Update on Regulatory Review of Lecanemab
for Early Alzheimer’s Disease in the European UnionTOKYO and CAMBRIDGE, Mass., July 26, 2024 – Eisai Co., Ltd. (Headquarters: Tokyo, CEO: HaruoNaito, “Eisai”) and Biogen Inc. (Nasdaq: BIIB, Corporate headquarters: Cambridge, Massachusetts,
CEO: Christopher A. Viehbacher, “Biogen”) announced today that the Committee for Medicinal
Products for Human Use (CHMP) of the European Medicines Agency (EMA) has adopted a negative
opinion on the Marketing Authorization Approval (MAA) for the humanized anti-soluble aggregatedamyloid-beta (Aβ) monoclonal antibody lecanemab as treatment for early AD (mild cognitive impairment
due to Alzheimer’s disease (AD) and mild AD). 1“We are extremely disappointed by the CHMP’s negative opinion and understand that this may also bedisappointing for the wider Alzheimer’s disease (AD) community. AD is an irreversible,neurodegenerative disease that poses significant challenges to those living with AD, their care partners
and society,” said Lynn Kramer, M.D., Chief Clinical Officer at Eisai. “There is a significant unmet needfor new innovative treatment options that target an underlying cause of disease progression. We remain
focused on making a meaningful difference to those living with early AD and those closest to them.”
Eisai will seek re-examination of the CHMP opinion and work with the relevant authorities to ensure thistreatment is available for eligible people living with early AD in the European Union (EU) as soon aspossible.
Lecanemab is already approved in the United States, Japan, China, South Korea, Hong Kong and Israel,and is being marketed in the U.S., Japan and China
AD currently affects 6.9 million people in Europe,2 and this figure is expected to nearly double by 2050
as aging populations increase.3
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 decisionmaking authority.
MEDIA CONTACTS
Eisai Co., Ltd.
Public Relations Department
TEL: +81 (0)3-3817-5120
Eisai Europe, Ltd.
EMEA Communications Department+44 (0) 786 601 1272
Emea-comms@eisai.net

Biogen Inc.
Jack Cox+ 1-781-464-3260
public.affairs@biogen.com

Eisai Inc. (U.S.)
Libby Holman+1-201-753-1945
Libby_Holman@eisai.com

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INVESTOR CONTACTS
Eisai Co., Ltd.
Investor Relations Department
TEL: +81 (0) 3-3817-5122

