Merck to buy T-cell engager firm Harpoon for $680m

Merck & Co. will acquire Harpoon Therapeutics, adding a pipeline of T-cell engager targeting delta-like ligand 3 (DLL3).

The JPM Conference, which begins in San Francisco today, historically brings with it a host of M&A activity. Merck & Co. (known as MSD outside North America) has kicked off the proceedings paying $23.00 per share for South San Francisco-based Harpoon, totaling $680 million.

The deal, set to close in the next few months, brings Merck a portfolio of T-cell engagers that employ Harpoon’s Tri-specific T-cell Activating Construct (TriTAC) technology. The platform engineers proteins to direct a patient’s own immune cells to kill tumor cells. When applied with Harpoon’s prodrug concept ‘ProTriTAC platform,’ a therapeutic T-cell engager is created designed to remain inactive until it reaches the tumor.

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Lead candidate HPN328 is in early clinical development for small cell lung cancer (SCLC) and neuroendocrine prostate cancer (NEPC), with positive interim tolerability and response data recently published by Harpoon. The candidate is also being evaluated in combination with Roche’s atezolizumab in patients with SCLC.

“With Merck’s recognized leadership in oncology clinical development and global commercial footprint, our lead candidate, HPN328, is well positioned moving forward,” said Julie Eastland, CEO at Harpoon.

“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 Merck has recognized the significant potential of our pipeline.”

HPN217, meanwhile, is being investigated for multiple myeloma. AbbVie had partnered on the candidate but announced it would not exercise the exclusive licensing option in September 2023.

The acquisition comes days after Merck’s CEO Rob Davis spoke about his firm’s M&A ambitions at the Goldman Sachs Healthcare C-Suite conference.

“What we've demonstrated is because of our approach, because of the strength of our science, where we see synergy, a strategic fit, and we were compelled by the science, we will move quickly and we've been able to move successfully in deals that not only bring strategic value but are positive economic value returning for the business as well.”