Formalin-fixed Paraffin-embedded Clinical Samples Research Articles

Endometrioid ovarian carcinoma landscape: pathological and molecular characterization.

Endometrioid ovarian cancers (EOvC) are usually managed as serous tumors. In this study, we conducted a comprehensive molecular investigation to uncover the distinct biological characteristics of EOvC. This retrospective multicenter study involved patients from three European centers. We collected clinical data and formalin-fixed paraffin-embedded (FFPE) samples for analysis at the DNA level using panel-based next-generation sequencing and array-comparative genomic hybridization. Additionally, we examined mRNA expression using NanoString nCounter® and protein expression through tissue microarray. We compared EOvC with other ovarian subtypes and uterine endometrioid tumors. Furthermore, we assessed the impact of molecular alterations on patient outcomes, including progression-free survival (PFS) and overall survival (OS). Preliminary analysis of clinical data from 668 patients, including 86 (12.9%) EOvC, revealed more favorable prognosis for EOvC compared with serous ovarian carcinoma (5-year OS of 60% versus 45%; P = 0.001) driven by diagnosis at an earlier stage. Immunohistochemistry and copy number alteration (CNA) profiles of 43 cases with clinical data and FFPE samples available indicated that EOvC protein expression and CNA profiles were more similar to endometrioid endometrial tumors than to serous ovarian carcinomas. EOvC exhibited specific alterations, such as lower rates of PTEN loss, mutations in DNA repair genes, and P53 abnormalities. Survival analysis showed that patients with tumors harboring loss of PTEN expression had worse outcomes (median PFS 19.6 months vs. not reached; P = 0.034). Gene expression profile analysis confirmed that EOvC differed from serous tumors. However, comparison to other rare subtypes of ovarian cancer suggested that the EOvC transcriptomic profile was close to that of ovarian clear cell carcinoma. Downregulation of genes involved in the PI3K pathway and DNA methylation was observed in EOvC. In conclusion, EOvC represents a distinct biological entity and should be regarded as such in the development of specific clinical approaches.

Microsatellite Instability Detection in Cancer: A Multiplex qPCR Approach that Obviates the Need for Matching Normal Samples.

Microsatellite instability (MSI) indicates DNA mismatch repair deficiency in certain types of cancer, such as colorectal cancer. The current gold standard technique, PCR-capillary electrophoresis (CE), requires matching normal samples and specialized instrumentation. We developed VarTrace, a rapid and low-cost quantitative PCR (qPCR) assay, to evaluate MSI using solely the tumor sample DNA, obviating the requirement for matching normal samples. One hundred and one formalin-fixed paraffin-embedded (FFPE) tumor samples were tested using VarTrace and compared with the Promega OncoMate assay utilizing PCR-CE. Tumor percentage limit of detection was evaluated on contrived samples derived from clinical high MSI (MSI-H) samples. Analytical sensitivity, specificity, limit of detection, and input requirements were assessed using synthetic commercial reference standards. VarTrace successfully analyzed all 101 clinical FFPE samples, demonstrating 100% sensitivity and 98% specificity compared to OncoMate. It detected MSI-H with 97% accuracy down to 10% tumor. Analytical studies using synthetic samples showed a limit of detection of 5% variant allele frequency and a limit of input of 0.5 ng. This study validates VarTrace as a swift, accurate, and economical assay for MSI detection in samples with low tumor percentages without the need for matching normal DNA. VarTrace's capacity for highly sensitive MSI analysis holds potential for enhancing the efficiency of clinical work flows and broadening the availability of this test.

RNA-seq RNAaccess identified as the preferred method for gene expression analysis of low quality FFPE samples.

Clinical tumor tissues that are preserved as formalin-fixed paraffin-embedded (FFPE) samples result in extensive cross-linking, fragmentation, and chemical modification of RNA, posing significant challenges for RNA-seq-based gene expression profiling. This study sought to define an optimal RNA-seq protocol for FFPE samples. We employed a common RNA extraction method and then compared RNA-seq library preparation protocols including RNAaccess, RiboZero and PolyA in terms of sequencing quality and concordance of gene expression using FFPE and case-matched fresh-frozen (FF) triple-negative breast cancer (TNBC) tissues. We found that RNAaccess, a method based on exome capture, produced the most concordant results. Applying RNAaccess to FFPE gastric cancer tissues, we established a minimum RNA DV200 requirement of 10% and a RNA input amount of 10ng that generated highly reproducible gene expression data. Lastly, we demonstrated that RNAaccess and NanoString platforms produced highly concordant expression profiles from FFPE samples for shared genes; however, RNA-seq may be preferred for clinical biomarker discovery work because of the broader coverage of the transcriptome. Taken together, these results support the selection of RNA-seq RNAaccess method for gene expression profiling of FFPE samples. The minimum requirements for RNA quality and input established here may allow for inclusion of clinical FFPE samples of sub-optimal quality in gene expression analyses and ultimately increasing the statistical power of such analyses.

