Eisai Co., Ltd. (Headquarters: Tokyo, CEO: Haruo Naito, “Eisai”) and Biogen Inc. (Nasdaq: BIIB, Corporate headquarters: Cambridge, Massachusetts, CEO: Christopher A. Viehbacher, “Biogen”) announced today that the humanized amyloid-beta (Aβ) monoclonal antibody “Leqembi?” (brand name, generic name: lecanemab) has been granted a Marketing Authorization by the Medicines and Healthcare products Regulatory Agency (MHRA) in Great Britain. Lecanemab is indicated for the treatment of mild cognitive impairment (MCI) and mild dementia due to Alzheimer’s disease (AD) in adult patients that are apolipoprotein E ε4 (ApoE ε4)* heterozygotes or non-carriers.1 Lecanemab becomes the first treatment for early AD (MCI and mild dementia due to AD) that targets an underlying cause of the disease, to be authorized in a country in Europe.

Lecanemab selectively binds to Aβ aggregate species, with preferential activity for toxic Aβ protofibrils**
(as well as fibrils, which are a major component of Aβ plaques). It binds to these aggregate Aβ
species to neutralize and clear them from the brain.

The approval was primarily based on Phase 3 data from Eisai’s global, placebo-controlled, double-blind,
parallel-group, randomized Clarity AD clinical trial, in which the medicine met its primary endpoint
(change from baseline in the Clinical Dementia Rating Sum of Boxes [CDR-SB]? at 18 months) and all
key secondary endpoints with statistically significant results. In the indicated population in Great Britain,
the most common adverse reactions were infusion-related reaction, amyloid-related imaging
abnormalities with hemorrhage (small spots of bleeding) (ARIA-H)?, fall, headache and amyloid-related
imaging abnormalities with cerebral edema (build-up of fluid) (ARIA-E)??.

In the United Kingdom, it is estimated that 982,000 people are living with dementia, and AD is the
cause in 60-70% of people with dementia. These numbers are expected to rise, as the population
ages.

Eisai is working collaboratively with the National Institute for Health and Care Excellence (NICE), the
Scottish Medicines Consortium (SMC) and the National Health Service (NHS) to make this medicine
available to eligible people living with early AD as soon as possible.

Eisai serves as the lead for lecanemab’s development and regulatory submissions globally with Eisai
and Biogen co-commercializing and co-promoting the product and Eisai having final decision-making
authority. In Great Britain, Eisai and Biogen will co-promote the medicine, with Eisai distributing the
product as the Marketing Authorization holder.

*Apolipoprotein E is a protein involved in the metabolism of fats in humans. It is implicated in AD.

**Protofibrils are thought to be the most toxic Aβ species that contribute to brain damage in AD and play a major role in the cognitive decline of this progressive and devastating disease. Protofibrils can cause neuronal damage in the brain, which can subsequently adversely affect cognitive function through multiple mechanisms.? The mechanism by which this occurs has been reported not only by increasing the formation of insoluble Aβ plaques, but also by directly damaging signaling between neurons and other cells. It is believed that reducing protofibrils may reduce neuronal damage and cognitive impairment, potentially preventing the progression of AD.

?CDR-SB is a commonly used diagnostic tool, which can help to stage dementia due to AD. It is a global cognitive and functional scale that measures six domains of functioning, including memory, orientation, judgement and problem solving, community affairs, home and hobbies, and personal care.

?ARIA-H: amyloid-related imaging abnormalities with hemorrhage (microhemorrhages, and superficial siderosis).

??ARIA-E: amyloid-related imaging abnormalities with oedema (edema/effusion).

 

Eisai Co., Ltd. (Headquarters: Tokyo, CEO: Haruo Naito, “Eisai”) reconfirmed today that the regulatory
status for anti-amyloid beta (Aβ) protofibril antibody LEQEMBI? (generic name: lecanemab) subcutaneous
(SC) autoinjector, explained at the Financial Disclosure Meeting on August 2, 2024, is as follows.

 

The SC formulation (including initiation and maintenance dosing) received Fast Track designation from the
U.S. Food and Drug Administration (FDA). In agreement with the FDA, Eisai initiated a rolling submission
and review for SC maintenance dosing in May 2024. In parallel, discussions are ongoing with the FDA
regarding optimal dosage and the fastest regulatory pathway for the SC initiation dosing. There are no
changes to the previously announced timeline for the SC application at this time. We expect to complete
the rolling application for SC maintenance dosing in the third quarter of fiscal year 2024 ending March
2025, with a review period of six months if designated for priority review or ten months under standard
review. For SC initiation dosing, we aim to obtain a regulatory approval by the end of fiscal year 2025
ending March 2026.

