If a new Alzheimer’s drug works, was there any point to the Aduhelm controversy? Yes

The announcement Tuesday night from Eisai and Biogen that their experimental medicine, lecanemab, reduced Alzheimer’s patients’ decline as measured by a clinical questionnaire is one of the biggest — and potentially happiest — shocks in the recent history of medicine.

It’s a shock because Biogen had so bungled the launch of their previous Alzheimer’s drug, Aduhelm, with failed clinical trials, a tortuous path to approval, and a wholesale rejection by Medicare and by the market. Wall Street analysts, who advise investors on what to buy, were not expecting success.

It’s even more of a shock because drug companies have been testing a litany of similar drugs for two decades without success. Proponents of these would-be medicines, which target peptides in the brain known as beta-amyloid, insisted with each new study that there were signs that the medicines were working and that a slightly better medicine was needed. But a growing chorus of voices seemed to think that this approach, often referred to as “the amyloid hypothesis,” was never going to work.

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