Merck to acquire Harpoon Therapeutics

Jan. 8, 2024

In a bid to diversify its oncology pipeline, Merck & Co. (MSD), through a subsidiary, will acquire Harpoon Therapeutics in deal worth approximately $680 million.

The star of the deal is San Francisco-based Harpoon's lead asset, HPN328, an investigational delta-like ligand 3 (DLL3) targeting T-cell engager being evaluated in patients with small cell lung cancer and neuroendocrine tumors.

Harpoon's portfolio of novel T-cell engagers employ the company’s proprietary Tri-specific T-cell Activating Construct (TriTAC) platform, an engineered protein technology designed to direct a patient’s own immune cells to kill tumor cells. Harpoon's proprietary ProTriTAC platform applies 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.

HPN328 is currently being evaluated as a monotherapy in a phase 1/2 clinical trial in patients with advanced cancers associated with expression of DLL3. The study is also evaluating HPN328 in combination with Roche's Tecentriq — a competitor to Merck's Keytruda — in patients with small cell lung cancer.

Merck says it plans to further evaluate HPN328 in combination with other pipeline candidates.