RAHWAY, N.J., March 13, 2024 – Our company’s foundation, a private charitable organization funded by MSD (tradename of Merck & Co., Inc., Rahway, N.J., USA), has made an $11 million, six-year (2023 – 2028) commitment to University of New Mexico Health (UNM Health) in support of its new initiative to bring high-quality care to an estimated 11 million people living with cancer in underserved communities throughout India, Indonesia, Malaysia and Vietnam. The new initiative aims to train and mentor more than 33,000 local health workers and is being led by Project ECHO® at UNM Health, a global movement to democratize knowledge and expand access to best-practice care.

This support builds on a $7 million, five-year commitment our company’s foundation made to UNM Health in 2017. Project ECHO used that funding to help improve access to high-quality specialty care for complex chronic conditions, such as hepatitis C, HIV and tuberculosis, and non-communicable diseases, like diabetes, in underserved areas aross India and Vietnam.

Our company’s foundation is committed to advancing global health equity and will continue to support innovative initiatives that aim to improve the health and well-being of people around the world.

About Our Company’s Foundation

Our company’s foundation (Foundation) is a U.S.-based, private charitable organization. Established in 1957 by MSD (tradename of Merck & Co., Inc., Rahway, N.J., USA), a leading global biopharmaceutical company, the Foundation is funded entirely by the company and is MSD’s chief source of funding support to qualified non-profit charitable organizations. Since its inception, the Foundation has contributed more than $1 billion to support important initiatives that address critical global health and societal needs that are consistent with MSD’s purpose: to save and improve lives around the world. For more information, visit www.msd.com/company-overview/sustainability/philanthropy/.

Media Contact:

Olivia Finucane

+44 7881 262476

olivia.finucane@msd.com

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Acquisition broadens oncology pipeline with a portfolio of novel T-cell engagers including HPN328 (MK-6070), an investigational delta-like ligand 3 (DLL3) targeting T-cell engager

RAHWAY, N.J., March 11, 2024 – MSD (tradename of Merck & Co., Inc., Rahway, N.J., USA) (NYSE: MRK) today announced the completion of the acquisition of Harpoon Therapeutics, Inc. (Nasdaq: HARP). Harpoon is now a wholly-owned subsidiary of MSD, and Harpoon’s common stock will no longer be publicly traded or listed on the Nasdaq Stock Market.

“We continue to augment and diversify our oncology pipeline with innovative approaches to help people with cancer worldwide,” said Dr. Dean Y. Li, president, MSD Research Laboratories. “We are pleased to welcome our Harpoon colleagues to MSD and look forward to working together to advance a novel portfolio of T-cell engagers, including MK-6070.”

Harpoon’s lead candidate, MK-6070 (formerly known as HPN328), is a T-cell engager targeting delta-like ligand 3 (DLL3), an inhibitory canonical Notch ligand that is expressed at high levels in small cell lung cancer (SCLC) and neuroendocrine tumors. The safety, tolerability and pharmacokinetics of MK-6070 is currently being evaluated as monotherapy in a Phase 1/2 clinical trial (NCT04471727) in certain patients with advanced cancers associated with expression of DLL3. The study is also evaluating MK-6070 in combination with atezolizumab in certain patients with SCLC. In March 2022, the U.S. Food and Drug Administration (FDA) granted Orphan Drug Designation to MK-6070 for the treatment of SCLC.

Additional pipeline candidates include HPN217, a T-cell engager targeting B-cell maturation antigen (BCMA), currently in Phase 1 clinical development for the treatment of patients with relapsed/refractory multiple myeloma, and several preclinical stage candidates, including HPN601, a conditionally activated targeting epithelial cell adhesion molecule (EpCAM) for the treatment of certain patients with EpCAM expressing tumors.

Transaction details

Under the terms of the merger agreement, MSD, through a subsidiary, has acquired all outstanding shares of Harpoon. As previously disclosed, this transaction is being accounted for as an asset acquisition. MSD is recording a non-tax deductible charge of approximately $650 million of R&D expense. The impact of the transaction on expected full-year non-GAAP EPS is approximately $0.26 per share, which was included in MSD’s full-year 2024 financial outlook issued on February 1, 2024.

MSD’s focus on cancer

Our goal is to translate breakthrough science into innovative oncology medicines to help people with cancer worldwide. At MSD, the potential to bring new hope to people with cancer drives our purpose and supporting accessibility to our cancer medicines is our commitment. As part of our focus on cancer, MSD 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 to strengthen our portfolio through strategic acquisitions and are prioritizing the development of several promising oncology candidates with the potential to improve the treatment of advanced cancers.

About MSD

At MSD, known as Merck & Co., Inc., Rahway, N.J., USA in the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.msd.com and connect with us on X (formerly Twitter), LinkedIn and YouTube.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

This news release of Merck & Co., Inc., Rahway, N.J., 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 and uncertainties. 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 commercially successful. 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 and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign 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 be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2023, and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov).

MSD Media Contacts:

Robert Josephson

(203) 914-2372

Justine Moore

(347) 281-3754

MSD Investor Contacts:

Peter Dannenbaum

(732) 594-1579

Damini Chokshi

(732) 594-1577

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Acquisition includes HPN328, an investigational delta-like ligand 3 (DLL3) targeting T-cell engager being evaluated in certain patients with small cell lung cancer and neuroendocrine tumors

RAHWAY, N.J., and SOUTH SAN FRANCISCO, Calif., Jan. 8, 2024 – MSD (tradename of Merck & Co., Inc., Rahway, N.J., USA) (NYSE: MRK), and Harpoon Therapeutics, Inc. (Nasdaq: HARP) today announced that the companies have entered into a definitive agreement under which MSD, through a subsidiary, will acquire Harpoon for $23.00 per share in cash for an approximate total equity value of $680 million.

“At MSD, we continue to enhance our oncology pipeline through strategic acquisitions that complement our current portfolio and advance breakthrough science to help address the needs of people with cancer worldwide,” said Dr. Dean Y. Li, president, MSD Research Laboratories. “This agreement reflects the creativity and commitment of scientists and clinical development teams at Harpoon. We look forward to further evaluating HPN328 in innovative combinations with other pipeline candidates.”