RNA in situ hybridisation as a molecular diagnostic technique targeting IBA‐1 and CD204 in canine histiocytic sarcoma

BackgroundCanine histiocytic sarcoma (HS) is an aggressive cancer with morphologically variable features; therefore, obtaining a definitive diagnosis can be challenging. Two proteins, IBA‐1, ionised calcium‐binding adapter molecule 1, and CD204, a macrophage scavenger receptor, have been shown to be specific immunohistochemical markers helpful in distinguishing HS from other tumour types with similar morphological features.ObjectivesThis study was performed to demonstrate the use of RNA in situ hybridisation (ISH) technology allowing single‐molecule RNA visualisation in formalin‐fixed paraffin‐embedded (FFPE) tissues as a molecular tool for the diagnosis of canine HS.MethodsReverse transcription polymerase chain reaction (RT‐PCR) and western blot analysis for IBA‐1 and CD204 were performed to correlate gene expression and protein expression of these two markers in the histiocytic sarcoma DH82 cell line. RNA‐ISH for IBA‐1 and CD204 was performed on the DH82 cell line to validate the RNA‐ISH probes. RNA‐ISH and immunohistochemistry (IHC) were performed in clinical HS FFPE samples to demonstrate mRNA and protein expression of IBA‐1 and CD204. FFPE archived samples of canine round cell tumours, melanoma and anaplastic sarcoma were used as negative controls.ResultsRNA‐ISH and IHC showed moderate to strong expression for IBA‐1 and CD204 in the neoplastic cells in both the canine DH82 cell line and the archived canine HS samples. RNA‐ISH and IHC showed scattered positive staining in the control tumours samples, consistent with macrophagic infiltration.ConclusionRNA‐ISH for CD204 and IBA‐1 appeared to have a high specificity and sensitivity in our samples and may be an additional valuable diagnostic technique in identifying HS.

Extraction and isolation of histones from paraffin-embedded tissues and quantitative analysis of post-translational modifications

组蛋白翻译后修饰(HPTMs)参与基因转录调控,其异常与肿瘤等重大疾病的发生发展密切相关。石蜡包埋组织是当前疾病研究的重要样本资源,对肿瘤机制和标志物研究具有重要意义。目前基于质谱的蛋白质组学技术已成为HPTMs分析的有力工具,而针对福尔马林固定石蜡包埋(FFPE)组织样品的HPTMs分析还十分有限。该研究发展了一种基于高效液相色谱-串联质谱的FFPE组织样本HPTMs分离分析新方法。通过研究并优化组蛋白的提取策略,建立了FFPE组织样本脱蜡水化处理、蛋白质提取与聚丙烯酰胺凝胶电泳分离相结合的组蛋白提取和分离方法。通过研究FFPE切片数量、组蛋白化学衍生化方法等对组蛋白鉴定的影响,确定了组蛋白处理的具体步骤。通过HPLC分离结合非依赖性采集模式的质谱分析,鉴定了组蛋白修饰的类型、位点和丰度。最后,将优化的实验方法应用于FFPE临床样本的HPTMs分析,鉴定了2例人乳腺浸润性癌和癌旁正常组织的HPTMs图谱,均获得了100种以上的不同组蛋白修饰形式的多肽。定量分析了他们的差异性水平,通过主成分降维分析,发现浸润性癌和癌旁正常组织之间组蛋白修饰丰度存在明显的差异,且差异性具有一定的规律,特别是涉及转录调控的组蛋白修饰与乳腺癌的预后和治疗靶点具有相关性,进而探讨了乳腺癌中异常HPTMs的生物学意义。该研究对临床石蜡样本中组蛋白修饰的分离分析以及肿瘤表观遗传标志物的检测进行了有益的探索。

New Histoplasma Diagnostic Assays Designed via Whole Genome Comparisons

Histoplasmosis is a systemic fungal disease caused by the pathogen Histoplasma spp. that results in significant morbidity and mortality in persons with HIV/AIDS and can also affect immunocompetent individuals. Although some PCR and antigen-detection assays have been developed, conventional diagnosis has largely relied on culture, which can take weeks. Our aim was to provide a proof of principle for rationally designing and standardizing PCR assays based on Histoplasma-specific genomic sequences. Via automated comparisons of aligned genome contigs/scaffolds and gene (sub)sequences, we identified protein-coding genes that are present in existing sequences of Histoplasma strains but not in other genera. Two of the genes, PPK and CFP4, were used for designing primer sets for conventional and real-time PCR assays. Both resulted in a 100% analytical specificity in vitro and detected 62/62 H. capsulatum isolates using purified DNA. We also obtained positive detections of 2/2 confirmed H. capsulatum clinical FFPE (formalin-fixed paraffin-embedded) samples using both primer sets. Positive control plasmid 10-fold serial dilutions confirmed the analytical sensitivity of the assays. The findings suggest that these novel primer sets should allow for detection sensitivity and reduce false positive results/cross-reactions. New assays for detecting pathogenic fungi, constructed along these lines, could be simple and affordable to implement.

