Biogen, Eisai Stocks Soar On Landmark Alzheimer's Data, Lifting Rivals

Shares in Biogen and Eisai soared on Wednesday reflecting the surprise trial success of their experimental Alzheimer's drug, which also lifted the stocks of rival drugmakers Roche and Eli Lilly.

Nearly all drugs tested to treat Alzheimer's - a fatal brain disease that affects an estimated 55 million globally - have stumbled in clinical trials.

Against the odds, Biogen and Eisai on Tuesday said their experimental drug, lecanemab, slowed progress of the brain-wasting disease by 27% compared with a placebo, in a large trial of patients in the early stages of Alzheimer's.

The data is an "unequivocal win" for Alzheimer's patients and Biogen, said BMO analyst Evan Seigerman.

Biogen's stock surged 50% in early premarket trading. Shares of Eisai jumped 17% to the daily limit in Tokyo.

Shares of Roche, which is expected to report results on a rival Alzheimer's drug gantenerumab later this year, jumped as much as 6% to a two-month high in early trading.

Data on Eli Lilly's competing drug, donanemab, is expected by mid-2023. The U.S. drugmaker's stock was up 7.8% before the bell on Wednesday.

The three drugs target a toxic protein plaque known as amyloid beta that has long been considered crucial to arresting the progression of the fatal brain disease, but previous attempts have led to failure after failure.

This so-called amyloid hypothesis suffered a particularly heavy blow last year, after U.S. regulators overruled their own panel of outside experts to approve another Biogen drug called Aduhelm, based on its plaque-clearing ability rather than proof that it helped slow cognitive decline.

The latest trial boost for Biogen and Eisai's lecanemab has raised hope for success in trials testing Roche's gantenerumab and Lilly's donanemab.

"There haven't been many wins to celebrate, nor anything close to approaching a return on investment, so it is important that results like this are rewarded and incentivised," said Daniel Chancellor, healthcare analyst at Citeline.

"Companies that can establish an anti-amyloid antibody market will then look for ways to compete and differentiate, and part of this will undoubtedly be through building a non-amyloid pipeline and/or exploring combination treatment strategies."

Shares of smaller Alzheimer's drug developers also rose in premarket U.S. trading. Prothena Corporation Plc jumped 36.5% to $42.21, while shares of Acumen Pharmaceuticals Inc rose 29.4% to $6.08.