This is an international, multicenter, randomized, double-blind, active-controlled, phase 3 clinical trial. The purpose of this trial is to compare the efficacy and safety of palazestrant in combination with ribociclib +letrozole -matching placebo (Arm A: investigational arm) with letrozole in combination with ribociclib + palazestrant-matching placebo (Arm B: control arm).
This trial is seeking adult participants with ER+, HER2- advanced breast cancer who have not received prior systemic anti-cancer treatment for advanced disease. Approximately 1,000 participants will be randomized in a 1:1 ratio to one of the two study arms.
