DYNE-255

DYNE-255 is an investigational therapeutic being developed by Dyne Therapeutics for the treatment of Duchenne muscular dystrophy (DMD) in patients with mutations amenable to exon 55 skipping. The drug utilizes Dyne's proprietary FORCE platform, which consists of a phosphorodiamidate morpholino oligomer (PMO) conjugated to an antigen-binding fragment (Fab) that binds to the transferrin receptor 1 (TfR1). This targeted delivery mechanism is designed to enhance the concentration of the PMO in skeletal and cardiac muscle tissues, which are primary sites of pathology in DMD. Once delivered to the muscle cells, the PMO promotes the skipping of exon 55 during the splicing of the dystrophin pre-mRNA, allowing for the production of a truncated but functional dystrophin protein. As of early 2026, DYNE-255 is in IND-enabling studies, following the same technological approach as the company's more advanced candidate, z-rostudirsen (DYNE-251).