Shares of Biogen and other drugmakers researching AlzheimerB次元官网网址檚 disease soared early Wednesday after JapanB次元官网网址檚 Eisai Co. said its potential treatment appeared to slow the fatal disease in a late-stage study.

The drugmaker said early results showed that its treatment, lecanemab, reduced patient clinical decline by 27% when compared to a placebo or fake drug after 18 months of the infused treatment.

Eisai announced results late Tuesday from a global study of nearly 1,800 people with early-stage AlzheimerB次元官网网址檚.

Patients were monitored using a scale that measures mental decline and their ability to do daily activities like getting dressed or feeding oneself.

Eisai Co. Ltd. said it would discuss full results from the research at a conference in late November. It also plans to publish findings in a peer-reviewed medical journal.

The company is already seeking an accelerated approval from the U.S. Food and Drug Administration, and the agency is expected to decide by early next year. Eisai and Biogen will co-promote the drug.

Researchers typically urge caution in evaluating a study until the full results are released. But the initial findings appear to be B次元官网网址渜uite robustB次元官网网址� and will likely support regulatory approval, Mizuho Securities analyst Graig Suvannavejh said in a research note.

A statement from the AlzheimerB次元官网网址檚 Association called the findings the most encouraging to date for potential treatments of the underlying disease causes.

Some 6 million people in the U.S. and many more worldwide have AlzheimerB次元官网网址檚, which gradually attacks areas of the brain needed for memory, reasoning, communication and basic daily tasks.

AlzheimerB次元官网网址檚 has no known cure. Long-standing treatments on the market just manage symptoms, and researchers donB次元官网网址檛 fully understand what causes the disease.

Last year, BiogenB次元官网网址檚 became the first new AlzheimerB次元官网网址檚 drug introduced in nearly two decades. But it has largely flopped after debuting with a price tag of $56,000 annually, which Biogen later slashed.

Doctors have been hesitant to prescribe it, given weak evidence that the drug slows the progression of AlzheimerB次元官网网址檚. Insurers have blocked or restricted coverage due to concerns over the drugB次元官网网址檚 high price tag and uncertain benefit.

Earlier this year, the federal Medicare program imposed strict limits on who can get the drug, wiping out most of its potential U.S. market. Biogen announced afterward that it would stop most of its spending on the treatment.

Like Aduhelm, lecanemab, which Eisai developed, aims to clear a protein called beta-amyloid from the brain.

The protein forms a plaque that researchers believe is a contributor to AlzheimerB次元官网网址檚. They also point to other potential factors like family history and chronic conditions such as diabetes.

Eisai executives say lecanemab focuses more on floating clumps of the protein before it forms the plaque, which is what Aduhelm targets.

Eli Lilly and Co. also is developing a potential treatment, donanemab, that targets the protein.

Shares of Cambridge, Massachusetts-based Biogen Inc. jumped 35% to $267.29 in Wednesday morning trading as the broader indexes edged higher. The stock had largely tumbled since AduhelmB次元官网网址檚 debut last year.

Shares of Indianapolis-based Eli Lilly and Co. were up more than 8%.

Tom Murphy, The Associated Press

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