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

Merck & Co., Inc., Rahway, NJ, USA
Investor RelationsPeter Dannenbaum: +1-(732) 594-1579
Damini Chokshi: +1-(732) 594-1577

Positive Scenario [Met P
rimary Endpoints of [OS/PFS]

Eisai and Merck & Co., Inc., Rahway, NJ, USA Provide
Update on Phase 3 LEAP-010 Trial Evaluating
LENVIMA® (lenvatinib) Plus KEYTRUDA® (pembrolizumab) inPatients With Certain Types of Recurrent or
Metastatic Head and Neck Squamous Cell Carcinoma
TOKYO and RAHWAY, N.J., August 25, 2023 – Eisai (Headquarters: Tokyo, CEO:Haruo Naito, “Eisai”) and Merck & Co., Inc., Rahway, NJ, USA (known as MSD outside of theUnited States and Canada) today provided an update on the Phase 3 LEAP-010 trial evaluating
LENVIMA®, the orally available multiple receptor tyrosine kinase inhibitor (TKI) discovered byEisai, plus KEYTRUDA®, the anti-PD-1 therapy from Merck & Co., Inc., Rahway, NJ, USA, as afirst-line treatment for patients with recurrent or metastatic head and neck squamous cellcarcinoma (HNSCC) whose tumors express PD-L1. The primary endpoints of the study wereoverall survival (OS), progression-free survival (PFS), and objective response rate (ORR).
Two planned interim analyses were conducted by an independent Data Monitoring
Committee (DMC) over an 11-month period. In the first analysis, LENVIMA plus KEYTRUDA
showed a statistically significant improvement in PFS and ORR versus placebo plus KEYTRUDA.
At the second analysis, LENVIMA plus KEYTRUDA did not demonstrate an improvement in OS
compared to placebo plus KEYTRUDA, and the likelihood of reaching the protocol-specified
threshold for statistical significance for OS was evaluated by Merck and Eisai and deemed to below. Accordingly, the study will be closed, and the companies are informing investigators of thisdecision. The safety profile of KEYTRUDA plus LENVIMA was consistent with previously reported
data on the combination. A full evaluation of the data from this study, including pre-plannedsubgroup analyses, is ongoing. The companies will work with investigators to share the resultswith the scientific community.
-1-“With the LEAP-010 trial, we aimed to explore whether this combination could improveupon options already available with KEYTRUDA-based regimens for appropriate patients withmetastatic or with unresectable, recurrent HNSCC,” said Dr. Gregory Lubiniecki, Vice President,
Global Clinical Development, Merck Research Laboratories. “Although the progression-freesurvival results from this study were encouraging, unfortunately the combination did not result inan overall survival benefit for patients. We will apply lessons from this trial to help continue
advancing research of this combination.”“While we were initially encouraged to see that LENVIMA plus KEYTRUDA met two of
its three primary endpoints at an earlier interim analysis, unfortunately the combination did notmeet the threshold for the third primary endpoint of overall survival.” said Corina Dutcus, M.D.,
Senior Vice President, Global Clinical Development, Oncology at Eisai Inc. “Our clinical programis designed to help accelerate our efforts to tackle difficult-to-treat, advanced cancers, and while
the outcome may not always be what we anticipate, we know that this is part of clinicaldevelopment, and we remain committed to scientific exploration in pursuit of improving care forpatients.”
LENVIMA plus KEYTRUDA is approved in the U.S., the EU, Japan and other countries
for the treatment of advanced renal cell carcinoma (RCC) and certain types of advanced
endometrial carcinoma. Lenvatinib is marketed as KISPLYX® for advanced RCC in the EU. Eisaiand Merck & Co., Inc., Rahway, NJ, USA are studying the LENVIMA plus KEYTRUDA
combination through the LEAP (LEnvatinib And Pembrolizumab) clinical program in various tumortypes, including but not limited to endometrial carcinoma, hepatocellular carcinoma, non-small
cell lung cancer, RCC, head and neck cancer, gastric cancer and esophageal cancer acrossmultiple clinical trials. KEYTRUDA is currently approved as monotherapy and in combination
regimens for appropriate patients with metastatic or with unresectable, recurrent HNSCC in theU.S., Europe, China, Japan and other countries around the world.
Results from the LEAP-010 trial do not affect the current approved indications for
LENVIMA plus KEYTRUDA or other ongoing trials from the LEAP clinical program, including theongoing LEAP-009 trial, evaluating LENVIMA in combination with KEYTRUDA versus
chemotherapy in people living with recurrent or metastatic HNSCC who progressed after platinum
therapy and immunotherapy.

