Background:

KI696 is a high affinity probe that disrupts the Keap1/NRF2 interaction.

KI696 (compound 7) exhibits very high affinity for the KEAP1 Kelch domain (ITC Kd=1.3 nM with the exception of the organic anion transporting polypeptide 1B1 (OATP1B1) (IC50=2.5 µM), the bile salt export pump BSEP (IC50=4.0 µM), and the phosphodiesterase PDE3A (IC50=10 µM), no significant cross-reactivity is observed. No cytotoxicity is observed towards BEAS-2B cells with KI696 at concentrations up to 10 µM. KI696 increases NRF2 Nuclear Translocation in Normal Human Bronchial Epithelial cells. KI696 increases mRNA expression of the NRF2-dependent genes NQO1 and GCLM in NHBE cells transfected with the non-targeting siRNA, while NRF2 gene silencing significantly decreases compound activity. KI696 increases NQO1 Activity in an NRF2-Dependent Manner. Treatment with tBHP clearly has a detrimental effect on cell health and appearance while pre-treatment of cells with 1 µM KI696 before the exposure to tBHP maintained cell morphology consistent with the DMSO control. KI696 Induces the Expression of NRF2-Regulated Genes in COPD patient-derived bronchial epithelial cells[1].

KI696 induces the expression of each of the Nqo1, Ho-1, Txnrd1, Srxn1, Gsta3, Gclc genes in a dose-dependent manner, with maximum increases over vehicle controls of 37-(Nqo1), 17-(Ho-1), 9-(Txnrd1), 28-(Srxn1), 15-(Gsta3) and 13-fold (Gclc) occurring at the 50 µmol/kg dose. EC50 values are 44.0, 25.7, 42.6, 33.8, 28.4, and 44.1 µmol/kg, respectively, giving an average EC50 value of 36.4±3.4 µmol/kg. KI696 attenuates ozone-Induced pulmonary inflammation. KI696 restores ozone-induced depletion of lung GSH levels. KI696 is administered to rats at 10, 35 and 50 µmol/kg by IV infusion, resulting in steady state compound concentrations in the blood of 407±44 nM, 946±50 nM and 1437±186 nM, respectively, over the 6 hour infusion period. Exposure to ozone 24 hours post-dose produces a significant depletion in lung levels of the anti-oxidant molecule, GSH, which is restored by KI696 in a dose-dependent manner[1].

[1]. Davies TG, et al. Monoacidic Inhibitors of the Kelch-like ECH-Associated Protein 1: Nuclear Factor Erythroid 2-Related Factor 2 (KEAP1:NRF2) Protein-Protein Interaction with High Cell Potency Identified by Fragment-Based Discovery. J Med Chem. 2016 Apr 28;59(8):3991-4006.