Development of an Nrf2 inhibitor for the treatment of Nrf2-addicted cancer

2019 Fiscal Year Research-status Report

• Project/Area Number: 19K16512
• Research Institution: Tohoku University
• Principal Investigator: Baird Liam 東北大学, 医学系研究科, 助教 (90724914)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: Keap1 / Nrf2

Outline of Annual Research Achievements

In order to selectively target tumours with aberrant NRF2 activity, we developed a novel synthetic lethal screening strategy utilizing an isogenic pair of fluorescently labelled cell lines for use in the identification of novel anti-cancer drugs. We have characterized these cells to show that they accurately model NRF2 activation in cancer, and are thus well suited for use in screening. We then developed our own custom small compound screening library which targets a wide variety of cell stress pathways in order to determine whether NRF2-dependent cancers may be specifically sensitive to modulation of such pathways. From this screen, we identified a single compound which exhibits synthetic lethality with NRF2 activity. We then generated a third isogenic cell line in which Keap1 and Nrf2 are knocked out together. This double knockout state was sufficient to rescue the lethal phenotype, which clearly demonstrates that NRF2 activity is responsible for the synthetic lethal interaction with the hit compound. Furthermore, we validated the results of the screen using pairs of WT and NRF2 active human cancer cell lines derived from lung, oesophagus and liver tumours, and found that in all cases, the compound was able to kill cells in an NRF2-dependent manner.

Current Status of Research Progress

1: Research has progressed more than it was originally planned.

Reason

Because we have successfully identified a hit from our screen, and have validated this result in many different cancer cell lines, we are happy with the progress of the project.

Strategy for Future Research Activity

As we have identified a compound which is synthetic lethal with NRF2 activity in our model screening system, and in human cancer-derived cell lines, we plan to further validate the significance of our result in vivo using a mouse xenograft model. Furthermore, we plan to carry out mechanistic studies to determine how this compound is specifically killing cells with aberrant NRF2 activition, in order to gain a complete understanding of the synthetic lethal relationship between the compound and NRF2.

Causes of Carryover

Next year I plan to validate the activity of the drug that I have discovered in a mouse model of cancer, and therefore I would like to use my budget to pay for the mouse study and to buy a quantity of the drug suitable for administration to mice. In addition, I would also like to discover the mechanism through which the drug is working, and therefore I would like to use my budget to carry out a variety of experiments in cell culture to clearly delineate this mechanism.