Novartis Phase III HARBOR trial of del-desiran misses primary endpoint in myotonic dystrophy type 1

Novartis reports that the Phase III HARBOR study of del-desiran did not meet its primary endpoint in patients with myotonic dystrophy type 1.
The trial failed to demonstrate a statistically significant improvement on the primary vHOT functional endpoint, although Novartis reported activity across a number of secondary and exploratory measures.
The setback is significant because del-desiran is a central asset from Novartis' acquisition of Avidity Biosciences and had been positioned as a potential disease-modifying treatment for DM1.
Field | Content |
Alert Type | Phase III clinical trial results |
Company | Novartis |
Drug / Asset | Delpacibart etedesiran (del-desiran) |
Trial | HARBOR |
Development Stage | Phase III |
Therapy Area(s) | Neuromuscular disease |
Indication | Myotonic dystrophy type 1 |
Primary Endpoint | vHOT functional endpoint |
What Happened | The Phase III HARBOR study did not achieve a statistically significant improvement on its primary vHOT endpoint. |
Why It Matters | Del-desiran is a strategically important asset for Novartis following its acquisition of Avidity, making the Phase III miss a significant pipeline setback. |
Supporting Context | Novartis reported activity across a number of secondary and exploratory measures despite the primary endpoint miss. |
Key Takeaway | HARBOR missed its primary Phase III endpoint, creating uncertainty around the development path for del-desiran in DM1. |
What to Watch | Full HARBOR results, regulatory discussions and Novartis' next development steps for del-desiran. |
Primary Source | Novartis |
Relevant Date | September 2026 |
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