Ino de Bruijn

Massively parallel sequencing of phyllodes tumours of the breast reveals actionable mutations, and TERT promoter hotspot mutations and TERT gene amplification as likely drivers of progression

Phyllodes tumours (PTs) are breast fibroepithelial lesions that are graded based on histological criteria as benign, borderline or malignant. PTs may recur locally. Borderline PTs and malignant PTs may metastasize to distant sites. Breast fibroepithelial lesions, including PTs and fibroadenomas, are characterized by recurrent MED12 exon 2 somatic mutations. We sought to define the repertoire of somatic genetic alterations in PTs and whether these may assist in the differential diagnosis of these lesions. We collected 100 fibroadenomas, 40 benign PTs, 14 borderline PTs and 22 malignant PTs; six, six and 13 benign, borderline and malignant PTs, respectively, and their matched normal tissue, were subjected to targeted massively parallel sequencing (MPS) using the MSK‐IMPACT sequencing assay. Recurrent MED12 mutations were found in 56% of PTs; in addition, mutations affecting cancer genes (eg TP53, RB1, SETD2 and EGFR) were exclusively detected in borderline and malignant PTs. We found a novel recurrent clonal hotspot mutation in the TERT promoter (−124 C>T) in 52% and TERT gene amplification in 4% of PTs. Laser capture microdissection revealed that these mutations were restricted to the mesenchymal component of PTs. Sequencing analysis of the entire cohort revealed that the frequency of TERT alterations increased from benign (18%) to borderline (57%) and to malignant PTs (68%; p < 0.01), and TERT alterations were associated with increased levels of TERT mRNA (p < 0.001). No TERT alterations were observed in fibroadenomas. An analysis of TERT promoter sequencing and gene amplification distinguished PTs from fibroadenomas with a sensitivity and a positive predictive value of 100% (CI 95.38–100%) and 100% (CI 85.86–100%), respectively, and a sensitivity and a negative predictive value of 39% (CI 28.65–51.36%) and 68% (CI 60.21–75.78%), respectively. Our results suggest that TERT alterations may drive the progression of PTs, and may assist in the differential diagnosis between PTs and fibroadenomas. Copyright

Uterine adenosarcomas are mesenchymal neoplasms

Uterine adenosarcomas (UAs) are biphasic lesions composed of a malignant mesenchymal (ie stromal) component and an epithelial component. UAs are generally low‐grade and have a favourable prognosis, but may display sarcomatous overgrowth (SO), which is associated with a worse outcome. We hypothesized that, akin to breast fibroepithelial lesions, UAs are mesenchymal neoplasms in which clonal somatic genetic alterations are restricted to the mesenchymal component. To characterize the somatic genetic alterations in UAs and to test this hypothesis, we subjected 20 UAs to a combination of whole‐exome (n = 6), targeted capture (n = 13) massively parallel sequencing (MPS) and/or RNA sequencing (n = 6). Only three genes, FGFR2, KMT2C and DICER1, were recurrently mutated, all in 2/19 cases; however, 26% (5/19) and 21% (4/19) of UAs harboured MDM2/CDK4/HMGA2 and TERT gene amplification, respectively, and two cases harboured fusion genes involving NCOA family members. Using a combination of laser‐capture microdissection and in situ techniques, we demonstrated that the somatic genetic alterations detected by MPS were restricted to the mesenchymal component. Furthermore, mitochondrial DNA sequencing of microdissected samples revealed that epithelial and mesenchymal components of UAs were clonally unrelated. In conclusion, here we provide evidence that UAs are genetically heterogeneous lesions and mesenchymal neoplasms. Copyright

Diverse BRCA1 and BRCA2 Reversion Mutations in Circulating Cell-Free DNA of Therapy-Resistant Breast or Ovarian Cancer

