Dyne Therapeutics announces FDA granted BTD to DYNE-101

Dyne Therapeutics (DYN) announced that the U.S. Food and Drug Administration, FDA, has granted Breakthrough Therapy Designation, BTD, to DYNE-101 for the treatment of myotonic dystrophy type 1. The company also announced an updated plan for obtaining U.S. Accelerated Approval for DYNE-101 in DM1 following a Type C meeting with the FDA and analysis of new long-term functional data. Accelerated Approval Pathway for DYNE-101 in DM1: Dyne has revised the ongoing Registrational Expansion Cohort in the ACHIEVE trial as follows: The primary endpoint is change from baseline in middle finger myotonia as measured by vHOT at 6 months, compared to placebo. Secondary endpoints include change from baseline in splicing as measured by the composite alternative splicing index, muscle strength as assessed by Quantitative Muscle Testing, performance on both the 10-Meter Walk/Run Test and 5 Times Sit to Stand Test, and the Myotonic Dystrophy Health Index patient reported outcome measure, all at 6 months compared to placebo. New Long-term Data from Multiple Ascending Dose Portion of ACHIEVE Trial: Today, Dyne reported new long-term data from adult DM1 patients enrolled in the randomized, placebo-controlled MAD portion of the DYNE-101 ACHIEVE trial, including data from the 6.8 mg/kg Q8W cohort at up to 12 months. At the registrational dose of 6.8 mg/kg Q8W, DYNE-101 demonstrated robust and sustained improvement in myotonia as measured by vHOT as well as sustained improvements across multiple other endpoints.