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Uncovering the genomic heterogeneity of multifocal breast cancer.

ABSTRACT: Multifocal breast cancer (MFBC), defined as multiple synchronous unilateral lesions of invasive breast cancer, is relatively frequent and has been associated with more aggressive features than unifocal cancer. Here, we aimed to investigate the genomic heterogeneity between MFBC lesions sharing similar histopathological parameters. Characterization of different lesions from 36 patients with ductal MFBC involved the identification of non-silent coding mutations in 360 protein-coding genes (171 tumour and 36 matched normal samples). We selected only patients with lesions presenting the same grade, ER, and HER2 status. Mutations were classified as 'oncogenic' in the case of recurrent substitutions reported in COSMIC or truncating mutations affecting tumour suppressor genes. All mutations identified in a given patient were further interrogated in all samples from that patient through deep resequencing using an orthogonal platform. Whole-genome rearrangement screen was further conducted in 8/36 patients. Twenty-four patients (67%) had substitutions/indels shared by all their lesions, of which 11 carried the same mutations in all lesions, and 13 had lesions with both common and private mutations. Three-quarters of those 24 patients shared oncogenic variants. The remaining 12 patients (33%) did not share any substitution/indels, with inter-lesion heterogeneity observed for oncogenic mutation(s) in genes such as PIK3CA, TP53, GATA3, and PTEN. Genomically heterogeneous lesions tended to be further apart in the mammary gland than homogeneous lesions. Genome-wide analyses of a limited number of patients identified a common somatic background in all studied MFBCs, including those with no mutation in common between the lesions. To conclude, as the number of molecular targeted therapies increases and trials driven by genomic screening are ongoing, our findings highlight the presence of genomic inter-lesion heterogeneity in one-third, despite similar pathological features. This implies that deeper molecular characterization of all MFBC lesions is warranted for the adequate management of those cancers.

SUBMITTER: Desmedt C

PROVIDER: S-EPMC4691324 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Uncovering the genomic heterogeneity of multifocal breast cancer.

Desmedt Christine C Fumagalli Debora D Pietri Elisabetta E Zoppoli Gabriele G Brown David D Nik-Zainal Serena S Gundem Gunes G Rothé Françoise F Majjaj Samira S Garuti Anna A Carminati Enrico E Loi Sherene S Van Brussel Thomas T Boeckx Bram B Maetens Marion M Mudie Laura L Vincent Delphine D Kheddoumi Naima N Serra Luigi L Massa Ilaria I Ballestrero Alberto A Amadori Dino D Salgado Roberto R de Wind Alexandre A Lambrechts Diether D Piccart Martine M Larsimont Denis D Campbell Peter J PJ Sotiriou Christos C

The Journal of pathology 20150507 4

Multifocal breast cancer (MFBC), defined as multiple synchronous unilateral lesions of invasive breast cancer, is relatively frequent and has been associated with more aggressive features than unifocal cancer. Here, we aimed to investigate the genomic heterogeneity between MFBC lesions sharing similar histopathological parameters. Characterization of different lesions from 36 patients with ductal MFBC involved the identification of non-silent coding mutations in 360 protein-coding genes (171 tum ...[more]

