Updated at 10:32 am EST
Science.org reported the 65-year-old woman's death Sunday, noting deposits of amyloid, a protein targeted by Bigoen's lecanemab, had been found surrounding blood vessels in her brain.
Biogen unveiled better-than-expected results from a late-stage study of lecanemab in late September, telling investors it improved the slowdown in cognitive function and functional decline of patients with early-stage Alzheimer's disease, when compared to use of a placebo.
Eisai Co Ltd., Biogen's Japan-based partner, said at the time it will apply for full approval of the treatment with the U.S. Food & Drug Administration last this year, with an aim for commercial use of the drug in late 2023. Eisai is expected to publish details of the phase 3 trial, known as Clarity AD, later this week.
Biogen shares were marked 3.4% lower in early trading Monday to change hands at $294.65 each.
Alzheimer's disease is a progressive brain disorder that affects more than 50 million people around the world. To date, no drug has been found to address the disease, which can accelerate into dementia and other more serious cognitive conditions.
Treatment pricing, however, has been a controversial issue and the U.S. Centers of Medicare and Medicaid Services noted in September that its decision to only cover treatment with Aduhelm -- Biogen's FDA-approved Alzheimer's drug -- if patients are enrolled in a clinical trial as a major factor in lowering overall premiums for Medicare Part B.
Biogen was forced to slash the price of Aduhelm by around 50%, to $28,200 per year, in order to help expand its potential reach following the CMS decision late last year.
Aduhelm, Biogen noted in earlier studies, has been show to erode amyloid beta, a plaque which builds up around the brain and can lead to neuron damage.
The FDA approved Aduhelm for the treatment of Alzheimer’s through its accelerated approval pathway, which can be used for a drug for a serious or life-threatening illness that provides a meaningful therapeutic advantage over existing treatments, last year.