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§ Private Profile · 131 Oyster Point Blvd Ste 300, South San Francisco, California, 94080, United States
Biotechnology company developing T-cell engaging biologics for immuno-oncology therapies, focused on solid tumors.
Harpoon Therapeutics, a biotechnology company based in South San Francisco, California, develops novel T-cell engaging biologics, including its proprietary TriTAC platform. These innovative therapies are designed to activate patients' immune systems against cancer cells, with a focus on immuno-oncology treatments optimized for solid tumors and other diseases. In early 2024, Harpoon Therapeutics was notably acquired by Merck for approximately $680 million in equity value, or $23 per share. The company had previously secured $45 million in Series B financing from key investors such as MPM Capital, Arix Bioscience, and New Leaf Venture Partners. Founded in 2015 by Patrick Baeuerle and MPM Capital, its leadership included co-founder Patrick Baeuerle, co-founder and Chairman Luke Evnin of MPM Capital, and CEO Julie Eastland.
Harpoon Therapeutics has raised $115.0M across 2 funding rounds.
Harpoon Therapeutics has raised $115.0M in total across 2 funding rounds.
Harpoon Therapeutics has raised $115.0M across 2 funding rounds. Most recently, it raised $70.0M Series C in November 2018.
| Date | Round | Lead Investors | Other Investors | Status |
|---|---|---|---|---|
| Nov 1, 2018 | $70M Series C | Arix Bioscience | Canaan Partners, Cormorant Asset Management, Lilly Asia Ventures, NEW Leaf Venture Partners, NS Investment, Oncology Impact Fund, OrbiMed, Ridgeback Capital Investments, Taiho Ventures | Announced |
| May 1, 2017 | $45M Series B | Arix Bioscience, RON Hunt | Amplitude VC, Canaan Partners, MPM Capital, Venrock, Sakae Asanuma | Announced |
Harpoon Therapeutics has raised $115.0M in total across 2 funding rounds.
Harpoon Therapeutics's investors include Arix Bioscience, Canaan Partners, Cormorant Asset Management, Lilly Asia Ventures, New Leaf Venture Partners, NS Investment, Oncology Impact Fund, OrbiMed, Ridgeback Capital Investments, Taiho Ventures, Ron Hunt, Amplitude VC.
Harpoon Therapeutics is a clinical-stage immunotherapy company developing T cell engagers—engineered proteins that direct patients' T cells to kill cancer cells expressing specific antigens—primarily targeting solid tumors and hematologic malignancies like small cell lung cancer (SCLC) and multiple myeloma.[1][2][3] Its proprietary platforms include the TriTAC (tri-specific T cell activating construct) for immune activation, ProTriTAC (a prodrug version that activates only at tumors), and TriTAC-XR (to reduce cytokine release syndrome).[2][3][4] Key candidates serve oncology patients with advanced cancers: lead asset HPN328 (now MK-6070 post-acquisition) targets DLL3 in SCLC and neuroendocrine tumors (Phase 1/2 trials); HPN217 targets BCMA in multiple myeloma (Phase 1); and preclinical HPN601 targets EpCAM in solid tumors.[1][3][5] The company addressed unmet needs in hard-to-treat cancers but was acquired by Merck in March 2024 for ~$650-680M, integrating its pipeline into Merck's oncology efforts amid Keytruda patent cliffs.[6][7]
Founded in 2015 and headquartered in South San Francisco, California, Harpoon Therapeutics emerged from innovations in T cell engager technology to harness the immune system against cancer.[1][2] While specific founders are not detailed in available sources, the company quickly advanced its TriTAC platform, securing a discovery collaboration with AbbVie for soluble T cell receptor integration.[1] Early traction included advancing HPN328 into Phase 1/2 trials (NCT04471727) showing 48% tumor shrinkage in SCLC patients, despite pauses for cytokine issues like respiratory failure in neuroendocrine trials (later revised).[3][6] Pivotal growth led to Merck's acquisition in early 2024, valuing its bispecific tech amid rising demand for next-gen immunotherapies beyond blood cancers.[5][6][7]
Harpoon stood out in immuno-oncology through targeted platforms optimizing T cell engagement:
These features differentiated Harpoon from traditional bispecifics, prioritizing solid tumor penetration and tolerability.[6]
Harpoon rode the bispecific T cell engager wave, extending blood cancer successes (e.g., approved bispecifics) to solid tumors amid immunotherapy evolution post-PD-1 dominance like Keytruda.[3][6] Timing aligned with 2020s urgency: SCLC's poor prognosis (chemo/Tecentriq standards) and DLL3's promise after AbbVie’s ADC failure made HPN328 compelling, with 48% response rates fueling interest.[6] Market forces favoring it included Big Pharma's pipeline diversification—Merck's $680M buyout countered Keytruda's 2028 exclusivity loss, blending Harpoon's tech with Keytruda combos.[5][6][7] Harpoon influenced the ecosystem by validating prodrug and CRS-mitigating platforms, accelerating T cell therapies for antigen-rich solids and inspiring rivals in immuno-oncology.[2][3]
Post-2024 Merck acquisition, Harpoon's assets like MK-6070 (HPN328) advance in Phase 1/2 for DLL3+ cancers, potentially combining with Keytruda to sustain Merck's dominance.[3][6][7] Trends shaping it include bispecific maturation for solids, AI-driven antigen discovery, and CRS solutions enabling broader adoption.[2][6] Influence evolves via Merck's scale: faster trials, global reach, and pipeline integration could yield approvals by late 2020s, transforming SCLC treatment while validating Harpoon's immune-harnessing vision from a nimble biotech to pharma powerhouse.[1][5]