Harpoon Therapeutics, Inc., a clinical-stage immunotherapy company, engages in the development of a novel class of T cell engagers that harness the power of the body's immune system to treat patients suffering from cancer and other diseases in the United States. The company develops tri-specific T cell activating construct (TriTAC) product candidate, including HPN328, which is in Phase I/II clinical trials for the treatment of small cell lung cancer and other Delta-like canonical Notch ligand 3-expressing tumors; and HPN217 that is in Phase I clinical trials for the treatment of multiple myeloma. Its preclinical stage product is HPN601 for the treatment of multiple solid tumor indications. It has a discovery collaboration and license agreement with AbbVie Biotechnology Ltd. to develop and commercialize products that incorporate its proprietary TriTAC platform technology together with soluble T cell receptors. The company was incorporated in 2015 and is headquartered in South San Francisco, California. As of March 11, 2024, Harpoon Therapeutics, Inc. operates as a subsidiary of Merck Sharp & Dohme LLC.