ARV-471 is a novel, potent, orally bioavailable PROTAC that selectively targets the ER and is currently in phase I/II clinical trial in association with palcociclib (NCT04072952) and as monotherapy in the VERITAC phase II for the treatment of ER+/HER2− locally advanced or metastatic BC [260,261]. Here, ESR1 is linked to breast cancer.