Bardoxolone methyl is an activator of the KEAP1-Nrf2 pathway [1] and also inhibits the pro-inflammatory transcription factor NF-kB [2] which can protect kidneys from aristolochic acid (AA)-induced acute kidney injury (AKI) with IC50 value of 1.5 nM and LC50 value of 2.1 µM [3].
Nrf2, a transcription factor, is a basic leucine zipper (bZIP) protein that regulates the expression of antioxidant proteins that protect against oxidative damage triggered by injury and inflammation [4], such as NADPH, Glutathione, SRXN1, TXNRD1, HMOX1, GST, UGT and Mrps. Nrf2 plays an important role in the maintenance of homeostasis which can control the basal and inducible expression of a battery of genes with diverse physiological roles, including the preservation of redox balance, the metabolism and detoxification of xenobiotics, and the regulation of multiple metabolic pathways that ensure the provision of cellular energy[5].
Bardoxolone methyl is a synthetic oleanane triterpenoid compound, which has no effect on the function and histology of normal kidneys but increased renal expression of Nrf2, HO-1 and NQO1 by western blotting analysis of mice kidneys and immunofluorescence staining, and can prevent AA-induced acute kidney injury and reduce AAI-induced TI injury in mRNA and protein levels through real-time PCR.[6] In conclusion, Bardoxolone methyl can prevent AAI-induced renal damage, and it may exert this renoprotective effects by activating the Nrf2 signaling pathway and inducing the downstream target genes expression. A phase 3 clinical trial evaluating bardoxolone methyl for the treatment of chronic kidney disease (CKD) was terminated in October 2012 after patients treated with the drug were found to have experienced a higher rate of heart-related adverse events, including heart failure, hospitalizations and deaths.[7] Now in 2014, Kyowa Hakko Kirin announced plans to evaluate both safety and efficacy of bardoxolone methyl in a Phase 2 clinical study to be performed in Japan for the treatment of CKD associated with type 2 diabetes.[8]
References:
1.Yates MS, Tauchi M, Katsuoka F, et al."Pharmacodynamic characterization of chemopreventive triterpenoids as exceptionally potent inducers of Nrf2-regulated genes." Mol Cancer Ther 2007, 6 (1): 154–62.
2.Ahamd R, Raina D, Meyer C, et al.. "Triterpenoid CDDO-Me blocks the NF-kappaB pathway by direct inhibition of IKKbeta on Cys-179.". J Biol Chem, 2006, 281 (47): 35764–9.
3.Ian M. Copple. et al. Chemical Tuning Enhances Both Potency Toward Nrf2 and In Vitro Therapeutic Index of Triterpenoids. TOXICOLOGICAL SCIENCES,2014,140(2), 462–469.
4.Gold R, Kappos L. Et al. Placebo-controlled phase 3 study of oral BG-12 for relapsing multiple sclerosis. N. Engl. J. Med. 2012, 367 (12): 1098–107.
5.Ma, Q. Role of nrf2 in oxidative stress and toxicity. Annu. Rev. Pharmacol. Toxicol. 2013,53:401–426.
6.Juan Wua. et al. Bardoxolone methyl (BARD) ameliorates aristolochic acid (AA)-induced acute kidney injury through Nrf2 pathway. Toxicology. 2014, 318(6):22–31.
7.de Zeeuw D, Akizawa T, Audhya P, et al. "Bardoxolone methyl in type 2 diabetes and stage 4 chronic kidney disease.". N Engl J Med,2013,369 (26): 2492–503.
8.Kyowa Hakko Kirin Co Ltd announces future development direction for bardoxolone methyl (RTA 402).