REFILE-UPDATE 2-Biogen, Ionis to discontinue development of experimental ALS drug

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May 16 (Reuters) -

Biogen and Ionis Pharmaceuticals said on Thursday they will terminate the development of their experimental treatment for amyotrophic lateral sclerosis (ALS) after failing to show improvement in patients in an early-to-mid stage study.

Shares of Biogen and Ionis were each down nearly 2% in premarket trading.

This marks another setback in the search for new treatments for ALS, a rare neurodegenerative disease that affects the voluntary control of limbs and leads to breathing trouble. Most patients die from the disease within five years, according to U.S. government data.

Commonly known as Lou Gehrig's disease, ALS affects roughly 60,000 people in the U.S. and Europe.

Biogen and Ionis' drug, BIIB105, did not succeed in significantly reducing neurodegeneration or improving functional measures such as breathing, they said.

The drug also showed no evidence of benefit in any subgroup evaluated in the 99-patient study.

The companies' failure comes a little more than a month after Amylyx Pharmaceuticals said it will withdraw its ALS drug Relyvrio from the U.S. and Canada after the treatment failed in a key late-stage trial.

Currently, there are two drugs with traditional approval — Japanese firm Mitsubishi Tanabe's Radicava and generic drug riluzole — for the treatment of ALS.

Biogen and Ionis' other drug for ALS, Qalsody, received an accelerated approval in the United States in April last year, based on preliminary data.

The company plans to seek traditional approval after it gets data from a late-stage trial that confirms the drug's benefits. The study is expected to complete in 2027, according to the government's clinical trial registry. (Reporting by Christy Santhosh and Mariam Sunny in Bengaluru; Editing by Sonia Cheema and Vijay Kishore)