Bound for the clinic with a new approach to synthetic lethality, Cyteir bags $29M

As an associate professor at The Jackson Laboratory, Kevin Mills zeroed in on the supporting role that the RAD51 protein played in repairing the DNA damage caused by elevated levels of activation-induced cytidine deaminase, or AID.

Kevin Mills

Tripping up RAD51 with a small molecule, he thought, would throw a monkey wrench in the whole DNA repair pathway, allowing mutated cancer cells and other stressed cells involved in autoimmune diseases to die, playing an assisting role in synthetic lethality.

Mills would go on to found a biotech in Cambridge, MA called Cyteir. And today a group of high profile venture backers are coming up with the $29 million that Mills and his team need to get into the clinic with a lead cancer drug. The CSO is also being joined by Celgene vet Markus Renschler, who’s now the new CEO.

“My whole career has been spent on DNA damage and DNA damage responses,” Mills tells me. The work on RAD51 goes back a decade, and Cyteir was spun out of The Jackson Lab in 2012, patiently doing the preclinical work needed to advance a lead program.

Markus Renschler

If their first Phase I/II study goes well, Renschler says there are a number of options for developing the program. “We can develop it as a monotherapy for over-expressed AID,” he notes, as well as in combination with platinum-based chemo, PARP inhibitors (which also trigger synthetic lethality), radiation as well as the popular new generation of checkpoint inhibitors.

Renschler, though, wants to retain rights to the drug for now, looking to partner later as they get deeper into the clinic. With enough money to nab proof-of-concept human data, he has options on raising more cash later. Right now he wants to explore just how much value is here before dickering any of it away.

Starting in hematology just makes sense, he adds. Tumors that arise from B cells have this activated pathway, he says, highlighting DLBCL, non-Hodgkin lymphoma and multiple myeloma as prime targets. That’s where it’s easiest to find a high number of patients with the AID biomarker.

But Mills and Renschler are also pumped about their prospects in autoimmune diseases, noting that the same targeted approach could provide plenty of added upside.

It’s early days for clinical work at Cyteir, which will now grow from a virtual staff of 6 to 20. But they have big plans.

Venrock led the round, joined by returning investors including Celgene. New investors included Lightstone Ventures and DROIA Oncology Ventures.

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