Large scale, robust, and accurate whole transcriptome profiling from clinical formalin-fixed paraffin-embedded samples

Transcriptome profiling can provide information of great value in clinical decision-making, yet RNA from readily available formalin-fixed paraffin-embedded (FFPE) tissue is often too degraded for quality sequencing. To assess the clinical utility of FFPE-derived RNA, we performed ribo-deplete RNA extractions on > 3200 FFPE slide samples; 25 of these had direct FFPE vs. fresh frozen (FF) replicates, 57 were sequenced in 2 different labs, 87 underwent multiple library analyses, and 16 had direct microdissected vs. macrodissected replicates. Poly-A versus ribo-depletion RNA extraction methods were compared using transcriptomes of TCGA cohort and 3116 FFPE samples. Compared to FF, FFPE transcripts coding for nuclear/cytoplasmic proteins involved in DNA packaging, replication, and protein synthesis were detected at lower rates and zinc finger family transcripts were of poorer quality. The greatest difference in extraction methods was in histone transcripts which typically lack poly-A tails. Encouragingly, the overall sequencing success rate was 81%. Exome coverage was highly concordant in direct FFPE and FF replicates, with 98% agreement in coding exon coverage and a median correlation of whole transcriptome profiles of 0.95. We provide strong rationale for clinical use of FFPE-derived RNA based on the robustness, reproducibility, and consistency of whole transcriptome profiling.

Defining the Celiac Disease Transcriptome using Clinical Pathology Specimens Reveals Biologic Pathways and Supports Diagnosis

Celiac disease is provoked by gluten exposure, but the complete pathogenic process in the duodenum and the loss of tolerance to gluten is not well understood. We aimed to define the core celiac transcriptomic signature and pathologic pathways in pre-treatment formalin-fixed paraffin-embedded (FFPE) duodenum biopsies used for clinical diagnosis. We use mRNAseq to define pre-treatment diagnostic duodenum gene expression in 54 pediatric celiac patients and non-celiac controls, and we validate our key findings in two independent cohorts of 67 adults and pediatric participants that used fresh frozen biopsies. We further define similar and divergent genes and pathways in 177 small bowel Crohn disease patients and controls. We observe a marked suppression of mature epithelial metabolic functions in celiac patients, overlapping substantially with the Crohn disease signature. A marked adaptive immune response was noted for the up-regulated signature including interferon response, alpha-beta, and gamma-delta T-cells that overlapped to some extent with the Crohn disease signature. However, we also identified a celiac disease specific signature linked to increased cell proliferation, nuclear division, and cell cycle activity that was localized primarily to the epithelia as noted by CCNB1 and Ki67 staining. Lastly, we demonstrate the utility of the transcriptomic date to correctly classify disease or healthy states in the discovery and validation cohorts. Our data supplement recently published datasets providing insights into celiac pathogenesis using clinical pathology FFPE samples, and can stimulate new approaches to address this highly prevalent condition.

A Clinically Applicable Gene-Expression Classifier Reveals Intrinsic and Extrinsic Contributions to Consensus Molecular Subtypes in Primary and Metastatic Colon Cancer.

Four consensus molecular subtypes (CMS1-4) of colorectal cancer were identified in primary tumors and found to be associated with distinctive biological features and clinical outcomes. Given that distant metastasis largely accounts for colorectal cancer-related mortality, we examined the molecular and clinical attributes of CMS in metastatic colorectal cancer (mCRC). We developed a colorectal cancer-focused NanoString-based CMS classifier that is ideally suited to interrogate archival tissues. We successfully used this panel in the CMS classification of formalin-fixed paraffin-embedded (FFPE) tissues from mCRC cohorts, one of which is composed of paired primary tumors and metastases. Finally, we developed novel mouse implantation models to enable modeling of colorectal cancer in vivo at relevant sites. Using our classifier, we find that the biological hallmarks of mCRC, including CMS, are in general highly similar to those observed in nonmetastatic early-stage disease. Importantly, our data demonstrate that CMS1 has the worst outcome in relapsed disease, compared with other CMS. Assigning CMS to primary tumors and their matched metastases reveals mostly concordant subtypes between primary and metastasis. Molecular analysis of matched discordant pairs reveals differences in stromal composition at each site. The development of two novel in vivo orthotopic implantation models further reinforces the notion that extrinsic factors may impact on CMS identification in matched primary and metastatic colorectal cancer. We describe the utility of a NanoString panel for CMS classification of FFPE clinical samples. Our work reveals the impact of intrinsic and extrinsic factors on colorectal cancer heterogeneity during disease progression.

