• New funding brings total Series B raise to $75.2 million
• Novo Holdings led round, joined by Venrock, DROIA, Osage University Partners, Lightstone and Celgene Corpo­ra­tion
• RAD51 in­hib­i­tor CYT-0851 now being eval­u­ated in patients with re­lapsed, re­frac­tory B-cell malig­nan­cies and ad­vanced solid tumors

Lexington, MA (Press Release) – Cyteir Thera­peutics, a leader in the discovery and devel­op­ment of next-generation syn­thet­ic lethal ther­a­pies for cancer, today announced the close of an addi­tional $40.2 million in the com­pany's Series B financing, for a total of $75.2 million in this financing. The addi­tional funding will be used to ex­pand the clin­i­cal in­ves­ti­ga­tion of Cyteir's first-in-class RAD51 in­hib­i­tor and lead com­pound, CYT-0851, and to identify new targets using the com­pany's novel gain-of-function syn­thet­ic lethality screen­ing plat­form.

Novo Holdings led the round, joined by existing in­vestors Venrock, DROIA Oncology Ventures, Osage University Partners (OUP), Lightstone Ventures and Celgene Corpo­ra­tion. As part of this closing, Karen Hong, Ph.D., of Novo Ventures, which provides con­sult­ing services to Novo Holdings, will join the Cyteir Board.

"The con­tinued sup­port for Cyteir from highly knowledgeable in­vestors reflects the growing excitement around our novel appli­ca­tion of syn­thet­ic lethality," said Markus Renschler, M.D., Cyteir pres­i­dent and CEO. "This financing will sup­port the recently launched first-in-human phase 1/2 study of CYT-0851 while simultaneously allow­ing us to con­tinue investigating our syn­thet­ic lethality plat­form to find new targets that inhibit DNA damage repair. We believe this ap­proach could lead to valuable new treat­ment options for cancer patients."

Cyteir's plat­form is based on the discovery of a rela­tion­ship be­tween DNA-damaging enzymes known as cytidine deaminases, and RAD51, a protein that is essential for the repair of DNA breaks. These enzymes are non-damaging in healthy tissues, but gain hyperactive function in a wide range of cancers and cause elevated DNA damage. Cyteir is devel­op­ing selective small-molecule in­hib­i­tors of RAD51 to reduce the ability of cancer cells to self-repair through homologous recombination. This causes the cancer cells to be­come overwhelmed by accumulated DNA damage and undergo cell death – resulting in the thera­peutic effect known as "synthetic lethality."

In pre­clin­i­cal experiments, CYT-0851 dem­onstrated synergy with PARP in­hib­i­tors, con­sis­tent with its DNA damage-repair path­way in­hib­i­tory activity. These results sug­gest CYT-0851 has the poten­tial to overcome PARP in­hib­i­tor resistance.

Researchers at Sarah Cannon Research Institute in Nashville, Tenn., recently dosed the first patient in a Phase 1/2 study of CYT-0851. This study will enroll up to 200 patients with B-cell malig­nan­cies and solid tumors.

"We are pleased to be part of this study, which will help define the poten­tial of an entirely new class of targeted cancer ther­apy," said Johanna Bendell, M.D., chief devel­op­ment officer at Sarah Cannon Research Institute and the study's lead investigator. "Pre-clinical evaluations of CYT-0851 have been very en­cour­ag­ing, and we look for­ward to seeing how this com­pound impacts patients in this trial."

In March 2019, Cyteir presented pre-clinical data at the 2019 American Association for Cancer Research annual meeting that val­i­dated the mech­a­nism of action under­lying the com­pany's syn­thet­ic lethal plat­form and con­firmed that CYT-0851 is a potent in­hib­i­tor of RAD51-mediated homologous recombination with the poten­tial to target multiple cancers that have high levels of cytidine deaminase-related DNA damage. The data in­di­cated that CYT-0851 could poten­tially be clin­i­cally active as a mono­therapy against B-cell lym­phomas and multiple solid tumors, in­clud­ing pancreatic cancer.

About the CYT-0851 Phase 1/2 Trial

CYT-0851-01 is a phase 1/2 study of CYT-0851 in patients with re­lapsed, re­frac­tory non-Hodgkin lym­phoma, chronic lym­pho­cytic leukemia, multiple myeloma, or ad­vanced breast cancer, ovarian cancer, head and neck cancer, soft tissue sarcoma, and pancreatic cancer. The study will be conducted at leading research institutions in the United States. An initial dose-escalation phase will estab­lish­ the safety and tolerability of CYT-0851 and identify the rec­om­mended phase 2 dose. This will be followed by an ex­pan­sion phase to eval­u­ate response rates among each of six dis­ease cohorts. Cyteir is also devel­op­ing a companion diagnostic assay to identify patients with tumors that overexpress cer­tain cytidine deaminases that may make them more sus­cep­tible to RAD51 inhibition.

About CYT-0851

CYT-0851 is an experimental, oral, selective in­hib­i­tor of RAD51, a protein in­volve­d in homologous recombination. Cancer cells that overexpress cer­tain DNA-damaging cytidine deaminases rely on RAD51 to repair DNA damage. In pre­clin­i­cal models, inhibition of RAD51 with CYT-0851 induces cell death in cytidine deaminase overexpressing cell lines and reduces pro­lif­er­a­tion.

About Cyteir Thera­peutics

Cyteir, a private com­pany based in Lexington, Mass., is an innovator in DNA repair, devel­op­ing the next generation of syn­thet­ic lethal ther­a­pies designed to treat cancer. Cyteir exploits the syn­thet­ic lethality of gain-of-function DNA-damaging genes and DNA repair inhibition, resulting in selective death among cells with high levels of DNA damage. The com­pany is backed by leading health­care in­vestors, in­clud­ing Novo Holdings, Venrock, DROIA, Osage University Partners (OUP) and Lightstone Ventures, as well as Celgene Corpo­ra­tion. For more in­for­ma­tion, visit www.cyteir.com.

Source: Cyteir Thera­peutics.