Unmet Need
DNA Double-strand breaks (DSB) occur when it is exposed to ionizing radiation and can result in cancerous mutations when repaired via homologous recombination (HR) or non-homologous end-joining (NHEJ) [1]. Cancer cells rely on these mutagenic repair mechanisms for survival [2]. But, the dynamics between the two repair pathways is unclear. DNA repair machinery is complex as there are a large number of proteins involved in the process and alterations in repair machinery and pathways can indicate sensitivity to therapeutic agents such as PARP inhibitors, cisplatin, and immunotherapy. Therefore, functional assays to measure rates of HR and NHEJ are of significant interest for facilitating drug discovery. Several methods have been developed to measure rates of HR or NHEJ; however, most require the use of multiple tools to fully assess rates of repair by each pathway individually using multiple samples. Therefore, there is a need to assess the relationship between the HR and NHEJ pathway, as well as the functional impact of DNA repair mutations on rates of repair in order to develop research tools and pathway-specific therapies.
Technology Overview
Researchers at Johns Hopkins have developed the RepairSwitch assay, the first flow cytometric assay to simultaneously detect the rates of HR or NHEJ mediated repair of Cas9 induced DSBs using a novel fluorescence switching reporter system. The assay exhibits low background signal and is capable of detecting rare repair events in the 1 in 10,000 range. The utility of the RepairSwitch has been assessed by measuring the potency of inhibitors targeting ATM, DNA-PK, and PARP, which modulate DSB repair rates in HEK293FT cells. The value of this technology is the ability to simultaneously detect the type of DNA repair pathway (HR, NHEJ, or both) in the setting of new drug discovery and genetic perturbations that will show synthetic lethality with existing therapeutic agents.
Stage of Development
All constructs and processes have been developed. Next steps include packaging into a kit and scaling to market.
Publication
Cancer Res (2020) 80 (16_Supplement): 2383. (https://doi.org/10.1158/1538-7445.AM2020-2383)
