Results
ADVERSE EVENTS, RECRUITMENT
Enrollment was stopped early because of slow recruitment, in the context of the COVID-19 pandemic. The modified intent-to-treat population consisted of 95 study participants with baseline and post-treatment Ki67 values, whereas the safety population included 104 participants who had received at least one dose of study medication. Relative change from baseline in Ki67 was − 75.9% (95% confidence interval [CI] − 81.9 to − 67.9) for amcenestrant 400 mg, − 68.2% (− 75.7 to − 58.4) for amcenestrant 200 mg, and − 77.7% (− 83.4 to − 70.0) for letrozole (geometric least-squares mean [LSM] estimates). Absolute change in ER H-score from baseline (LSM estimate) was − 176.7 in the amcenestrant 400 mg arm, − 202.9 in the amcenestrant 200 mg arm, and − 32.5 in the letrozole arm. There were no Grade ≥ 3 treatment-related adverse events.