Robustness of biomarker determination in breast cancer by RT-qPCR: impact of tumor cell content, DCIS and non-neoplastic breast tissue

BackgroundTissue heterogeneity in formalin-fixed paraffin-embedded (FFPE) breast cancer specimens may affect the accuracy of reverse transcription quantitative real-time PCR (RT-qPCR). Herein, we tested the impact of tissue heterogeneity of breast cancer specimen on the RT-qPCR-based gene expression assay MammaTyper®.MethodsMammaTyper® quantifies the mRNA expression of the four biomarkers ERBB2, ESR1, PGR, and MKI67. Based on pre-defined cut-off values, this molecular in vitro diagnostic assay permits binary marker classification and determination of breast cancer subtypes as defined by St Gallen 2013. In this study, we compared data from whole FFPE sections with data obtained in paired RNA samples after enrichment for invasive carcinoma via macro- or laser-capture micro-dissection.ResultsCompared to whole sections, removal of surrounding adipose tissue by macrodissection generated mean absolute 40-ddCq differences of 0.28–0.32 cycles for all four markers, with ≥90% concordant binary classifications. The mean raw marker Cq values in the adipose tissue were delayed by 6 to 7 cycles compared with the tumor-enriched sections, adding a trivial linear fold change of 1.0078 to 1.0156. Comparison of specimens enriched for invasive tumor with whole sections with as few as 20% tumor cell content resulted in mean absolute differences that remained on average below 0.59 Cq. The mean absolute difference between whole sections containing up to 60% ductal carcinoma in situ (DCIS) and specimens after dissection of DCIS was only 0.16–0.25 cycles, although there was a tendency for higher gene expression in DCIS. Observed variations were related to small size of samples and proximity of values to the limit of detection.ConclusionExpression of ESR1, PGR, ERBB2 and MKI67 by MammaTyper® is robust in clinical FFPE samples. Assay performance was unaffected by adipose tissue and was stable in samples with as few as 20% tumor cell content and up to 60% DCIS.

Detection of driver mutations in FFPE samples from patients with verified malignant melanoma.

Malignant melanoma is an oncological disease characterized by etiologic heterogeneity and it has increasing incidence and mortality in the Slovak Republic. While it is treated surgically in combination with chemotherapy, targeted therapy, and immunotherapy, malignant melanomas can ulcerate and are susceptible to infections. These are highly aggressive cancers with metastasis, and recent studies have shown the presence of mutations in RAC1, PPP6C and STK19 genes in melanoma patients. Mutations in these genes are driver mutations; important in oncogenesis and providing selective advantage to tumor cells. The aim of our study is to establish a method to detect driver mutations in formalin-fixed, paraffin embedded (FFPE) tissue DNA. We applied Sanger sequencing to detect driver somatic mutations in RAC1, PPP6C, STK19 and BRAF genes in patients with malignant melanoma. Confirmation of BRAF V600E mutation was obtained by allele-specific PCR. The BRAF V600E mutation was present in 15 of 113 patients (13.2%) and the driver mutation in 7 of 113 patients (6.2 %). Our results demonstrate that Sanger sequencing analysis detects mutations in FFPE clinical samples. The identification of these somatic driver mutations in samples with verified malignant melanomas enabled development of a molecular classification of melanomas, and our study provides evidence of diversity of novel driver mutations implicated in malignant melanoma pathogenesis. These findings could have very important implications for targeted therapy.

Abstract 422: Single-stranded library preparation enables unbiased sequencing of damaged, FFPE-derived DNA for both targeted gene capture and WGS applications

Abstract Next Generation Sequencing is increasingly used in translational cancer research and as a diagnostic test. Most tumor specimens available for testing are formalin-fixed, paraffin-embedded (FFPE) blocks. FFPE-derived DNA is typically damaged, causing difficulties for standard library preparation methods. Frayed ends prevent blunt-ended double-stranded adapter ligation, used for whole genome sequencing (WGS) and targeted bait hybridization library preparation. Fragmented DNA and modified bases interfere with PCR, which underlies amplification based targeted sequencing. We present a single-stranded library preparation method especially forgiving for low quality FFPE-derived DNA. By excising damaged bases and using single-stranded adapter ligation, we omit repair aimed at generating blunt-ended double-stranded DNA, and eliminate the need for whole genome PCR. After ligation of the first adapter, libraries can either undergo second adapter ligation to generate WGS libraries, or be used as input to oligo-selective sequencing (OS-Seq) target capture. We show that our FFPE-derived PCR-free WGS libraries exhibit coverage depth and uniformity highly similar to double-stranded PCR-free libraries of matched cell line (non-FFPE) materials. Additionally, we present performance of our WGS library preparation on clinical FFEP samples. We further demonstrate reproducible high and uniform coverage for reference standards and clinical FFPE samples in targeted capture. We show a lack of correlation between DNA quality and sequencing metrics such as on-target rate (R2=0.005), uniformity (R2=0.0002), and coverage (R2=0.06), with successful removal of C>T FFPE artifacts comparable to standard repair methods. We demonstrate sensitive copy number alteration detection through analysis of coverage depth, feasible due to the absence of pre-capture PCR. In conclusion, our single-stranded library preparation method is forgiving for sample quality and provides uniform and high coverage as the basis for somatic variant calling. Citation Format: Anna Vilborg. Single-stranded library preparation enables unbiased sequencing of damaged, FFPE-derived DNA for both targeted gene capture and WGS applications [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 422.

