Matched Formalin-fixed Paraffin-embedded Research Articles

Single nucleus DNA sequencing of flow sorted archived frozen and formalin fixed paraffin embedded solid tumors.

Archived samples, including frozen and formalin fixed paraffin embedded (FFPE) tissues, are a vast resource of clinically annotated materials for the application of high-definition genomics to improve patient management and provide a molecular basis for the delivery of personalized cancer therapeutics. Notably, FFPE tissues are stable, provide repeat sampling of tissues of interest, and can be stored indefinitely at ambient temperature. The development of single cell DNA sequencing (scDNA-seq) technologies provides an unparalleled opportunity for the study of tumor heterogeneity and the identification of often rare subclonal cell populations that drive tumor evolution and progression to advanced therapy resistant disease. However, major limitations to the use of archived tissues for scDNA-seq include the low yields of intact cells in the presence of high levels of subcellular debris in biopsies, and the highly variable quantity and quality of the DNA extracted from samples of interest. The latter is of high significance for the use of FFPE tissues due to the presence of DNA-protein crosslinks. In addition, many samples, notably tumors arising in solid tissues, contain admixtures of reactive stroma, inflammatory cells, and necrosis in immediate contact with tumor cells. To expand their use for translational studies, we optimized flow sorting and sequencing of single nuclei from archived fresh frozen (FF) and FFPE tumor tissues. Our methods, which include isolation of intact nuclei suitable for library preparations, quality control (QC) metrics for each step, and a single cell sequencing bioinformatic processing and analysis pipeline, were validated with flow sorted nuclei from matching FF and FFPE ovarian cancer surgical samples and a sequencing panel of 553 amplicons targeting single nucleotide and copy number variants in genes of interest. Our flow sorting based protocol provides intact nuclei suitable for snDNA-seq from archival FF and FFPE tissues. Furthermore, we have developed QC steps that optimize the preparation and selection of samples for deep single cell clonal profiling. Our data processing pipeline captures rare subclones in tumors with highly variable genomes based on variants in genes of interest.

Abstract 5021: Circulating mutated and methylated tumor DNA detection for colorectal cancer diagnosis

Abstract Introduction: Detection of mutation and methylation patterns in liquid biopsies has emerged as a promising approach for screening early-stage cancers. We have developed a targeted next-generation sequencing (NGS)-based assay “OptiSeqTM Colorectal Cancer Detection Panel”, a combined platform for assessing mutation and methylation in both low-quantity (plasma cfDNA) and low-quality formalin-fixed paraffin-embedded (FFPE) tissue for colorectal cancer (CRC) detection. Methods: The OptiSeqTM Colorectal Cancer Detection Panel targets 442 SNVs and 434 CpG sites to detect circulating tumor DNA (ctDNA) in early-stage patients. With this panel, we profiled 6 early-stage and 6 metastatic CRC samples (matching cfDNA and FFPE) along with 2 primary colon specimens with adjacent normal tissue DNA. We also profiled 2 matching cfDNA and FFPE samples from precancerous adenomas (advanced adenomas (AA)) and 6 AA FFPE tissue DNA. In addition, we characterized the mutation and methylation pattern in 10 CRC fresh-frozen tissue DNA samples. For healthy individuals, we profiled 12 normal colon FFPE samples and 10 plasma cfDNA. The clinical performance for the CRC detection panel was calculated using AA, CRC, and cancer-free individuals. Results: For CRC early and metastatic matching cfDNA and FFPE samples, clinical samples testing showed that the CRC detection panel had a sensitivity of 100% (95% CI: 69.8-100.0) and specificity of 100% (95% CI: 81.5-100). For precancerous AA FFPE tissues, combined DNA mutation and methylation increased the CRC detection sensitivity to 100% (95% CI: 51.6-100.0) and specificity to 100% (95% CI: 61.8-100). More clinical samples testing is underway. Conclusion: We have developed the targeted NGS-based panel to detect clinically relevant mutation and methylation patterns and demonstrate its potential using the combined genetic and epigenetic markers making it a highly sensitive assay for early CRC diagnosis. Citation Format: Pushpinder Kaur Bains, Mikhail Kulak, Zhen Cui, Alisha Babu, Stella Tran, Aiguo Zhang, Michael Sha. Circulating mutated and methylated tumor DNA detection for colorectal cancer diagnosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5021.

