Abstract P3-04-09: Genomic analysis to evaluate response to neoadjuvant anastrozole and fulvestrant in post-menopausal ER-positive HER2-negative breast cancer patients included in the UCBG CARMINA02 trial
Authors: Callens C , Bessoltane N , Ngo C , Chemlali W , Becette V , Bernard V , Delattre O , Lemonnier J , Mouret-Reynier M-A , Andre F , Bieche I , Lerebours F 
Published: March 2017

Background: CARMINA02 is a non-comparative multicenter phase II randomized trial evaluating the clinical response rate after up to 6 months of neoadjuvant endocrine therapy (NET) in HR+/HER2- patients with 1 mg anastrozole (Arm A) or 500 mg fulvestrant (Arm B). Secondary objectives included predictive markers of response and outcome. Between 2007 and 2011, 116 women with operable infiltrating breast adenocarcinoma T2-T4 N0-N3 M0 were randomized. Clinical response rates at 6 months (RECIST criteria) were 52.6% [95%CI 41-64%] in Arm A and 36.8% [95%CI 25-49%] in Arm B (Cancer 2016, in press). We aimed to identify the molecular predictive markers of resistance or sensitivity common to both treatments.

Methods: Ninety tumor RNA from clinical responder (n=34) and resistant patients (n=23) treated in arms A or B have been sequenced with Illumina Hiseq2500 technology leading to 2x100-nt paired-end RNA-seq reads. These samples are from pre-treatment (29 in arm A, 28 in arm B) and post-treatment tumors (6 months after, 17 in arm A and 16 in arm B). Alignment was performed with Tophat_2.0.6. Differential gene expression was analyzed with the Differential Expression analysis for Sequence count data package. Gene fusion was detected with ChimeraScan, TophatFusion and DeFuse tools. Variant calling including variations, insertions and deletions was processed following GATK recommendations for RNAseq datas. Quantitative RT-PCR experiments were done to confirm RNA-seq expression results in patient samples not selected for RNA-seq analysis (validation cohort).

Results: We first analyzed differentially expressed genes (DEGs) between responders and non-responders in pre-treatment or post-treatment samples to select potential predictive markers of response. We identified 51 DEGs before treatment common to anastrozole and fulvestrant. Among these 51 genes, SGK2 was the only gene more intensely expressed in responders than in non-responders. Then we compared DEGs between pre and post-treatment samples for responders or non-reponders for both treatment arms. SGK2 expression remains stable after treatment. Furthermore we identified 7 DEGs specific to responders and 11 DEGs specific to non-responders. Concerning genes fusion detection predicted by at least 2 tools, none was specific to a response type. We noted a higher number of fusions in non-responders samples. Variants detected by RNA-Seq are being confirmed by DNA-Seq using a home-made next-generation sequencing panel including 95 genes frequently mutated in breast cancers (analysis ongoing).

Conclusion:High expression of SGK2, encoding a kinase induced in response to signals that activate PI3kinase, may represent a predictive marker of sensitivity to NET. DEGs associated with NET response or resistance belong to cell cycle, DNA replication and repair, cell death and drug metabolism. Ongoing DNA-seq datas will complete this genomic analysis. This research was conducted with support from AstraZeneca and Institut Curie.

Citation Format: Callens C, Bessoltane N, Ngo C, Chemlali W, Becette V, Bernard V, Delattre O, Lemonnier J, Mouret-Reynier M-A, Andre F, Bieche I, Lerebours F. Genomic analysis to evaluate response to neoadjuvant anastrozole and fulvestrant in post-menopausal ER-positive HER2-negative breast cancer patients included in the UCBG CARMINA02 trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-04-09.