PDF file - 187K, Supplementary Table 1: Detailed demographic information of all patients with metastatic breast cancer, including cohorts LM+ and EM+. Supplementary Table 2: ESR1 variant sequence data details. Abbreviations: cvg, coverage, N/A, non-applicable. Supplementary Table 3: List of genes sequenced by captured next generation sequencing. Supplementary figure 1: Genomic profiles of primary and metastatic tumors. Genomic alterations were found in 32 genes in primary and metastatic ER+ breast cancers. Genes are listed from the most frequently altered to least altered gene. Supplementary figure 2: No change in WT and mutant ER activity across a wide range of E2 doses. Luciferase activity in 293T cells after co-transfection of the ERE-TK-Luc reporter vector along with WT-ER, Y537N or D538G and E2 stimulation using doses of E2 ranging from 0.01nM to 100nM or vehicle treatment.
ARTICLE ABSTRACT
Purpose: We undertook this study to determine the prevalence of estrogen receptor (ER) α (ESR1) mutations throughout the natural history of hormone-dependent breast cancer and to delineate the functional roles of the most commonly detected alterations.Experimental Design: We studied a total of 249 tumor specimens from 208 patients. The specimens include 134 ER-positive (ER+/HER2−) and, as controls, 115 ER-negative (ER−) tumors. The ER+ samples consist of 58 primary breast cancers and 76 metastatic samples. All tumors were sequenced to high unique coverage using next-generation sequencing targeting the coding sequence of the estrogen receptor and an additional 182 cancer-related genes.Results: Recurring somatic mutations in codons 537 and 538 within the ligand-binding domain of ER were detected in ER+ metastatic disease. Overall, the frequency of these mutations was 12% [9/76; 95% confidence interval (CI), 6%–21%] in metastatic tumors and in a subgroup of patients who received an average of 7 lines of treatment the frequency was 20% (5/25; 95% CI, 7%–41%). These mutations were not detected in primary or treatment-naïve ER+ cancer or in any stage of ER− disease. Functional studies in cell line models demonstrate that these mutations render estrogen receptor constitutive activity and confer partial resistance to currently available endocrine treatments.Conclusions: In this study, we show evidence for the temporal selection of functional ESR1 mutations as potential drivers of endocrine resistance during the progression of ER+ breast cancer. Clin Cancer Res; 20(7); 1757–67. ©2014 AACR.
