title: Detection of ESR1 mutations in plasma and tumors from metastatic breast cancer patients using next-generation sequencing.
abstract: OBJECTIVE
  Liquid biopsy using digital PCR (dPCR) has been widely used for the screening of ESR1 mutations, since they are frequently identified in the hotspot. However, dPCR is limited to the known mutations. Therefore, we aimed to analyze the utility of next-generation sequencing (NGS) to discover novel ESR1 mutations.
  
  
  METHODS
  Whole exon sequencing of the ESR1 gene using NGS was performed in 16 primary and 47 recurrent tumor samples and 38 plasma samples from hormone receptor-positive metastatic breast cancer patients. Functional analyses were then performed for the novel mutations we detected.
  
  
  RESULTS
  We identified no mutations in primary tumors and six mutations in five recurrent tumors, including three types of known mutations (Y537C, Y537N, and D538G) and two novel mutations (E279V and G557R). We also identified seven mutations in five plasma samples, including three types of known mutations (S463P, Y537S, and D538G) and one mutation not reported in COSMIC database (L536H). All nine patients with ESR1 mutations were treated with aromatase inhibitors (AIs) prior to sampling, and the mutations were frequently detected in patients who received AI treatments in the metastatic setting. Among the three novel mutations (E279V, L536H, and G557R), L536H, but not E279V and G557R, showed ligand-independent activity. All three mutant proteins showed nuclear localization and had no relation with non-genomic ER pathways.
  
  
  CONCLUSIONS
  Although the molecular mechanisms of the E279V and G557R mutations remain unclear, our data suggest the utility of NGS as a liquid biopsy for metastatic breast cancer patients and the potential to identify novel ESR1 mutations.
authors.affiliation: Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Yanagawa
authors.affiliation: Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan. kagaran@onsurg.med.osaka-u.ac.jp.
authors.forename: Naofumi
authors.initials: N
authors.lastname: Kagara
authors.affiliation: Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Miyake
authors.affiliation: Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tanei
authors.affiliation: Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan.
authors.forename: Yasuto
authors.initials: Y
authors.lastname: Naoi
authors.affiliation: Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Shimoda
authors.affiliation: Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan.
authors.forename: Kenzo
authors.initials: K
authors.lastname: Shimazu
authors.affiliation: Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan.
authors.forename: Seung Jin
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamadaoka, Suita-shi, Osaka, 565-0871, Japan.
authors.forename: Shinzaburo
authors.initials: S
authors.lastname: Noguchi
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics*; D001943:Breast Neoplasms / Q000097:blood / Q000235:genetics* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000097:blood / Q000235:genetics* / Q000556:secondary; D045744:Cell Line, Tumor; D004252:DNA Mutational Analysis; D047628:Estrogen Receptor alpha / Q000097:blood / Q000235:genetics*; D005260:Female; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008875:Middle Aged; D020125:Mutation, Missense
chemical_list: D014408:Biomarkers, Tumor; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha
keywords: Circulating tumor DNA; ESR1 mutation; Resistance to endocrine therapy; Whole exon sequencing