Merck Data to be Presented at ASH 2025 Annual Meeting Showcase Continued Advancements in Hematology Pipeline and Novel Therapeutic Approaches

First presentation for MK-1045, a novel CD19xCD3 T-cell engager in patients with certain types of leukemia and lymphoma, and for bomedemstat, an LSD1 inhibitor, in patients with polycythemia vera

New data demonstrate continued progress with nemtabrutinib, an investigational non-covalent BTK inhibitor

Merck (NYSE:MRK), known as MSD outside of the United States and Canada, today announced that new data across multiple hematologic malignancies will be presented at the American Society of Hematology (ASH) Annual Meeting and Exposition in Orlando, Fla. from Dec. 6-9. The data shared at the meeting will highlight the company's ongoing commitment to advancing clinical research in hematology across Merck's expanding and diverse pipeline of investigational candidates, with more than 20 abstracts being presented.

"The data we're sharing at ASH 2025 reflect the continued growth and evolution of our promising hematology pipeline," said Dr. Gregory Lubiniecki, vice president, global clinical development, Merck Research Laboratories. "We continue to build on our leadership in oncology by advancing a diverse portfolio of investigational candidates and exploring novel modalities with the goal of improving outcomes and helping to address significant unmet needs for patients with hematologic neoplasms and malignancies."

Data presentations will feature Merck's pipeline candidates, including: MK-1045, an investigational CD19xCD3 T-cell engager; bomedemstat (MK-3543), an investigational, orally available lysine-specific demethylase 1 (LSD1) inhibitor; and nemtabrutinib (MK-1026), an investigational, non-covalent Bruton's tyrosine kinase (BTK) inhibitor. Additionally, Merck will present new and updated results highlighting zilovertamab vedotin (MK-2140), an investigational antibody-drug conjugate (ADC) that targets receptor tyrosine kinase-like orphan receptor 1 (ROR1).

Key data from Merck's pipeline to be presented at the ASH 2025 Annual Meeting and Exposition:

- First presentation by Merck of updated results from the dose escalation and expansion portion of a Phase 1b/2 study assessing the efficacy and safety of MK-1045 in adults with relapsed or refractory B-cell acute lymphoblastic leukemia (Abstract #647)

- First-time results from the Phase 2 Shorespan-004 study evaluating bomedemstat for patients with polycythemia vera (PV) resistant or intolerant to cytoreductive therapy (Abstract #83)

- Initial results from an exploratory analysis of the BELLWAVE-003 study of acquired resistance and prognostic mutations in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) treated with nemtabrutinib (Abstract #797)

Details on abstracts listed above and additional key abstracts for Merck:

About Merck in hematology

Merck is committed to advancing innovation and care for people with hematologic neoplasms and malignancies. Building on its leadership in oncology, the company has a broad clinical development program that evaluates novel mechanisms of action to address longstanding unmet needs for patients with hematologic neoplasms and malignancies. Among Merck's research efforts are studies evaluating multiple investigational medicines as monotherapy or in combination with other therapies across a range of hematologic neoplasms and malignancies.

About MK-1045

MK-1045 (previously CN201) is a novel, investigational CD19xCD3 T-cell engager, designed to redirect T-cells to specifically deplete malignant or pathogenic B cells. It is currently being evaluated in a Phase 1 trial for the treatment of patients with relapsed or refractory B-cell non-Hodgkin lymphoma (NCT06189391) and in a Phase 1b/2 trial for patients with relapsed or refractory B-cell acute lymphocytic leukemia (ALL) (NCT05579132).

About bomedemstat (MK-3543)

Bomedemstat (MK-3543) is an investigational, orally available small molecule that inhibits lysine-specific demethylase 1 (LSD1), an enzyme that is potentially important for regulating the rapid reproduction of blood stem cells and the maturation of blood cells in the bone marrow. Bomedemstat is being studied across myeloproliferative neoplasms, including essential thrombocythemia, myelofibrosis and polycythemia vera. Two Phase 3 trials are ongoing: Shorespan-006 (NCT06079879), an open-label study comparing bomedemstat to best available therapy in patients with essential thrombocythemia who have an inadequate response to or are intolerant of hydroxyurea, and Shorespan-007 (NCT06456346), a double-blind study evaluating bomedemstat versus hydroxyurea in patients with essential thrombocythemia who have not previously received cytoreductive therapy.

About nemtabrutinib (MK-1026)

Nemtabrutinib is an investigational oral, reversible, non-covalent BTK inhibitor that suppresses oncogenic B-cell receptor signaling with activity against wild-type BTK and BTK pathway mutants. Nemtabrutinib aims to address a common mechanism of resistance with currently available covalent, BTK inhibitors by binding in an alternative way to the BTK protein. Merck is advancing research with nemtabrutinib across B-cell malignancies through its BELLWAVE clinical program. Two Phase 3 trials are ongoing: BELLWAVE-008 (NCT05624554), comparing nemtabrutinib to chemoimmunotherapy in previously untreated CLL/SLL without TP53 aberrations, and BELLWAVE-011 (NCT06136559), evaluating nemtabrutinib versus investigator's choice of BTK inhibitors (ibrutinib or acalabrutinib) in previously untreated CLL/SLL.

About zilovertamab vedotin (MK-2140)

Zilovertamab vedotin is an investigational ADC that targets ROR1. ROR1 is a transmembrane protein that is overexpressed in multiple hematologic malignancies. Merck is committed to research with zilovertamab vedotin across B-cell malignancies and has established a robust program of clinical trials under the name waveLINE. The waveLINE program includes a Phase 3 study in patients with relapsed/refractory DLBCL (waveLINE-003, NCT05139017), a Phase 3 study in patients with previously untreated DLBCL (waveLINE-010, NCT06717347), a Phase 2 study in patients with select B-cell lymphomas (waveLINE-006, NCT05458297), a Phase 2 study in patients with germinal center B-cell-like DLBCL (waveLINE-011, NCT06890884) and a Phase 2 study in patients with previously untreated DLBCL (waveLINE-007, NCT05406401).

About Merck

At Merck, known as MSD outside of 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.merck.com and connect with us on X (formerly Twitter), Facebook, Instagram, YouTube and LinkedIn.

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, 2024 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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