<i>ESR1</i> F404 Mutations and Acquired Resistance to Fulvestrant in <i>ESR1</i> -Mutant Breast Cancer

Abstract

Novel F404 ESR1 mutations may be acquired to cause overt resistance to fulvestrant when combined with preexisting activating ESR1 mutations. Novel combinations of mutations in the ER ligand binding domain may cause drug-specific resistance, emphasizing the potential of similar drug-specific mutations to impact the efficacy of oral ER degraders in development. This article is featured in Selected Articles from This Issue, p. 201.