Harpoon Therapeutics

What Harpoon Therapeutics does

Harpoon Therapeutics is a clinical-stage immunotherapy company that develops novel T-cell engaging biologic therapies for cancer, headquartered in South San Francisco and operating with 51-100 employees. The company's core technology is its proprietary TriTAC (Trispecific T-cell Activator) platform, which engineers trispecific antibodies designed to redirect T-cells to recognize and destroy cancer cells. Its lead clinical candidate, HPN328, was in Phase 1/2 trials for small cell lung cancer and neuroendocrine tumors and demonstrated 40% disease control rates in heavily pretreated patients. The pipeline focuses on immuno-oncology applications where conventional therapies have produced limited durable responses.

Harpoon operated as a pre-revenue clinical-stage biotech with no commercialized products or disclosed pricing; its revenue model relied on future commercialization of approved therapies, supplemented by licensing and partnership economics. The company raised capital through multiple private placements from specialist biotech investors including New Leaf Venture Partners, Arix Bioscience, OrbiMed, Invus, K2 HealthVentures, and MPM Capital, including a $25M round in March 2023 and a placement of up to $150M announced in October 2023. The company pursued a NASDAQ IPO (ticker HARP) and ultimately was acquired by Merck & Co. in 2024 for $680 million, after which it operates as a wholly-owned subsidiary folded into Merck's immuno-oncology franchise.

The company's customer base is entirely future-facing: it targets heavily pretreated oncology patients with limited therapeutic options, and its go-to-market relies on pharmaceutical partnerships and large-pharma M&A rather than direct sales. Distribution would flow through specialty pharmacies, hospital formularies, and oncology treatment centers upon approval. Scientific and corporate communications are conducted through SEC filings, investor relations, and clinical-trial publications rather than traditional marketing channels.

Name

Harpoon Therapeutics

Legal name

Harpoon Therapeutics

Website

https://harpoontx.com

Company type

Private

Founded year

2015

Operating status

Acquired

Headcount range

51–100 employees

Short description

Harpoon Therapeutics is a clinical-stage immunotherapy company developing proprietary trispecific T-cell engager (TriTAC) therapies for solid tumors, with lead candidate HPN328 in Phase 1/2 trials for small cell lung cancer and neuroendocrine tumors. Acquired by Merck for $680 million in 2024.

Ownership category

akta.pro rank

Product category

Cancer Immunotherapy / Oncology Biologics

NAICS

Biological Product (except Diagnostic) Manufacturing (325414), Research and Development in Biotechnology (except Nanobiotechnology) (541714), Scientific Research and Development Services (5417)

SIC

Pharmaceutical Preparations (2834), Services-Commercial Physical & Biological Research (8731)

akta.pro primary industry

Bispecific & Multispecific Antibodies (HLAAAAAF)

akta.pro secondary industries

CAR-T & TCR-T Therapies (HLAAABAC), Cell Therapy Enabling Technologies (gene editing, cell engineering, delivery methods) (HLAAABAL)

Keywords

• Clinical-stage immunotherapy
• T-cell engager therapies
• Trispecific antibody platform
• Cancer immunotherapy biologics
• Oncology drug development

Headquarters

HQ city

South San Francisco

HQ country

United States

HQ region

North America

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Technology or R&D, Personnel, Operations

Revenue model

1. Drug Development and Commercialization: Pre-revenue clinical-stage biotech company. Revenue potential through commercialization of proprietary T-cell engager therapies upon regulatory approval. Lead candidate HPN328 projected to exceed $1 billion peak sales if approved.
2. M&A / Acquisition: Company was acquired by Merck & Co. for $680 million to enhance Merck's immuno-oncology portfolio.

Go-to-market motion1 record

Marketing channels1 record

Core offering

Harpoon Therapeutics is a clinical-stage immunotherapy company developing T-cell engager cancer therapies built on its proprietary TriTAC (Trispecific T-cell Activator) platform — a trispecific antibody-based technology that redirects T-cells to target and destroy cancer cells. The company's lead clinical candidate, HPN328, is being evaluated in Phase 1/2 trials for small cell lung cancer and neuroendocrine tumors. Harpoon had no commercialized products and operated as a pre-revenue development-stage biotech prior to its acquisition by Merck & Co.