A supplemental Biologics License Application (sBLA) for intravenous (IV) maintenance dosing was
submitted to the FDA in March 2024 and accepted in June of the same year. The PDUFA (Prescription
Drugs User Fee Act) action date is set for January 25, 2025.

Eisai is committed to making the IV maintenance dosing and SC formulation available as new treatment
options to people with early AD as soon as possible.

Eisai serves as the lead for lecanemab’s development and regulatory submissions globally with both Eisai
and Biogen co-commercializing and co-promoting the product and Eisai having final decision-making
authority.

TOKYO and CAMBRIDGE, Mass., May 27, 2024 – Eisai Co., Ltd. (Headquarters: Tokyo, CEO: Haruo
Naito, “Eisai”) and Biogen Inc. (Nasdaq: BIIB, Corporate headquarters: Cambridge, Massachusetts,
CEO: Christopher A. Viehbacher, “Biogen”) announced today that the Ministry of Food and Drug Safety
(MFDS) in South Korea has approved humanized anti-soluble aggregated amyloid-beta (Aβ)
monoclonal antibody “LEQEMBI?” (lecanemab) for treatment in adult patients with mild cognitive
impairment due to Alzheimer’s disease (AD) or mild AD (early AD).

LEQEMBI selectively binds to soluble Aβ aggregates (protofibrils*), as well as insoluble Aβ aggregates
(fibrils) which are a major component of Aβ plaques in AD, thereby reducing both Aβ protofibrils and Aβ
plaques in the brain. LEQEMBI is the first and only approved treatment shown to reduce the rate of
disease progression and to slow cognitive and functional decline through this mechanism. South Korea
is the fourth country to grant approval, following approvals in the U.S., Japan, and China.

It is estimated there were approximately 900,000 dementia patients in South Korea in 2021,1 with one
in ten people over the age of 65 suffering from dementia, and one in five from mild cognitive impairment
(MCI). The average annual nursing care and medical costs per dementia patient is estimated to be
21.1 million KRW, while the cost for patients with severe dementia reaches 33.1 million KRW.

Eisai serves as the lead of LEQEMBI development and regulatory submissions globally with both Eisai
and Biogen co-commercializing and co-promoting the product and Eisai having final decision-making
authority. In South Korea, Eisai Korea Inc. will distribute the product and conduct information provision
activities. Eisai is committed to working together with healthcare professionals and other stakeholders
to realize the early diagnosis and treatment of AD.

* Protofibrils are believed to contribute to the brain injury that occurs with AD and are considered to be
the most toxic form of Aβ, having a primary role in the cognitive decline associated with this
progressive, debilitating condition. Protofibrils cause injury to neurons in the brain, which in turn, can
negatively impact cognitive function via multiple mechanisms, not only increasing the development
of insoluble Aβ plaques but also increasing direct damage to brain cell membranes and the
connections that transmit signals between nerve cells or nerve cells and other cells. It is believed the
reduction of protofibrils may prevent the progression of AD by reducing damage to neurons in the
brain and cognitive dysfunction.

ADDRESSING MEDICAL NEEDS FOR PATIENTS WHO CANNOT TAKE THE MEDICATION ORALLY

Eisai Co., Ltd. (Headquarters: Tokyo, CEO: Haruo Naito, “Eisai”) announced today that the injection formulation of its in-house discovered antiepileptic drug (AED) Fycompa? (perampanel hydrate) for intravenous (IV) infusion has been launched in Japan. The injection formulation of Fycompa received manufacturing and marketing approval on January 18, 2024 and was included in the Japan’s National Health Insurance (NHI) Drug Price List today.

Fycompa is a first-in-class AED discovered at Eisai’s Tsukuba Research Laboratories. The agent is a selective, noncompetitive AMPA receptor antagonist that is postulated to reduce neuronal hyper-excitation associated with seizures by targeting glutamate activity at AMPA receptors on postsynaptic membranes.

Two oral formulations of Fycompa are available in Japan: a tablet and a fine granule formulation. Due to concern about the risks of seizures associated with interruption of administration when the drug cannot be taken orally temporarily, such as during surgery, it is suggested that epilepsy patients should continue treatment via routes other than oral administration.

Since Fycompa is the only AMPA receptor antagonist-based AED, Eisai developed this injection formulation to meet the needs of patients who are unable to use oral administration, and leading to the launch today.

Eisai considers neurology, including epilepsy, a therapeutic area of focus. As a human health care company, Eisai pursues its mission to provide “seizure freedom” to a greater number of patients with epilepsy. Eisai remains committed to further addressing the diverse needs of, and increasing the benefits provided to, patients with epilepsy and their families.

Media Inquiries:
Public Relations Department,
Eisai Co., Ltd.
+81-(0)3-3817-5120