A Phase 1/2 Study of CYT-0851, an Oral RAD51 Inhibitor, in B-Cell Malignancies and Advanced Solid Tumors

  • days left to enroll
  • participants needed
  • sponsor
    Cyteir Therapeutics, Inc.
Updated on 25 February 2022
lymphoid leukemia
chronic lymphocytic leukemia
multiple myeloma
hodgkin's disease
measurable disease
breast cancer
squamous cell carcinoma
bone marrow procedure
lymphocytic leukemia
chemotherapy regimen
primary cancer
cancer chemotherapy
diffuse large b-cell lymphoma
b-cell lymphoma
solid tumour
solid tumor
triple negative breast cancer
ovarian cancer
stage iv breast cancer
solid neoplasm
squamous cell carcinoma of head and neck
metastatic breast cancer
anti-cd20 antibody
chronic lymphocytic leukemia refractory
soft tissue sarcoma
head and neck carcinoma
cancer of the ovary


This clinical trial is an interventional, active-treatment, open-label, multi-center, Phase 1/2 study. The study objectives are to assess the safety, tolerability and pharmacokinetics (PK) of the oral RAD51 inhibitor CYT-0851 in patients with relapsed/refractory B-cell malignancies and advanced solid tumors and to identify a recommended Phase 2 dose as a monotherapy and in combination with chemotherapy for evaluation in these patients.


Overexpression of activation-induced cytidine deaminase (AID) or other cytidine deaminases causes high rates of deoxyribonucleic acid (DNA) damage (mutations, double strand DNA breaks, and chromosome rearrangements) in a high number of patients with B-cell malignancies, such as NHL, MM, and CLL, and in a subset of patients with solid tumors, such as non-small cell lung cancer (NSCLC), sarcoma, breast cancer, ovarian cancer, and squamous cell carcinoma of the head and neck. Cancer cells that overexpress AID and other cytidine deaminases rely on RAD51, a protein involved in homologous recombination, to repair the DNA damage caused by cytidine deaminases. Inhibition of RAD51 with CYT-0851 in preclinical models induces cell death, tumor growth delay or tumor regression.

The Phase 1 part of the study will follow an accelerated titration design, which includes enrollment of single patient cohorts until certain criteria are met, followed by a standard 3+3 design. This design will allow for identification of a recommended phase 2 dose (RP2D) level while dosing the least number of patients as possible at potentially sub-therapeutic doses. Upon identification of the RP2D in the monotherapy, the study will open to three combination treatment arms to identify the RP2D in combination with rituximab and bendamustine in Non-Hodgkin Lymphoma and capecitabine or gemcitabine for solid tumors. In the Phase 2 part of the study, preliminary efficacy will be evaluated in 8 expansion cohorts (total n = 92-220), using a Simon two-stage design. The RP2D will be selected based on the MTD, the safety profile, PK, and available pharmacodynamics data generated from all subjects in Phase 1.

In both Phase 1 and Phase 2, patients will be treated in continuous 21-day or 28-day cycles and all patients will be assessed for response every 2 cycles. Treatment will be terminated if the patient progresses, cannot tolerate treatment, or withdraws consent from active therapy. Patients will undergo a safety evaluation approximately 1 month (28-35 days) after the last dose. Patients will be followed for response until progression is documented.

Condition Malignancy, Non-hodgkin Lymphoma, Multiple Myeloma, Breast Cancer, Ovarian Cancer, Soft Tissue Sarcoma, Head and Neck Cancer, DLBCL, Mantle Cell Lymphoma, Follicular Lymphoma, Pancreatic Cancer, CLL, Small Cell Lung Cancer, Squamous Cell Carcinoma of Head and Neck, Triple Negative Breast Cancer
Treatment CYT-0851
Clinical Study IdentifierNCT03997968
SponsorCyteir Therapeutics, Inc.
Last Modified on25 February 2022


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