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

Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced the completion of the acquisition of Harpoon Therapeutics, Inc. (Nasdaq: HARP). Harpoon is now a wholly-owned subsidiary of Merck, 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, Merck Research Laboratories. “We are pleased to welcome our Harpoon colleagues to Merck 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, Merck, through a subsidiary, has acquired all outstanding shares of Harpoon. As previously disclosed, this transaction is being accounted for as an asset acquisition. Merck is recording a non-tax deductible charge to R&D expense of approximately $650 million. The impact of the transaction on expected full-year non-GAAP EPS is approximately $0.26 per share, which was included in Merck’s full-year 2024 financial outlook issued on February 1, 2024.

Merck’s focus on cancer

Our goal is to translate breakthrough science into innovative oncology medicines to help people with cancer worldwide. At Merck, 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, Merck 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. For more information about our oncology clinical trials, visit https://www.merckclinicaltrials.com/.

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.

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