The homogeneous mutation status of a 22 gene panel justifies the use of serial sections of colorectal cancer tissue for external quality assessment

Intra-Tumoral Genomic Heterogeneity in Rectal Cancer: Mutational Status Is Dependent on Preoperative Biopsy Depth and Location

Neoadjuvant therapy before surgical resection is indicated for patients with locally advanced rectal cancer. However, a significant number of patients show minimal or no response to neoadjuvant therapy. Unfortunately, we are currently unable to predict response and identify non-responding patients before neoadjuvant treatment is given. Genomic mutational status might provide valuable prognostic information. However, it is unclear whether predictions based on genomic mutational status in single preoperative biopsies are reliable due to intra-tumoral heterogeneity. In this study we aim to investigate the reliability of genomic mutations found in single pre-operative biopsies by comparing genomic mutations to four other locations within the same tumor using next generation sequencing. Rectal cancer patients undergoing primary resection without neoadjuvant therapy were included. From each patient, one biopsy, two deep and two superficial samples were obtained and sequenced using a targeted next generation sequencing gene panel. Concordance between these five samples was assessed. In this feasibility study we included 11 patients. In 7 out of 11 (64%) patients, all 5 samples showed concordant mutations. In 4 out of 11 patients (36%) discordant mutations were observed. In conclusion, assessment of mutational status on a single pre-operative biopsy shows discordance with tumor tissue from other locations in 36% of cases. These results warrant careful interpretation of biopsy material analysis, as these might be influenced by tumor heterogeneity.

A study of associations between CUBN, HNF1A, and LIPC gene polymorphisms and coronary artery disease

The aim of this study was to identify novel genetic markers related to coronary artery disease (CAD) using a whole-exome sequencing (WES) approach and determine any associations between the selected gene polymorphisms and CAD prevalence. CUBN, HNF1A and LIPC gene polymorphisms related to CAD susceptibility were identified using WES screening. Possible associations between the five gene polymorphisms and CAD susceptibility were examined in 452 CAD patients and 421 control subjects. Multivariate logistic regression analyses indicated that the CUBN rs2291521GA and HNF1A rs55783344CT genotypes were associated with CAD (GG vs. GA; adjusted odds ratio [AOR] = 1.530; 95% confidence interval [CI] 1.113–2.103; P = 0.002 and CC vs. CT; AOR = 1.512; 95% CI 1.119–2.045; P = 0.007, respectively). The CUBN rs2291521GA and HNF1A rs55783344CT genotype combinations exhibited a stronger association with CAD risk (AOR = 2.622; 95% CI 1.518–4.526; P = 0.001). Gene-environment combinatorial analyses indicated that the CUBN rs2291521GA, HNF1A rs55783344CT, and LIPC rs17269397AA genotype combination and several clinical factors (fasting blood sugar (FBS), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) levels) were associated with increased CAD risk. The CUBN rs2291521GA, HNF1A rs55783344CT, and LIPC rs17269397AA genotypes in conjunction with abnormally elevated cholesterol levels increase the risk of developing CAD. This exploratory study suggests that polymorphisms in the CUBN, HNF1A, and LIPC genes can be useful biomarkers for CAD diagnosis and treatment.

Comparison of Fresh Frozen Tissue With Formalin-Fixed Paraffin-Embedded Tissue for Mutation Analysis Using a Multi-Gene Panel in Patients With Colorectal Cancer

Background: Next generation sequencing (NGS)-based multi-gene panel tests have been performed to predict the treatment response and prognosis in patients with colorectal cancer (CRC). Whether the multi-gene mutation results of formalin-fixed paraffin-embedded (FFPE) tissues are identical to those of fresh frozen tissues remains unknown.

Methods: A 22-gene panel with 103 hotspots was used to detect mutations in paired fresh frozen tissue and FFPE tissue from 118 patients with CRC.

Results: In our study, 117 patients (99.2%) had one or more variants, with 226 variants in FFPE tissue and 221 in fresh frozen tissue. Of the 129 variants identified in this study, 96 variants were present in both FFPE and fresh frozen tissues; 27 variants were found in FFPE tissues only; 6 variants were found only in fresh frozen tissues. The mutation results demonstrated >94.0% concordance in all variants, with Kappa coefficient >0.500 in 64.3% (83/129) of variants. At the gene level, concordance ranged from 73.8 to 100.0%, with Kappa coefficient >0.500 in 81.3% (13/16) of genes.

Conclusions: The results of mutation analysis performed with a multi-gene panel and FFPE and fresh frozen tissue were highly concordant in patients with CRC, at both the variant and gene levels. There were, however, some important differences in mutation results between the two tissue types. Therefore, fresh frozen tissue should not routinely be replaced with FFPE tissue for mutation analysis with a multi-gene panel. Rather, FFPE tissue is a reasonable alternative for fresh frozen tissue when the latter is unavailable.

Clinical significance of multiple gene detection with a 22-gene panel in formalin-fixed paraffin-embedded specimens of 207 colorectal cancer patients

BACKGROUND

Simultaneous detection of multiple molecular biomarkers is helpful in the prediction of treatment response and prognosis for colorectal cancer (CRC) patients.

METHODS

A 22-gene panel consisting of 103 hotspot regions was utilized in the formalin-fixed paraffin-embedded (FFPE) tissue samples of 207 CRC patients, using the next-generation sequencing (NGS)-based multiplex PCR technique. Those 22 genes included AKT1, ALK, BRAF, CTNNB1, DDR2, EGFR, ERBB2, ERBB4, FBXW7, FGFR1, FGFR2, FGFR3, KRAS, MAP2K1, MET, NOTCH1, NRAS, PIK3CA, PTEN, SMAD4, STK11, and TP53.