Purpose: Resistance to platinum-based chemotherapy or PARP inhibition in germline BRCA1 or BRCA2 mutation carriers may occur through somatic reversion mutations or intragenic deletions that restore BRCA1 or BRCA2 function. We assessed whether BRCA1/2 reversion mutations could be identified in circulating cell-free DNA (cfDNA) of patients with ovarian or breast cancer previously treated with platinum and/or PARP inhibitors. Experimental Design: cfDNA from 24 prospectively accrued patients with germline BRCA1 or BRCA2 mutations, including 19 patients with platinum-resistant/refractory ovarian cancer and five patients with platinum and/or PARP inhibitor pretreated metastatic breast cancer, was subjected to massively parallel sequencing targeting all exons of 141 genes and all exons and introns of BRCA1 and BRCA2. Functional studies were performed to assess the impact of the putative BRCA1/2 reversion mutations on BRCA1/2 function. Results: Diverse and often polyclonal putative BRCA1 or BRCA2 reversion mutations were identified in cfDNA from four patients with ovarian cancer (21%) and from two patients with breast cancer (40%). BRCA2 reversion mutations were detected in cfDNA prior to PARP inhibitor treatment in a patient with breast cancer who did not respond to treatment and were enriched in plasma samples after PARP inhibitor therapy. Foci formation and immunoprecipitation assays suggest that a subset of the putative reversion mutations restored BRCA1/2 function. Conclusions: Putative BRCA1/2 reversion mutations can be detected by cfDNA sequencing analysis in patients with ovarian and breast cancer. Our findings warrant further investigation of cfDNA sequencing to identify putative BRCA1/2 reversion mutations and to aid the selection of patients for PARP inhibition therapy. Clin Cancer Res; 23(21); 6708–20. ©2017 AACR.

Genetic Heterogeneity in Therapy-Naïve Synchronous Primary Breast Cancers and Their Metastases

Purpose: Paired primary breast cancers and metachronous metastases after adjuvant treatment are reported to differ in their clonal composition and genetic alterations, but it is unclear whether these differences stem from the selective pressures of the metastatic process, the systemic therapies, or both. We sought to define the repertoire of genetic alterations in breast cancer patients with de novo metastatic disease who had not received local or systemic therapy. Experimental Design: Up to two anatomically distinct core biopsies of primary breast cancers and synchronous distant metastases from nine patients who presented with metastatic disease were subjected to high-depth whole-exome sequencing. Mutations, copy number alterations and their cancer cell fractions, and mutation signatures were defined using state-of-the-art bioinformatics methods. All mutations identified were validated with orthogonal methods. Results: Genomic differences were observed between primary and metastatic deposits, with a median of 60% (range 6%–95%) of shared somatic mutations. Although mutations in known driver genes including TP53, PIK3CA, and GATA3 were preferentially clonal in both sites, primary breast cancers and their synchronous metastases displayed spatial intratumor heterogeneity. Likely pathogenic mutations affecting epithelial-to-mesenchymal transition–related genes, including SMAD4, TCF7L2, and TCF4 (ITF2), were found to be restricted to or enriched in the metastatic lesions. Mutational signatures of trunk mutations differed from those of mutations enriched in the primary tumor or the metastasis in six cases. Conclusions: Synchronous primary breast cancers and metastases differ in their repertoire of somatic genetic alterations even in the absence of systemic therapy. Mutational signature shifts might contribute to spatial intratumor genetic heterogeneity. Clin Cancer Res; 23(15); 4402–15. ©2017 AACR.

Abstract 5277: The cBioPortal for cancer genomics and its application in precision oncology

The cBioPortal for Cancer Genomics provides intuitive visualization and analysis of complex cancer genomics data. The public site (http://cbioportal.org/) is accessed by more than 1,500 researchers per day, and there are now dozens of local instances of the software that host private data sets at cancer centers around the globe. We have recently released the software under an open source license, making it free to use and modify by anybody. The software and detailed documentation are available at https://github.com/cBioPortal/cbioportal. We are now establishing a multi-institutional software development network, which will coordinate and drive the future development of the software and associated data pipelines. This group will focus on four main areas: 1. New analysis and visualization features, including: a. Improved support for cross-cancer queries and cohort comparisons. b. Enhanced clinical decision support for precision oncology, including an improved patient view with knowledge base integration, patient timelines and improved tools for visualizing tumor evolution. 2. New data pipelines, including support for new genomic data types and streamlined pipelines for TCGA and the International Cancer Genome Consortium (ICGC). 3. Software architecture and performance improvements. 4. Community engagement: Documentation, user support, and training. This coordinated effort will help to further establish the cBioPortal as the software of choice in cancer genomics research, both in academia and the pharmaceutical industry. Furthermore, as the sequencing of tumor samples has entered clinical practice, we are expanding the features of the software so that it can be used for precision medicine at cancer centers. In particular, clean, web-accessible, interactive clinical reports integrating multiple sources of genome variation and clinical annotation over time has potential to improve clinical action beyond current text-based molecular reports. By making complex genomic data easily interpretable and linking it to information about drugs and clinical trials, the cBioPortal software has the potential to facilitate the use of genomic data in clinical decision making. Citation Format: Jianjiong Gao, James Lindsay, Stuart Watt, Istemi Bahceci, Pieter Lukasse, Adam Abeshouse, Hsiao-Wei Chen, Ino de Bruijn, Benjamin Gross, Dong Li, Ritika Kundra, Zachary Heins, Jorge Reis-Filho, Onur Sumer, Yichao Sun, Jiaojiao Wang, Qingguo Wang, Hongxin Zhang, Priti Kumari, M. Furkan Sahin, Sander de Ridder, Fedde Schaeffer, Kees van Bochove, Ugur Dogrusoz, Trevor Pugh, Chris Sander, Ethan Cerami, Nikolaus Schultz. The cBioPortal for cancer genomics and its application in precision oncology. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5277.