Harpoon has developed a portfolio of novel T-cell engagers that employ the company’s proprietary Tri-specific T cell Activating Construct (TriTAC®) platform, an engineered protein technology designed to direct a patient’s own immune cells to kill tumor cells, and ProTriTAC™ platform, applying a prodrug concept to its TriTAC® platform to create a therapeutic T-cell engager that is designed to remain inactive until it reaches the tumor.

“At Harpoon, we have always been committed to advancing our cancer immunotherapy candidates to improve the lives of patients. With MSD’s recognized leadership in oncology clinical development and global commercial footprint, our lead candidate, HPN328, is well positioned moving forward,” said Julie Eastland, president and chief executive officer, Harpoon Therapeutics. “The talented, passionate and dedicated Harpoon team has made great progress over the past eight years in leveraging our research platform to develop an innovative suite of candidates, and we are pleased that MSD has recognized the significant potential of our pipeline. I want to personally thank all of our key stakeholders, including our entire team at Harpoon, trial participants, physicians and our shareholders, who have supported us.”

Harpoon’s lead candidate, HPN328, is a T-cell engager targeting delta-like ligand 3 (DLL3), an inhibitory canonical Notch ligand that is expressed at high levels in small cell lung cancer (SCLC) and neuroendocrine tumors. HPN328 is currently being evaluated in a Phase 1/2 clinical trial (NCT04471727) evaluating the safety, tolerability and pharmacokinetics of HPN328 monotherapy in patients with advanced cancers associated with expression of DLL3. The study is also evaluating HPN328 in combination with atezolizumab in patients with SCLC. In October 2023, Harpoon announced the presentation of positive interim tolerability and response data for HPN328 in certain patients with SCLC and neuroendocrine tumors.

Additional pipeline candidates include HPN217 targeting B-cell maturation antigen (BCMA), currently in Phase 1 clinical development for the treatment of patients with relapsed/refractory multiple myeloma, and several preclinical stage candidates, including HPN601, a conditionally activated targeting epithelial cell adhesion molecule (EpCAM) for the treatment of certain patients with EpCAM expressing tumors.

Under the terms of the agreement, MSD, through a subsidiary, will acquire all outstanding shares of Harpoon Therapeutics, Inc. for a price per share of $23.00 in cash. The Board of Directors of Harpoon has unanimously approved the transaction. Closing of the acquisition is subject to certain conditions, including approval of the merger by Harpoon’s stockholders, the expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act, and other customary conditions. The transaction is expected to close in the first half of 2024 and will be accounted for as an asset acquisition. MSD expects to record a charge (non-tax deductible) of approximately $650 million, or approximately $0.26 per share, that will be included in non-GAAP results in the quarter that the transaction closes.

Advisors

Evercore Group L.L.C. acted as financial advisor to MSD in this transaction and Covington & Burling LLP acted as its legal advisor. Centerview Partners LLC acted as financial advisor to Harpoon and Goodwin Procter LLP acted as its legal advisor.

About HPN328

HPN328 targets delta-like ligand 3 (DLL3), an inhibitory canonical Notch ligand. HPN328 uses Harpoon’s proprietary Tri-specific T cell Activating Construct (TriTAC^®) platform that is designed to recruit a patient’s own immune cells to kill tumor cells. HPN328 is being evaluated as monotherapy and in combination in an ongoing open-label, multicenter two-part study (NCT04471727) to assess the safety, tolerability, and pharmacokinetics in patients with certain advanced cancers associated with expression of DLL3.

In March 2022, the U.S. Food and Drug Administration (FDA) granted Orphan Drug Designation to HPN328 for the treatment of small cell lung cancer.

About TriTACs

TriTACs are novel investigational T-cell-engaging therapeutic proteins optimized for the treatment of solid tumors. TriTACs have an extended serum half-life and may be manufactured using routine biologic techniques.

MSD’s focus on cancer

Our goal is to translate breakthrough science into innovative oncology medicines to help people with cancer worldwide. At MSD, the potential to bring new hope to people with cancer drives our purpose and supporting accessibility to our cancer medicines is our commitment. As part of our focus on cancer, MSD 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 to strengthen our portfolio through strategic acquisitions and are prioritizing the development of several promising oncology candidates with the potential to improve the treatment of advanced cancers.

About Harpoon Therapeutics

Harpoon Therapeutics is a clinical-stage immunotherapy company developing a novel class of T-cell engagers designed to harness the power of the body’s immune system to treat patients suffering from cancer and other diseases. T-cell engagers are engineered proteins that direct a patient’s own T-cells to kill target cells that express specific proteins, or antigens, carried by the target cells. Using its proprietary Tri-specific T cell Activating Construct (TriTAC^®) platform, Harpoon is developing a pipeline of novel TriTACs initially focused on the treatment of certain types of solid tumors and hematologic malignancies. Harpoon has also developed a proprietary ProTriTAC™ platform, which applies a prodrug concept to its TriTAC platform to create a therapeutic T-cell engager that is designed to remain inactive until it reaches the tumor. Harpoon’s third proprietary technology platform, extended release TriTAC-XR, is designed to mitigate cytokine release syndrome. For additional information about Harpoon Therapeutics, please visit www.harpoontx.com.

About MSD

At MSD, known as Merck & Co., Inc., Rahway, N.J., USA in the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.msd.com and connect with us on X (formerly Twitter), LinkedIn and YouTube.

Additional Information and Where to Find it

In connection with the proposed transaction between Harpoon and MSD, Harpoon will file with the Securities and Exchange Commission (SEC) a proxy statement on Schedule 14A relating to a special meeting of its stockholders. Additionally, Harpoon may file other relevant materials with the SEC in connection with the proposed transaction. Investors and securityholders of Harpoon are urged to read the proxy statement and any other relevant materials filed or that will be filed with the SEC, as well as any amendments or supplements to these materials and documents incorporated by reference therein, carefully and in their entirety when they become available because they contain or will contain important information about the proposed transaction and related matters. The definitive version of the proxy statement will be mailed or otherwise made available to Harpoon’s securityholders. Investors and securityholders will be able to obtain a copy of the proxy statement (when it is available) as well as other filings containing information about the proposed transaction that are filed by Harpoon or MSD with the SEC, free of charge on EDGAR at www.sec.gov, on the investor relations page of Harpoon’s website at ir.harpoontx.com/investors, by contacting Harpoon’s investor relations department at investors@harpoontx.com, or on MSD’s website at www.msd.com.