About LEAP-010
LEAP-010 is a randomized, placebo-controlled, double-blinded, Phase 3 trial(ClinicalTrials.gov, NCT04199104) evaluating LENVIMA plus KEYTRUDA versus KEYTRUDA-2-monotherapy as a first-line treatment for patients with recurrent or metastatic HNSCC whosetumors express PD-L1. The trial’s three primary endpoints are OS, PFS and ORR. PFS and ORR
were assessed by blinded independent central review (BICR) per Response Evaluation Criteria
in Solid Tumors Version (RECIST) v1.1 modified to follow a maximum of 10 target lesions and amaximum of 5 target lesions per organ. The study enrolled an estimated 511 patients who wererandomized 1:1 to receive: LENVIMA (20 mg orally once daily) plus KEYTRUDA (200 mg intravenously [IV] on Day
1 of each three-week cycle); or Placebo (orally once daily) plus KEYTRUDA (200 mg IV on Day 1 of each three-weekcycle).
In both arms, KEYTRUDA was administered for up to 35 cycles (approximately two years) or until
protocol-specified discontinuation criteria were met. After completing two years of combination
therapy, LENVIMA may have been administered as a single agent until protocol-specified
discontinuation criteria were met.

About head and neck cancer
Head and neck cancer describes a number of different tumors that develop in or aroundthe throat, larynx, nose, sinuses and mouth.1 Most head and neck cancers are squamous cell
carcinomas that begin in the flat, squamous cells that make up the thin surface layer of thestructures in the head and neck.1 Two substances that greatly increase the risk of developing
head and neck cancer are tobacco and alcohol.1 Worldwide, it is estimated there were morethan 930,000 new cases of head and neck cancer diagnosed and over 465,000 deaths from thedisease in 2020.2 In the U.S., it is estimated there will be more than 66,000 new cases of headand neck cancer diagnosed and more than 15,000 deaths from the disease in 2023.3
About LENVIMA® (lenvatinib) Capsules
LENVIMA, discovered and developed by Eisai, is an orally available multiple receptor
tyrosine kinase inhibitor that inhibits the kinase activities of vascular endothelial growth factor(VEGF) receptors VEGFR1 (FLT1), VEGFR2 (KDR), and VEGFR3 (FLT4). LENVIMA inhibits
other kinases that have been implicated in pathogenic angiogenesis, tumor growth, and cancer
progression in addition to their normal cellular functions, including fibroblast growth factor (FGF)
receptors FGFR1-4, the platelet derived growth factor receptor alpha (PDGFRα), KIT, and RET.
In syngeneic mouse tumor models, LENVIMA decreased tumor-associated macrophages,
increased activated cytotoxic T cells, and demonstrated greater antitumor activity in combination-3-

with an anti-PD-1 monoclonal antibody compared to either treatment alone. LENVIMA has been
approved for the indications below.
Thyroid cancer Indication as monotherapy(Approved in over 80 countries including Japan, the United States, China, and countries in Europeand Asia)
Japan: Unresectable thyroid cancer
The United States: The treatment of patients with locally recurrent or metastatic, progressive,radioiodine-refractory differentiated thyroid cancer (DTC)
Europe: The treatment of adult patients with progressive, locally advanced or metastatic,differentiated (papillary/follicular/Hürthle cell) thyroid carcinoma (DTC), refractory to radioactive
iodine (RAI)
Hepatocellular carcinoma
 Indication as monotherapy(Approved in over 80 countries including Japan, the United States, China, and countries in Europeand Asia)
Japan: Unresectable hepatocellular carcinoma
The United States: The first-line treatment of patients with unresectable hepatocellular carcinoma(HCC)
Europe: The treatment of adult patients with advanced or unresectable hepatocellular carcinoma(HCC) who have received no prior systemic therapy
Thymic carcinoma
 Indication as monotherapy (Approved in Japan)
Japan: Unresectable thymic carcinoma
Renal cell carcinoma (In Europe, the agent was launched under the brand name Kisplyx®)
 Indication in combination with everolimus(Approved in over 65 countries including the United States, and countries in Europe and Asia)
The United States: The treatment of adult patients with advanced renal cell carcinoma (RCC)
following one prior anti-angiogenic therapy
Europe: The treatment of adult patients with advanced renal cell carcinoma following one priorvascular endothelial growth factor (VEGF) targeted therapy
 Indication in combination with KEYTRUDA-4-

