Closely watched experimental Parkinson’s drug fails key clinical trial

Results deal blow to patient community and to drug developers Biogen, Denali Therapeutics

Denali Therapeutics’ headquarters in South San Francisco.Smith Collection/Gado/Sipa/AP

Jason is a general assignment reporter, with particular focus on genetic medicine and rare disease. Confidential tips can be sent on Signal at JasonMast.77.Matthew Herper covers medical innovation — both its promise and its perils.

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, dealing a substantial blow to a scientific approach that stoked excitement among advocates and academics.

In the study, 648 adults with Parkinson’s were randomized to receive either a placebo or a pill targeting a protein called LRRK2. In 2004, researchers discovered that mutations in the LRRK2 gene can cause a rare, inherited form of Parkinson’s. And in 2018, another group of scientists showed that blocking the protein might actually benefit all patients with the disease.