Elacestrant Demonstrates Strong Anti-Estrogenic Activity in PDX Models of Estrogen-Receptor Positive Endocrine-Resistant and Fulvestrant-Resistant Breast Cancer

Comparison of the orally bioavailable investigational elacestrant, versus fulvestrant, demonstrated both drugs impacted tumor growth of estrogen receptor (ER)+ patient-derived xenograft (PDX) models harboring several ESR1 mutations but that elacestrant was active after acquired resistance to fulvestrant.