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ESR1 Mutations Are Not a Common Mechanism of Endocrine Resistance in Patients With Estrogen Receptor-Positive Breast Cancer Treated With Neoadjuvant Aromatase Inhibitor Therapy.

ABSTRACT: Introduction: Mutations in the ESR1 gene (ESR1m) are important mechanisms of resistance to endocrine therapy in estrogen receptor-positive (ER+) metastatic breast cancer and have been studied as a potential therapeutic target, as well as a predictive and prognostic biomarker. Nonetheless, the role of ESR1m as a possible mechanism of primary endocrine resistance, as well as whether it also occurs in tumors that are resistant to ET administered in early-stage disease as (neo)adjuvant, has not been adequately studied. In this study, we evaluated the prevalence of ESR1m in tumor samples from patients with ER+ breast cancer resistant to neoadjuvant aromatase inhibitor therapy. Methods: We followed a prospective cohort of patients with ER+ HER2- stages II and III breast cancer treated with neoadjuvant endocrine therapy (NET). Tumor samples from patients with a pattern of primary endocrine resistance [defined as a Preoperative Endocrine Prognostic Index (PEPI) score of ?4] were identified and analyzed for the presence of ESR1m. Results: One hundred twenty-seven patients were included in the cohort, of which 100 (79%) had completed NET and underwent surgery. Among these patients, the PEPI score ranged from 0 to 3 in 70% (70/100), whereas 30% (30/100) had a PEPI score of 4 or more. Twenty-three of these patients were included in the analysis. ESR1 mutations were not identified in any of the 23 patients with early-stage ER+ breast cancer resistant to NET. Discussion: Growing evidence supports the notion that there are different mechanisms for primary and secondary endocrine resistance. Our study suggests that ESR1 mutations do not evolve rapidly and do not represent a common mechanism of primary endocrine resistance in the neoadjuvant setting. Therefore, ESR1m should be considered a mechanism of acquired endocrine resistance in the context of advanced disease. Further research should be conducted to identify factors associated with intrinsic resistance to ET.

SUBMITTER: Reinert T

PROVIDER: S-EPMC7145981 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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ESR1 Mutations Are Not a Common Mechanism of Endocrine Resistance in Patients With Estrogen Receptor-Positive Breast Cancer Treated With Neoadjuvant Aromatase Inhibitor Therapy.

Reinert Tomás T Ramalho Susana S de Vasconcelos Vivian Castro Antunes VCA Silva Leonardo Roberto LR da Silva Ana Elisa Ribeiro AER de Andrade Camila Annicchino CA Kraft Maria Beatriz de Paula Leite MBPL Coelho Guilherme Portela GP Mandelli Jovana J Binotto Monique M Cabello Cesar C de Paiva Silva Geisilene Russano GR Bines José J Barrios Carlos H CH Ellis Matthew J MJ Graudenz Marcia Silveira MS

Frontiers in oncology 20200403

Introduction: Mutations in the ESR1 gene (ESR1m) are important mechanisms of resistance to endocrine therapy in estrogen receptor-positive (ER+) metastatic breast cancer and have been studied as a potential therapeutic target, as well as a predictive and prognostic biomarker. Nonetheless, the role of ESR1m as a possible mechanism of primary endocrine resistance, as well as whether it also occurs in tumors that are resistant to ET administered in early-stage disease as ...[more]