Abstract 2302: Detection of tumor-associated methylation and mutation signatures for early colorectal cancer diagnosis

Abstract Introduction: The ability to identify epigenetic signatures, together with genetic alterations, has expanded the translational utility of genomic sequencing in clinical settings. Epigenetic changes may appear at very early stages before diagnosis. Thus, they could be used as epigenetic biomarkers for early detection or risk of cancer development. Circulating cell-free DNA (cfDNA) profiling has emerged as a promising biomarker for cancer diagnosis and prognosis. Herein, we developed targeted next-generation sequencing (NGS) based assays for assessing multiple DNA methylated and mutated regions in both low-quantity (plasma cfDNA) and low-quality formalin-fixed paraffin-embedded (FFPE) tissue for colorectal cancer (CRC) detection. Methods: For the OptiSeqTM CRC methylation panel, we assessed the methylation status of CpG dinucleotides in 42 genes. With this panel, we profiled 6 CRC samples (matching cfDNA and FFPE), 2 primary colon tumors with adjacent normal, and 6 advanced adenomas (AA) FFPE tissue DNA. For healthy individuals, we profiled 12 normal colon FFPE samples and 31 plasma cfDNA (26 matching buffy coat DNA samples). For the OptiSeqTM CRC mutation panel, the mutation status was assessed in 43 genes. Here, we profiled 6 CRC samples (matching cfDNA and FFPE), 19 CRC plasma cfDNA, 4 AA FFPE and 42 healthy individuals’ plasma cfDNA (26 matching buffy coat DNA samples). The analytical and clinical performance for both panels (separately and combined) were calculated using advanced adenoma (AA), CRC, and cancer-free individuals. Results: For CRC cfDNA samples, clinical samples testing showed that the methylation panel had a sensitivity of 50% (95% CI: 13.9-86.0) and specificity of 100% (95% CI: 86.2-100) while the mutation panel yielded the sensitivity 88% (95% CI: 67.7-96.8) and specificity 100% (95% CI: 89.5-100). Combining the mutation panel with the methylation panel, the sensitivity increased to 100% (95% CI: 51.6-100) and specificity to 100% (95% CI: 65.1-93.3). For AA FFPE samples, the methylation panel analysis yielded a sensitivity of 100% (95% CI: 39.5-100.0) and a specificity of 100% (95% CI: 67.8-100). Conclusion: We have developed and validated the targeted NGS-based panels to detect clinically relevant mutation and methylation patterns and demonstrate its potential as a highly sensitive assay for early CRC diagnosis. Citation Format: Pushpinder Bains, Mikhail Kulak, Zhen Cui, Alisha Babu, Stella Tran, Bongyong Lee, Aiguo Zhang, Michael Sha. Detection of tumor-associated methylation and mutation signatures for early colorectal cancer diagnosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2302.

Abstract 2347: Metabolomics profiling of formalin-fixed paraffin-embedded prostate tissues

