The prevalence of estrogen receptor-1 mutation in advanced breast cancer: The estrogen receptor one study (EROS1).

Breast cancer has, due its high incidence, the highest mortality of cancer in women. The most common molecular variety of breast cancer is luminal subtype that expresses estrogen and progesterone receptors. Estrogen receptor alpha (ERα), encoded by the estrogen receptor1 (ESR1) gene, is expressed in approximately 70% of all breast cancers, and hormonal therapy represents a major treatment modality in all stages of ER positive breast cancers. Acquired mutations in the ligand-binding domain (LBD) of ERα, referred as ESR1 mutation, result in resistance to different endocrine therapies leading to disease progression or recurrence. Recent studies reviled that these ESR1 mutations lead to constitutive activity of the estrogen receptor ER, meaning that the receptor is active in absence of its ligand conferring resistance against endocrine therapy and tumor growth. Published studies have not yet been able to determine the exact prevalence rate of ESR1 mutations, but set the outer boundaries between 11-55%. The goal of the present study is to determine the frequency rate of ESR1 mutations in ER positive recurrent breast cancer by using digital droplet PCR (ddPCR) technique. This retrospective study was conducted in the Multidisciplinary Breast Clinic of Antwerp University Hospital. The seven most common ESR1mutations (c.1138G>C (p. (E380Q)), c.1610A>G (p.(Y537C)), c.1613A>G (p.(p.D538G)), c.1607T>G (p.(L536R)), c.1387T>C (p.S463R)), c.16410A>C (p.(Y537S)), c.609T>A (p.(Y537N)) were assessed in available baseline plasma samples of 21 patients with ER positive recurrent breast cancer. Inclusion criteria for study participation were: female, age above 18 years, ER positive breast cancer, 5years adjuvant hormonal therapy of primary disease, and disease recurrence or metastasis during or after stop of endocrine therapy. ESR1 mutations were analyzed in cell-free DNA (cfDNA) by using digital droplet PCR (ddPCR). cfDNA was obtained from 21 patients with recurrent breast cancer. ESR1 mutations were found in 4/21 (19%; 95% CI, 5%-42%). The test sensitivity was lower than the targeted value <0.1% in 29% of patients (6/21). No significant statistical difference in baseline clinical characteristics was observed in patients with wild-type and mutant ER (p>0.05). Adjuvant endocrine therapy for primary disease was Tamoxifen (TAM) for 57% of patients (12 of 21) of whom 8 patients had received aromatase inhibitor (AI) after two years, while 43% of patients (9 of 21) had received AI as first line adjuvant hormonal therapy. All the patients had received aromatase inhibitor AI therapy in first or second line therapy with initially a variable period of good response. ESR1 mutation analysis could be determined in archived plasma samples using simple non-invasive methods. In the future, screening for mutation status could improve the therapeutic strategies in controlling ER signaling before the occurrence of wide spread disease metastasis.

Najim O ，Huizing M ，Papadimitriou K ，Trinh XB ，Pauwels P ，Goethals S ，Zwaenepoel K ，Peterson K ，Weyler J ，Altintas S ，van Dam P ，Tjalma W ... -  《-》

The association between type of endocrine therapy and development of estrogen receptor-1 mutation(s) in patients with hormone-sensitive advanced breast cancer: A systematic review and meta-analysis of randomized and non-randomized trials.

Breast cancer has, due to its high incidence, the highest mortality of cancer in women. The most common molecular type of breast cancer is the luminal subtype, which expresses estrogen and progesterone receptors and is typically treated with surgery and adjuvant endocrine therapy (ET). Estrogen receptor alpha (ERα), encoded by the estrogen receptor-1 (ESR1) gene, is expressed in approximately 70% of all breast cancers, and ET represents a major treatment modality in ERα-positive cancers. However, resistance to different ET evolves frequently, leading to disease progression or recurrence in ER+ breast cancer. Acquired mutations in the Ligand Binding Domain (LBD) of the ERα referred as ESR1 mutations; could be selected by ET itself leading to resistance over the course of ET therapy. The goal of this review is to estimate the effect of Aromatase Inhibitors (AIs), Tamoxifen (TAM) and Fulvestrant (FUL) on the development of ESR1 mutations in hormone-sensitive advanced breast cancer. A systematic review of qualitative studies published between January 1st, 2007 and March 1st, 2019 was conducted using the PubMed and Thomas Reuters Web of Science databases. Search terms included ESR1 mutations, estrogen receptor, breast cancer, recurrent, metastatic disease, aromatase inhibitors, fulvestrant and tamoxifen. Only full-text studies in English concerning the development of ESR1 mutations and their outcomes on disease progression were included. Selection of studies was performed using predefined data fields, taking study quality indicators into consideration. Inclusion criteria of the study populations were: Ghoncheh et al. (2016) [1] female patients above 18 years; Nielsen et al. (2011) [2] Estrogen-receptor positive (ER+) breast cancer in the advanced setting; Reinert et al. (2017) [3] previous exposure to endocrine therapy including SERDs (preferably Fulvestrant), SERMs (preferably Tamoxifen) or Aromatase Inhibitors. The current review enrolled 16 articles, including 4 multicentre double blinded RCTs and 12 cohorts and comprising a total of 2632 patients. The overall incidence rate of the ESR1 mutation was 24% (95% CI: 18%-31%). We observed that D538G was the most frequent ESR1 mutation. Several studies showed that prior endocrine therapy (AIs, TAM, FUL) could result in an ESR1 mutation and therapy resistance leading to disease progression or recurrence. Different mechanisms had been implied to explain the underlying ET resistance. One of the key findings of this work is the significant difference in ESR1 mutation incidence between patients with and without AI therapy (OR: 9.34, 95% CI: 3.28-26.62, P ≤.001). ESR1 mutations are not uncommon phenomenon in patients with hormone-sensitive advanced breast cancer. There is a significant higher incidence rate of ESR1 mutations in patients with previous AI-containing therapeutic regimens, compared to those who received non-AI containing regimes. These ESR1 mutations could lead to the development of complete endocrine resistance to AI, whereas only partial resistance is seen in case of TAM or FUL.

Najim O ，Seghers S ，Sergoynne L ，Van Gaver H ，Papadimitriou K ，Wouters K ，Trinh XB ，Huizing MT ，Tjalma W ... -  《-》

ESR1 mutations are frequent in newly diagnosed metastatic and loco-regional recurrence of endocrine-treated breast cancer and carry worse prognosis.

Zundelevich A ，Dadiani M ，Kahana-Edwin S ，Itay A ，Sella T ，Gadot M ，Cesarkas K ，Farage-Barhom S ，Saar EG ，Eyal E ，Kol N ，Pavlovski A ，Balint-Lahat N ，Dick-Necula D ，Barshack I ，Kaufman B ，Gal-Yam EN ... -  《-》

Prevalence of ESR1 E380Q mutation in tumor tissue and plasma from Japanese breast cancer patients.

Takeshita T ，Yamamoto Y ，Yamamoto-Ibusuki M ，Sueta A ，Tomiguchi M ，Murakami K ，Omoto Y ，Iwase H ... -  《BMC CANCER》

Detection of ESR1 mutations in plasma and tumors from metastatic breast cancer patients using next-generation sequencing.

Yanagawa T ，Kagara N ，Miyake T ，Tanei T ，Naoi Y ，Shimoda M ，Shimazu K ，Kim SJ ，Noguchi S ... -  《-》