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

Novartis has reported that its global Phase III HARBOR trial evaluating delpacibart etedesiran, also known as del desiran, in people with myotonic dystrophy type 1 did not achieve its primary endpoint.

The study assessed video hand opening time, known as vHOT, as a measure of hand myotonia. Treatment with del desiran did not produce a statistically significant improvement in this measure compared with placebo.

Despite the primary endpoint result, Novartis said signs of clinical activity were identified across secondary endpoints and exploratory analyses. Safety observations from HARBOR were broadly in line with findings reported previously for the therapy.

The company is now reviewing the complete HARBOR dataset and plans to consult health authorities before deciding on the most appropriate direction for further development of del desiran.

Shreeram Aradhye, president of Development and chief medical officer at Novartis, highlighted the continued treatment need in myotonic dystrophy type 1, noting that no therapies are currently approved for the condition despite decades of research.

He said developing treatments for a complex disorder such as DM1 remains difficult and that unsuccessful study outcomes can form part of scientific progress. As Novartis continues its assessment of the HARBOR data, Aradhye said the company remains focused on determining the appropriate path for the del desiran programme while continuing to develop new approaches for DM1 and other serious neuromuscular diseases.

Myotonic dystrophy type 1 is a progressive neuromuscular condition associated with substantial unmet medical need and currently has no approved treatment options.

Del desiran is one of three antibody oligonucleotide conjugate therapies that joined Novartis’ neuromuscular portfolio following its acquisition of Avidity Biosciences.

Another programme in the portfolio, delpacibart zotadirsen, or del zota, is being developed for people with Duchenne muscular dystrophy who have mutations suitable for exon 44 skipping. Novartis has submitted del zota for accelerated approval, and the US Food and Drug Administration has granted the application priority review.

The company is also progressing delpacibart braxlosiran, known as del brax, for facioscapulohumeral muscular dystrophy. Following positive biomarker findings from a Phase I/II study, Novartis is planning discussions with the FDA regarding the next steps for the programme.

Novartis said its wider antibody oligonucleotide conjugate pipeline continues to progress despite the outcome of HARBOR. The company also maintained its guidance for a five year sales compound annual growth rate of 5% to 6% between 2025 and 2030.

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clinical trial, myotonic dystrophy, neuromuscular, neuromuscular disease, Novartis, pharma news, Phase 3