Participants in the Solicitation

Harpoon, MSD and certain of their directors and executive officers may be deemed to be participants in the solicitation of proxies from the stockholders of Harpoon in respect of the proposed transaction and any other matters to be voted on at the special meeting. Information about Harpoon’s directors and executive officers, including a description of their direct interests, by security holdings or otherwise, will be included in the proxy statement (when available). Information about MSD and its directors and executive officers can be found in MSD’s proxy statement filed on April 3, 2023 and MSD’s other filings with the SEC available at the SEC’s Internet site (www.sec.gov), including any statements of beneficial ownership on Form 3 or Form 4 filed with the SEC after such proxy statement. Harpoon stockholders may obtain additional information regarding the direct and indirect interests of the participants in the solicitation of proxies in connection with the proposed transaction, including the interests of Harpoon directors and executive officers in the proposed transaction, which may be different than those of Harpoon stockholders generally, by reading the proxy statement and any other relevant documents that are filed or will be filed with the SEC relating to the proposed transaction. You may obtain free copies of these document using the sources indicated above.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

This news release of Merck & Co., Inc., Rahway, N.J., USA (the “company”) includes statements that are not statements of historical fact, or “forward-looking statements,” including with respect to MSD’s proposed acquisition of Harpoon, and readers are cautioned not to place undue reliance on such statements. Such forward-looking statements include, but are not limited to, the ability of MSD and Harpoon to complete the transactions contemplated by the merger agreement, including the parties’ ability to satisfy the conditions to the consummation of the merger contemplated thereby, statements about the expected timetable for completing the transaction, MSD’s and Harpoon’s beliefs and expectations and statements about the benefits sought to be achieved in MSD’s proposed acquisition of Harpoon, the potential effects of the acquisition on both MSD and Harpoon, the possibility of any termination of the merger agreement, as well as the expected benefits and success of Harpoon’s product candidates. These statements are based upon the current beliefs and expectations of MSD’s management and are subject to significant risks and uncertainties. There can be no guarantees that the conditions to the closing of the proposed transaction will be satisfied on the expected timetable or at all, or that any product candidates will receive the necessary regulatory approvals or prove to be commercially successful. 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, uncertainties as to the timing of the merger; the risk that competing offers or acquisition proposals will be made; the possibility that various conditions to the consummation of the merger contained in the merger agreement may not be satisfied or waived (including the failure to obtain the requisite vote by Harpoon’s stockholders); the effects of disruption from the transactions contemplated by the merger agreement and the impact of the announcement and pendency of the transactions on Harpoon’s business; the risk that stockholder litigation in connection with the merger may result in significant costs of defense, indemnification and liability; general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; MSD’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of MSD’s patents and other protections for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory actions.

MSD undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise, except to the extent required by law. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in MSD’s 2022 Annual Report on Form 10-K and MSD’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov).

Forward-Looking Statements of Harpoon Therapeutics

Any statements in this press release about Harpoon’s future expectations, plans and prospects, as well as any other statements regarding matters that are not historical facts, may constitute “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements are subject to risks and uncertainties and actual results may differ materially from those expressed or implied by such forward-looking statements. Such statements include, but are not limited to, statements about MSD’s proposed acquisition of Harpoon, the ability of MSD and Harpoon to complete the transactions contemplated by the merger agreement, including the parties’ ability to satisfy the conditions to the consummation of the merger contemplated thereby and the other conditions set forth in the merger agreement, statements about the expected timetable for completing the transaction, MSD’s and Harpoon’s beliefs and expectations and statements about the benefits sought to be achieved in MSD’s proposed acquisition of Harpoon, the potential effects of the acquisition on Harpoon, the possibility of any termination of the merger agreement, as well as the expected benefits and success of Harpoon’s product candidates, and other statements containing the words “anticipates,” “believes,” “continue,” “expects,” “intends,” “look forward,” “plans,” “toward,” “will” and similar expressions. You should not place undue reliance on forward-looking statements because they involve known and unknown risks, uncertainties, and assumptions that are difficult or impossible to predict and, in some cases, beyond Harpoon’s control. These forward-looking statements are based upon Harpoon’s current expectations and involve assumptions that may never materialize or may prove to be incorrect. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of various risks and uncertainties. Such risks and uncertainties include, without limitation, (i) the occurrence of any event, change or other circumstance that could give rise to the termination of the merger agreement; (ii) the satisfaction (or waiver) of closing conditions to the consummation of the proposed transaction, including the receipt of required regulatory approval and the requisite approval of Harpoon’s stockholders; (iii) the effects of disruption from the proposed transaction contemplated by the merger agreement and the impact of the announcement and pendency of the proposed transaction on Harpoon’s business; (iv) the effects of the proposed transaction on relationships with employees, other business partners or governmental entities; (v) the response of competitors to the proposed transaction; (vi) risks associated with the disruption of management’s attention from ongoing business operations due to the proposed transaction; (vii) the ability of the parties to consummate the proposed transaction in a timely manner or at all; (viii) significant costs associated with the proposed transaction; (ix) potential litigation relating to the proposed transaction; (x) restrictions during the pendency of the proposed transaction that may impact Harpoon’s ability to pursue certain business opportunities; (xi) risks related to the advancement of product candidates into, and successful completion of, preclinical studies and clinical trials; (xii) risks and uncertainties related to regulatory application, review and approval processes and Harpoon’s compliance with applicable legal and regulatory requirements; (xiii) general industry conditions and competition; and (xiv) general economic factors. These and other risks are described in additional detail in Harpoon’s Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2023 and Harpoon’s other filings with the U.S. Securities and Exchange Commission (SEC), available on the SEC’s website at www.sec.gov. All forward-looking statements contained in this press release speak only as of the date hereof, and Harpoon specifically disclaims any obligation to update any forward-looking statement, whether because of new information, future events or otherwise.

