ESR1 and breast cancer: For instance, in August 2022, Sanofi discontinued the clinical development of amcenestrant based upon the interim analysis of the phase III AMEERA-5 trial (NCT04478266) evaluating amcenestrant in combination with palbociclib vs. letrozole combined with palbociclib in patients with estrogen receptor-positive ER+/HER2− advanced breast cancer.