Abstract 5356: Robust gene fusion detection in formalin-fixed tissue sample with QIAseq RNAscan Oncology Panel

Abstract Introduction: Gene fusions are frequently associated with tumorigenesismalignant tumors. Highly sensitive and reproducible detection of gene fusions in clinical samples, especially formalin-fixed paraffin-embedded (FFPE) specimens, is important for diagnosis, prognosis, and treatment guidance. Although many clinical tests utilize next-generation-sequencing (NGS) for detection of genetic alterations, reliable detection of gene fusions by NGS in FFPE samples remains a challenge. Methods: Five FFPE non-small cell lung cancer samples confirmed by FISH to contain EML4-ALK or KIF5B-RET fusions were selected for testing along with the Seraseq™ FFPE Tumor Fusion RNA Reference Material, v1, which evaluates forcontains 12 known fusions. Four operators prepared NGS libraries for each sample (89-250ng input) using the commercially available QIAseq RNAscan Oncology Panel, which targets 223 fusion gene pairs or 576 unique breakpoints. The resulting libraries were sequenced on an Illumina® NextSeq 500 sequencer. Demultiplexed FASTQ files were analyzed using cloud-based QIAseq RNAscan Analysis pipeline v1.7.20.2. Detected fusions that are on the panel's target list were reported as curated gene fusions and assigned a score based on unique molecules supporting the transcript. Results: For the Seraseq™ FFPE Tumor Fusion RNA Reference v1 sample, all 12 expectedknown fusions were detected in each of the libraries generated by four different operators. The analysis pipeline correctly called the expected fusion in all four replicates of the five clinical FFPE samples tested, which varied in both input quantityamount and quality. Reproducibility was evaluated by comparing the score values across replicate libraries for each sample; expected fusion detection was 100% consistent between users, and the average correlation coefficient for the fusion score was 0.995. Conclusions: The commercially available QIAseq RNAscan Oncology panel is a highly sensitive and robust product for detection of gene fusions in FFPE samples. QIAseq RNAscan methodology provides a useful tool for studying gene fusions in tumor samples and with optimization, customization, and validation can further fit the specific needs for of clinical laboratories. Citation Format: Jeffrey Falk, Parth Sitlani, Claire Orosco, Maya Panjikaran, Dana Weiner, Song Tian, Raed Samara, John DiCarlo, Yexun Wang, Eric Lader, Frank Reinecke. Robust gene fusion detection in formalin-fixed tissue sample with QIAseq RNAscan Oncology Panel [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5356.

Abstract 3398: Analysis of whole transcriptome RNA-seq of large numbers of clinical FFPE samples

Abstract Background: We evaluate the feasibility, quality, and analytical potential of whole-transcriptome RNA-seq on over one thousand clinical FFPE tumor samples. Transcriptional profiling of RNA is used for clinical decision making in many tumor types. Clinical analysis of RNA is complicated by the common use of formalin-fixed paraffin-embedded (FFPE) tissue storage, which can cause low yield and RNA degradation. Methods: RNA was extracted from FFPE material using commercially available kits using an RNAseH based ribodeplete. Multiple libraries per sample are sequenced using standard Illumina sequencing. Bowtie2, RSEM, and custom software are used for alignment, transcript quantification, fusion detection, and variant expression analysis. Results: We observe a >85% success rate on whole transcriptome RNA-seq on our cohort of more than 1000 samples. We find reliable transcript quantification upon successful sequencing, and on a subset of samples quantify differences between FFPE and fresh-frozen material when using ribodeplete. We also compare transcriptional profiles of clinical FFPE samples to an independent set of fresh frozen, poly-A capture samples from The Cancer Genome Atlas (TCGA) and show differences between poly-A capture and ribodeplete RNA isolation methods as well as FFPE vs. FF effects. We present a robust mapping methodology for comparison of public FF poly-A dataset to our FFPE ribodeplete samples. We demonstrate that we are able to utilize this joint gene expression space to perform site of origin prediction on FFPE samples. This is especially important for clinical application in analyzing Cancer of Unknown Primary (CUP) samples as well as detecting outlier samples whose molecular features may suggest additional therapeutic avenues. Finally, we show reliable detection of fusion transcripts from FFPE RNA-seq material from whole-transcriptome analysis and expression of somatic tumor variants detected from DNA sequencing. Conclusions: Large scale sequencing of RNA from clinical FFPE materials provides reliable transcriptomic results comparable to existing public databases of RNA, enabling research on cohorts of tumors that are FFPE-banked and unavailable as frozen tissue. Citation Format: Yulia Newton, Justin Golovato, Mark Johnson, Shahrooz Rabizadeh, Zack Sanborn, Steve Benz, Charles J. Vaske. Analysis of whole transcriptome RNA-seq of large numbers of clinical FFPE samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3398.