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MSD Investor Contact:

Peter Dannenbaum (732) 594-1579

MSD Media Contact:

Robert Josephson (203) 914-2372

Harpoon Investor & Media Contact:

Ana Kapor akapor@harpoontx.com

Acquisition underscores MSD’s ongoing commitment to developing treatments for neurodegenerative diseases

RAHWAY, N.J., and CAMBRIDGE, Mass., November 21, 2023 – MSD (tradename of Merck & Co., Inc., Rahway, N.J., USA) (NYSE: MRK), and Caraway Therapeutics, Inc. announced today that the companies have entered into a definitive agreement under which MSD, through a subsidiary, will acquire Caraway Therapeutics for a total potential consideration of up to $610 million, including an undisclosed upfront payment as well as contingent milestone payments. The upfront payment will be expensed by MSD in the fourth quarter of 2023 and included in non-GAAP results.

“Caraway’s multidisciplinary approach has yielded important progress in evaluating novel mechanisms of modulation of lysosomal function with potential for the treatment of progressive neurodegenerative diseases,” said George Addona, senior vice president, discovery, preclinical development and translational medicine, MSD Research Laboratories. “We look forward to applying our expertise to build upon this work with the goal of developing much needed disease-modifying therapies for these conditions.”

Caraway is a preclinical biopharmaceutical company pursuing innovative approaches for the treatment of genetically defined neurodegenerative and rare diseases. The company has built a pipeline of novel, small-molecule therapeutics for the treatment of genetically defined neurodegenerative and rare diseases.

“This important milestone is a testament to the hard work and dedication of the Caraway team and our mission to develop therapeutics with the potential to alter the progression of devasting neurodegenerative diseases and help patients,” said Martin D. Williams, chief executive officer, Caraway Therapeutics. “This acquisition leverages MSD’s industry-leading research and development capabilities to help further advance our discovery and preclinical programs. We thank and appreciate our investors, including SV Health Investors and its Dementia Discovery Fund, AbbVie Ventures, Amgen Ventures, Eisai Innovation and MRL Ventures Fund, for their support.”

Under the terms of the agreement, MSD, through a subsidiary, will acquire all outstanding shares of Caraway with earnout milestones associated with the development of certain pipeline candidates. The Board of Directors of Caraway Therapeutics has approved the transaction. MSD, through its MRL Ventures Fund, has been a shareholder of Caraway Therapeutics since 2018.

About Caraway Therapeutics

Caraway Therapeutics is a biopharmaceutical company pursuing novel approaches for the treatment of genetically defined neurodegenerative and rare diseases. The company is a leader in the cutting-edge science of activating cellular recycling processes to clear toxic materials and defective cellular components by modulating lysosomal function. Caraway is utilizing its unique product engine to develop proprietary insights into lysosomal function and small molecule ion channel modulation and advance a robust pipeline of precision therapeutic candidates with disease-modifying potential for patients. The company is backed by top-tier investors, including SV Health Investors and its Dementia Discovery Fund, AbbVie Ventures, MRL Ventures Fund, Amgen Ventures, and Eisai Innovation. Caraway is based in Cambridge, MA. For more information, please visit www.carawaytx.com.

About MSD

            At MSD, known as Merck & Co., Inc., Rahway, N.J., USA in the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.msd.com and connect with us on Twitter, LinkedIn and YouTube.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

This news release of Merck & Co., Inc., Rahway, N.J., 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 and uncertainties. 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 commercially successful. 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 and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of the global outbreak of novel coronavirus disease (COVID-19); the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign 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 be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2022 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov).

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MSD Investor Contact:

Peter Dannenbaum (908) 447-6900

MSD Media Contacts:

Justine Moore (347) 281-3754

Olivia Finucane 00 / + 44 7881 262476

Caraway Media Contact:

Carolyn Noyes CNoyes@macdougall.bio

Exploratory post-hoc analysis of STELLAR shows potential of sotatercept to improve cardiovascular function

Interim results from SOTERIA open-label extension study represent longest safety and efficacy analysis of sotatercept to date; safety profile of sotatercept consistent with previous studies and efficacy improvements maintained after one year of therapy

Nine MSD-sponsored abstracts in PAH featured at European Respiratory Society (ERS) International Congress 2023

RAHWAY, N.J., Aug 25, 2023 – MSD (tradename of Merck & Co., Inc., Rahway, N.J., USA) (NYSE: MRK), today announced new analyses from studies of sotatercept, MSD’s novel investigational activin signaling inhibitor biologic, for adults with pulmonary arterial hypertension (PAH) (WHO Group 1) at the European Respiratory Society (ERS) International Congress 2023. A new exploratory post-hoc analysis of right heart catheterization and echocardiography data from patients in the Phase 3 STELLAR study showed treatment with sotatercept for 24 weeks on top of background therapy reduced right heart size and improved right-ventricular (RV) function and hemodynamic status. This analysis was featured in an oral presentation, with simultaneous publication in the European Respiratory Journal. An interim analysis of the Phase 3 SOTERIA open-label extension study was also presented, representing the longest safety and efficacy analysis of sotatercept to date.

“There is an urgent need for new approaches to manage PAH, a rare, progressive, and ultimately life-threatening disease,” said Dr. Eliav Barr, senior vice president and head of global clinical development, chief medical officer, MSD Research Laboratories. “These latest data build on the clinically meaningful efficacy results from the STELLAR trial and support our belief that sotatercept has the potential to transform the treatment of PAH. PAH can strain the heart and lead to eventual right heart failure, so we are particularly encouraged by the exploratory analysis from STELLAR suggesting that treatment with sotatercept improved right heart size and function.”

Primary efficacy results from STELLAR, in which sotatercept on top of background therapy demonstrated a statistically significant and clinically meaningful improvement in 6-minute walk distance (6MWD) at 24 weeks and eight of nine secondary outcome measures, were presented at ACC.23/WCC and published in The New England Journal of Medicine. MSD submitted an application for regulatory approval of sotatercept to the U.S. Food and Drug Administration and plans to submit applications to additional regulatory agencies worldwide.

At ERS 2023, nine MSD-sponsored studies in PAH were presented. These include an oral presentation of a population health model predicting the long-term impact of sotatercept on morbidity and mortality in patients with PAH (#OA740).

