ribociclib plus letrozole (n=334) vs. letrozole (n=334)
randomized controlled trial
ribociclib plus letrozole
ribociclib: PO 600mg/day on a 3-weeks-on, 1-week-offin 28-day cycle / letrozole: mg/day every day
placebo plus letrozole
letrozole: mg/day every day
la/mBC - HR-positive - 1st line (L1)
Exclusion criteria: previous CDK4/6 inhibitor or any previous systemic chemotherapy or endocrine therapy for advanced disease, previous neoadjuvant or adjuvant therapy with a nonsteroidal aromatase inhibitor was not allowed, unless the disease-free interval was more than 12 months, CNS metastases
double blind
29 countries at 223 trial centers
P3 / PFS at 1-sided at 2.5 with 1 IA (less than p=1.29×10^(-5) and the final analysis at p=0.02499) then for OS if PFS is significant, at 1-sided at 2.5%, with 4 IA
Adding ribociclib to letrozole increased significantly PFS