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Merck to acquire Harpoon Therapeutics for $680 million

Merck announced Monday it will acquire Harpoon Therapeutics and its pipeline of immune-based cancer drugs for $680 million. Merck will pay $23 per share, just over twice Harpoon’s market price entering the week.

The bolt-on deal comes as Merck’s top brass searches for ways to bolster the company’s revenue after it loses exclusivity on Keytruda, long the world’s most lucrative cancer drug. That could come as soon as 2028.


Keytruda, a PD-(L)1 inhibitor, works by turning off a “brake” on T cells, allowing roving immune cells to attack tumors. Harpoon’s pipeline belongs to a new class of cancer drugs designed to grab onto the T cells and tumor cells and bring them together.

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