Results from STELLAR hemodynamics and echocardiography analysis (Abstract #3111)

An exploratory post-hoc analysis from the STELLAR trial evaluated the effects of sotatercept on select hemodynamic parameters and right-ventricle (RV) function. The STELLAR trial enrolled 323 adults with PAH, randomized to receive sotatercept (n=163) or placebo (n=160), on top of background therapy. Participants with available data at screening and week 24 visits were included in this post-hoc analysis, which reported hemodynamic data from 298 participants and echocardiography data from 275 participants, representing 92% and 85% of total participants respectively. In the analysis, after 24 weeks, sotatercept was associated with meaningful improvements in certain measures of hemodynamic status and RV function.

Results from this exploratory analysis showed treatment with sotatercept compared to placebo, on top of background therapy, led to improvements from baseline in mean pulmonary arterial (PA) pressure (−13.9 mmHg), PA compliance (0.58 mL mmHg⁻¹), pulmonary vascular resistance (−254.8 dyn·s·cm⁻⁵), mean right atrial pressure (−2.7 mmHg), mixed venous oxygen saturation (3.84%), PA elastance (−0.42 mmHg mL⁻¹ beat⁻¹), cardiac efficiency (0.48 mL beat⁻¹ mmHg⁻¹), RV work (−0.85 g·m) and RV power (−32.70 mmHg·L min⁻¹). Echocardiography data showed improvements in the ratio of tricuspid annular plane systolic excursion to systolic pulmonary artery pressure (TAPSE/sPAP; 0.12 mm mmHg⁻¹), end-systolic and end-diastolic RV areas (−4.39 cm² and −5.31 cm², respectively), tricuspid regurgitation and RV fractional area change (2.04% p<0.050). No significant between-group changes from baseline were seen for TAPSE, heart rate, cardiac output/index or stroke volume/stroke volume index.

“Despite available therapies, PAH remains incurable, with high morbidity and mortality, highlighting the urgent need for novel treatments that target new pathways,” said Dr. Vallerie McLaughlin*, professor of medicine and director, Pulmonary Hypertension Program, Division of Cardiovascular Medicine, University of Michigan in Ann Arbor. “Sotatercept is the first activin signaling inhibitor therapy and is proposed to modulate the vascular proliferation underlying PAH. Acknowledging the exploratory nature of these findings, this is the first clinical evidence suggesting that sotatercept may positively impact certain measures of right heart function and dimensions. This is encouraging and further supports the primary results from the STELLAR analysis, underscoring the potential of sotatercept to play a critical role in the treatment of PAH.”

Results from SOTERIA study (Abstract #OA739)

SOTERIA (NCT04796337) is an ongoing open-label extension study evaluating the long-term safety, tolerability and efficacy of sotatercept when added to background therapy for the treatment of PAH in patients who have completed previous sotatercept studies without early discontinuation. The primary objective of SOTERIA is to evaluate long-term safety and tolerability. The secondary objective is to assess the continued efficacy of sotatercept, as measured by 6MWD, N-terminal pro-B-type natriuretic peptide (NT-proBNP), WHO functional class (FC), pulmonary vascular resistance, overall survival, and simplified French risk score.

“The SOTERIA study provides us with important insight into the longer-term safety and efficacy of sotatercept,” said Dr. Ioana Preston, director of the Pulmonary Hypertension Center and associate professor at Tufts University School of Medicine. “These results support the potential durability of clinical benefit and safety of sotatercept for the treatment of PAH.”

At the data cutoff of April 20, 2023, there were 409 participants enrolled in SOTERIA. All participants were evaluated for safety. The median duration of exposure to sotatercept was 462 days (range: 21-1,762 days), including any exposure to sotatercept during the parent study. One hundred forty-three participants rolled over from placebo. The median duration of exposure to sotatercept in SOTERIA was 189 days.

Sotatercept was well-tolerated and the safety profile was similar to previous studies. 98.5% of participants were on treatment at the time of the interim analysis. Treatment-emergent adverse events (TEAEs) occurred in 81.7% (n=334/409) of participants. Serious TEAEs occurred in 19.3% of participants but only a small proportion lead to treatment discontinuation (1.5%; n=6/409) or death (1.0%; n=4/409). Additionally, 22.7% (n=93/409) of participants experienced a telangiectasia event, 0% had a serious telangiectasia event, 0% discontinued treatment and 1% experienced dose reductions or holds due to telangiectasia. Clinical worsening events were documented. Seven participants (1.7%) experienced nine clinical worsening events.

Improvements in clinical efficacy measures measured at week 24 in SOTERIA were maintained at one year during the open-label period. One hundred thirty-one participants who reached one year of therapy in SOTERIA were evaluated for efficacy at one year; most of these participants rolled over from the Phase 2 sotatercept studies, PULSAR and SPECTRA trials. Mean change (SD) from baseline at week 24 in 6MWD (20.2 ±66.5 m) and NT-proBNP (−374.9 ±1479.4 pg/mL) were largely maintained at one year (10.9 ±73.6 m and −227.2 ±1580.1 pg/mL, respectively). The proportion of participants who improved or maintained WHO FC II from baseline at week 24 (77.2%) was similar to that at one year (76.3%). 30.1% of participants achieved low French risk score (WHO-FC I/II, 6MWD >440 m, NT-proBNP <300 pg/mL) at week 24, and 37.4% at one year.

Changes in background PAH therapy were also documented for all participants. Of participants on any prostacyclin, 29/272 (10.7%) had prostacyclin dose decreases. Of participants on infusion prostacyclin, 22/154 (14.3%) had prostacyclin dose decreases. Of participants on other PAH therapy, 21/406 (5.2%) had other PAH therapy dose decreases and 19/406 (4.6%) had other PAH therapy dose increased. As of April 20, 2023, 8 participants had discontinued prostacyclins entirely.