PMID: 25850943

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Project description:A significant proportion of breast cancer patients develop multiple synchronous unilateral breast tumors, also referred to as multifocal tumors, which represent a diagnostic and therapeutic challenge. Multifocality has been associated with a possible adverse patient outcome, propensity for axillary nodal involvement, and increased risk of local recurrence following breast conserving surgery when compared to unifocal tumors. Previous studies indicate that most lesions from multifocal tumors are concordant with regard to the currently used pathological parameters (histological subtype and grade, hormonal receptors and HER2 status). However, to our knowledge, no study has yet provided a detailed molecular analysis of multifocal breast cancer. Here, we aimed to better define the incidence of multifocal breast cancer using a systematic analysis of pathology reports of primary breast cancers and to compare different foci from 5 multifocal breast cancers in a global analysis using genomic, transcriptomic and epigenomic data. We demonstrate that multifocality is a frequent finding since it concerns 22% (945/4340) of breast cancer patients with primary ductal breast cancer. We find that different lesions from multifocal breast cancer can differ at the (epi)genomic and transcriptomic level even when the foci present similar histology, grading, hormonal and HER2 status despite having a common genetic background. Since the number of (epi)genetic alterations with potential clinical utility is rapidly growing due to increasing numbers of targeted therapies, these findings suggest that it might be necessary to interrogate the different lesions of multifocal breast cancers for adequate treatment management of these tumors. The biological characterization of multifocal breast cancer here is focused on 5 cancers for which the foci did not differ in terms of histological grade, hormonal receptors and HER2 status. The characterization of multifocal tumors involved the identification of somatic rearrangements in 2 foci from each patient via low-coverage whole genome sequencing. Putative rearrangements were amplified by polymerase chain reaction (PCR) and capillary sequenced in tumor and matching blood-derived germline DNA to validate the somatic rearrangements. For all patients, the presence of a number of validated rearrangements was assessed in different paraffin blocks of tumor-adjacent histologically normal tissue by nested PCR. We also performed transcriptomic and epigenomic profiling in 4 and 5 patients respectively using the HG-U133 Plus 2.0 Chips and Infinium Methylation 450K arrays (RNA was not available for patient E).

Project description:BackgroundHepatocellular carcinoma (HCC) often presents with multiple nodules within the liver, with limited effective interventions. The high genetic heterogeneity of HCC might be the major cause of treatment failure. We aimed to characterize genomic heterogeneity, infer clonal evolution, investigate RNA expression pattern and explore tumour immune microenvironment profile of multifocal HCC.Patients and methodsWhole-exome sequencing and RNA sequencing were carried out in 34 tumours and 6 adjacent normal liver tissue samples from 6 multifocal HCC patients. Protein expression of Ki67, AFP, P53, Survivin and CD8 was detected by immunohistochemistry. Fluorescence in situ hybridization was carried out to validate the amplification status of sorafenib-targeted genes.ResultsWe deciphered genomic and transcriptional heterogeneity among tumours in each multifocal HCC patient including mutational profiles, copy number alterations, tumour evolutionary trajectory and tumour immune microenvironment profiles. Of note, sorafenib-targeted alterations were identified in the trunk of phylogenetic tree in only one out of the six patients, which may explain the relative low treatment response rate to sorafenib in clinical practice. Moreover, we demonstrated RNA expression patterns and tumour immune microenvironment profiles of all nodules. We found that RNA expression pattern was associated with Edmondson-Steiner grading. Based on the differential expression of 66 reported immune markers, unsupervised hierarchical clustering analysis of 34 nodules identified immune subsets: one low expression cluster with seven nodules and one high expression cluster with 11 nodules. CD8+ T cells were more enriched in nodules of the high expression cluster.ConclusionsOur study provided a detailed view of genomic and transcriptional heterogeneity, clonal evolution and immune infiltration of multifocal HCC. The heterogeneity of druggable targets and immune landscape might help interpret the clinical responsiveness to targeted drugs and immunotherapy for multifocal HCC patients.

