By Manas Mishra and Puyaan Singh
(Reuters) -The European Union's drugs regulator has rejected Eisai and Biogen's Leqembi treatment for early Alzheimer's disease, saying the risk of serious brain swelling did not outweigh its small impact on slowing cognitive decline.
The decision is a blow to the companies as the drug faces slow take-up in the U.S. and underscores the complexities tied to a new class of drugs that have benefited early-stage patients, but could cause rare and serious side effects.
Following the rejection, Biogen's shares fell about 7% in U.S. trading, while rival Eli Lilly, which makes a similar drug, slipped 1%.
Eisai and Biogen said they will seek re-examination of the recommendation, but did not disclose what information they would provide the regulator.
The therapy, also known as lecanemab, is approved in the U.S., China, Hong Kong, Israel, Japan and South Korea, and would have been Europe's first drug to treat the neurodegenerative condition rather than its symptoms.
The infusion, given twice a month, removes sticky clumps of protein amyloid beta from the brain, believed to be a hallmark of Alzheimer's disease.
In clinical trials, the drug slowed cognitive decline by 27% in early Alzheimer's patients, compared with a placebo.
In Europe, seven million people live with the disease, according to non-profit Alzheimer's Europe, which was disappointed with the decision.
The EU regulator said it relied on the analysis by the agency's Committee for Medicinal Products for Human Use, and cited three primary concerns.
An 18-point scale used in the trial to measure functions such as memory and problem-solving showed only a small absolute difference in patients who received lecanemab versus a placebo, it said.
It also pointed to cases of ARIA, a type of brain swelling and bleeding, seen in its clinical trials that led to hospitalizations of some patients.
The committee noted elevated risk of brain swelling and bleeding in people who have two copies of the APOE4 gene, which is also associated with a higher risk of Alzheimer's.
SCRUTINY IN EUROPE
Reuters reported last year, citing researchers, that the drug was unlikely to be used widely even if approved in Europe, where cost-conscious countries rigorously scrutinize new drugs.
Leqembi's U.S. launch has been lackluster, with bottlenecks due to its requirements such as additional diagnostic tests, twice-monthly infusions and regular brain scans.
One Alzheimer's expert said the decision reflected the complex considerations around the drug, which costs roughly $26,500 per year in the U.S.
The requirements "lead to the question if limited resources (not just money but also trained staff) could produce better results for patients if used elsewhere," said Sebastian Walsh, NIHR Doctoral Fellow, University of Cambridge.
The decision puts pressure on European regulators to create clear guidance on what is the clinically meaningful benefit for treating Alzheimer's disease, said Ivan Koychev, principal clinical investigator at the United Kingdom Dementia Platform.
The recommendation must be backed by the European Commission, which usually follows the regulator's decision.
The drug has been under review in the region since January 2023. The U.S. approved it last year and requires a warning against brain-related side effects.
Lilly's amyloid-lowering drug Kisunla, also known as donanemab, gained U.S. approval this year and is being reviewed by European regulators.
Given the Leqembi rejection, "we are hard-pressed to see the EU approving Lilly's donanemab," Piper Sandler analyst Christopher Raymond said in a research note on Friday.
Officials at Lilly declined to comment on the EU decision, but John Sims, Lilly's senior medical director, told Reuters that the company believes in the favorable benefit-risk profile for amyloid-targeting therapies.
(Reporting by Manas Mishra and Puyaan Singh in Bengaluru; Deena Beasley in Los Angeles; Editing by Mrigank Dhaniwala, Josephine Mason, Arun Koyyur and Rod Nickel)