PMID: 32309212

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Project description:LESSONS LEARNED:Studies targeting the androgen receptor (AR) signaling pathway in aromatase inhibitor (AI)-resistant breast cancer are limited. Bicalutamide, one of the commonly used AR inhibitors in prostate cancer, in combination with AI, did not show synergistic activity in patients with estrogen receptor-positive and AI-resistant disease in this phase II, single-arm study. The clinical benefit rate and objective response rate at 6 months were 16.7% and 0%, respectively, and the study was terminated after the first stage. BACKGROUND:Endocrine resistance is a major problem in clinical practice. Studies have shown that androgen receptor (AR) signaling activation may be one of the mechanisms, and targeting AR showed some promising results in AR-positive triple-negative breast cancer. The aim of this study was to assess the efficacy and safety of bicalutamide plus another aromatase inhibitor in patients with nonsteroidal aromatase inhibitor (AI) or steroidal AI resistance and estrogen receptor (ER)-positive and AR-positive advanced breast cancer. METHODS:A Simon's two-stage, phase II, single-arm study was conducted. We assumed the clinical benefit rate (CBR) of 40% would be significant in clinical practice. In this case, if ?4 patients of the 19 patients in the first stage benefited from treatment, the CBR would achieve the assumed endpoint. If fewer than four patients benefited from treatment in the first stage, the trial would be terminated. All patients received bicalutamide 50 mg per day orally plus another aromatase inhibitor. The primary outcome was CBR; secondary outcomes included objective response rate (ORR), progression-free survival (PFS), and tolerability. RESULTS:A total of 19 patients enrolled in the first stage, and 18 patients met all criteria for analysis. The trial terminated according to protocol after the first stage. After a median follow-up of 14 months, the CBR at 6 months was 16.7% (3/18); no patients with partial or complete response were observed. The median PFS was 2.7 months. Bicalutamide in combination with AI was well tolerated. CONCLUSION:Bicalutamide in combination with another AI did not show synergistic activity in patients with ER-positive breast cancer and AI resistance. Results suggest that no more large-sample clinical trials should be conducted in this population for overcoming endocrine resistance.

Project description:Importance:Estrogen receptor-positive (ER+) tumors of the breast are generally highly responsive to endocrine treatment. Although endocrine therapy is the mainstay of adjuvant treatment for ER+ breast cancer, the role of endocrine therapy in the neoadjuvant setting is unclear. Objective:To evaluate the effect of neoadjuvant endocrine therapy (NET) on the response rate and the rate of breast conservation surgery (BCS) for ER+ breast cancer. Data Sources:Based on PRISMA guidelines, a librarian-led search of PubMed and Ovid MEDLINE was performed to identify eligible trials published from inception to May 15, 2015. The search was performed in May 2015. Study Selection:Inclusion criteria were prospective, randomized, neoadjuvant clinical trials that reported response rates with at least 1 arm incorporating NET (n?=?20). Two authors independently analyzed the studies for inclusion. Data Extraction and Synthesis:Pooled odds ratios (ORs), 95% CIs, and P values were estimated for end points using the fixed- and random-effects statistical model. Results:The analysis included 20 studies with 3490 unique patients. Compared with combination chemotherapy, NET as monotherapy with aromatase inhibitors had a similar clinical response rate (OR, 1.08; 95% CI, 0.50-2.35; P?=?.85; n?=?378), radiological response rate (OR, 1.38; 95% CI, 0.92-2.07; P?=?.12; n?=?378), and BCS rate (OR, 0.65; 95% CI, 0.41-1.03; P?=?.07; n?=?334) but with lower toxicity. Aromatase inhibitors were associated with a significantly higher clinical response rate (OR, 1.69; 95% CI, 1.36-2.10; P?<?.001; n?=?1352), radiological response rate (OR, 1.49; 95% CI, 1.18-1.89; P?<?.001; n?=?1418), and BCS rate (OR, 1.62; 95% CI, 1.24-2.12; P?<?.001; n?=?918) compared with tamoxifen. Dual combination therapy with growth factor pathway inhibitors was associated with a higher radiological response rate (OR, 1.59; 95% CI, 1.04-2.43; P?=?.03; n?=?355), but not clinical response rate (OR, 0.76; 95% CI, 0.54-1.07; P?=?.11; n?=?537), compared with endocrine monotherapy. The incidence of pathologic complete response was low (<10%). Conclusions and Relevance:Neoadjuvant endocrine therapy, even as monotherapy, is associated with similar response rates as neoadjuvant combination chemotherapy but with significantly lower toxicity, suggesting that NET needs to be reconsidered as a potential option in the appropriate setting. Additional research is needed to develop rational NET combinations and predictive biomarkers to personalize the optimal neoadjuvant strategy for ER+ breast cancer.

Dataset Information

ESR1 Mutations Are Not a Common Mechanism of Endocrine Resistance in Patients With Estrogen Receptor-Positive Breast Cancer Treated With Neoadjuvant Aromatase Inhibitor Therapy.

Publications

<i>ESR1</i> Mutations Are Not a Common Mechanism of Endocrine Resistance in Patients With Estrogen Receptor-Positive Breast Cancer Treated With Neoadjuvant Aromatase Inhibitor Therapy.

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