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Project description:BackgroundCommercial gene expression assays are guiding clinical decision making in patients with prostate cancer, particularly when considering active surveillance. Given heterogeneity and multifocality of primary prostate cancer, such assays should ideally be robust to the coexistence of unsampled higher grade disease elsewhere in the prostate in order to have clinical utility. Herein, we comprehensively evaluated transcriptomic profiles of primary multifocal prostate cancer to assess robustness to clinically relevant multifocality.MethodsWe designed a comprehensive, multiplexed targeted RNA-sequencing assay capable of assessing multiple transcriptional classes and deriving commercially available prognostic signatures, including the Myriad Prolaris Cell Cycle Progression score, the Oncotype DX Genomic Prostate Score, and the GenomeDX Decipher Genomic Classifier. We applied this assay to a retrospective, multi-institutional cohort of 156 prostate cancer samples. Derived commercial biomarker scores for 120 informative primary prostate cancer samples from 44 cases were determined and compared.ResultsDerived expression scores were positively correlated with tumor grade (rS = 0.53-0.73; all P < 0.001), both within the same case and across the entire cohort. In cases of extreme grade-discordant multifocality (co-occurrence of grade group 1 [GG1] and ?GG4 foci], gene expression scores were significantly lower in low- (GG1) versus high-grade (?GG4) foci (all P < 0.001). No significant differences in expression scores, however, were observed between GG1 foci from prostates with and without coexisting higher grade cancer (all P > 0.05).ConclusionsMultifocal, low-grade and high-grade prostate cancer foci exhibit distinct prognostic expression signatures. These findings demonstrate that prognostic RNA expression assays performed on low-grade prostate cancer biopsy tissue may not provide meaningful information on the presence of coexisting unsampled aggressive disease.FundingProstate Cancer Foundation, National Institutes of Health (U01 CA214170, R01 CA183857, University of Michigan Prostate Specialized Program of Research Excellence [S.P.O.R.E.] P50 CA186786-05, Weill Cornell Medicine S.P.O.R.E. P50 CA211024-01A1), Men of Michigan Prostate Cancer Research Fund, University of Michigan Comprehensive Cancer Center core grant (2-P30-CA-046592-24), A. Alfred Taubman Biomedical Research Institute, and Department of Defense.

Project description:BackgroundThe intra-tumor diversity of cancer cells is under intense investigation; however, little is known about the heterogeneity of the tumor microenvironment that is key to cancer progression and evolution. We aimed to assess the degree of microenvironmental heterogeneity in breast cancer and correlate this with genomic and clinical parameters.Methods and findingsWe developed a quantitative measure of microenvironmental heterogeneity along three spatial dimensions (3-D) in solid tumors, termed the tumor ecosystem diversity index (EDI), using fully automated histology image analysis coupled with statistical measures commonly used in ecology. This measure was compared with disease-specific survival, key mutations, genome-wide copy number, and expression profiling data in a retrospective study of 510 breast cancer patients as a test set and 516 breast cancer patients as an independent validation set. In high-grade (grade 3) breast cancers, we uncovered a striking link between high microenvironmental heterogeneity measured by EDI and a poor prognosis that cannot be explained by tumor size, genomics, or any other data types. However, this association was not observed in low-grade (grade 1 and 2) breast cancers. The prognostic value of EDI was superior to known prognostic factors and was enhanced with the addition of TP53 mutation status (multivariate analysis test set, p = 9 × 10-4, hazard ratio = 1.47, 95% CI 1.17-1.84; validation set, p = 0.0011, hazard ratio = 1.78, 95% CI 1.26-2.52). Integration with genome-wide profiling data identified losses of specific genes on 4p14 and 5q13 that were enriched in grade 3 tumors with high microenvironmental diversity that also substratified patients into poor prognostic groups. Limitations of this study include the number of cell types included in the model, that EDI has prognostic value only in grade 3 tumors, and that our spatial heterogeneity measure was dependent on spatial scale and tumor size.ConclusionsTo our knowledge, this is the first study to couple unbiased measures of microenvironmental heterogeneity with genomic alterations to predict breast cancer clinical outcome. We propose a clinically relevant role of microenvironmental heterogeneity for advanced breast tumors, and highlight that ecological statistics can be translated into medical advances for identifying a new type of biomarker and, furthermore, for understanding the synergistic interplay of microenvironmental heterogeneity with genomic alterations in cancer cells.

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Uncovering the genomic heterogeneity of multifocal breast cancer.

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Uncovering the genomic heterogeneity of multifocal breast cancer.

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