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Seattle Genetics Pays $25M to Buy Into Unum’s Souped-Up T-Cell Therapy

Xconomy Boston — 

Unum Therapeutics started up last year with its own twist on the increasingly crowded field of cellular immunotherapy. Today, that plan got a stamp of support from Seattle Genetics.

SeaGen (NASDAQ: SGEN) has agreed to team up with Cambridge, MA-based Unum in a broad deal to use the former’s antibodies with Unum’s cellular immunotherapy technology for cancer.

In the deal, SeaGen has made a $25 million cash payment up front and has agreed to put another $5 million into Unum’s next round of financing. The two companies will work together to develop two products that harness both of their technologies, though SeaGen has an option to add a third product into the fold.

SeaGen will fund the early work Unum does on these projects, and then split the costs with Unum after Phase 1 testing (unless one of the companies opts out). They’ll also evenly split U.S. profits on any marketed therapy that comes out of the collaboration (SeaGen will get full rights outside of the U.S., and pay Unum royalties). The deal includes up to $615 million in total downstream payments.

The pact is a big validating step for Unum, which Atlas Venture, Fidelity Biosciences, and Sanofi-Genzyme BioVentures started up last year with a $12 million Series A round. Unum is part of the fast-moving field of T-cell therapy, in which a patient’s own T cells are extracted, genetically engineered to be efficient killers of certain types of tumors, and infused back into the body. Juno Therapeutics (NASDAQ: JUNO), Kite Pharma (NASDAQ: KITE) and others have fast become multi-billion dollar companies on the promise of these therapies, which have produced stunning results in certain types of blood cancers in clinical testing.

But there’s plenty of room for improvement, and Unum is one of the companies trying a different, more universal type of approach. Rather than fixate on a specific cancer type or protein—many of the leading T-cell therapies modify immune cells to seek out tumor cells that have a protein called CD19 on their surface, for instance—Unum is engineering T cells with a surface protein that helps them latch onto a wide array of antibodies. The idea is that the antibodies serve as beacons to find tumors, lighting the way for the killer T cells to follow. The upshot: Unum could both supercharge an antibody and apply a T-cell therapy approach to any cancer to which antibody therapies are being applied—potentially even cancers from solid tumors, which are a much trickier technical challenge for companies in this field. Unum calls this approach “antibody-coupled T-cell receptor” technology, or ACTR.

As CEO Chuck Wilson (pictured above) told Xconomy last year, Unum’s goal is to partner with companies that want to enhance experimental antibody therapies, hopefully stringing together co-development and co-commercialization deals where Unum supplies the T cells (and its partner, the antibodies).

The SeaGen deal is the first example of this concept taking shape. SeaGen develops antibody-drug conjugates, which are antibodies chemically linked to tumor-killing toxins. While these drugs have a lot of promise—they’re meant to serve effectively as smart bombs that seek out cancer and spare healthy tissue—only a few of them have hit the market as of yet, one of them being SeaGen’s brentuximab-vedotin (Adcetris), which is approved to treat blood cancers like Hodgkin’s lymphoma.

“Unum’s innovative technology for a universal, antibody-directed cellular immunotherapy is differentiated from other engineered T-cell approaches, and may have broad applicability across a range of cancer targets,” said SeaGen CEO Clay Siegall, in a statement.

For more on Unum, and the T-cell therapy field as a whole, check out these two pieces.