Summary of Presentations

MSD-sponsored studies and analyses for PAH, sotatercept and MK-5475, an investigational inhaled soluble guanylate cyclase (sGC) stimulator, featured at ERS International Congress 2023 include:

Clinical studies

• Effects of Sotatercept on Haemodynamics and Right Heart Function: Analysis of STELLAR Trial; Marius M. Hoeper; Abstract #3111
• Sotatercept for the Treatment of PAH: An Update; Marius M. Hoeper; Abstract #807
• Late Breaking Abstract – A Long-Term Follow-Up (LTFU) Study of Sotatercept for Pulmonary Arterial Hypertension (PAH); Ioana R. Preston; Abstract #807
• A Randomized Study to Evaluate the Effects of Single-Dose MK-5475 Co-Administered with Sildenafil on Systemic Hemodynamics; Mahesh J. Patel; Abstract #PA1208

Population Health and Real-World Evidence

• Vallerie McLaughlin; Abstract #OA740

• Concordance between physician and patient reported presence of symptoms in patients with pulmonary arterial hypertension in the US, Europe and Japan; Rogier Klok; Abstract #PA3966
• Diagnosing pulmonary arterial hypertension in the Real World; Rogier Klok; Abstract #PA1190
• End-of-life healthcare resource utilization and costs in patients with PAH: a real-world analysis; Dominik Lautsch; Abstract #PA1195
• Health related quality of life in pulmonary arterial hypertension in the US, Europe and Japan; Rogier Klok; Abstract #PA3969

*Dr. McLaughlin is an investigator in the STELLAR trial and a paid consultant to MSD.

About pulmonary arterial hypertension (PAH)

PAH is a rare, progressive and life-threatening blood vessel disorder characterized by the constriction of small pulmonary arteries and elevated blood pressure in the pulmonary circulation. Approximately 40,000 people in the U.S. are living with PAH. The disease progresses rapidly for many patients. PAH results in significant strain on the heart, leading to limited physical activity, heart failure and reduced life expectancy. The five-year mortality rate for patients with PAH is approximately 43%.

About sotatercept

Sotatercept is an investigational, potential first-in-class activin signaling inhibitor biologic being studied for the treatment of PAH (WHO Group 1). PAH is a rare disease caused by hyperproliferation of cells in the arterial walls in the lung, leading to narrowing and abnormal constriction. In pre-clinical models, sotatercept has been shown to modulate vascular cell proliferation, reversing vascular and right ventricle remodeling.

In addition to STELLAR and SOTERIA, the sotatercept clinical development program includes multiple Phase 2 and 3 trials across a broad range of patients. Studies are underway in adult patients with PAH (WHO Group 1) at intermediate or high risk of disease progression or mortality, as well as with pulmonary hypertension due to left heart disease (WHO Group 2).

MSD acquired exclusive rights to sotatercept in the pulmonary hypertension field through the acquisition of Acceleron Pharma Inc. Sotatercept is the subject of a licensing agreement with Bristol Myers Squibb.

About MK-5475

MK-5475 is an investigational dry-powder formulation of a small-molecule stimulator of soluble guanylate cyclase (sGC), designed for inhaled delivery to the pulmonary arterial circulation through the lungs. MK-5475 may stimulate sGC in the blood vessels of the lungs, which, if occurring, relaxes and widens these blood vessels. It is currently being studied in a Phase 2/3 trial for the treatment of PAH and a Phase 2 trial for the treatment of PH associated with chronic obstructive pulmonary disease.

MSD’s Focus on Cardiovascular Disease

MSD has a long history of developing treatments for cardiovascular disease. More than 60 years ago, we introduced our first cardiovascular therapy – and our scientific efforts to understand and treat cardiovascular-related disorders have continued. Cardiovascular disease continues to be one of the most serious health challenges of the 21st century. Approximately 18 million people across the globe die every year, and in the United States, one person dies every 36 seconds from cardiovascular disease.

Advancements in the treatment of cardiovascular disease can make a critical difference for patients and health systems around the world. At MSD, we strive for scientific excellence and innovation in all stages of research, from discovery through approval and life cycle management. We work with experts throughout the cardiovascular and pulmonary community to advance research that can help improve the lives of patients globally.

Information for other currently enrolling cardiovascular studies can be found by visiting: https://www.msdclinicaltrials.com/

About MSD

At MSD, known as Merck & Co., Inc., Rahway, N.J., USA in the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.msd.com and connect with us on Twitter, LinkedIn and YouTube.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

This news release of Merck & Co., Inc., Rahway, N.J., 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 and uncertainties. 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 commercially successful. 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 and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of the global outbreak of novel coronavirus disease (COVID-19); the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign 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 be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2022 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov).

Media Contacts:

Julie Cunningham

(617) 519-6264

Ayn Wisler

(917) 691-6218

Investor Contacts:

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(732) 594-1579

Damini Chokshi

(732) 594-1577

• Reached more than 500 million people with its innovations across commercial channels, clinical trials, access strategies, voluntary licensing and its donations in 2022
• Expanded two of its Access to Health goals
• Added sustainability metrics tied to its Access to Health and Employees focus areas in its 2023 Company Scorecard, which impacts annual incentive pay for executives and the majority of global employees
• Committed to Science Based Targets initiative (SBTi) to set net-zero target for greenhouse gas (GHG) emissions across global operations (Scopes 1, 2 and 3)
• Allocated $760 million of the net proceeds from its $1 billion sustainability bond to social and green projects, in alignment with its sustainability financing framework, through June 2022

RAHWAY, N.J., August 10, 2023 – MSD (tradename of Merck & Co., Inc., Rahway, N.J., USA (NYSE: MRK), has published its Impact Report 2022/2023, outlining sustained momentum and strong performance across the company’s four sustainability areas: Access to Health, Employees, Environmental Sustainability and Ethics & Values.

“The positive impact we continue to have on patients, communities and society is a direct result of our commitment to innovation and the principles and values that shape our company,” said Robert M. Davis, chairman and chief executive officer, MSD. “At our core, we believe in operating responsibly, putting patients first and raising the bar on scientific excellence. This unwavering commitment enables us to deliver value to all our stakeholders as we work with speed and urgency to save and improve lives around the world.”

Importantly, MSD has exceeded and expanded two of its Access to Health goals:

• Two years ago, MSD set a goal to enable 100 million more people to access its innovative portfolio¹ globally, through access strategies, solutions and partnerships, by 2025. The company exceeded this goal already in 2022. As a result, the company increased its ambition and more than tripled the original goal. MSD now aims to enable 350 million more people to access its innovative portfolio by 2025.
• Through 2022, MSD reached more than 33 million people in low-and middle-income countries (LMICs) and underserved populations in the U.S. with its social investments, exceeding its goal to reach more than 30 million people by 2025. The company’s expanded goal is to reach over 50 million people in LMICs, underserved populations in the U.S. and, going forward, underserved populations in other high-income countries, by 2025.