Abstract The metabolic landscape of the prostate changes with malignant transformation, and metabolomics is a means of identifying diagnostic and prognostic biomarkers for prostate cancer. Epidemiology and registry studies containing archival formalin-fixed paraffin-embedded (FFPE) specimens are a rich resource for this work but this method of tissue preservation presents a challenge due to loss of metabolites. We optimized global metabolic profiling in FFPE tissue and identified metabolites distinguishing tumor from normal prostate tissue, and aggressive from non-aggressive prostate cancer. For optimization of metabolomics in FFPE tissues, we obtained matched frozen and FFPE tumor tissue from 62 prostate cancer cases who underwent radical prostatectomy (RP) at the University of North Carolina (UNC) hospital, of which 24 also had adjacent normal prostate tissue. To identify metabolites associated with tumor aggressiveness, we obtained matched tumor and normal FFPE tissue from 60 prostate cancer patients (Gleason ≥4+3, n=30; Gleason ≤3+4, n=30) who underwent RP participating in the UNC Health Registry/Cancer Survivorship Cohort. Following log transformation and imputation of missing values with the minimum observed value for each compound, Welch's two-sample t-test was used to identify biochemicals that differed significantly between groups. Random forest analysis evaluated predictive accuracy of metabolites for distinguishing tumor from normal prostate tissue. We identified 768 compounds of known identity in frozen and 119 in matched FFPE tissues. Therefore, only 15% of the metabolites detected in frozen samples were recovered from corresponding FFPE tissue, with 80% of these common to both FFPE and matched frozen tissues. We found a predictive accuracy of 78% and 67% for frozen and FFPE tissue, respectively, for distinguishing tumor from normal. Of 39 metabolites significantly altered between matched tumor and normal FFPE tissue, 47% belonged to the lipid class, and despite a greater number of significantly altered metabolites in frozen tissue (246), the proportion belonging to the lipid class was similar (50%). Citrate, integral to normal prostate metabolism, and citrulline, involved in nitric oxide synthesis, had significantly lower levels in aggressive versus non-aggressive tumors. Cell membrane phospholipids were found at significantly higher levels in aggressive tumors. Common patterns of altered metabolites in tumor vs. normal prostate were observed irrespective of tissue preservation method, despite loss of a large proportion of metabolites during the process of FFPE. As such, FFPE studies are feasible particularly when lipid metabolism is of interest as this class appears one of the best preserved in FFPE. This work will pave the way for incorporating metabolomics profiling of FFPE specimens into epidemiology and registry-based studies of prostate cancer. Citation Format: Sophia Rachael Halliday, Linnea T. Olsson, Alina Hamilton, Sivapriya Ramamoorthy, Jason Kitchen, Erin Kirk, Laura Farnan, Adrian Gerstel, Melissa A. Troester, Jannette T. Bensen, Sara E. Wobker, Emma Allott. Metabolomics profiling of formalin-fixed paraffin-embedded prostate tissues [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2347.

Comparative analysis of somatic variant calling on matched FF and FFPE WGS samples

BackgroundResearch grade Fresh Frozen (FF) DNA material is not yet routinely collected in clinical practice. Many hospitals, however, collect and store Formalin Fixed Paraffin Embedded (FFPE) tumor samples. Consequently, the sample size of whole genome cancer cohort studies could be increased tremendously by including FFPE samples, although the presence of artefacts might obfuscate the variant calling. To assess whether FFPE material can be used for cohort studies, we performed an in-depth comparison of somatic SNVs called on matching FF and FFPE Whole Genome Sequence (WGS) samples extracted from the same tumor.MethodsFour variant callers (i.e. Strelka2, Mutect2, VarScan2 and Shimmer) were used to call somatic variants on matching FF and FFPE WGS samples from a metastatic prostate tumor. Using the variants identified by these callers, we developed a heuristic to maximize the overlap between the FF and its FFPE counterpart in terms of sensitivity and precision. The proposed variant calling approach was then validated on nine matched primary samples. Finally, we assessed what fraction of the discrepancy could be attributed to intra-tumor heterogeneity (ITH), by comparing the overlap in clonal and subclonal somatic variants.ResultsWe first compared variants between an FF and an FFPE sample from a metastatic prostate tumor, showing that on average 50% of the calls in the FF are recovered in the FFPE sample, with notable differences between callers. Combining the variants of the different callers using a simple heuristic, increases both the precision and the sensitivity of the variant calling. Validating the heuristic on nine additional matched FF-FFPE samples, resulted in an average F1-score of 0.58 and an outperformance of any of the individual callers. In addition, we could show that part of the discrepancy between the FF and the FFPE samples can be attributed to ITH.ConclusionThis study illustrates that when using the correct variant calling strategy, the majority of clonal SNVs can be recovered in an FFPE sample with high precision and sensitivity. These results suggest that somatic variants derived from WGS of FFPE material can be used in cohort studies.

