Merck entered into a definitive agreement to acquire Harpoon Therapeutics, Inc. for an approximate total equity value of $680 million.
 
Harpoon has a portfolio of novel T-cell engagers that employ the company’s 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, and ProTriTAC platform, applying a prodrug concept to its TriTAC platform to create a therapeutic T-cell engager that’s designed to remain inactive until it reaches the tumor.
 
Harpoon’s lead candidate, 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. HPN328 is currently being evaluated in a Phase 1/2 clinical trial (NCT04471727) evaluating the safety, tolerability and pharmacokinetics of HPN328 monotherapy in advanced cancers associated with expression of DLL3. The study is also evaluating HPN328 in combination with atezolizumab in SCLC. 
 
Additional pipeline candidates include HPN217 targeting B-cell maturation antigen (BCMA), currently in Phase 1 clinical development for the treatment of 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.
 
“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,” said Dr. Dean Y. Li, president, Merck Research Laboratories. “This agreement reflects the creativity and commitment of scientists and clinical development teams at Harpoon. We look forward to further evaluating HPN328 in innovative combinations with other pipeline candidates.”