Harpoon Therapeutics said today it has completed a $45 million Series B financing round, which the company plans to use toward developing its immuno-oncology platform and advancing two lead candidates based on this technology into clinical trials.
The company’s antibody-based tri-specific T-cell activating construct (TriTAC™) platform creates constructs that consist of single polypeptides designed to bind with one arm to cancer cells and capture and engage bypassing T cells with their second arm. Activation of T cells by TriTAC antibodies is intended to release toxic factors leading to the death of target cells. T cells proliferate and search for and repetitively destroy cancer cells in the entire body as long as the TriTAC antibody is present, according to Harpoon.
A third domain in TriTAC antibodies attaches to human serum albumin, which the company says allows for more optimal drug exposure and less frequent treatment of patients. While TriTAC antibodies have three binding domains, their overall size is only one-third of that of monoclonal antibodies, which Harpoon reasons will enable faster penetration into tissues, especially tumor tissue.
TriTAC is specifically engineered to treat solid tumors, but can also eliminate cells causing other severe diseases, like acute and chronic inflammation or infections, Harpoon adds.
Harpoon expects to advance its first clinical candidate HPN424 into Phase I clinical trials next year, followed within a year by one or more additional clinical candidates.
HPN424 is a prostate-specific membrane antigen (PSMA)-targeting TriTAC designed to treat metastatic prostate cancer.
Harpoon said it plans to expand its product pipeline through discovery and partnering initiatives, as well as increase its commitment to developing additional therapeutic platforms, including those that become activated by proteases.
Arix Bioscience and New Leaf Venture Partners, both new investors, co-led the financing, which also saw participation by a third new investor, Taiho Ventures, as well as existing investor MPM Capital.
In conjunction with the financing, Mark Chin, investment manager at Arix, and Ron Hunt, managing director at New Leaf, will join Harpoon’s board as full directors, while Sakae Asanuma, president of Taiho Ventures, will join the board in an observer capacity.
This investment is a clear validation of Harpoon’s TriTAC platform, which offers a new way to unleash the targeted cell-killing properties of a patient’s own immune system with a potential best-in-class T-cell engager platform,” Harpoon president and CEO Jerry McMahon, Ph.D., said in a statement.
Harpoon was founded in 2015 by a team led by Patrick Baeuerle, Ph.D., a pioneer in the development of T-cell-based human therapies and key consultant for the company, and Luke Evnin, Ph.D., a founder of MPM Capital.
Dr. Baeuerle is an executive partner of MPM. He previously oversaw development of Amgen’s marketed CD19-directed CD3 T-cell engaging antibody Blincyto® (blinatumomab) and spearheaded the development of the Bispecific T cell Engager (BiTE) platform as CSO for Micromet and as vp, research for Amgen, which acquired Micromet in 2012.