The impact of RNA extraction method on accurate RNA sequencing from formalin-fixed paraffin-embedded tissues

BackgroundUtilization of RNA sequencing methods to measure gene expression from archival formalin-fixed paraffin-embedded (FFPE) tumor samples in translational research and clinical trials requires reliable interpretation of the impact of pre-analytical variables on the data obtained, particularly the methods used to preserve samples and to purify RNA.MethodsMatched tissue samples from 12 breast cancers were fresh frozen (FF) and preserved in RNAlater or fixed in formalin and processed as FFPE tissue. Total RNA was extracted and purified from FF samples using the Qiagen RNeasy kit, and in duplicate from FFPE tissue sections using three different kits (Norgen, Qiagen and Roche). All RNA samples underwent whole transcriptome RNA sequencing (wtRNAseq) and targeted RNA sequencing for 31 transcripts included in a signature of sensitivity to endocrine therapy. We assessed the effect of RNA extraction kit on the reliability of gene expression levels using linear mixed-effects model analysis, concordance correlation coefficient (CCC) and differential analysis. All protein-coding genes in the wtRNAseq and three gene expression signatures for breast cancer were assessed for concordance.ResultsDespite variable quality of the RNA extracted from FFPE samples by different kits, all had similar concordance of overall gene expression from wtRNAseq between matched FF and FFPE samples (median CCC 0.63–0.66) and between technical replicates (median expression difference 0.13–0.22). More than half of genes were differentially expressed between FF and FFPE, but with low fold change (median |LFC| 0.31–0.34). Two out of three breast cancer signatures studied were highly robust in all samples using any kit, whereas the third signature was similarly discordant irrespective of the kit used. The targeted RNAseq assay was concordant between FFPE and FF samples using any of the kits (CCC 0.91–0.96).ConclusionsThe selection of kit to purify RNA from FFPE did not influence the overall quality of results from wtRNAseq, thus variable reproducibility of gene signatures probably relates to the reliability of individual gene selected and possibly to the algorithm. Targeted RNAseq showed promising performance for clinical deployment of quantitative assays in breast cancer from FFPE samples, although numerical scores were not identical to those from wtRNAseq and would require calibration.

Feasibility of developing reliable gene expression modules from FFPE derived RNA profiled on Affymetrix arrays.

The reliability of differential gene expression analysis on formalin-fixed, paraffin-embedded (FFPE) expression profiles generated using Affymetrix arrays is questionable, due to the high range of percent-present values reported in studies which profiled FFPE samples using this technology. Moreover, the validity of gene-modules derived from external datasets in FFPE microarray expression profiles is unknown. By generating matched gene expression profiles using RNAs derived from fresh-frozen (FF) and FFPE preserved breast tumors with Affymetrix arrays and FF/FFPE RNA specific amplification-and-labeling kits, the reliability of differential expression analysis and the validity of gene modules derived from external datasets were investigated. Specifically, the reliability of differential expression analysis was investigated by developing de-novo ER/HER2 pathway gene-modules from the matched datasets and validating them on external FF/FFPE gene expression datasets using ROC analysis. Spearman's rank correlation coefficient of module scores between matched FFPE/frozen datasets was used to measure the reliability of gene-modules derived from external datasets in FFPE expression profiles. Independent of the array/amplification-kit/sample preservation method used, de-novo ER/HER2 gene-modules derived from all matched datasets showed similar prediction performance in the independent validation (AUC range in FFPE dataset; ER: 0.93–0.95, HER2: 0.85–0.91), except for the de-novo ER/HER2 gene-module derived from the FFPE dataset using the 3'IVT kit (AUC range in FFPE dataset; ER: 0.79–0.81, HER2: 0.78). Among the external gene modules considered, roughly ~50% gene modules showed high concordance between expression profiles derived from matching FF and FFPE RNA. The remaining discordant gene modules between FF and FFPE expression profiles showed high concordance within matching FF datasets and within matching FFPE datasets independently, implying that microarrays still require improved amplification-and-sample-preparation protocols for deriving 100% concordant expression profiles from matching FF and FFPE RNA.

