13-gene signature to predict rapid development of brain metastases in patients with HER2-positive advanced breast cancer.

Abstract

505 Background: Brain metastases (BM) of breast cancer constitute an important part of therapeutic failures and are associated with severe morbidity and mortality. The risk of BM is particularly high in HER2+ advanced breast cancer pts. We earlier developed in this group a 13-gene signature strongly predicting for rapid development of BM (J Clin Oncol 2008; 26: 45s). Now, we validated these results in an independent group of pts and on culture model system. Methods: Discovery group included 87 samples analyzed using cDNA synthesis, annealing, selection, extension, ligation and array hybridization (DASL). Independent validation group included 75 samples analyzed using quantitative reverse-transcriptase PCR. 3D culture validation model system used immortal, non-tumorigenic human MCF10A breast epithelial cells with and without ectopic expression of HER-2 and RAD51, a DNA double strand break repair gene (one of the three genes of this group overexpressed in 13-gene signature). The number and morphology of breast acini were scored using indirect immunoflourescence and confocal microscopy. Results: Median brain metastasis-free survival (BMFS) in the discovery group for ‘high’ vs. ‘low’ expression signature tumors was 36 months and 66 months, respectively (P=0.0068), and in the validation group 54 and 86 months, respectively (P=0.032). Short BMFS was also associated with ER-negativity; BMFS in the cohort of ‘high’ 13-gene signature and ER- tumors vs. other 3 groups was 31 months and 66 months in discovery group, and 41 and 77 months in validation group (P<0.0001 and P=0.02, respectively). Overexpression of RAD51 in MCF-10A breast cells altered their three-dimensional acinar morphology and increased the percentage of invasive structures by 6.5 fold, both in the presence and absence of HER2 overexpression. Conclusions: 13-gene signature and ER-negativity predict rapid development of BM in HER+ advanced breast cancer pts. RAD51 may promote aggressiveness in breast epithelial cells. These data may be useful in the design of BM preventive trials and may prompt new treatment strategies.

Predicting early brain metastases based on clinicopathological factors and gene expression analysis in advanced HER2-positive breast cancer patients

“…In order to increase the potential clinical applicability of this signature, a qRT-PCR based analysis of the 13 genes (and 3 references) was performed and showed promising preliminary results [ 15 , 16 ]. The TaqMan gene expression assay IDs for each gene was chosen to meet FFPE sample requirements for custom TLDA based on Applied Biosystems guidelines.…”

Emerging Biomarkers for Diagnosis, Prevention and Treatment of Brain Metastases—From Biology to Clinical Utility

“…These studies often share a common goal of being able to predict the risk of BrM at the point of primary cancer diagnosis. For example, Duchnowska identified a 13 gene BrM prediction signature for HER2+ breast cancer [ 28 ], and this was further refined to a 3 gene classifier that included RAD51 (RAD51 homolog), HDGF (hepatoma-derived growth factor), and TPR (translocated promoter region) genes. Interestingly, multivariate analysis revealed that this 3 gene signature was highly predictive of early BrM in the discovery cohort, but it was not confirmed in the validation cohort.…”

Advances in Breast Cancer – Looking Back over the Year

“…A better understanding of the molecular background of the mechanisms of brain metastasis could help in the development of new treatment strategies or treatment algorithms. One study has in fact reported that genes from the HER2 signal transduction pathway and DNA repair genes can help [21]. The time interval until onset of brain metastasis was 54 months in a group identified with a high-risk gene signature vs. 86 months in the low-risk group (p = 0.038).…”