Additional key highlights from this year’s report include:

Access to Health

• In 2022, MSD reached more than 500 million people with its innovations across commercial channels, clinical trials, access strategies, voluntary licensing and its donations.
  • This includes nearly 360 million people reached through the MECTIZAN® Donation Program to treat river blindness and lymphatic filariasis².
• In 2022, the company invested $38 million to advance health equity and initiatives, including MSD for Mothers, in support of its goal to reach over 30 million people with its social investments.
• Through 2022, MSD’s multi-faceted strategy to facilitate timely and equitable access to its investigational antiviral COVID-19 medicine has led to the delivery of more than 5 million courses of generic COVID-19 therapy to over 20 LMICs.
  • In addition, the company’s direct supply has treated more than 4 million patients worldwide through 2022.
• Through a long-term agreement with UNICEF from 2021–2025, MSD has committed to provide more than 100 million doses of its human papillomavirus (HPV) vaccine for use in Gavi-supported countries.

Employees

• MSD achieved greater than 99 percent pay equity in the U.S. for female and male employees, as well as for non-white (including Black, Hispanic and Asian employees) and white employees.
• In 2022, 47 percent of the company’s new hires in the U.S. were members of underrepresented ethnic groups.

Environmental Sustainability

• The company committed to the Science Based Targets Initiative (SBTi) to set a net-zero target for GHG emissions across its global operations (Scopes 1, 2 and 3).
• In 2022, the company sourced 45 percent of its purchased electricity from renewable sources.

Ethics & Values

• The company increased its spend with diverse Tier 1 and 2 suppliers globally from $2.9 billion in 2021 to $3.2 billion in 2022.

The company is utilizing the net proceeds from the sustainability bond offering to support projects and partnerships in its priority sustainability areas and to contribute to the advancement of the United Nations Sustainable Development Goals. Through June 2022 (the most recent reporting period for the bond), MSD has allocated $760 million of the net proceeds toward social and green projects, in alignment with its sustainability financing framework.

MSD also added sustainability metrics tied to its Access to Health and Employees focus areas in its 2023 Company Scorecard, which impacts annual incentive pay for executives and the majority of global employees.

Learn more about MSD’s approach to sustainability, the company’s commitment to creating value for society and all its stakeholders, and its progress on key goals in MSD’s Impact Report 2022/2023.

About MSD

At MSD, known as Merck & Co., Inc., Rahway, N.J., USA in the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.msd.com and connect with us on Twitter, LinkedIn, and YouTube.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

This news release of Merck & Co., Inc., Rahway, N.J., 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 and uncertainties. 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 commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties 10 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 and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of the global outbreak of novel coronavirus disease (COVID-19); the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign 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 be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2022 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov).

¹ “Innovative portfolio” of products refers to our Company’s on-patent products.

² Countries receiving donated Mectizan are located in Africa, Asia, the Middle East, South America, and the Western Pacific

Media Contact:
mediarelations@msd.com

Investor Contact:
Peter Dannenbaum – (732) 594-1579

Steve Graziano – (732) 594-1583

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RAHWAY, N.J., July 21, 2023 – MSD (tradename of Merck & Co., Inc., Rahway, N.J., USA (NYSE: MRK), today announced that the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) has recommended the approval of gefapixant, an investigational, non-narcotic, oral selective P2X3 receptor antagonist, developed for the treatment for adults with refractory or unexplained chronic cough. The CHMP’s recommendation will now be reviewed by the European Commission (EC) for marketing authorization in the European Union (EU) and a final decision is expected later this year.

“Today’s positive CHMP opinion is the next step for gefapixant to become the first treatment approved in the European Union for adults with refractory or unexplained chronic cough,” said Dr. Joerg Koglin, senior vice president, global clinical development, MSD Research Laboratories. “Refractory or unexplained chronic cough as a condition with often disruptive, uncontrolled coughing associated with major physical, social and emotional consequences represents a large unmet clinical need.”

The CHMP’s positive opinion is based on results from the COUGH-1 and COUGH-2 clinical trials, which are the first companion Phase 3 studies ever completed in patients with refractory or unexplained chronic cough, a cough that persists despite appropriate treatment of underlying conditions or for which the underlying cause cannot be identified despite a thorough evaluation. Both studies met the primary endpoint, demonstrating a statistically significant reduction in 24-hour cough frequency in adults treated with gefapixant 45 mg twice daily versus placebo at 12 weeks (COUGH-1) and 24 weeks (COUGH-2).

About the COUGH-1 and COUGH-2 trials

COUGH-1 (NCT03449134) and COUGH-2 (NCT03449147) are Phase 3 multinational, randomized, double-blind, placebo-controlled studies that evaluated the efficacy and safety of gefapixant in reducing cough frequency in adult participants with refractory chronic cough (RCC) or unexplained chronic cough (UCC). A total of 2,044 participants were treated in COUGH-1 (n=730) and COUGH-2 (n=1,314). In both studies, patients were randomly selected to receive one of the following: gefapixant 45 mg twice daily, gefapixant 15 mg twice daily, or placebo. The primary efficacy outcomes for COUGH-1 and COUGH-2 were 24-hour cough frequency at week 12 and 24-hour cough frequency at week 24, respectively, measured using an ambulatory digital audio recording device. Secondary endpoints included awake cough frequency and percentage of participants with a greater than 1.3-point increase from baseline in the Leicester Cough Questionnaire (LCQ) total score. COUGH-1 had a 12-week treatment period and a 40-week safety-extension period, while COUGH-2 had a 24-week treatment period and a 28-week safety-extension period.

In these studies, adults treated with gefapixant 45 mg twice daily demonstrated a statistically significant reduction in 24-hour cough frequency (measured objectively, as coughs per hour, using 24-hour sound recordings) versus placebo at 12 weeks (COUGH-1) (18.45% reduction relative to placebo, 95% CI [-32.92, -0.9; p=0.041]) and 24 weeks (COUGH-2) (14.64% reduction relative to placebo, 95% CI [-26.01, -1.4; p=0.031]). The gefapixant 15 mg twice daily treatment arms did not meet the primary efficacy endpoint in either Phase 3 study. The Phase 3 study results were published in The Lancet.

