A Study to Evaluate Atumelnant in Adults With Congenital Adrenal Hyperplasia

This is a Phase 3, global, multicenter, randomized, double-blind, placebo-controlled study in adult participants (male or female age ≥18 to \<75 years) with classic CAH due to 21-OHD who have been on a stable regimen of GCs for at least 2 months to evaluate efficacy, safety, PK, and PD of atumelnant administered once per day. Following a 3- to 6-week Screening Period, eligible participants will enter the Treatment Period where they will be randomly assigned in a 2:1 ratio to receive either atumelnant 80 mg once daily (with an option for dose escalation to 120 mg once daily at Week 20) or placebo. A total of approximately 150 participants may be enrolled in the study.