Novartis shares update from Phase III trial in myotonic dystrophy type 1

6 October 2026

Novartis has announced Phase III trial results for del-desiran, an investigational treatment for myotonic dystrophy type 1 (DM1). Although the study did not meet its main goal of improving hand stiffness, further analysis of the findings is ongoing.

Novartis has recently announced results from its Phase III HARBOR study of delpacibart etedesiran (del-desiran), an experimental treatment for myotonic dystrophy type 1 (DM1). The company reported that the study did not meet its primary endpoint, which measured improvement in hand myotonia (hand stiffness) using a test called ‘video hand opening time’ (vHOT).

DM1 is a genetic muscle wasting condition that can affect many parts of the body, including muscle strength, movement, heart function and breathing. Currently, there are no approved treatments that target the underlying cause of DM1.

While the study did not achieve its primary endpoint, it reported signs of benefit in some of the trial’s secondary measures and additional exploratory analyses. The company also said that the safety findings of del-desiran was generally in line with what had been seen in earlier studies

Novartis is now carrying out further analysis of the full dataset and says it will discuss the findings with regulatory authorities to determine the most appropriate next steps for the programme.

Although these results will be disappointing for many people in the DM1 community, clinical trials play an important role in improving understanding of the condition and helping researchers identify the most promising approaches for future treatments. More detailed findings from the HARBOR study are expected to be shared once the full analysis is complete.

If you have any questions, please contact research@musculardystrophyuk.org