Biogen Inc.
Chuck Triano+ 1-781-464-2442
IR@biogen.com

Notes to Editors
1. About lecanemab (generic name, brand name: Leqembi®)
Lecanemab is the result of a strategic research alliance between Eisai and BioArctic. It is ahumanized immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregatedsoluble (protofibril) and insoluble forms of amyloid-beta (Aβ).
Lecanemab is approved in the U.S., Japan, China, South Korea, Hong Kong and Israel for thetreatment of MCI due to AD and mild AD dementia. Lecanemab’s approvals in these countries werebased on Phase 3 data from Eisai’s, global Clarity AD clinical trial, in which it met its primary
endpoint and all key secondary endpoints with statistically significant results.4,5 The primary
endpoint was the global cognitive and functional scale, Clinical Dementia Rating Sum of Boxes(CDR-SB). In the Clarity AD clinical trial, treatment with lecanemab reduced clinical decline on CDRSB by 27% at 18 months compared to placebo.4 The mean CDR-SB score at baseline wasapproximately 3.2 in both groups. The adjusted least-squares mean change from baseline at 18months was 1.21 with lecanemab and 1.66 with placebo (difference, −0.45; 95% confidence interval[CI], −0.67 to −0.23; P<0.001).4 In addition, the secondary endpoint from the AD Cooperative StudyActivities of Daily Living Scale for Mild Cognitive Impairment (ADCS-MCI-ADL), which measuresinformation provided by people caring for patients with AD, noted a statistically significant benefitof 37% compared to placebo.4 The adjusted mean change from baseline at 18 months in the ADCSMCI-ADL score was −3.5 in the lecanemab group and −5.5 in the placebo group (difference, 2.0;
95% CI, 1.2 to 2.8; P<0.001).4 The ADCS MCI-ADL assesses the ability of patients to function
independently, including being able to dress, feed themselves and participate in communityactivities. The most common adverse events (>10%) in the lecanemab group were infusion
reactions, ARIA-H (combined cerebral microhemorrhages, cerebral macrohemorrhages, andsuperficial siderosis), ARIA-E (edema/effusion), headache, and fall.4
Eisai has submitted applications for approval of lecanemab in 12 countries and regions, including
the European Union (EU). A supplemental Biologics License Application (sBLA) for intravenous
maintenance dosing was submitted to the U.S. Food and Drug Administration (FDA) in March 2024,
which was accepted in June 2024. The rolling submission of a Biologics License Application (BLA)
for maintenance dosing of a subcutaneous injection formulation, which is being developed toenhance convenience for patients, was initiated in the U.S. under Fast Track status in May 2024.
Since July 2020 the Phase 3 clinical study (AHEAD 3-45) for individuals with preclinical AD,
meaning they are clinically normal and have intermediate or elevated levels of amyloid in theirbrains, is ongoing. AHEAD 3-45 is conducted as a public-private partnership between theAlzheimer's Clinical Trial Consortium that provides the infrastructure for academic clinical trials in
AD and related dementias in the U.S, funded by the National Institute on Aging, part of the National
Institutes of Health, Eisai and Biogen. Since January 2022, the Tau NexGen clinical study for
Dominantly Inherited AD (DIAD), that is conducted by Dominantly Inherited Alzheimer NetworkTrials Unit (DIAN-TU), led by Washington University School of Medicine in St. Louis, is ongoing andincludes lecanemab as the backbone anti-amyloid therapy.
2. About the Collaboration between Eisai and Biogen for AD
Eisai and Biogen have been collaborating on the joint development and commercialization of AD
treatments since 2014. Eisai serves as the lead of lecanemab development and regulatory
submissions globally with both companies co-commercializing and co-promoting the product andEisai having final decision-making authority.

