Abstract P3-08-50: Genome-wide association study predict prognosis of hormone receptor positive metastatic breast cancer in premenopausal women with endocrine therapy
Authors: Kim Ji-Yeon , Im Seock-Ah , Jung Kyung Hae , Lee Keun Seok , Sohn Joohyuk , Kim Jee Hyun , Jung Hae Hyun , Lee Minjoo , Im Young-Hyuck 
Published: March 2020

Introduction: According to phase II clinical trial of endocrine treatment for hormone receptor positive (HR+) metastatic breast cancer(MBC) after tamoxifen treatment in premenopausal women, fulvestrant plus goserelin (F+G) has better clinical outcome than goserelin (G) alone in premenopausal women, in terms of time to progression (TTP). However, aromatase inhibitor (AI) with goserelin (A+G) is not superior to goserelin alone. Among three treatment arms, difference of overall survival (OS) was not observed.

Accompanied with this clinical trial, we conducted further genotyping to identify alleles at some genomic loci associated with clinical outcome of endocrine treatments in premenopausal women with HR+ MBC.

Methods: This prospective genotyping study included patients enrolled in a randomized phase II clinical trial of fulvestrant plus goserelin versus anastrozole plus goserelin versus goserelin alone for HR+, human epidermal growth factor receptor 2(HER2)-negative tamoxifen-pretreated premenopausal women with recurrent or metastatic breast cancer (KCSG BR10-04).

To isolate genomic DNA from peripheral blood leukocytes, we used the Wizard Genomic DNA Purification Kit according to the manufacturer’s instructions (Promega, WI) and Axiom Precision Medicine Research Array (PMRA) (ThermoFisher, CA) was used to genotyping array.

Survival analyses for time-to-progression (TTP) and overall survival (OS) were performed using the Kaplan-Meier method. To determine the association between clinical outcomes and single nucleotide polymorphisms (SNPs), we used an R package for genome-wide survival analysis (gwasurvivr). Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for univariate and multivariate analyses. Finally, SNPs with adjusted p-value &lt;0.05 were selected and used for survival analysis.

Results: Of 138 participants, genomic DNA was collected and extracted from 127 participants. After quality control (QC), 103 genomic DNA were finally selected for genotyping (35 in F+G, 36 in A+G and 32 in G group). Patients with age under 40 were 34 (33%) and visceral metastases were observed in 50 patients (49%). Medial TTP was 16.3 months (95% confidence interval (CI): 13.3, 19.3) and median OS was 59.6 months (95% CI: 41.1, 78.1).

Among 523,289 SNPs, 76 SNPs were associated with TTP (adjusted p-value &lt;0.05, respectively). Of 76 SNPs, 47 were in coding lesions including ELF3, ARHGEF3, FOXP2, NTRK2, XPO5 and PI3KC2A. Other 29 were in non-coding lesions. In terms of OS, 13SNPs were associated and eleven were in coding lesions (ZMYM4, GRM7, ERC2, LEKR1, C3orf700, CEP135, ZNF827, LOC285692, DNAH11, FLJ42102 and LOC283440).

Conclusions: Genetic polymorphisms influenced the clinical outcome of HR+ MBC patients treated with anti-hormonal therapy. Further studies on the functional mechanisms relating to these SNPs in these genes are warranted.

Citation Format: Ji-Yeon Kim, Seock-Ah Im, Kyung Hae Jung, Keun Seok Lee, Joohyuk Sohn, Jee Hyun Kim, Hae Hyun Jung, Minjoo Lee, Young-Hyuck Im. Genome-wide association study predict prognosis of hormone receptor positive metastatic breast cancer in premenopausal women with endocrine therapy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-08-50.