Novartis stock sinks 12.5% as del-desiran flunks Phase 3 — SkimNews
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- Del-desiran missed its primary endpoint in the Phase 3 Harbor trial of 159 myotonic dystrophy type 1 patients, showing no statistically significant improvement versus placebo on video hand opening time (vHOT) after seven doses infused every eight weeks.
- Novartis stock dropped 12.5% to $139.98 in pre-market trading Tuesday, down from a Friday close of $159.99, after the Harbor flop.
- Guggenheim Securities analysts had called the Harbor readout "crucial" for validating the $12 billion Avidity acquisition, noting it was one of three events in H2 2026 that would shape Novartis' growth beyond 2030.
- Novartis now sits at one win and two failures from three back-to-back readouts: Rhapsido succeeded in relapsing MS, pelacarsen failed in cardiovascular disease, and del-desiran flunked in DM1.
- Novartis acquired two other late-stage neuromuscular programs in the Avidity buyout — it has filed delpacibart zotadirsen for accelerated approval in Duchenne muscular dystrophy and plans FDA talks on delpacibart braxlosiran in FSHD following positive Phase 1/2 data.
- Novartis had presented del-desiran as the largest opportunity unlocked by the Avidity deal, with external forecasts projecting peak annual revenues as high as $6 billion, versus roughly $4 billion for FSHD.
Why it matters: The Harbor flop directly undermines the thesis of Novartis' $12 billion Avidity acquisition — del-desiran had been pitched as the crown jewel with up to $6 billion in peak sales, and Guggenheim had flagged it as 'crucial' to deal validation. With two of three H2 2026 readouts now failed, investors are repricing Novartis' mid- and long-term growth story, though two other Avidity neuromuscular assets (delpacibart zotadirsen and delpacibart braxlosiran) remain in regulatory or clinical play.
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