Biogen BIIB and Japan-based partner, Eisai, announced an update regarding the regulatory review of an application seeking the approval of Leqembi (lecanemab) for mild cognitive impairment due to Alzheimer’s disease (AD) and mild AD, collectively known as early AD, in the EU.

Please note that, in November 2024, the European Medicines Agency’s (EMA) Committee for Medicinal Products for Human Use (CHMP) rendered a positive opinion recommending marketing approval for Leqembi for early AD.

Biogen and Eisai announced that the European Commission (EC) has requested the CHMP to reassess new safety data that emerged after the positive opinion and determine if any updates are needed. Additionally, the CHMP will review the clarity of risk minimization measures in its opinion to ensure proper implementation. These discussions are scheduled for an upcoming CHMP meeting later this month.

Biogen and Eisai stated that the safety profile of lecanemab observed in clinical studies across the United States, Japan and other countries aligns with its approved labels, with no new safety concerns identified. Given the clarity and sufficiency of the available information, the companies believe that existing data will address the EC’s requests, which the CHMP will review.

BIIB stock lost 1.6% on Friday following the news. Shares of Biogen have plunged 17.1% in the past three months compared with the industry’s decline of 6.5%.

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We remind the investors that the CHMP had earlier given a negative opinion regarding marketing approval for Leqembi for early Alzheimer's disease in July 2024.

The negative opinion was reportedly due to a brain swelling side effect called amyloid-related imaging abnormalities associated with the use of anti-amyloid therapies like Leqembi. Eisai requested the CHMP to re-examine its opinion back then.

BIIB, Eisai's Leqembi Approved in Other Countries

Leqembi gained full approval from the FDA for early AD in the United States and broad reimbursement from the Centers for Medicare & Medicaid Services in July 2023. The drug is also approved in China, Japan, Israel, Hong Kong, South Korea, the UAE and Great Britain.

Biogen has developed Leqembi in collaboration with Eisai, with the latter leading the clinical development and regulatory submissions. Though the companies co-commercialize and co-promote the drug, Eisai has the final decision-making authority.

Other Updates on BIIB & Eisai's Leqembi

Recently, Biogen announced that the FDA has approved a monthly maintenance dosing version for its intravenously (IV) administered AD drug, Leqembi. Post the FDA approval, patients have the option to transition to a monthly maintenance dosing regimen of Leqembi after completing an 18-month course of biweekly infusions of the drug. Alternatively, patients can also opt to continue with the biweekly dosing regimen. The new option provides relief to AD patients taking Leqembi, as IV administrations are time-consuming — nearly one hour for each infusion.

A regulatory filing seeking approval for a subcutaneous (SC) maintenance dosing version of Leqembi is currently under the FDA’s review. A final decision is expected by Aug. 31, 2025. If approved, this SC version could be used by patients at home or medical centers as the process takes less time than the IV formulation of the drug.

Though the drug’s launch was initially slow, sales started picking up in 2024. Eisai recorded nearly $67 million in global revenues from Leqembi sales in the third quarter of 2024, showing a strong improvement from $40 million in the second quarter of 2024.

Eisai and Biogen believe that Leqembi has the potential to generate blockbuster sales as there is a huge unmet medical need for AD.

Biogen Inc. Price and Consensus

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Other Players in the AD Space

AD is a progressive condition caused by a neurotoxic process that persists before and after amyloid-beta (Aβ) plaque removal. Biogen/Eisai’s Leqembi is designed to address AD through dual mechanisms, continuously clearing toxic protofibrils and rapidly removing Aβ plaque. Continuous treatment is critical as protofibrils can cause ongoing neuronal damage even after plaque clearance.

Eli Lilly LLY received FDA approval for Kisunla in 2024, making it the second drug on the market to treat AD after Leqembi. LLY’s drug is based on a similar mechanism as Leqembi, also designed to reduce the accumulation of Aβ plaque in the brain.

Prothena PRTA is evaluating multiple AD candidates in early-stage studies targeting the AD indication. PRTA is evaluating AD drug PRX012, also an amyloid-targeting therapy, in an early-stage study. Prothena is also developing a dual Aβ-tau vaccine, PRX123, a potential prevention and treatment for AD.

BIIB’s Zacks Rank & Stock to Consider

Biogen currently carries a Zacks Rank #3 (Hold).

A better-ranked stock from the sector is Castle Biosciences CSTL, which currently sportsa Zacks Rank #1 (Strong Buy). You can see the complete list of today’s Zacks #1 Rank stocks here.

In the past 30 days, Castle Biosciences’ earnings estimates for 2024 have increased from 34 cents to 39 cents per share. During the same timeframe, the loss per share for 2025 has improved from $1.84 to $1.70. In the past three months, shares of Castle Biosciences have plunged 16%.

CSTL’s earnings beat estimates in each of the trailing four quarters, delivering an average surprise of 172.72%.

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