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Biogen and Denali Parkinson’s Drug Fails Randomized Trial

Biogen and Denali Therapeutics reported that an experimental therapy targeting the LRRK2 protein did not slow Parkinson’s disease progression in a randomized study of 648 adults. The companies announced the results on May 21, 2026.

Stat
1 source·May 21, 11:53 PM(7 days ago)·1m read
Biogen and Denali Parkinson’s Drug Fails Randomized TrialStat
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Biogen and Denali Therapeutics said Thursday that their experimental therapy for Parkinson’s disease failed to slow the degenerative brain disorder in a randomized trial. The study enrolled 648 adults with Parkinson’s who received either a placebo or a pill targeting a protein called LRRK2.

Researchers discovered in 2004 that mutations in the LRRK2 gene can cause a rare, inherited form of the disease.

2018, another group of scientists showed that blocking the LRRK2 protein might benefit all patients with Parkinson’s. Thursday’s results represent a significant setback to that approach. The companies did not release additional details on safety or secondary outcomes in the initial announcement.

Key Facts

648 adults
enrolled in randomized Parkinson’s trial
LRRK2 protein
target of experimental therapy
May 21, 2026
date companies announced trial results

Story Timeline

3 events
  1. May 21, 2026

    Biogen and Denali announced LRRK2 therapy failed to slow Parkinson’s in randomized trial.

    1 source@statnews
  2. 2018

    Scientists showed blocking LRRK2 protein might benefit all Parkinson’s patients.

    1 source@statnews
  3. 2004

    Researchers discovered LRRK2 gene mutations can cause rare inherited Parkinson’s.

    1 source@statnews

Potential Impact

  1. 01

    Further development of LRRK2-targeted Parkinson’s therapies may be reassessed.

Transparency Panel

Sources cross-referenced1
Confidence score75%
Synthesized bySubstrate AI
Word count109 words
PublishedMay 21, 2026, 11:53 PM
Bias signals removed2 across 1 outlet
Signal Breakdown
Loaded 1Amplifying 1

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