(Approved in over 45 countries including Japan, the United States, and countries in Europe andAsia)
Japan: Radically unresectable or metastatic renal cell carcinoma
The United States: The first-line treatment of adult patients with advanced renal cell carcinoma
Europe: The first-line treatment of adult patients with advanced renal cell carcinoma
Endometrial carcinoma
 Indication in combination with KEYTRUDA(Approved [including conditional approval] in over 50 countries including Japan, the United States,
and countries in Europe and Asia)
Japan: Unresectable, advanced or recurrent endometrial carcinoma that progressed after cancer
chemotherapy
The United States: The treatment of patients with advanced endometrial carcinoma (EC) that ismismatch repair proficient (pMMR), as determined by an FDA-approved test, or not microsatellite
instability-high (MSI-H), who have disease progression following prior systemic therapy in any
setting and are not candidates for curative surgery or radiation.
Europe: The treatment of adult patients with advanced or recurrent endometrial carcinoma (EC)
who have disease progression on or following prior treatment with a platinum-containing therapy
in any setting and are not candidates for curative surgery
About KEYTRUDA® (pembrolizumab) Injection, 100 mg
KEYTRUDA is an anti-programmed death receptor-1 (PD-1) therapy that works byincreasing the ability of the body’s immune system to help detect and fight tumor cells.
KEYTRUDA is a humanized monoclonal antibody that blocks the interaction between PD-1 andits ligands, PD-L1 and PD-L2, thereby activating T lymphocytes which may affect both tumor cells
and healthy cells.
Merck & Co., Inc., Rahway, NJ, USA has the industry’s largest immuno-oncology clinicalresearch program. There are currently more than 1,600 trials studying KEYTRUDA across a wide
variety of cancers and treatment settings. The KEYTRUDA clinical program seeks to understandthe role of KEYTRUDA across cancers and the factors that may predict a patient's likelihood of
benefitting from treatment with KEYTRUDA, including exploring several different biomarkers.

About the Eisai and Merck & Co., Inc., Rahway, NJ, USA Strategic Collaboration
In March 2018, Eisai and Merck & Co., Inc., Rahway, NJ, USA, known as MSD outside of
the United States and Canada, through an affiliate, entered into a strategic collaboration for the-5-

worldwide co-development and co-commercialization of LENVIMA. Under the agreement, thecompanies will jointly develop, manufacture and commercialize LENVIMA, both as monotherapy
and in combination with KEYTRUDA, the anti-PD-1 therapy from Merck & Co., Inc., Rahway, NJ,USA.
In addition to ongoing clinical studies evaluating the LENVIMA plus KEYTRUDA
combination across several different tumor types, the companies have jointly initiated clinicalstudies through the LEAP (LEnvatinib And Pembrolizumab) clinical program and are evaluating
the combination in various tumor types across multiple clinical trials.
Eisai’s Focus on CancerEisai acknowledges “Oncology” as one of its key strategic areas, and will continue to focus
on the discovery and development of anti-cancer drugs within drug discovery domains including“microenvironment”, “proteostasis disruption”, “cell lineage and cell differentiation”, and“inflammation, hypoxia, oxidative stress and cell senescence” under the Deep Human Biology
Learning (DHBL) drug discovery and development organization. Eisai aspires to discover
innovative new drugs with new targets and mechanisms of action from these domains, with theaim of contributing to the cure of cancers.