In 2022, MSD announced that additional analyses were underway to address questions received from regulatory authorities. The questions were primarily related to the cough counting system used in generating the Phase 3 data, on which the marketing authorization application for gefapixant was based. The results of the additional analyses were generally consistent with the published Phase 3 results from COUGH-1 and COUGH-2.

About gefapixant

Gefapixant is an investigational, orally administered, selective P2X3 receptor antagonist, for the potential treatment of refractory or unexplained chronic cough. P2X3 receptors are one of the receptor types found on sensory nerve fibers, predominantly C fibers, in the airway lining. Chemical stimuli, including adenosine triphosphate (ATP), can be released from airway lining cells due to airway inflammation, irritation, and mechanical stress/injury. Binding of extracellular ATP to P2X3 receptors on C fibers in the airway can be sensed as a signal of potential damage, creating an action potential, which may initiate coughing. The inhibition of binding of extracellular ATP to P2X3 receptors is thought to reduce sensory nerve activation and, subsequently, cough.

In 2022, gefapixant under the brand name LYFNUA^®, was approved in Japan and Switzerland for treatment of adults with refractory or unexplained chronic cough.

About chronic cough

The prevalence of chronic cough (a cough lasting more than 8 weeks) is estimated to be approximately 5 to 10% of adults globally. In a subset of these cases, patients either do not respond to treatment of underlying conditions (such as asthma or gastroesophageal reflux), known as refractory chronic cough (RCC), or they have no identifiable underlying condition despite a thorough evaluation, known as unexplained chronic cough (UCC). In the EU, there are currently no approved therapies for the treatment of RCC or UCC.

About MSD

At MSD, known as Merck & Co., Inc., Rahway, N.J., USA in in the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.msd.com and connect with us on Twitter, LinkedIn, and YouTube.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

This news release of Merck & Co., Inc., Rahway, N.J., 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 and uncertainties. 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 commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties 10 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 and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of the global outbreak of novel coronavirus disease (COVID-19); the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign 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 be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2022 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov).

###

Media Contacts:

Julie Cunningham (617) 519-6264

Deb Wambold (215) 779-2234

Investor Contacts:

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Acquisition delivers industry-leading research capability, and strengthens pipeline with a novel candidate for ulcerative colitis, Crohn’s disease and other autoimmune conditions

RAHWAY, N.J. — MSD (tradename of Merck & Co., Inc., Rahway, N.J., USA (NYSE: MRK)) today announced the completion of the Prometheus Biosciences, Inc. (“Prometheus”) (NASDAQ: RXDX) acquisition. Prometheus is now a wholly-owned subsidiary of MSD and the common stock of Prometheus will no longer be listed or traded on the Nasdaq Global Market.

“The Prometheus acquisition accelerates our growing presence in immunology, augments our diverse pipeline and increases our ability to deliver patient value. This transaction is another example of MSD acting strategically and decisively when science and value align,” said Robert M. Davis, chairman and chief executive officer, MSD. “Prometheus brings us a potential best-in-class candidate that creates an opportunity for us to transform treatment for patients with immune-mediated diseases. We are excited to welcome our Prometheus colleagues to MSD and we look forward to working together, driven by our common purpose of saving and improving lives.”

Prometheus’ leading clinical candidate, PRA-023, which will be known as MK-7240, is a humanized monoclonal antibody (mAb) directed to tumor necrosis factor (TNF)-like ligand 1A (TL1A), a target associated with both intestinal inflammation and fibrosis. It is being developed for the treatment of immune-mediated diseases, including ulcerative colitis (UC), Crohn’s disease (CD) and other autoimmune conditions. In December 2022, Prometheus announced positive results for MK-7240 from ARTEMIS-UC, a Phase 2, placebo-controlled study evaluating safety and efficacy in patients with moderate-to-severely active UC and APOLLO-CD, and a Phase 2A, open-label study evaluating safety and efficacy in patients with moderate-to-severe CD. The findings were recently presented at the 18th Congress of European Crohn’s and Colitis Organisation (ECCO).

“At MSD we have deep expertise in clinical development with a proven record of implementing precision medicine strategies,” said Dr. Dean Y. Li, president of MSD Research Laboratories. “By combining our strengths, MSD and Prometheus are well positioned to advance MK-7240 and additional pipeline candidates.”

Additional Transaction Details

Under the terms of the acquisition agreement, MSD, through a subsidiary, has acquired all outstanding shares of Prometheus for $200.00 per share in cash for a total equity value of approximately $10.8 billion. MSD’s full-year financial outlook provided during the first-quarter earnings call did not account for the then proposed acquisition of Prometheus or any additional significant potential business development transactions.

As previously disclosed, because this transaction is being accounted for as an asset acquisition, MSD is recording a charge of approximately $10.3 billion, or approximately $4.00 per share. The impact of this charge will result in a reduction in both second-quarter and full-year 2023 GAAP and non-GAAP results. In addition, this transaction is expected to negatively impact EPS by approximately $0.25 in the first 12 months following the close of the transaction due to investment to advance pipeline assets and cost of financing, approximately half of which will be incurred in the second half of 2023.

As a matter of policy, MSD provides updates to its financial outlook once each quarter. When considering MSD’s financial outlook issued on April 27, 2023, investors and analysts should deduct the expenses outlined above. MSD will provide an update to its financial outlook when it reports second quarter 2023 results on August 1.

About Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a term used to collectively describe Crohn’s disease and ulcerative colitis. These conditions are characterized by chronic inflammation of the gastrointestinal (GI) tract. Prolonged inflammation results in damage to the tissues lining the GI tract. Both ulcerative colitis and Crohn’s disease are usually characterized by diarrhea, rectal bleeding, abdominal pain, fatigue and weight loss.

About MSD

At MSD, known as Merck & Co., Inc., Rahway, N.J., USA in the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.msd.com and connect with us on Twitter, LinkedIn and YouTube.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

This news release of Merck & Co., Inc., Rahway, N.J., 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 and uncertainties. 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 commercially successful. 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 and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of the global outbreak of novel coronavirus disease (COVID-19); the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign 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 be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2022 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov).

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Media Contact:

Robert Josephson (203) 914-2372

Investor Contact:          

Peter Dannenbaum (908) 740-1037