Story perspectives

Novartis del-desiran fails Phase 3 HARBOR trial

9/10/2026

Summary

Novartis Trial Failure

Novartis announced del-desiran failed the Phase III HARBOR trial in DM1.
The study missed its primary endpoint, showing no significant improvement in video hand opening time.
Novartis shares fell 9% to CHF 111.80, the steepest one-day drop since March 2020.
The failure threatens the $12 billion Avidity acquisition that delivered del-desiran, del-zota and del-brax.
Chief medical officer Shreeram Aradhye said Novartis will review the data and meet regulators.

Summary

Therapeutics Shares Drop

Dyne Therapeutics shares fell 27% after Novartis del-desiran failure.
Sarepta Therapeutics stock dropped 11% following the same trial disappointment.
Ionis Pharmaceuticals sank 10% after its cardiovascular trial miss was announced.
NewAmsterdam Pharma’s U.S.-listed shares fell 12% on news of the Lp(a) drug failure.
Analysts warn the cascade of setbacks could pressure valuations of other rare-disease developers.

History

Historical Context

In 2013 Pfizer’s drisapersen Phase III trial missed its primary endpoint, and after GlaxoSmithKline ended its collaboration, Prosensa regained rights before the FDA rejected the exon 51-targeting drug in January 2016. BioMarin, which bought Prosensa, stopped drisapersen development in May 2016, prompting investors to turn to Sarepta’s competing exon-skipping therapy, eteplirsen, illustrating the high risk of rare-disease drug development.

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Novartis Trial Failure

Novartis announced del-desiran failed the Phase III HARBOR trial in DM1.
The study missed its primary endpoint, showing no significant improvement in video hand opening time.
Novartis shares fell 9% to CHF 111.80, the steepest one-day drop since March 2020.
The failure threatens the $12 billion Avidity acquisition that delivered del-desiran, del-zota and del-brax.
Chief medical officer Shreeram Aradhye said Novartis will review the data and meet regulators.

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