Final results from the Phase 1/2 MARINA® trial of delpacibart etedesiran (del-desiran) for the treatment of myotonic dystrophy type 1 (DM1) were published today in The New England Journal of Medicine, according to a statement released by Avidity Biosciences, Inc.
The trial, described in the manuscript titled “An Antibody Oligonucleotide Conjugate for Myotonic Dystrophy Type 1,” demonstrated that del-desiran effectively delivered siRNA to muscle tissue, resulting in an approximate 40% imply reduction in DMPK mRNA – a key indicator of disease pathology. This reduction correlated with improvements across multiple clinical measures, including myotonia, muscle function and strength, mobility, and patient-reported outcomes.
DM1 is a progressive neuromuscular disease with no currently approved disease-modifying therapies. Del-desiran is designed to target the underlying genetic cause of the disease by reducing levels of toxic DMPK mRNA. The accumulation of this mRNA disrupts RNA regulatory proteins, leading to missplicing of genes and the diverse clinical symptoms associated with DM1.
The MARINA trial was a randomized, double-blind, placebo-controlled study evaluating the safety and tolerability of single and multiple ascending doses of del-desiran administered intravenously to adults with DM1 over a six-month period. Results indicated that del-desiran exhibited acceptable safety and tolerability, with most adverse events reported as mild or moderate.
The publication of the MARINA trial results in The New England Journal of Medicine coincides with a recent policy shift by the Food and Drug Administration (FDA), announced earlier this month, which designates a single pivotal trial, supplemented by confirmatory evidence, as the new default standard for drug approval.
Avidity Biosciences, Inc. (Nasdaq: RNA) is a biopharmaceutical company focused on the development of RNA therapeutics using its Antibody Oligonucleotide Conjugate (AOC™) technology.
The February 19, 2026 issue of The New England Journal of Medicine, Volume 394, Issue 8, includes the full study findings, spanning pages 784-792.