About Eisai
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 our human health care (hhc) Concept], we aim to effectively achieve social good in the form ofrelieving 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 Neurology and Oncology.
In addition, our continued commitment to the elimination of neglected tropical diseases(NTDs), which is a target (3.3) of the United Nations Sustainable Development Goals (SDGs), isdemonstrated by our work on various activities together with global partners.
For more information about Eisai, please visit www.eisai.com (for global headquarters:Eisai. Co., Ltd.), us.eisai.com (for U.S. headquarters: Eisai, Inc.) or www.eisai.eu (for Europe,Middle East, Africa, Russia, Australia and New Zealand headquarters: Eisai Europe Ltd.), andconnect with us on Twitter (U.S. and global) and LinkedIn (for U.S. and EMEA).

-6-Merck & Co., Inc., Rahway, NJ, USA’s Focus on Cancer
Our goal is to translate breakthrough science into innovative oncology medicines to help
people with cancer worldwide. At Merck & Co., Inc., Rahway, NJ, USA, the potential to bring newhope to people with cancer drives our purpose and supporting accessibility to our cancer
medicines is our commitment. As part of our focus on cancer, Merck & Co., Inc., Rahway, NJ,
USA is committed to exploring the potential of immuno-oncology with one of the largest
development programs in the industry across more than 30 tumor types. We also continue tostrengthen our portfolio through strategic acquisitions and are prioritizing the development ofseveral promising oncology candidates with the potential to improve the treatment of advancedcancers. For more information about our oncology clinical trials, visit www.merck.com/clinicaltrials.

About Merck & Co., Inc., Rahway, NJ, USA
For over 130 years, Merck & Co., Inc., Rahway, NJ, USA, known as MSD outside of theUnited States and Canada, has been inventing for life, bringing forward medicines and vaccines
for many of the world’s most challenging diseases in pursuit of our mission to save and improve
lives. We demonstrate our commitment to patients and population health by increasing access tohealth care through far-reaching policies, programs and partnerships. Today, Merck & Co., Inc.,
Rahway, NJ, USA continues to be at the forefront of research to prevent and treat diseases thatthreaten people and animals – including cancer, infectious diseases such as HIV and Ebola, andemerging animal diseases – as we aspire to be the premier research-intensive biopharmaceuticalcompany in the world. For more information, visit www.merck.com and connect with us on Twitter,Facebook, Instagram, YouTube and LinkedIn.

Forward-Looking Statement of Merck & Co., Inc., Rahway, NJ, USA
This news release of Merck & Co., Inc., Rahway, NJ, USA (the “company”) includes“forward-looking statements” within the meaning of the safe harbor provisions of the U.S. Private
Securities Litigation Reform Act of 1995. These statements are based upon the current beliefs
and expectations of the company’s management and are subject to significant risks anduncertainties. There can be no guarantees with respect to pipeline candidates that the candidates
will receive the necessary regulatory approvals or that they will prove to be commerciallysuccessful. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual
results may differ materially from those set forth in the forward-looking statements.
Risks and uncertainties include but are not limited to, general industry conditions andcompetition; general economic factors, including interest rate and currency exchange rate-7-fluctuations; the impact of the global outbreak of novel coronavirus disease (COVID-19); theimpact of pharmaceutical industry regulation and health care legislation in the United States andinternationally; global trends toward health care cost containment; technological advances, newproducts and patents attained by competitors; challenges inherent in new product development,
including obtaining regulatory approval; the company’s ability to accurately predict future marketconditions; manufacturing difficulties or delays; financial instability of international economies andsovereign risk; dependence on the effectiveness of the company’s patents and other protections
for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory
actions.
The company undertakes no obligation to publicly update any forward-looking statement,
whether as a result of new information, future events or otherwise. Additional factors that could
cause results to differ materially from those described in the forward-looking statements can befound in the company’s Annual Report on Form 10-K for the year ended December 31, 2022 andthe company’s other filings with the Securities and Exchange Commission (SEC) available at theSEC’s Internet site (www.sec.gov).
Cancer Net. Website, “introduction.” Head and Neck Cancer.
https://www.cancer.net/cancer-types/head-and-neck-cancer/introduction .
International Agency for Research on Cancer, World Health Organization. Cancer Today, 2020.
Cancer Today (iarc.fr) .
3Cancer Net. Website, “statistics.” Head and Neck Cancer.
https://www.cancer.net/cancer-types/head-and-neck-cancer/statistics .
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