23. About the Collaboration between Eisai and BioArctic for ADSince 2005, Eisai and BioArctic have had a long-term collaboration regarding the development andcommercialization of AD treatments. Eisai obtained the global rights to study, develop, manufacture
and market lecanemab for the treatment of AD pursuant to an agreement with BioArctic inDecember 2007. The development and commercialization agreement on the antibody lecanemab
back-up was signed in May 2015.
4. About Eisai Co., Ltd.
Eisai's Corporate Concept is "to give first thought to patients and people in the daily living domain,
and to increase the benefits that health care provides." Under this Concept (also known as humanhealth care (hhc) Concept), we aim to effectively achieve social good in the form of relieving anxiety
over health and reducing health disparities. With a global network of R&D facilities, manufacturing
sites and marketing subsidiaries, we strive to create and deliver innovative products to target
diseases with high unmet medical needs, with a particular focus in our strategic areas of Neurologyand Oncology.
In addition, we demonstrate our commitment to the elimination of neglected tropical diseases(NTDs), which is a target (3.3) of the United Nations Sustainable Development Goals (SDGs), byworking on various activities together with global partners.
For more information about Eisai, please visit www.eisai.com (for global headquarters: Eisai Co.,Ltd.), and connect with us on X, LinkedIn and Facebook. The website and social media channels
are intended for audiences outside of the UK and Europe. For audiences based in the UK andEurope, please visit www.eisai.eu and Eisai EMEA LinkedIn.
5. About Biogen
Founded in 1978, Biogen is a leading biotechnology company that pioneers innovative science todeliver new medicines to transform patient’s lives and to create value for shareholders and ourcommunities. We apply deep understanding of human biology and leverage different modalities toadvance first-in-class treatments or therapies that deliver superior outcomes. Our approach is totake bold risks, balanced with return on investment to deliver long-term growth.
The company routinely posts information that may be important to investors on its website
at www.biogen.com. Follow Biogen on social media – Facebook, LinkedIn, X, YouTube. The
website and social media channels are intended for audiences outside of the UK and Europe.
Biogen Safe Harbor
This news release contains forward-looking statements, about the potential clinical effects oflecanemab; the potential benefits, safety and efficacy of lecanemab; potential regulatory
discussions, submissions and approvals and the timing thereof; the treatment of Alzheimer'sdisease; the anticipated benefits and potential of Biogen's collaboration arrangements with Eisai;
the potential of Biogen's commercial business and pipeline programs, including lecanemab; andrisks and uncertainties associated with drug development and commercialization. Thesestatements may be identified by words such as "aim," "anticipate," "believe," "could," "estimate,""expect," "forecast," "intend," "may," "plan," "possible," "potential," "will," "would" and other words
and terms of similar meaning. Drug development and commercialization involve a high degree ofrisk, and only a small number of research and development programs result in commercializationof a product. Results in early-stage clinical studies may not be indicative of full results or resultsfrom later stage or larger scale clinical studies and do not ensure regulatory approval. You should
not place undue reliance on these statements.
These statements involve risks and uncertainties that could cause actual results to differ materiallyfrom those reflected in such statements, including without limitation unexpected concerns that may
arise from additional data, analysis or results obtained during clinical studies; the occurrence of3adverse safety events; risks of unexpected costs or delays; the risk of other unexpected hurdles;
regulatory submissions may take longer or be more difficult to complete than expected; regulatory
authorities may require additional information or further studies, or may fail or refuse to approve or
may delay approval of Biogen's drug candidates, including lecanemab; actual timing and content ofsubmissions to and decisions made by the regulatory authorities regarding lecanemab; uncertainty
of success in the development and potential commercialization of lecanemab; failure to protect andenforce Biogen's data, intellectual property and other proprietary rights and uncertainties relating tointellectual property claims and challenges; product liability claims; and third party collaboration
risks, results of operations and financial condition. The foregoing sets forth many, but not all, of thefactors that could cause actual results to differ from Biogen's expectations in any forward-lookingstatement. Investors should consider this cautionary statement as well as the risk factors identified
in Biogen's most recent annual or quarterly report and in other reports Biogen has filed with the U.S.
Securities and Exchange Commission. These statements speak only as of the date of this news
release. Biogen does not undertake any obligation to publicly update any forward-looking
statements.

References
1 Meeting highlights from the Committee for Medicinal Products for Human Use (CHMP) 22-25 July2024 https://www.ema.europa.eu/en/news/meeting-highlights-committee-medicinal-products-humanuse-chmp-22-25-july-2024.
2 Gustavsson, A., et al. Global estimates on the number of persons across the Alzheimer's disease
continuum. Alzheimer’s & Dementia. 2023;19:658-670. https://alzjournals.onlinelibrary.wiley.com/doi/full/10.1002/alz.12694.
3 Alzheimer Europe. Prevalence of dementia in Europe. Available at: https://www.alzheimereurope.org/dementia/prevalence-dementia-europe.
4 van Dyck, H., et al. Lecanemab in Early Alzheimer’s Disease. New England Journal of Medicine.
2023;388:9-21. https://www.nejm.org/doi/full/10.1056/NEJMoa2212948.
5 Eisai Global. 2023. Eisai Presents Full Results of Lecanemab Phase 3 Confirmatory Clarity AD
Study for early Alzheimer’s Disease at Clinical Trials on Alzheimer’s Disease (CTAD) Conference.
Available at: https://www.eisai.com/news/2022/news202285.html. Last accessed: July 2024.

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