Next-generation sequencing (NGS) technology has expanded in the last decades with significant improvements in the reliability, sequencing chemistry, pipeline analyses, data interpretation and costs. Such advances make the use of NGS feasible in clinical practice today. This review describes the recent technological developments in NGS applied to the field of oncology. A number of clinical applications are reviewed, i.e., mutation detection in inherited cancer syndromes based on DNA-sequencing, detection of spliceogenic variants based on RNA-sequencing, DNA-sequencing to identify risk modifiers and application for pre-implantation genetic diagnosis, cancer somatic mutation analysis, pharmacogenetics and liquid biopsy. Conclusive remarks, clinical limitations, implications and ethical considerations that relate to the different applications are provided.

Next-Generation Sequencing in Oncology: Genetic Diagnosis, Risk Prediction and Cancer Classification.

Head and neck squamous cell carcinoma (HNSCC) is a common, morbid, and frequently lethal malignancy. To uncover its mutational spectrum, we analyzed whole-exome sequencing data from 74 tumor-normal pairs. The majority exhibited a mutational profile consistent with tobacco exposure; human papillomavirus was detectable by sequencing DNA from infected tumors. In addition to identifying previously known HNSCC genes (TP53, CDKN2A, PTEN, PIK3CA, and HRAS), our analysis revealed many genes not previously implicated in this malignancy. At least 30% of cases harbored mutations in genes that regulate squamous differentiation (for example, NOTCH1, IRF6, and TP63), implicating its dysregulation as a major driver of HNSCC carcinogenesis. More generally, the results indicate the ability of large-scale sequencing to reveal fundamental tumorigenic mechanisms.

The Mutational Landscape of Head and Neck Squamous Cell Carcinoma

Analysis of clinical trial specimens such as formalin-fixed paraffin-embedded (FFPE) tissue for molecular mechanisms of disease progression or drug response is often challenging and limited to a few markers at a time. This has led to the increasing importance of highly multiplexed assays that enable profiling of many biomarkers within a single assay. Methods for gene expression analysis have undergone major advances in biomedical research, but obtaining a robust dataset from low-quality RNA samples, such as those isolated from FFPE tissue, remains a challenge. Here, we provide a detailed evaluation of the NanoString Technologies nCounter platform, which provides a direct digital readout of up to 800 mRNA targets simultaneously. We tested this system by examining a broad set of human clinical tissues for a range of technical variables, including sensitivity and limit of detection to varying RNA quantity and quality, reagent performance over time, variability between instruments, the impact of the number of fields of view sampled, and differences between probe sequence locations and overlapping genes across CodeSets. This study demonstrates that Nanostring offers several key advantages, including sensitivity, reproducibility, technical robustness, and utility for clinical application.

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Evaluating Robustness and Sensitivity of the NanoString Technologies nCounter Platform to Enable Multiplexed Gene Expression Analysis of Clinical Samples

Recent next-generation sequencing studies have generated a comprehensive overview of the genomic landscape of Human Papillomavirus (HPV)-associated cancers. This review summarizes these findings to provide insight into the tumor biology of these cancers and potential therapeutic opportunities for HPV-driven malignancies. In addition to the tumorigenic properties of the HPV oncoproteins, integration of HPV DNA into the host genome is suggested to be a driver of the neoplastic process. Integration may confer a growth and survival advantage via enhanced expression of viral oncoproteins, alteration of critical cellular genes, and changes in global promoter methylation and transcription. Alteration of cellular genes may lead to loss of function of tumor suppressor genes, enhanced oncogene expression, loss of function of DNA repair genes, or other vital cellular functions. Recurrent integrations in RAD51B, NR4A2, and TP63, leading to aberrant forms of these proteins, are observed in both HPV-positive head and neck squamous cell carcinoma (HNSCC) and cervical carcinoma. Additional genomic alterations, independent of integration events, include recurrent PIK3CA mutations (and aberrations in other members of the PI3K pathway), alterations in receptor tyrosine kinases (primarily FGFR2 and FGFR3 in HPV-positive HNSCC, and ERBB2 in cervical squamous cell carcinoma), and genes in pathways related to squamous cell differentiation and immune responses. A number of the alterations identified are potentially targetable, which may lead to advances in the treatment of HPV-associated cancers.