Performance validation of an amplicon-based targeted next-generation sequencing assay and mutation profiling of 648 Chinese colorectal cancer patients.

Next-generation sequencing (NGS) has become a promising approach for tumor somatic mutation detection. However, stringent validation is required for its application on clinical specimens, especially for low-quality formalin-fixed paraffin-embedded (FFPE) tissues. Here, we validated the performance of an amplicon-based targeted NGS assay, OncoAim™ DNA panel, on both commercial reference FFPE samples and clinical FFPE samples of Chinese colorectal cancer (CRC) patients. Then we profiled the mutation spectrum of 648 Chinese CRC patients in a multicenter study to explore its clinical utility. This NGS assay achieved 100% test specificity and 95-100% test sensitivity for variants with mutant allele frequency (MAF) ≥5% when median read depth ≥ 500×. The orthogonal methods including amplification refractory mutation system (ARMS)-PCR and Sanger sequencing validated that NGS generated three false negatives (FNs) but no false positives (FPs) among 516 clinical samples for KRAS aberration detection. Genomic profiling of Chinese CRC patients with this assay revealed that 63.3% of the tumors harbored clinically actionable alterations. Besides the commonly mutated genes including TP53 (52.82%), KRAS (46.68%), APC (24.09%), PIK3CA (18.94%), SMAD4 (9.47%), BRAF (6.15%), FBXW7 (5.32%), and NRAS (4.15%), other less frequently mutated genes were also identified. Statistically significant association of specific mutated genes with certain clinicopathological features was detected, e.g., both BRAF and PIK3CA were more prevalent in right-side CRC (p < 0.001 and p = 0.002, respectively). We concluded this targeted NGS assay is qualified for clinical practice, and our findings could help the diagnosis and prognosis of Chinese CRC patients.

Detection of EGFR and BRAF mutations by competitive allele-specific TaqMan polymerase chain reaction in lung adenocarcinoma.

Epithelial growth factor receptor (EGFR)-tyrosine kinase inhibitors are the standard first-line treatment for patients with metastatic non-small cell lung cancer (NSCLC) expressing sensitive EGFR-mutants. Other drugs target different driver mutants, including the serine/threonine-protein kinase B-raf (BRAF) inhibitor dabrafenib, which has exhibited promising efficacy for treating patients with metastatic BRAF-mutated NSCLC. Therefore, identifying patients carrying mutations that may be treated using targeted therapies is important. However, the methods of molecular detection presently applied in clinical practice, particularly detection of BRAF in NSCLC patients, require further investigation. Therefore, more sensitive and economic methods are required. The present study applied the competitive allele-specific TaqMan polymerase chain reaction (CastPCR) technology to the molecular detection of EGFR (del2235-2249, del2236-2250, T790M, L858R) and BRAF (V600E, G469A, D594G) mutations in 144 treatment-naive patients with lung adenocarcinoma, and analyzed the association between the mutation rates and patients' clinicopathological features. 51.4% (74/144) cases were identified harboring EGFR mutations. A total of 40.3% (58/144) patients carried sensitizing mutations (exon 19 deletion or L858R) and 14.6% (21/144) carried T790M mutations. 6.9% (10/144) mutation-positive patients were double-mutated. Total EGFR mutation rate was significantly increased in female compared with that of males (60.9 vs. 43.8%, P<0.05), in non-smokers compared with that of smokers (62.8 vs. 34.5%, P<0.05). In total, 8.3% (12/144) patients were identified with BRAF mutations. 16.7% were V600E (2/12) and 83.3% (10/12) were non-V600E mutants. Among the 10 non-V600E mutations, D594G accounted for 90.0% (9/10) and G469A accounted for 10.0% (1/10). Statistical analysis demonstrated that the BRAF mutation rate was not associated with any of the following clinicopathological features: Sex, age, smoking history, clinical stages, distant metastasis, differentiation degree, tumor size and regional lymph node metastasis (P≥0.05). CastPCR technology is a robust method with high sensitivity for the molecular detection of EGFR and BRAF mutations in clinical formalin-fixed paraffin-embedded samples.

