New Therapy Shows Promise for Myotonic Dystrophy Type 1

A novel antibody-oligonucleotide conjugate (AOC), delpacibart etedesiran (del-desiran), has demonstrated significant benefits in individuals with myotonic dystrophy type 1 (DM1), according to final results from the Phase 1/2 MARINA® trial published in the February 19, 2026, issue of The New England Journal of Medicine.

Understanding Myotonic Dystrophy Type 1

Myotonic dystrophy type 1 (DM1) is a progressive and often fatal neuromuscular disease affecting multiple systems in the body. It is characterized by the accumulation of toxic mRNA, leading to missplicing of genes and a wide range of clinical symptoms. Currently, there are no disease-modifying therapies available for DM1.

How Del-Desiran Works

Del-desiran is designed to target the underlying genetic cause of DM1 by reducing levels of the toxic DMPK (myotonic dystrophy protein kinase) mRNA. By reducing DMPK mRNA, the treatment aims to restore proper RNA regulation and correct the missplicing that drives the disease.

Key Findings from the MARINA® Trial

The Phase 1/2 MARINA trial involved 38 participants with DM1 who were randomized to receive either del-desiran or a placebo. Key findings include:

• Del-desiran effectively delivered siRNA to muscle tissue.
• The treatment resulted in an approximately 40% mean reduction in DMPK mRNA levels.
• Improvements were observed in several measures, including myotonia (muscle stiffness), muscle function, strength, mobility, and patient-reported outcomes.
• Del-desiran demonstrated acceptable safety and tolerability, with most adverse events being mild or moderate.

What’s Next?

These findings represent a significant step forward in the development of therapies for DM1. Further research and clinical trials will be necessary to confirm these results and evaluate the long-term efficacy and safety of del-desiran. The publication of the MARINA® trial results in The New England Journal of Medicine highlights the potential of antibody-oligonucleotide conjugates as a novel therapeutic approach for genetic diseases.