerated in a GLP toxicology study . Dyne held its inaugural R & D Day on October 13 , 2021 , highlighting preclinical data and clinical development plans for DYNE - 251 in DMD and DYNE - 101 in DM1 . Following the IND submissions and review with regulators , the Company plans to initiate global , placebo - controlled multiple ascending dose ( MAD ) clinical trials for each of these candidates , evaluating safety , key disease markers and muscle function in patients with DMD and DM1 , 1