ESR1 and breast cancer: The results demonstrated that elacestrant, an oral selective ER degrader, produced a more significant PFS improvement and a more controllable safety profile in the overall population and ER+/HER2-advanced breast cancer patients with ESR1 mutations, compared with standard-of-care endocrine therapy (26 Subgroup Analysis of Patients With No Prior Chemotherapy in EMERALD: A Phase 3 Trial Evaluating Elacestrant, an Oral Selective Estrogen Receptor Degrader SERD, Vs.