Fig. 1.

ESR1 mutation analysis in the metastatic cohort and its clinical significance. a Analysis of matched samples from the metastatic cohort through the course of disease: primary tumor, newly diagnosed metastases, and advanced metastases. Samples are colored according to their mutation type. Red indicates ESR1 Mut. Green indicates ESR1 WT. ESR1 mutations at an allele frequency of > 1% are marked by an asterisk. Dark gray indicates that a tumor was present at this time point but a sample was not available. Lower bars represent the treatments given for each patient pre-biopsy, either at the adjuvant phase before the metastatic disease or at the advanced phase before the advanced metastatic biopsy. TAM, tamoxifen, light blue; AI, aromatase inhibitor, blue. b Prevalence of ESR1 mutations divided according to the metastatic disease stage and the type of treatment prior to biopsy. c Kaplan-Meier plots of progression-free survival calculated from the start of AI treatment at the metastatic setting