MPM founded Harpoon Therapeutics and seeded its early work looking to make the leap into next-gen immuno-oncology drugs with some insights from one of the pioneers in the field. Now it has put together a global syndicate of some A-list venture investors to back a $45 million B round to move their lead drug into the clinic next year.
Harpoon was inspired by Patrick Baeuerle, who led the development work on Micromet BiTE platform, which used an antibody to redirect killer T cells to destroy tumor cells. Amgen went on to acquire Micromet in 2012, back when Roger Perlmutter was running R&D and fell in love with the work. Perlmutter, now running R&D at Merck, brought Baeuerle on board at Amgen to continue work on Blincyto, which was approved in late 2014 as the first bispecific CD19-directed CD3 T-cell engager.
The scientist then left for MPM, bringing along some ideas on how next-wave drugs could go much, much further.
The big idea now, to be tested with HPN424 for prostate cancer, is built around a new platform dubbed TriTAC, for tri-specific T-cell activating drugs. Done properly, the biotech believes it has a better way “to unleash the targeted cell-killing properties of a patient’s own immune system through T-cell activation.” That’s a big goal, and done properly the biotech believes it will penetrate tissue better and extend serum exposure, with applications in cancer as well as immunology.
“We’re giving an antibody-type molecule, not an antibody per se, and we give that to patients,” says Harpoon CEO Jerry McMahon, had been CEO at Kolltan until Celldex bought it out last year. “The molecule will create a bridge between the tumor cells and the T cells, and that bridge – or synapse – allows the T cell to kill the tumor cell.”
McMahon sees this as a third class of I/O drug, following checkpoint inhibitors and CAR-T, advantaged by their ability to be able to adjust dosage and regimen.
The latest round brings the total amount raised so far to $60 million, with enough cash to get at least through the next two years, with plans to double the current 15-member staff by the end of next year. In addition to its prostate cancer drug, McMahon adds that the biotech also has another therapy being prepped for human studies that targets lung, ovarian and pancreatic cancer.
Harpoon, founded in 2015, spun one of its other platforms using the tumor microenvironment to activate T cells into a separate biotech called Maverick, which attracted a $125 million investment last January tied to an option to acquire it.
Baeuerle has been busy of late, booting up new companies. He and MPM also founded TCR2 Therapeutics, another immuno-oncology company that hopes to pioneer a new class of T cell therapies that reprograms the natural T cell receptor complex to recognize specific antigens found on tumors, rapidly killing cancer cells.
London-based Arix Bioscience and New Leaf Venture Partners co-led the latest round, with help from MPM Capital and Taiho Ventures, another new investor.
“Harpoon Therapeutics has a novel, T-cell engager platform which we believe will be instrumental to the discovery and development of important new therapeutics in oncology,” said Mark Chin, investment manager at Arix Bioscience. “Coupled with its scientific expertise and strong management team, Harpoon is well-positioned to play a leading role in the immuno-oncology field.”
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