Another Alzheimer's drug fails

A Biogen sign in front of its headquarters building.
Biogen's Alzheimer's failure drove its stock down 29%. Photo: John Tlumacki/The Boston Globe via Getty Images

Biogen and Eisai have ended late-stage trials for an Alzheimer's disease drug, less than a year after the pharmaceutical companies painted a rosy picture of the drug's potential. Biogen's stock plunged 29% on the news.

The big picture: It's always a bad sign when clinical trials are discontinued before data are analyzed. It's an even worse sign for Alzheimer's research and raises questions about whether scientists should abandon the idea that the brain disease is "caused by sticky clumps of protein called amyloid plaques," according to a 2016 story by Stat.

Biogen faces patent loss for lucrative MS drug

Biogen headquarters building.
Biogen's top drug is its multiple scleroris drug, Tecfidera. Photo: Dominick Reuter/AFP via Getty Images

Biogen's blockbuster drug Tecfidera is on the hot seat after federal patent judges ruled today that competing drug maker Mylan "demonstrated a reasonable likelihood" that one of the drug's main patents can be thrown out.

Why it matters: Biogen has faced a lot of patent challenges over Tecfidera, a pricey multiple sclerosis drug that registered $4.3 billion in sales in 2018. But if the board's final decision next year invalidates the Tecfidera patent in question, cheaper generic versions of the drug could hit the market as soon as 2021 instead of 2028.