Validation of the Complexity INdex in SARComas prognostic signature on formalin-fixed, paraffin-embedded, soft-tissue sarcomas

BackgroundPrediction of metastatic outcome in sarcomas is challenging for clinical management since they are aggressive and carry a high metastatic risk. A 67-gene expression signature, the Complexity INdex in SARComas (CINSARC), has been identified as a better prognostic factor than the reference pathological grade. Since it cannot be applied easily in standard laboratory practice, we assessed its prognostic value using nanoString on formalin-fixed, paraffin-embedded (FFPE) blocks to evaluate its potential in clinical routine practice and guided therapeutic management. MethodsA code set consisting of 67 probes derived from the 67 genes of the CINSARC signature was built and named NanoCind®. To compare the performance of RNA-seq and nanoString (NanoCind®), we used expressions of various sarcomas (n=124, frozen samples) using both techniques and compared predictive values based on CINSARC risk groups and clinical annotations. We also used nanoString on FFPE blocks (n=67) and matching frozen and FFPE samples (n=45) to compare their level of agreement. Metastasis-free survival and agreement values in classification groups were evaluated. ResultsCINSARC strongly predicted metastatic outcome using nanoString on frozen samples (HR=2.9, 95% CI: 1.23–6.82) with similar risk-group classifications (86%). While more than 50% of FFPE blocks were not analyzable by RNA-seq owing to poor RNA quality, all samples were analyzable with nanoString. When similar (risk-group) classifications were measured with frozen tumors (RNA-seq) compared with FFPE blocks (84% agreement), the CINSARC signature was still a predictive factor of metastatic outcome with nanoString on FFPE samples (HR=4.43, 95% CI: 1.25–15.72). ConclusionCINSARC is a material-independent prognostic signature for metastatic outcome in sarcomas and outperforms histological grade. Unlike RNA-seq, nanoString is not influenced by the poor quality of RNA extracted from FFPE blocks. The CINSARC signature can potentially be used in combination with nanoString (NanoCind®) in routine clinical practice on FFPE blocks to predict metastatic outcome.

Utility of bronchial lavage fluids for epithelial growth factor receptor mutation assay in lung cancer patients: Comparison between cell pellets, cell blocks and matching tissue specimens.

The detection of epidermal growth factor receptor (EGFR) mutations is necessary for the selection of suitable patients with non-small cell lung cancer (NSCLC) for treatment with EGFR tyrosine kinase inhibitors. Cytology specimens are known to be suitable for EGFR mutation detection, although tissue specimens should be prioritized; however, there are limited studies that examine the utility of bronchial lavage fluid (BLF) in mutation detection. The purpose of the present study was to investigate the utility of BLF specimens for the detection of EGFR mutations using a conventional quantitative EGFR polymerase chain reaction (PCR) assay. Initially, quantification cycle (Cq) values of cell pellets, cell-free supernatants and cell blocks obtained from three series of 1% EGFR mutation-positive lung cancer cell line samples were compared for mutation detection. In addition, PCR analysis of BLF specimens obtained from 77 consecutive NSCLC patients, detecting EGFR mutations was validated, and these results were compared with those for the corresponding formalin-fixed paraffin-embedded (FFPE) tissue specimens obtained by surgical resection or biopsy of 49 of these patients. The Cq values for mutation detection were significantly lower in the cell pellet group (average, 29.58) compared with the other groups, followed by those in cell-free supernatants (average, 34.15) and in cell blocks (average, 37.12) for all three series (P<0.05). Mutational status was successfully analyzed in 77 BLF specimens, and the results obtained were concordant with those of the 49 matching FFPE tissue specimens. Notably, EGFR mutations were even detected in 10 cytological specimens that contained insufficient tumor cells. EGFR mutation testing with BLF specimens is therefore a useful and reliable method, particularly when sufficient cancer cells are not obtained.

