Summary
The purpose of this trial is to compare how safe and effective palazestrant is in combination with ribociclib and a placebo that matches letrozole, versus letrozole, ribociclib and a placebo that matches palazestrant.
Palazestrant is a targeted hormone therapy, ribociclib is a targeted therapy and letrozole is a hormone therapy.
This trial is seeking adults with ER+, HER2- advanced breast cancer who have not received prior systemic anti-cancer treatment for their advanced disease.
Eligible participants will be randomly allocated (by chance) to one of two treatment arms.
In the Experimental Arm, participants will receive palazestrant once daily
will receive palazestrant once daily on a 4-week cycle, plus ribociclib once daily on Days 1-21 of a 4 week cycle, and a placebo that matches letrozole once daily on a 4-week cycle.
In the Active Comparator Arm, participants will receive letrozole once daily on a 4 week cycle, plus ribociclib once daily on Days 1-21 of a 4 week cycle, and a placebo that matches palazestrant once daily on a 4 week cycle.