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Getting the latest healthcare news for you
A promising drug for a rare muscle disease hits a wall. Novartis announced that del-desiran failed to meet its primary endpoint in the Phase 3 HARBOR trial for myotonic dystrophy type 1 (DM1), a disease with no approved treatments. While some signals of clinical activity were seen in secondary measures, the drug didn't significantly improve hand myotonia compared to placebo, sending the program back for further evaluation.
A promising drug for a rare muscle disease hits a wall. Novartis announced that del-desiran (delpacibart etedesiran), an investigational therapy for myotonic dystrophy type 1 (DM1), failed to meet its primary endpoint in the Phase 3 HARBOR trial. The study measured improvement in video hand opening time (vHOT) — a key indicator of hand myotonia — over 54 weeks in ~150 patients, but del-desiran showed no statistically significant benefit over placebo.
Despite the disappointing headline result, Novartis noted signals of clinical activity across secondary and exploratory endpoints, though no numerical data were shared. The company says it's evaluating the full dataset and plans to engage with regulators to chart a path forward. This follows earlier Phase 1/2 MARINA trial data that had shown promising target engagement — including reduced disease-associated DMPK mRNA and improved RNA missplicing — which had justified advancing to Phase 3.
Key Takeaways:
Why it matters: DM1 is the most common adult-onset muscular dystrophy, and patients have long awaited an effective therapy. Del-desiran's Phase 3 failure underscores how difficult it is to translate early molecular signals into meaningful clinical outcomes — a sobering reminder for the neuromuscular disease field.