Abstract 3983: A cross comparison of technologies for the detection of immune system related gene expression signatures in clinical FFPE samples of metastatic prostate cancer patients

Abstract The success of immunotherapy for the treatment of metastatic cancers relies on the prediction and identification of potential neo-antigens. In recent years expression levels of these neo-antigens along with other immune system related genes have been evaluated in an effort to better understand response rates for immunotherapy in various cancers. Gene expression levels can be assessed by numerous techniques including hybridization-based or direct sequencing technologies. Two platforms-HTG Molecular and NanoString nCounter have been utilized to profile changes in gene expression and offer unique advantages for analyzing challenging specimens such as formalin-fixed paraffin embedded (FFPE) tissues. The NanoString nCounter platform utilizes hybridized fluorescent probes targeted against genes of interest for a non-amplified measurement of gene expression. Several studies have been shown that the NanoString platform has good sensitivity, specificity, and reproducibility for the assessment of gene expression levels from FFPE samples. The HTG platform is relatively new and also uses a hybridization based method to enrich genes of interest without first isolating RNA. To determine the robustness of the HTG platform, we profiled a set of 30 metastatic prostate cancer samples using the HTG Molecular EdgeSeq Immuno-Oncology Assay. In these experiments, we found that expression data obtained by using both extracted RNA and lysate from FFPE slides was highly reproducible (Spearman coefficient &amp;gt; 0.85). In addition, the expression profile of targeted genes obtained by using different slides from the same blocks was also highly correlated (Spearman coefficient &amp;gt; 0.90). Our experiments also showed a high correlation between gene expressions profiles obtained by HTG, the NanoString PanCancer Immune Profiling panel and RNA-Seq from the same set of 30 metastatic prostate cancer samples. Further analysis to evaluate and compare the sensitivity of different platforms is being performed and results of these will be presented. Citation Format: Kimberly Kruse, Fang Yin Lo, Ryan Fleming, Douglas Chung, Vickie Satele, Lindsey Maassel, Tuuli Saloranta, Inah Golez, Saman Tahir, Sally Dow, Evan Anderson, Spencer Chee, Raghavee Venkatramanan, Steve Anderson, Peter S. Nelson, Colm Morrissey, Anup Madan, Sharon Austin, Kellie Howard. A cross comparison of technologies for the detection of immune system related gene expression signatures in clinical FFPE samples of metastatic prostate cancer patients [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 3983. doi:10.1158/1538-7445.AM2017-3983

Adaptation of a RAS pathway activation signature from FF to FFPE tissues in colorectal cancer.

BackgroundThe KRAS gene is mutated in about 40 % of colorectal cancer (CRC) cases, which has been clinically validated as a predictive mutational marker of intrinsic resistance to anti-EGFR inhibitor (EGFRi) therapy. Since nearly 60 % of patients with a wild type KRAS fail to respond to EGFRi combination therapies, there is a need to develop more reliable molecular signatures to better predict response. Here we address the challenge of adapting a gene expression signature predictive of RAS pathway activation, created using fresh frozen (FF) tissues, for use with more widely available formalin fixed paraffin-embedded (FFPE) tissues.MethodsIn this study, we evaluated the translation of an 18-gene RAS pathway signature score from FF to FFPE in 54 CRC cases, using a head-to-head comparison of five technology platforms. FFPE-based technologies included the Affymetrix GeneChip (Affy), NanoString nCounter™ (NanoS), Illumina whole genome RNASeq (RNA-Acc), Illumina targeted RNASeq (t-RNA), and Illumina stranded Total RNA-rRNA-depletion (rRNA).ResultsUsing Affy_FF as the “gold” standard, initial analysis of the 18-gene RAS scores on all 54 samples shows varying pairwise Spearman correlations, with (1) Affy_FFPE (r = 0.233, p = 0.090); (2) NanoS_FFPE (r = 0.608, p < 0.0001); (3) RNA-Acc_FFPE (r = 0.175, p = 0.21); (4) t-RNA_FFPE (r = −0.237, p = 0.085); (5) and t-RNA (r = −0.012, p = 0.93). These results suggest that only NanoString has successful FF to FFPE translation. The subsequent removal of identified “problematic” samples (n = 15) and genes (n = 2) further improves the correlations of Affy_FF with three of the five technologies: Affy_FFPE (r = 0.672, p < 0.0001); NanoS_FFPE (r = 0.738, p < 0.0001); and RNA-Acc_FFPE (r = 0.483, p = 0.002).ConclusionsOf the five technology platforms tested, NanoString technology provides a more faithful translation of the RAS pathway gene expression signature from FF to FFPE than the Affymetrix GeneChip and multiple RNASeq technologies. Moreover, NanoString was the most forgiving technology in the analysis of samples with presumably poor RNA quality. Using this approach, the RAS signature score may now be reasonably applied to FFPE clinical samples.Electronic supplementary materialThe online version of this article (doi:10.1186/s12920-016-0225-2) contains supplementary material, which is available to authorized users.