https://clincancerres.aacrjournals.org/content/clincanres/21/9/2009.full.pdf

Genomic Landscape of Human Papillomavirus–Associated Cancers

Diffuse large B-cell lymphomas (DLBCLs) are clinically heterogeneous and need a biomarker that can predict the outcome of treatments accurately. To assess the prognostic significance of the cell-of-origin type for DLBCLs, we applied the Lymph2Cx assay using a NanoString gene expression platform on formalin-fixed paraffin wax-embedded pretreatment tissues obtained from 82 patients with de novo DLBCL, not otherwise specified. All patients were treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) as the first line of chemotherapy. Based on the expression levels of Bcl-6, CD10, and MUM-1 measured by immunohistochemistry, cases were subdivided into germinal center B-cell (GCB) and non-GCB types according to the Hans algorithm. NanoString assay was performed on 82 cases. The Lymph2Cx assay successfully classified 82 cases into three categories: activated B-cell (ABC), GCB, and unclassified types. The concordance rate between the Lymph2Cx assay and the Hans algorithm was 73.6%. The Lymph2Cx-defined ABC type had significantly poorer outcomes compared with the GCB type (5-year overall survival, GCB vs. ABC, 96.6% vs. 77.1%, P = 0.020; 5-year disease-free survival, GCB vs. ABC, 96.6% vs. 79.2%, P = 0.018). In contrast, no significant differences were observed in survival between the two patient subgroups with DLBCL types classified by the Hans algorithm. The Lymph2Cx assay is a robust, reliable method for predicting the outcome of patients with DLBCL treated with R-CHOP chemotherapy.

Cell-of-origin of diffuse large B-cell lymphomas determined by the Lymph2Cx assay: better prognostic indicator than Hans algorithm.

The role of molecular methods in the diagnosis of head and neck cancer is rapidly evolving and holds great potential for improving outcomes for all patients who suffer from this diverse group of malignancies . However, there is considerable debate as to the best clinical approaches, particularly for Next Generation Sequencing (NGS). The choices of NGS methods such as whole exome, whole genome, whole transcriptomes (RNA-Seq) or multiple gene resequencing panels, each have strengths and weakness based on data quality, the size of the data, the turnaround time for data analysis, and clinical actionability. There have also been a variety of gene expression signatures established from microarray studies that correlate with relapse and response to treatment, but none of these methods have been implemented as standard of care for oropharyngeal squamous cell carcinoma (OPSCC). Because many genomic methodologies are still far from the capabilities of most clinical laboratories, we chose to explore the use of a combination of off the shelf targeted mutation analysis and gene expression analysis methods to complement standard anatomical pathology methods. Specifically, we have used the Ion Torrent AmpliSeq cancer panel in combination with the NanoString nCounter Human Cancer Reference Kit on 8 formalin-fixed paraffin embedded (FFPE) OPSCC tumor specimens, (4) HPV-positive and (4) HPV-negative. Differential expression analysis between HPV-positive and negative groups showed that expression of several genes was highly likely to correlate with HPV status. For example, WNT1, PDGFA and OGG1 were all over-expressed in the positive group. Our results show the utility of these methods with routine FFPE clinical specimens to identify potential therapeutic targets which could be readily applied in a clinical trial setting for clinical laboratories lacking the instrumentation or bioinformatics infrastructure to support comprehensive genomics workflows. To the best of our knowledge, these preliminary experiments are among the earliest to combine both mutational and gene expression profiles using Ion Torrent and NanoString technologies. This reports serves as a proof of principle methodology in OPSCC.

Mutation and Transcriptional Profiling of Formalin-Fixed Paraffin Embedded Specimens as Companion Methods to Immunohistochemistry for Determining Therapeutic Targets in Oropharyngeal Squamous Cell Carcinoma (OPSCC): A Pilot of Proof of Principle

Juliana DaSilva

Papers

Mutation and Transcriptional Profiling of Formalin-Fixed Paraffin Embedded Specimens as Companion Methods to Immunohistochemistry for Determining Therapeutic Targets in Oropharyngeal Squamous Cell Carcinoma (OPSCC): A Pilot of Proof of Principle