Bardoxolone methyl

Bardoxolone methyl (also known as “RTA 402” and “CDDO-methyl ester”) is an orally-available first-in-class synthetic triterpenoid. It is an inducer of the Nrf2 pathway, which can suppress oxidative stress and inflammation, and is undergoing clinical development for the treatment of advanced chronic kidney disease (CKD) in type 2 diabetes mellitus patients.

Clinical development
Bardoxolone methyl was previously being investigated by Reata Pharmaceuticals, Inc. in partnership with Abbott Laboratories and Kyowa Hakko Kirin, as an experimental therapy for advanced chronic kidney disease (CKD) in type 2 diabetes mellitus patients. Reata, in consultation with the BEACON Steering Committee, has decided to terminate the Phase 3 BEACON trial of bardoxolone methyl in patients with stage 4 chronic kidney disease and type 2 diabetes. This decision was made based upon a recommendation of the Independent Data Monitoring Committee (IDMC) to stop the trial "for safety concerns due to excess serious adverse events and mortality in the bardoxolone methyl arm."

Phase 1
Bardoxolone methyl was first advanced into the clinic to assess its anticancer properties. In two Phase 1 trials that included 81 oncology patients, bardoxolone methyl reduced serum creatinine levels, with a corresponding improvement in estimated glomerular filtration rate (eGFR). Improvements were more pronounced in a subset of patients with established CKD and were maintained over time in patients who continued on bardoxolone methyl therapy for 5 months. Based on these observed effects and the well-described role of oxidative stress and inflammation in CKD, especially in type 2 diabetes, it was hypothesized that bardoxolone methyl could improve renal function in CKD patients with type 2 diabetes.

Phase 2
A multi-center, double-blind, placebo-controlled Phase 2b clinical trial (BEAM) conducted in the US studied 227 patients with moderate to severe CKD (eGFR 20 – 45 ml/min/1.73m²) and type 2 diabetes. The primary endpoint was change in estimated GFR following 24 weeks of treatment. Following 24 weeks, patients treated with bardoxolone methyl experienced a mean increase in estimated GFR of over 10 ml/min/1.73m², compared with no change in the placebo group. Approximately three-quarters of bardoxolone methyl treated patients experienced an improvement in eGFR of 10 percent or more, including one-quarter who saw a significant improvement of 50% or more compared to less than 2% of patients on placebo. Adverse events were generally manageable and mild to moderate in severity. The most frequently reported adverse event in the bardoxolone methyl group was muscle spasm. Final data was published in The New England Journal of Medicine.

Concerns have been raised whether there is a true improvement in kidney function because of the significant weight loss of the patients in the active-treatment-group that ranged from 7.7-10.1 kg (7-10% of the initial body weight) and whether this weight loss in patients receiving bardoxolone included muscle wasting with a commensurate decrease in the serum creatinine level. In that case the decrease in creatinine would not necessarily be a true improvement in kidney function.

Phase 3
A multinational, double-blind, placebo-controlled Phase 3 outcomes study (BEACON) was started in June 2011, testing bardoxolone methyl’s impact on progression to ESRD or cardiovascular death in 1600 patients with Stage 4 CKD (eGFR 15 – 30 ml/min/1.73m²) and type 2 diabetes. This phase 3 trail was halted in October 2012 because of adverse effects (namely a higher cardiovascular mortality in the treatment arm).

Mechanism of action
Bardoxolone methyl is an inducer of the KEAP1-Nrf2 pathway.