Abstract 2714: Analytical validation of clinical whole genome and transcriptome sequencing of patient derived tumors: clinical application of whole genome sequencing for reporting targetable variants in cancer

Abstract Next Generation DNA Sequencing (NGS) technologies are currently being applied in the clinical setting for the treatment of disease. The goal is to use high-throughput sequencing to identify specific variants within each tumor and recommend personalized treatment approaches or clinical trials tailored to the individual’s disease and genomic profile. These assays are comprised of either predefined sequencing panels, where a handpicked set of clinically significant genes are examined within each patient, or are cancer type specific targeted sequencing protocols or whole exome platforms covering only the coding region of the patient’s genome. Whole genome sequencing allows hypothesis-free interrogation of both coding and non-coding regions of the genome revealing more potential therapeutic options than examining a small set of genes or genomic loci. The protocol eliminates sequence capture related bias observed in whole exome or panel sequencing. The New York Genome Center therefore has performed analytical validation of whole genome and transcriptome sequencing (WGTS) of patient derived tumors and matched normals for the purposes of clinical testing and have devised a clinical reporting strategy of significant driver and therapeutic associated mutations. Many clinical NGS guidelines are directed toward targeted panel or exome sequencing validation. Here, we expanded on New York State’s Department of Health NGS guidelines developing them into novel standards applicable to WGTS for the purposes of clinical test validation. We first sequenced a virtual tumor at very high coverage (300x) and downsampled to determine the optimum depth of sequencing necessary for high confidence somatic variant calling across the entire genome. We then validated whole genome sequencing laboratory protocols for DNA and RNA sequencing on a total of 50 specimens derived from fresh frozen (FF) and formalin-fixed paraffin-embedded (FFPE) tumor samples. We performed a series of experiments to assess the accuracy and reliability of the results based on our laboratory and bioinformatics protocols. We performed our validation on the 50 tumor normal pairs, a subset of which had known genomic profiles. Comparisons were also made for variant calling concordance and reproducibility between matched FF and FFPE tumors. Here, we present our validation results and clinical WGTS standards for depth of sequencing, reproducibility, sensitivity, and present limit of detection analysis for SNV calling, copy number identification and structural variants. RNA sequencing is performed to call fusion or exon skipping events and to confirm the DNA variants. The New York Genome Center WGTS clinical assay is intended to provide a more comprehensive patient variant discovery approach suitable for directed oncological therapeutic applications. Citation Format: Kazimierz O. Wrzeszczynski, Avinash Abhyankar, Vanessa Felice, Esra Dikoglu, Lukasz Kozon, Nicolas Robine, Anne-Katrin Emde, Olca Basturk, Umesh K. Bhanot, Alex Kentsis, Mahesh Mansukhani, Govind Bhagat, Vaidehi Jobanputra. Analytical validation of clinical whole genome and transcriptome sequencing of patient derived tumors: clinical application of whole genome sequencing for reporting targetable variants in cancer [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 2714. doi:10.1158/1538-7445.AM2017-2714

Abstract 4281: Targeted or whole genome sequencing of formalin-fixed tissue samples

Abstract Background: To provide a systematic analysis of formalin fixation artifacts on Illumina sequencing libraries and results, we generated two complementary sequencing libraries (target enrichment sequencing and whole exome sequencing) from 11 pairs of matched formalin-fixed paraffin-embedded (FFPE) and fresh-frozen (FF) tumor samples and two pairs of matched FFPE and FF germline samples. We also generated whole genome sequencing data from a single pair of FF/FFPE tumor samples. Results: The results indicate minimal variations in library fragment size, coverage, and PCR duplicates within FF/FFPE paired samples that are less than 1 year old; whereas, a large variation in these parameters were observed in FF/FFPE pairs in samples that are approximately 2 years old. No significant increase in global mismatch rates and C•G&amp;gt;T•A substitutions were observed in FFPE samples from the former group; whereas, a discernible increase in mismatch rates and C•G&amp;gt;T•A substitutions were observed in FFPE samples from the latter group. However, over 99.7% and 99.5% of concordant calls were observed between matched FF and FFPE pairs at reference and non-reference positions within the targeted regions, respectively. Although an increased rate of global mismatches and C•G&amp;gt;T•A substitutions were observed in some FFPE samples, discordant rates were low (&amp;lt;0.26) in all samples because most of the FFPE artifacts were filtered out using GATK workflow. Consistent with this analysis, C•G&amp;gt;T•A substitutions are comparable in non-reference positions in paired FF and FFPE samples. Conclusions: We developed upfront quality assessment and library preparation method that use low input DNA from FFPE samples to perform next-generation sequencing. The results from our studies indicate the suitability of FFPE samples in sequencing studies. Citation Format: Sarah Munchel, Yen Hoang, Yue Zhao, Joseph Cottrell, Brandy Klotzle, Andrew Godwin, Janelle Noel, Brooke Fridley, Peter Beyerlein, Jian-Bing Fan, Marina Bibikova, Jeremy R. Chien. Targeted or whole genome sequencing of formalin-fixed tissue samples. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4281. doi:10.1158/1538-7445.AM2014-4281

