Multinational randomized phase 2 trial of amcenestrant versus standard endocrine monotherapy for ER-positive, HER2-negative advanced breast cancer

The oral selective estrogen receptor degrader amcenestrant demonstrated promising efficacy in earlier studies for patients with endocrine-resistant, ER-positive, HER2-negative advanced breast cancer (aBC). The multinational phase 2 AMEERA-3 trial randomized such patients to amcenestrant versus single-agent endocrine treatment of physician’s choice (TPC). Amcenestrant did not improve progression-free survival versus TPC (panel A), although there was a trend of improved PFS in patients with baseline ESR1 mutation (panel B). Safety with amcenestrant was consistent with standard of care for second-/third-line endocrine therapy for ER-HER2- aBC.