Latest U.S. Alzheimer's drug fix is a patch job

The Food and Drug Administration is already limiting one of the most controversial drug approvals in its 115-year history.

The medication is Biogen Inc.’s Alzheimer’s treatment Aduhelm, which won clearance recently despite mixed evidence and expert objections. The agency initially approved the drug for most Alzheimer’s patients, even though it was only studied in those with mild disease.

The decision risked bringing an expensive treatment to millions of additional patients without evidence of utility or safety. The FDA has now changes its prescription guidelines to suggest using the drug only in the smaller group in which it was studied. The initial approval was so inexplicably broad that investors reacted favorably to the restriction.

The new guidelines are good in that they may narrow the use of a drug that shouldn’t have been approved to begin with. But the rollback is an embarrassing black eye for the agency and the damage isn’t over.

How did we get here? No one is sure if the drug works; it showed mild patient benefit in one of two final-stage trials and flopped in another. The FDA sidestepped that debate by approving the medicine based on its ability to remove so-called amyloid brain plaques believed by some to cause Alzheimer’s, saying this intermediate measure was likely to predict benefit.

If anything, this created more skepticism because many previous drugs targeting the plaque didn’t work. Instead of acknowledging some uncertainty in its initial guidelines, the agency doubled down on amyloid, endorsing the notion that reducing plaque should help patients at all stages.

The FDA’s laissez-faire guidance created the strange circumstance of making Biogen executives seemingly worried about selling too much of its medicine and multiplying public criticism of the drug’s $56,000-a year cost. While the price is painful enough for mild Alzheimer’s patients given the uncertainty about its efficacy, it’s entirely unjustifiable in a larger unstudied group, where even modest uptake could see spending on the drug strain Medicare’s budget. The company said in late June that it would consider adjusting the price if more people than expected took the drug.

Lawmakers already plan to investigate the approval process and pricing. In the meantime, the new guidelines should make it easier for insurers and Medicare to limit coverage of the medicine. Narrow use was likely anyway given the state of the evidence, but with desperate late-stage patients likely calling doctors, the quick clarification is welcome.

If known side effects such as brain swelling are more pronounced in later-stage patients, which is entirely possible, the medicine would do significant harm. That’s one reason why for Biogen, expanded use risked bringing unwanted attention and other problems along with any expanded sales. The company will make plenty of money from mild patients alone. So while the stock’s rise on the FDA shift may seem strange at first, it makes some sense.

The process remains very concerning. The dangerously broad initial guidelines weren’t random, they followed directly from the flawed reasoning behind the initial approval.

Even after this latest update, U.S. taxpayers and patients will still likely spend billions on a medicine that may not work. Moreover, the Aduhelm approval was the biggest step yet in an agency shift toward weaker standards.

Eli Lilly & Co. has demonstrated that consequences are already here by pushing for another Alzheimer’s approval based on limited evidence and others will follow. Most of the agency’s decisions don’t receive national attention, which means they may not be rectified until substantial harm is done. In this case, the harm hasn’t even been eliminated, only reduced.

The recent patch job doesn’t eliminate the need for the FDA to rethink its standards and approval process. It makes an adjustment more urgent than ever.

Max Nisen is a Bloomberg Opinion columnist covering biotech, pharma and health care.