Product overview

Harpoon Therapeutics is a clinical-stage immunotherapy company developing a proprietary TriTAC platform for T-cell engager cancer therapies. The platform enables trispecific antibody development. Lead candidate HPN328 is in Phase 1/2 trials for small cell lung cancer and neuroendocrine tumors. The company's pipeline focuses on immuno-oncology applications.

Differentiator

Problem solved

Functional benefit

Products and services

• TriTAC Platform Proprietary trispecific antibody-based technology platform that enables development of T-cell engager cancer therapies by redirecting T-cells to target and destroy cancer cells; used internally by Harpoon to build its oncology pipeline and acquired by Merck & Co. as part of the 2024 acquisition to bolster immuno-oncology R&D.
• HPN328 Lead clinical-stage T-cell engager drug candidate from the TriTAC platform, in Phase 1/2 trials for small cell lung cancer and neuroendocrine tumors, with reported 40% disease control rates in heavily pretreated patients; intended for eventual regulatory approval and commercialization in oncology indications with high unmet need.

Quantifiable outcome

• HPN328 demonstrated 40% disease control rates in heavily pretreated patients

Segments1 record

Ideal customer profiles2 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature1 record

Partnerships

One partnership is on record.

• Merck & Co.coreStrategic or Co-development PartnerMerck & Co. completed a $680 million acquisition of Harpoon Therapeutics to enhance its immuno-oncology portfolio. The acquisition provides Merck access to Harpoon's TriTAC platform for T-cell engager cancer therapies and lead candidate HPN328.

Scale indicators5 records

Recent moves6 records

Expansion highlights4 records

Direct peers

• Maverick Therapeutics: Develops T-cell engager immunotherapies (COBRA platform) for solid tumors — closely comparable modality and oncology focus to Harpoon Therapeutics.
• MacroGenics: Clinical and commercial-stage oncology biotech with multiple bispecific antibody programs (e.g., DART platform), including T-cell engagers — directly comparable modality and indication strategy.
• Janux Therapeutics: Clinical-stage oncology company developing T-cell engager therapies (TRACTr platform) for solid tumors — directly comparable to Harpoon's TriTAC modality and target indications.
• Xencor: Clinical-stage biotech engineering bispecific and multispecific antibody therapeutics for cancer and autoimmune disease — overlapping T-cell engager and immuno-oncology development focus.
• Cullinan Therapeutics: Clinical-stage biopharmaceutical company developing immuno-oncology therapies including T-cell engagers and bispecific antibodies for cancer — overlapping modality and target space.

Emerging players

• CytomX Therapeutics: Clinical-stage oncology company developing Probody therapeutics, a conditionally activated antibody platform — comparable biologics-based immuno-oncology approach with T-cell engager candidates in pipeline.
• Adagene: Clinical-stage biotech developing bispecific antibodies (POWER and SAFE platforms) for solid tumors — comparable modality with T-cell engager programs targeting oncology.
• Bolt Biotherapeutics: Clinical-stage immuno-oncology company developing bispecific immune-stimulating antibody conjugates (ISACs) — adjacent immuno-oncology approach with comparable oncology indication focus.

Broad incumbents

• Regeneron (Bispecific Programs): Large commercial-stage biopharmaceutical with bispecific antibody programs (e.g., linvoseltamab, odronextamab) — broader oncology portfolio with overlapping T-cell engager modality and target indications.
• Genmab: Commercial-stage antibody company with the proprietary DuoBody bispecific platform — established player in bispecific/multispecific antibody-based cancer therapeutics broadly comparable to TriTAC.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat2 records

Key risks6 records

Key highlights6 records

Customer concentration

• Xx.com/harpoontx
• LinkedInlinkedin.com/company/harpoon-therapeutics

Revenue estimate

Valuation estimate

Number of profiles

Profiles7 records

Funding overview

Funding rounds5 records

Investors19 records

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Harpoon Therapeutics