The phase 1/2 MARINA® study tested delpacibart etedesiran (del-desiran), an antibody-oligonucleotide conjugate, in 38 adult patients with myotonic dystrophy type 1 (DM1).[1][2] It is a progressive neuromuscular disease with no course-modifying drugs, where toxic DMPK mRNA binds regulatory proteins and causes incorrect gene processing.[1][2] The drug, administered intravenously, reduced DMPK mRNA levels by an average of 40% and improved misprocessing.[1][4] Patients showed improvements in myotonia, muscle function and strength, mobility, and patient-rated outcomes.[1][3] The primary objective was to assess safety and tolerability, which was acceptable, with most adverse events being mild or moderate in severity.[1][3] The study was randomized, double-blind, and placebo-controlled with single and repeated ascending doses.[1][2]