Genomic and transcriptomic heterogeneity in metaplastic carcinomas of the breast

Metaplastic breast cancer (MBC) is a rare special histologic type of triple-negative breast cancer, characterized by the presence of neoplastic cells showing differentiation towards squamous epithelium and/or mesenchymal elements. Here we sought to define whether histologically distinct subgroups of MBCs would be underpinned by distinct genomic and/or transcriptomic alterations. Microarray-based copy number profiling identified limited but significant differences between the distinct MBC subtypes studied here, despite the limited sample size (nu2009=u200917). In particular, we found that, compared to MBCs with chondroid or squamous cell metaplasia, MBCs with spindle cell differentiation less frequently harbored gain of 7q11.22-23 encompassing CLDN3 and CLDN4, consistent with their lower expression of claudins and their association with the claudin-low molecular classification. Microarray-based and RNA-sequencing-based gene expression profiling revealed that MBCs with spindle cell differentiation differ from MBCs with chondroid or squamous cell metaplasia on the expression of epithelial-to-mesenchymal transition-related genes, including down-regulation of CDH1 and EPCAM. In addition, RNA-sequencing revealed that the histologic patterns observed in MBCs are unlikely to be underpinned by a highly recurrent expressed fusion gene or a pathognomonic expressed mutation in cancer genes. Loss of PTEN expression or mutations affecting PIK3CA or TSC2 observed in 8/17 MBCs support the contention that PI3K pathway activation plays a role in the development of MBCs. Our data demonstrate that despite harboring largely similar patterns of gene copy number alterations, MBCs with spindle cell, chondroid and squamous differentiation are distinct at the transcriptomic level but are unlikely to be defined by specific pathognomonic genetic alterations.Genetics: no common genetic basis found for metaplastic breast carcinomaRecurrent somatic genetic alterations in any known cancer gene are unlikely to underpin metaplastic breast carcinoma (MBC), a rare breast cancer type. Jorge Reis-Filho from Memorial Sloan Kettering Cancer Center in New York, NY, USA, and colleagues performed complete genomic work-ups of 17 MBCs, an invasive form of breast cancer characterized by tumor cells displaying differentiation towards other cell types. Albeit limited, important differences in gene copy number and gene expression profiles between different subtypes of MBC were observed. These tumors were incredibly variable from patient to patient, and there were no defining genomic features that could demarcate the disease on a genetic level from other forms of triple-negative breast cancer. The authors suggest that further studies are needed to explain the basis of the diversity seen in MBCs.

Loss-of-function mutations in ATP6AP1 and ATP6AP2 in granular cell tumors.