Formalin-fixed paraffin-embedded tissue as a source for quantitation of carcinogen DNA adducts: aristolochic acid as a prototype carcinogen.

DNA adducts are a measure of internal exposure to genotoxicants. However, the measurement of DNA adducts in molecular epidemiology studies often is precluded by the lack of fresh tissue. In contrast, formalin-fixed paraffin-embedded (FFPE) tissues frequently are accessible, although technical challenges remain in retrieval of high quality DNA suitable for biomonitoring of adducts. Aristolochic acids (AA) are human carcinogens found in Aristolochia plants, some of which have been used in the preparation of traditional Chinese herbal medicines. We previously established a method to measure DNA adducts of AA in FFPE tissue. In this study, we examine additional features of formalin fixation that could impact the quantity and quality of DNA and report on the recovery of AA-DNA adducts in mice exposed to AA. The yield of DNA isolated from tissues fixed with formalin decreased over 1 week; however, the levels of AA-DNA adducts were similar to those in fresh frozen tissue. Moreover, DNA from FFPE tissue served as a template for PCR amplification, yielding sequence data of comparable quality to DNA obtained from fresh frozen tissue. The estimates of AA-DNA adducts measured in freshly frozen tissue and matching FFPE tissue blocks of human kidney stored for 9 years showed good concordance. Thus, DNA isolated from FFPE tissues may be used to biomonitor DNA adducts and to amplify genes used for mutational analysis, providing clues regarding the origin of human cancers for which an environmental cause is suspected.

Abstract LB-398: Detection of copy number alterations in 124 head and neck squamous cell carcinomas using the Nanostring nCounter assay

Abstract Background: Head and Neck Squamous Cell Carcinoma (HNSCC) is the 6th most common cancer worldwide. Little is known about changes in copy number (CN) in many cancer associated genes in this tumor type, which may contribute to carcinogenesis and could become useful treatment targets in the future. Many analyses of CN are complicated by the need to use formalin-fixed paraffin-embedded (FFPE) tissues posing technical challenges. We determined copy number alterations (CNA) using a novel, medium-throughput technology (NanoString nCounter) in order to determine common cancer associated CNAs and assess its performance in FFPE tissues. Results were compared with more established technologies such as SNP array, aCGH, and qPCR. Methods: We investigated CNA in 124 tumor specimens and 22 cell lines for 100 literature curated cancer genes using the NanoString nCounter. Most samples were OCT frozen tissues, with a small subset having both OCT frozen, and FFPE tissues. Slides were assessed for tumor content by a HNC pathologist and samples with at least 60% tumor content selected. DNA was extracted using standard column-based methods (Qiagen). We performed CN analysis in 124 frozen (+4 matching FFPE) HNSCC specimens and cell lines (Nanostring nCounter assay) focusing on a selection of cancer associated genes. Furthermore we used aCGH and SNP-CHIP to analyse 20 and 4 cell lines respectively two of which were covered by all three methods. FGFR1 was assessed by qPCR. For FFPE samples a special Nanostring probeset was used with 3-5 probes per gene to provide redundancy with degraded DNA samples. HPV status of samples was assessed by a nested PCR for E6. Results Copy number changes detected by Nanostring and aCGH correlated well. The Nanostring nCounter assay appeared more accurate in calling deletions, which were detected in MST1R, PBRM1, PTPRD for instance. We found amplifications in multiple samples and genes, e.g. CCND1, EGFR, MDM4, MYC, VEGFA, PAX9, ITGB4, SSND1, CTTN, FADD, FGF19, ORAOV1, PPFIA1, some of which were frequently (n&amp;gt;50 samples) or highly amplified (&amp;gt;30 copies). Some of these amplifications such as ORAOV1 and PPFIA1 seemed higher/more frequent in HPV(-) compared to HPV(+) samples. Samples with FGFR1 amplification were validated using qPCR and correlated very closely. FFPE sample processing was uncomplicated using the FFPE probeset. While some probes failed, using degraded FFPE derived DNA, the redundancy of probes allowed accurate calling of CNA that closely correlated with frozen sample results. Conclusions Copy number alterations are frequent in HNSCC and involve many cancer associated genes, including potentially targetable genes such as EGFR, MDM4, and PIK3CA. Most of the CN changes are recurrent. Amplifications and deletions to some extent differed depending on HPV status. The role and implications of these CN aberrations in a clinical setting need to be further elucidated and validated. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-398. doi:1538-7445.AM2012-LB-398

