Harpoon Therapeutics Files for $75 Million IPO for Cancer Immunotherapy

Edward Kim  |

As 2018 draws to a close, several biotechnology companies have filed for initial public offerings that they hope to bring to fruition in the first quarter of 2019. Among the candidates we've been following is Harpoon Therapeutics (proposed Nasdaq: HARP), a South San Francisco-based cancer immunotherapy company that is developing a novel class of T cell-engaging antibodies (T cell engagers)—engineered proteins that direct a patient’s own T cells to kill target cells that express specific proteins. Harpoon's lead clinical candidate is in Phase 1 trials for prostate cancer, and the company is also developing treatments for ovarian cancer (and other solid tumors), multiple myeloma and small cell lung cancer.

$70 million Series C round in November 2018

Harpoon filed its Form S-1 yesterday for a $75 million IPO (the registration statement's $86.25 million placeholder would equate to a $75 million deal + full overallotment option) via Citigroup and Leerink Partners. Though the pipeline is at an early stage of development, the company has attracted seasoned venture investors. Harpoon just closed on a $70 million Series C round in November 2018 led by new investor OrbiMed with participation from other new investors Cormorant, Ridgeback Capital, Lilly Asia Ventures and NS Investment. Harpoon's existing investors MPM Capital, Oncology Impact Fund, Arix Bioscience, New Leaf Venture Partners and Taiho Ventures also participated in the round.

TriTACs - Tri-specific T cell Activating Construct

The company has developed a new class of T cell engagers called TriTACs, based on its proprietary Tri-specific T cell Activating Construct, which are designed to advance the therapeutic potential of T cell engagers, an established and meaningful mechanism of action. The first approved bispecific T cell engager (BiTE) was Amgen’s  (AMGN) Blincyto, was approved by the FDA in 2014 for the treatment of acute lymphoblastic leukemia, and other BiTEs have since shown promising therapeutic potential in clinical trials.

MPM Capital, led by Executive Partner Patrick Baeuerle, PhD, founded Harpoon Therapeutics in 2015. Dr. Baeuerle co-founded six of MPM's oncology portfolio companies and had joined MPM after serving as VP of Research and General Manager of Amgen Research Munich, where he was responsible for the development of Blincyto.

Harpoon's TriTACs are designed to incorporate the known strengths BiTEs, which include small size and activity at low levels of antigen expression, while improving upon their critical shortcomings, which include short half-life and limited stability.

Source: Harpoon Therapeutics

AbbVie collaboration

Harpoon has been collaborating with AbbVie  (ABBV) since October 2017. AbbVie has worldwide exclusive rights to develop and commercialize products that incorporate Harpoon's TriTAC technology with soluble T cell receptors (TCRs) provided by AbbVie. Harpoon received $17 upfront from AbbVie and is eligible to receive up to an additional $600 million in development, regulatory and commercial milestones, as well as tiered royalties, from AbbVie.


Gerald McMahon, PhD, has been President, CEO and a board member of Harpoon since December 2016. He was previously President and CEO of Kolltan Pharmaceuticals until its acquisition by Celldex  (CLDX), and was SVP of Oncology at MedImmune, a subsidiary of AstraZeneca AZN. Prior to MedImmune, he was Chairman and CEO of NeoRx, a venture partner at Bay City Capital and in executive leadership roles at Poniard Pharmaceuticals and SUGEN, which was acquired by Pfizer  (PFE). Dr. McMahon was a key player in the development and commercialization of cancer drugs Sutent and Palladia.

Natalie Sacks, MD, joined Harpoon in October 2018 as Chief Medical Officer. She most recently served as Chief Medical Officer of Aduro Biotech, and was previously VP of Clinical Development at Onyx Pharmaceuticals (acquired by Amgen) where she played a key role in the development and approval of Kyprolis, an FDA-approved therapy for the treatment of multiple myeloma. Dr. Sacks served as VP of Clinical Research for Exelixis where she directed the development of a portfolio of small molecules, including development of Cometriq for metastatic medullary thyroid cancer.

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Symbol Name Price Change % Volume
ABBV AbbVie Inc. 94.05 0.00 0.00 12,575 Trade
AMGN Amgen Inc. 223.48 0.00 0.00 4,940 Trade



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