Merck to acquire Harpoon Therapeutics for $680M, diversifying oncology pipeline

The Merck campus in Rahway and Linden.

Rahway-based Merck on Monday announced it agreed to pay $680 million for Harpoon Therapeutics and its pipeline of T-cell engagers. The deal will give Merck control of drug candidates that will expand its cancer pipeline and offer opportunities to offset the upcoming loss of Keytruda exclusivity.

Merck said the deal adds Harpoon’s HPN328, which is being evaluated in certain patients with small cell lung cancer and neuroendocrine tumors.

San Francisco-based Harpoon has developed a portfolio of novel T-cell engagers that employ the company’s proprietary Tri-specific T cell Activating Construct, or 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 Merck, 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,” Dr. Dean Y. Li, president, Merck Research Laboratories, said. “This agreement reflects the creativity and commitment of scientists and clinical development teams at Harpoon.”

Under the terms of the agreement, Merck will acquire all outstanding shares of Harpoon Therapeutics for a price per share of $23 in cash.

The board of directors of Harpoon has unanimously approved the transaction.

Closing of the acquisition is subject to certain conditions, but is expected in the first half of 2024 and will be accounted for as an asset acquisition.