The starting omaveloxolone (RTA 408) dose level for the first dose-escalation cohort in this study has been selected based on available safety and pharmacodynamic data from a Phase 1 study of RTA 408 (NCT02029729). Subsequent cohorts will be enrolled at dose levels based on available safety and PD data from this study, but they will not be greater than 2-fold above the prior dose level.