RARE Daily

Cyteir Secures $80 Million for Synthetic Lethalities

February 11, 2021

Rare Daily Staff

Cyteir Therapeutics, a leader in the discovery and development of next-generation synthetic lethal therapies for cancer, completed an oversubscribed $80 million series C financing.

RA Capital Management led the round with participation by Janus Henderson Investors, Acuta Capital Partners, Ally Bridge Group, Avidity Partners, Ample Plus Fund, and CaaS Capital Management, and joined by existing investors Novo Holdings, Venrock, Lightstone Ventures, DROIA Ventures, Osage University Partners, and another undisclosed U.S.-based, healthcare-focused fund.

The company will use the funds to advance its lead compound, the first-in-class inhibitor of RAD51-mediated DNA repair, CYT-0851, into phase 2 monotherapy trials in hematologic cancers and solid tumors, to initiate trials combining CYT-0851 with other cancer therapies, and to expand preclinical research to identify and advance additional novel cancer therapies.

Cyteir is leveraging its expertise in DNA damage response (DDR) to create a pipeline of novel, first-in-class drugs that selectively target a key cancer vulnerability. Cancer cells are acutely reliant on DNA damage repair for their survival and growth; inhibiting key DNA-repair pathways causes them to become overwhelmed by their own damage and self-destruct, a validated scientific approach known as synthetic lethality. Cyteir is pursuing a novel application of synthetic lethality based on the discovery that many tumors rely on a specific DNA-repair pathway that is dependent on the protein RAD51 to repair breaks in DNA.

“Our unique approach to inhibiting RAD51-mediated DNA repair allows us to potentially target hematologic cancers as well as solid tumors with reduced toxicity as compared to other DDR inhibitors,” said Markus Renschler, Cyteir president and CEO.

CYT-0851 is an oral, once daily, first-in-class small-molecule inhibitor of RAD51-mediated DNA repair. Preclinical and early clinical findings support the broad potential for CYT-0851 to selectively target various cancers, including B-cell malignancies, such as non-Hodgkin lymphoma and solid tumors. The findings also suggest there is significant potential to combine CYT-0851 with other therapies that target or induce DNA damage, such as PARP inhibitors and chemotherapy.

In addition, the company said it is developing a companion diagnostic assay to identify patients whose tumors overexpress certain cytidine deaminases, which may suggest that their cancer is more susceptible to CYT-0851. The company has received an investigational device exemption from the U.S. Food and Drug Administration to begin evaluating this companion diagnostic in patients.

CYT-0851 is currently being evaluated in the dose-escalation portion of a phase 1/2 monotherapy trial enrolling approximately 200 patients with solid tumors and hematologic malignancies at leading U.S. cancer centers. Cyteir expects to enter phase 2 later this year.

Beyond CYT-0851, Cyteir is actively identifying, prioritizing, and evaluating DDR pathway targets based on their role in cancer and whether they have an identifiable patient population that could be predicted to benefit from targeted therapy. The company will use a portion of the financing to initiate IND-enabling studies for CYT-1853, a second-generation RAD51 inhibitor. Cyteir also plans to initiate IND-enabling studies in 2023 for an undisclosed discovery compound targeted for the treatment of solid tumors.

Photo: Markus Renschler, Cyteir president and CEO

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