Granular cell tumors (GCTs) are rare tumors that can arise in multiple anatomical locations, and are characterized by abundant intracytoplasmic granules. The genetic drivers of GCTs are currently unknown. Here, we apply whole-exome sequencing and targeted sequencing analysis to reveal mutually exclusive, clonal, inactivating somatic mutations in the endosomal pH regulators ATP6AP1 or ATP6AP2 in 72% of GCTs. Silencing of these genes in vitro results in impaired vesicle acidification, redistribution of endosomal compartments, and accumulation of intracytoplasmic granules, recapitulating the cardinal phenotypic characteristics of GCTs and providing a novel genotypic–phenotypic correlation. In addition, depletion of ATP6AP1 or ATP6AP2 results in the acquisition of oncogenic properties. Our results demonstrate that inactivating mutations of ATP6AP1 and ATP6AP2 are likely oncogenic drivers of GCTs and underpin the genesis of the intracytoplasmic granules that characterize them, providing a genetic link between endosomal pH regulation and tumorigenesis.Granular cell tumors (GCTs) are rare tumors that arise in multiple anatomical locations. Here, the authors investigate the genomics of GCTs, finding inactivating somatic mutations in ATP6AP1 or ATP6AP2 in 72% of the 82 GCTs analyzed. In vitro manipulation of these genes recapitulated GCT phenotypes in cellular models.

Abstract 2607: The cBioPortal for Cancer Genomics: an open source platform for accessing and interpreting complex cancer genomics data in the era of precision medicine

The cBioPortal for Cancer Genomics is an open-access portal (http://cbioportal.org) that enables interactive, exploratory analysis of large-scale cancer genomics data. It integrates genomic and clinical data, and provides a suite of visualization and analysis options, including cohort and patient-level visualization, mutation visualization, survival analysis, enrichment analysis, and network analysis. The user interface is user-friendly, responsive, and makes genomic data easily accessible to translational scientists, biologists, and clinicians. The cBioPortal is a fully open source platform. All code is available on GitHub (https://github.com/cBioPortal/) under GNU Affero GPL license. The code base is maintained by multiple groups, including Memorial Sloan Kettering Cancer Center, Dana-Farber Cancer Institute, Children’s Hospital of Philadelphia, Princess Margaret Cancer Centre, and The Hyve, an open source bioinformatics company based in the Netherlands. More than 30 academic centers as well as multiple pharmaceutical and biotech companies maintain private instances of the cBioPortal. This includes the recently launched cBioPortal instance at the NCI Genomic Data Commons (https://cbioportal.gdc.nci.nih.gov/), and two large cBioPortal instances hosting genomic and clinical data at MSK and DFCI, supporting the MSK-IMPACT and DFCI Profile projects, two of the largest clinical sequencing efforts in the world. Our multi-institutional software team has accelerated the progress of evolving the core architectural technologies and developing new features to keep pace with the rapidly advancing fields of cancer genomics and precision cancer medicine. For example, we have integrated multi-platform genomics data with extensive clinical data including patient demographics, treatment history, and survival data. We have also developed a patient-centric view that visualizes both clinical and genomic data with annotation from OncoKB knowledge base. In the next few years, the development team will focus on the following areas: (1) Implementing major architectural changes to ensure future scalability and performance. (2) New features to support precision medicine, including (i) improved integration of knowledge base annotation, (ii) enhanced visualization of patient timeline, drug response, and tumor evolution, (iii) new patient similarity metrics, (iv) improved support for immunogenomics and immunotherapy, and (v) new visualization and analysis features for understanding response to therapy. (3) New analysis and target discovery features for large cohorts, including (i) supporting user-defined virtual cohort by selecting samples from multiple studies, and (ii) comparison of genomic or clinical characteristics of two or more selected cohorts. (4) Expanding community outreach, user support and training, and documentation. Citation Format: Jianjiong Gao, Ersin Ciftci, Pichai Raman, Pieter Lukasse, Istemi Bahceci, Adam Abeshouse, Hsiao-Wei Chen, Ino de Bruijn, Benjamin Gross, Zachary Heins, Ritika Kundra, Aaron Lisman, Angelica Ochoa, Robert Sheridan, Onur Sumer, Yichao Sun, Jiaojiao Wang, Manda Wilson, Hongxin Zhang, James Xu, Andy Dufilie, Priti Kumari, James Lindsay, Anthony Cros, Karthik Kalletla, Fedde Schaeffer, Sander Tan, Sjoerd van Hagen, Jorge Reis-Filho, Kees van Bochove, Ugur Dogrusoz, Trevor Pugh, Adam Resnick, Chris Sander, Ethan Cerami, Nikolaus Schultz. The cBioPortal for Cancer Genomics: an open source platform for accessing and interpreting complex cancer genomics data in the era of precision medicine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2607. doi:10.1158/1538-7445.AM2017-2607