RESULTS

Of the 207 patients, 193 had one or more variants, with 170, 20, and 3 having one, two, and three mutated genes, respectively. Of the total 414 variants identified in this study, 384, 25, and 5 were single-nucleotide variants, deletion, and insertion. The top four frequently mutated genes were TP53, KRAS, PIK3CA, and FBXW7. There was high consistency between the results of NGS-PCR technique and routine ARMS-PCR in KRAS and BRAF mutation detection. Univariate and multivariate analyses demonstrated that advanced TNM stage, elevated serum CEA, total variants number ≥ 2, AKT1 and PTEN mutation were independent predictors of shorter DFS; poor differentiation, advanced TNM stage, total variants number ≥ 2, BRAF, CTNNB1 and NRAS mutation were independent predictors of shorter OS.

CONCLUSIONS

It is feasible to detect multiple gene mutations with a 22-gene panel in FFPE CRC specimens. TNM stage and total variants number ≥ 2 were independent predictors of DFS and OS. Detection of multiple gene mutations may provide additional prognostic information to TNM stage in CRC patients.

The reliable assurance of detecting somatic mutations in cancer-related genes by next-generation sequencing: the results of external quality assessment in China

To evaluate the proficiencies of laboratories utilizing next-generation sequencing (NGS) to detect somatic mutations in cancer-related genes, an external quality assessment (EQA) was implemented by the National Center for Clinical Laboratories of China in 2015. We prepared a panel of samples that comprised eight samples made by mixing synthetic mutated DNA fragments with normal human genomic DNA and one reference sample containing only genomic DNA. We validated our sample panel, and then distributed it to laboratories across China. We received complete results from 64 laboratories. The performances of 51.6 % (33/64) respondent labs were acceptable and 26.6 % (17/64) of the labs returned perfect results. In total, 449 mistakes were reported, including 201 false-negatives (201/449, 44.8 %) and 222 false-positives (222/449, 49.4 %) and 26 slightly discordant results (26/449, 5.8 %). We believe these unsatisfactory results and varied performances are mainly due to the enrichment methods used, the diverse sequencing chemistries of the different NGS platforms, and other errors within the sequencing process. The results indicate that our sample panel is suitable for use in EQA studies, and that further laboratory training in targeted NGS testing is urgently required. To address this, we propose a targeted NGS workflow with details on quality assurance procedures according to the current guidelines.

Three-dimensional digital reconstruction of skin epidermis and dermis

This study describes how three-dimensional (3D) human skin tissue is reconstructed, and provides digital anatomical data for the physiological structure of human skin tissue based on large-scale thin serial sections. Human skin samples embedded in paraffin were cut serially into thin sections and then stained with hematoxylin-eosin. Images of serial sections obtained from lighting microscopy were scanned and aligned by the scale-invariant feature transform algorithm. 3D reconstruction of the skin tissue was generated using Mimics software. Fibre content, porosity, average pore diameter and specific surface area of dermis were analysed using the ImageJ analysis system. The root mean square error and mutual information based on the scale-invariant feature transform algorithm registration were significantly greater than those based on the manual registration. Fibre distribution gradually decreased from top to bottom; while porosity showed an opposite trend with irregular average pore diameter distribution. A specific surface area of the dermis showed a 'V' shape trend. Our data suggested that 3D reconstruction of human skin tissue based on large-scale serial sections could be a valuable tool for providing a highly accurate histological structure for analysis of skin tissue. Moreover, this technology could be utilized to produce tissue-engineered skin via a 3D bioprinter in the future.

Progress and potential of RAS mutation detection for diagnostics and companion diagnostics

INTRODUCTION

The importance of RAS mutation in carcinogenesis is established, and knowledge of an individual cancer's mutation status is important for optimal treatment. Areas covered: This paper is restricted to RAS testing in cancer, and highlights papers relevant to current practice. Expert commentary: Multiple laboratory methods are available for RAS gene analysis. PCR is commonly used to determine RAS status, providing a robust and inexpensive technology for clinical use. Next generation sequencing (NGS) platforms are changing the way in which mutation status is determined, though they require considerable expertise. Pre-analytical issues affect both methods and should be considered. The interpretation and reporting of results is not simple, particularly for NGS. External quality assurance is a pre-requisite for success, and is mandated by most laboratory accreditation schemes. The use of RAS testing is now extending beyond biopsy material to include the detection of mutations in circulating cell-free DNA and tumour cells.

Epigenetic effects of chromatin remodeling agents on organotypic cultures

BACKGROUND

Tumor epigenetic defects are of increasing relevance to clinical practice, because they are 'druggable' targets for cancer therapy using chromatin-remodeling agents (CRAs). New evidences highlight the importance of the microenvironment on the epigenome regulation and the need to use culture models able to preserve tissue morphology, to better understand the action of CRAs. Methods & methods: We studied the epigenetic response induced by culturing and CRAs in a preclinical model, preserving ex vivo the original tissue microenvironment and morphology, assessing different epigenetic signatures. Our overall findings suggest that culturing and CRAs cause heterogeneous effects on the genes methylation; CRAs affect the global DNA methylation and can trigger an active DNA demethylation; the culture induces alterations in the histone deacetylase expression.

CONCLUSION

Despite the limited number of cases, these findings can be considered a proof of concept of the possibility to test CRAs epigenetic effects on ex vivo tissues maintained in their native tissue architecture.