Unknown,Transcriptomics,Genomics,Proteomics

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Gene expression profiling of sequential metastatic biopsies for biomarker discovery in breast cancer

ABSTRACT: The feasibility of longitudinal metastatic biopsies for gene expression profiling in breast cancer is unexplored. Dynamic changes in gene expression can potentially predict efficacy of targeted cancer drugs. Patients enrolled in a phase III trial of metastatic breast cancer with sunitinib combined with docetaxel (SU+DOC) versus docetaxel alone (DOC) were offered to participate in a translational substudy comprising longitudinal fine needle aspiration biopsies (FNAB) and positron emission imaging before (T1) and two weeks after start of treatment (T2). Aspirated tumor material was used for microarray analysis, and treatment-induced changes (T2 versus T1) in gene expression and standardized uptake values were investigated. Twenty-one patients were included in the docetaxel ± sunitinib trial at Karolinska and 18 of them agreed to participate in the substudy. Of the 18 women enrolled, 8 were randomly assigned to SU+DOC and 10 to DOC. Metastatic FNAB were carried out in 17 of the 18 patients at both time points with no complications reported. Representative tumor material, sufficient for RNA extraction was obtained in 15 patients at T1 and 14 patients at T2. Matched samples both at T1 and T2 were obtained for 14 subjects, 7 in each arm. The main objective was to determine whether gene expression profiling is feasible using sequential, intra-patient FNAB. Secondary objectives were to identify potential biomarkers of early response by gene expression and/or functional imaging and to explore drug action in vivo by changes in gene expression. A Karolinska substudy of the docetaxel ± sunitinib phase III clinical trial utilising sequential metastatic fine needle aspiration biopsies (FNAB) and 18-F-2-fluoro-2-deoxyglucose positron emission tomography/computed tomography (FDG PET/CT). In brief, the randomized docetaxel ± sunitinib trial compared sunitinib combined with docetaxel (SU+DOC) versus docetaxel alone (DOC), as first line therapy in patients with HER2 negative metastatic breast cancer. Patients in the exploratory substudy were subjected to baseline FDG PET/CT assessment, followed by FNAB of one tumor lesion prior to start of treatment (Time point T1). FDG PET/CT and FNAB were repeated at Day 14 ± 1 (Time point T2) when sunitinib has achieved steady state.

ORGANISM(S): Homo sapiens

SUBMITTER: John Lövrot

PROVIDER: E-GEOD-54323 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Fluorine-18-fluoro-2-deoxy-D-glucose (FDG) is widely used as positron-emission-tomography (PET) radiotracer for the detection and staging of human cancer. Tumor uptake of FDG varies substantially between different cancer types and between patients with the same tumor type. The molecular basis for this heterogeneity is unknown. Using cancer cell lines and primary human tumors of distinct histologic origins, we here show that increased FDG uptake is universally associated with coordinate upregulation of genes within the glycolysis, pentose-phosphate, and other related metabolic pathways. In primary human breast cancers, this FDG signature shows significant overlap with established breast cancer signatures for the “basal-like” disease subtype and “poor prognosis”. FDG high breast cancer showed significantly more gene copy number alterations genome wide than FDG low cancers. About 50 % of primary breast cancers with high FDG uptake and FDG gene expression signature show DNA copy gain encompassing the c-myc gene locus and express gene sets regulated by the transcription factor MYC. Our data shows that FDG-PET marks a distinct subset of “basal-like” human breast cancer which is characterized by MYC and prognostically unfavorable gene expression signatures, suggesting that FDG-PET imaging may be useful to risk-stratify patients with locally advanced breast cancer. Our general strategy to identify molecular determinants of FDG-retention through a genome-wide approach consisted of FDG uptake measurements in cancer cell lines and primary human tumors, the selection of samples with particularly high versus low FDG-retention, and subsequent pathway-based analysis of RNA expression data collected from these samples. Cell line RNA was extracted from a 10 cm plate seeded simultaneously and at the same density as the wells for FDG-uptake assays. For primary human tumor samples, RNA was extracted from macrodissected frozen tumor tissue. All cell line RNA samples and the astrocytoma RNA aliquots were hybridized to Affymetrix U133 Plus 2.0 arrays. All primary breast cancer RNA samples were hybridized to Affymetrix U133A arrays.

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Gene expression profiling of sequential metastatic biopsies for biomarker discovery in breast cancer

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