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Novartis\' $12B del-desiran flops in crucial phase 3 trial

Novartis\' $12B del-desiran flops in crucial phase 3 trial

Money Moves

Harbor trial miss casts doubt on Avidity acquisition as patent expiries loom

Today: Harbor trial flops for del-desiran

Overview

Updated 2 hours ago

Novartis' experimental muscle-disease drug del-desiran failed its phase 3 Harbor trial, missing the primary endpoint and sending shares down. The drug was the centerpiece of the company's $12 billion acquisition of Avidity Biosciences, which closed last year.

The miss asts doubt on Novartis' pipeline strategy just when its older blockbusters face patent expiries. It also deals a blow to the broader class of RNA-based therapies;del-desiran was meant to prove the platform's worth.

Why it matters

The failure puts Novartis' $12 billion bet in question, threatening its plan to replace revenue from older drugs losing patent protection.

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Key Indicators

$12B
Acquisition price for Avidity Biosciences
Novartis paid this to acquire the RNA therapy platform in 2024.
Missed
Phase 3 Harbor trial primary endpoint
del-desiran did not beat placebo on the composite measure of disease progression.
1 win, 2 failures
Novartis' late-stage pipeline record since August 2026
Remibrutinib succeeded in MS; pelacarsen and del-desiran both flunked phase 3.

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People Involved

Organizations Involved

Timeline

August 2024 September 2026

3 events Latest: Today
  1. Harbor trial flops for del-desiran

    Today Clinical Trial

    Del-desiran failed its phase 3 Harbor trial, missing the primary endpoint and dealing a major blow to Novartis' Avidity acquisition.

  2. Pelacarsen fails phase 3 Lp(a) trial

    Clinical Trial

    Novartis' cholesterol drug pelacarsen missed its primary endpoint, a separate setback for the pipeline.

  3. Novartis bets $12B on Avidity

    Acquisition

    Novartis agreed to buy Avidity Biosciences, whose RNA platform includes del-desiran, arare-muscle-disease therapy.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

April 2018 - May 2019

Novartis/AveXis Zolgensma (2018-2019)

Novartis paid $8.7 billion for AveXis, whose gene therapy Zolgensma treated spinal muscular atrophy. The drug won FDA approval with strong efficacy data, becoming one of the most expensive drugs ever sold.

Then

Zolgensma generated billions in revenue and validated Novartis' rare-disease M&A strategy.

Now

It set a precedent that big bets on muscle-disease gene therapies could pay off,numazzicando later deals like Avidity.

Why this matters now

The AveXis success is why investors hoped del-desiran could repeat that magic;the Harbor failure now breaks that pattern, making the $12B Avidity purchase look far riskier.

December 2019 - March 2020

Astellas/Audentes Therapeutics (2019-2020)

Astellas paid $3 billion for Audentes, betting on its gene therapy for a rare muscle disease. In clinical hold issued in early 2020 after a patient died of liver toxicity, and the program never recovered.

Then

Astellas halted the trial, took awritedown, andabandoned the program.

Now

The failure chilled investor enthusiasm for high-priced rare-disease acquisitions.

Why this matters now

Like Astellas, Novartis paid a premium for arsingle-platform bet in rare muscle disease;the clinical failure now threatens to erase most of that value.

Sources

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