1174P - Detection of NRAS, KRAS and BRAF mutations in FFPE derived DNA with a novel targeted resequencing-based diagnostics assay

Identification of cancer-associated mutations has become standard care for cancer treatment. Somatic mutations in NRAS, KRAS and BRAF genes are important to decide the treatment options for patients with cancer. Mutations in NRAS, KRAS or BRAF help to determine the treatment options for patients when EGFR inhibitor or BRAF inhibitor treatment is considered. The novel SOMATIC 1 MASTRTM Plus Dx® assay has been developed to allow analysis of the hotspot mutations or of the full coding region of KRAS, NRAS and BRAF genes in combination with Next Generation Sequencing (NGS). To assess the performance characteristics of the SOMATIC 1 MASTRTM Plus Dx® assay, a multicenter study was performed. The performance of SOMATIC 1 MASTR Plus Dx to detect single nucleotide variants (SNV) and small insertions and/or deletions (indels) in the NRAS, KRAS and BRAF genes at a variant allele frequency (VAF) as 5% in the entire coding region and for specific hotspot mutations was evaluated. The sample population comprised 252 formalin-fixed, paraffin-embedded (FFPE) clinical samples derived from a variety of different cancer types and 4 proficiency samples (Tru-Q Reference Standards, Horizon Discovery). Amplicon libraries were analysed using Illumina MiSeq platform. Data analysis was performed with the SeqNext module (JSI Medical Systems) and the Sophia DDM platform (ILL1MR1S5_somatic1_v2). SOMATIC 1 MASTRTM Plus Dx® showed amplification uniformity of 97.8% (% of amplicons covered at 0.2x of the mean coverage) and a target specificity of 99.1%. The overall limit of detection (LOD) of the assay was determined as 2% VAF, and showed to be as low as 1% for hotspot mutations. Diagnostically, the assay showed 99.96% (95 % CI ≥ 99.90 %) accuracy, 99.96% (95 % CI ≥ 99.90 %) specificity and 100% (95 % CI ≥ 98.54 %) sensitivity. Furthermore, Somatic 1 MASTRTM Plus Dx® assay showed to be 99.99% (95 % CI ≥ 99.97 %) repeatable and 99.96% (95 % CI ≥ 99.91%) reproducible. We have established a targeted and cost-effective NGS assay for the detection of KRAS, NRAS, and BRAF somatic mutations in clinical FFPE samples that can be routinely incorporated into clinical practice.

Abstract 3637: Targeted exome and panel analysis from low input and FFPE DNA using hybridization capture for cancer genome studies

Abstract Introduction Hybridization-based target enrichment techniques coupled with Next Generation Sequencing (NGS) provide a useful and cost-efficient means to study disease specific target regions including whole exomes and gene panels. More than 500 whole exome analyses are behind The Cancer Genome Atlas (TCGA), which is the largest knowledge base for cancer studies including research, prevention, treatment, and care. Clinical samples may be limited in input and of compromised quality due to formalin fixation, however most current NGS library preparation methods require 50-100 ng high quality DNA for such studies. Here we present an efficient method which enables high quality target enrichment and variant calling from inputs as low as 1-25 ng. Method NGS libraries for hybridization capture were made from 1 to 100 ng of Coriell Hapmap samples (NA12878, etc), clinical Formalin Fixed Paraffin Embedded (FFPE) and Horizon Discovery (HDx) reference DNA (HDx 701) using the Accel-NGS® 2S Hyb DNA Library Kit. Amplified libraries were then enriched using specific targeted panels (xGen® Pan-Cancer and xGen® AML) or SeqCap™ EZ MedExome using manufacturer's specifications (IDT™ and Roche NimbleGen™). Enriched libraries were captured using streptavidin beads. Captured libraries were then amplified according to the manufacturer's specifications. Targeted panels were sequenced on an Illumina® MiSeq® using V2 chemistry and MedExome on a HiSeq® using V4 chemistry. Sequence analysis was performed with custom pipelines using BWA for alignment and GATK, Samtools, and Freebayes for variant calling. Results Sequencing analyses yielded a minimum average coverage of 30x and more than thirty fold enrichment. Enriched libraries exhibited significant sequence complexity with minimal duplicates and without any base-composition bias. The percent on-target varied with type of input and ranged from 50-80%. Germline variant calling results had &amp;gt; 99% concordance with the NIST GIAB truth list with sensitivity and precision of &amp;gt; 98%, even from inputs as low as 1 ng of DNA. Somatic variant calling down to 1-5% allele frequency was also evaluated at various DNA input quantities and greater depth of sequencing; results for FFPE and DNA standards will be presented. Conclusions Accel-NGS 2S Hyb technology can be used for whole exome and targeted enrichment studies from low quantity and low quality FFPE clinical samples. High complexity libraries with minimal bias yield high quality sequence data which enables discovery and detection of somatic variants in tumor samples to identify molecular drivers associated with different cancer types. The technique facilitates better understanding of complex cancer genomes and guide precision medicine. Citation Format: Sukhinder K. Sandhu, Cassie Schumacher, Laurie Kurihara, Tim Harkins, Vladimir Makarov. Targeted exome and panel analysis from low input and FFPE DNA using hybridization capture for cancer genome studies. [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 3637.