Establishment of a standardized gene-expression analysis system using formalin-fixed, paraffin-embedded, breast cancer specimens

It has recently being emphasized that gene-expression profiles are important clinical decision-making tools, and as such must be standardized across hospital laboratories in the same way as pathological investigations. In this study our objective was to independently establish a standardized gene-expression assay system using routinely processed, formalin-fixed, paraffin-embedded (FFPE) tissues. To verify gene expression by quantitative real-time polymerase chain reaction, the most stably expressed reference genes were explored using 30 matched FFPE and fresh frozen (FF) tissues. FFPE specimens from 290 female breast cancer patients were used for further RNA extraction; ESR1 and PGR were measured using 203 matched FFPE and FF specimens and normalized to these reference genes. RNA extracted from FFPE specimens was highly degraded, but almost the same selection of genes was identified-TAF, PUM1, and ACTB, and, for FFPE specimens only, FKBP15. Eventually 88.6% of all the FFPE samples were identified as quantitatively and qualitatively adequate for downstream analysis. The results revealed good correlation and excellent concordance with ERα and PgR protein expression evaluated by immunohistochemistry. Moreover, the distribution of ESR1 and PGR gene expression values was quite reasonable, reflecting differences between the transcriptional mechanisms of the respective genes. We successfully confirmed that our gene-expression analysis system provides good quality control for larger scale assays; it may therefore be suitable for development, in the near future, of a multiple gene assay as a routine clinical judgment tool.

Accurate Classification of Diffuse Large B-Cell Lymphoma into Germinal Center and Activated B-Cell Subtypes Using a Nuclease Protection Assay on Formalin-Fixed, Paraffin-Embedded Tissues

Classification of diffuse large B-cell lymphoma (DLBCL) into cell-of-origin (COO) subtypes based on gene expression profiles has well-established prognostic value. These subtypes, termed germinal center B cell (GCB) and activated B cell (ABC) also have different genetic alterations and overexpression of different pathways that may serve as therapeutic targets. Thus, accurate classification is essential for analysis of clinical trial results and planning new trials by using targeted agents. The current standard for COO classification uses gene expression profiling (GEP) of snap frozen tissues, and a Bayesian predictor algorithm. However, this is generally not feasible. In this study, we investigated whether the qNPA technique could be used for accurate classification of COO by using formalin-fixed, paraffin-embedded (FFPE) tissues. We analyzed expression levels of 14 genes in 121 cases of R-CHOP-treated DLBCL that had previously undergone GEP by using the Affymetrix U133 Plus 2.0 microarray and had matching FFPE blocks. Results were evaluated by using the previously published algorithm with a leave-one-out cross-validation approach. These results were compared with COO classification based on frozen tissue GEP profiles. For each case, a probability statistic was generated indicating the likelihood that the classification by using qNPA was accurate. When data were dichotomized into GCB or non-GCB, overall accuracy was 92%. The qNPA technique accurately categorized DLBCL into GCB and ABC subtypes, as defined by GEP. This approach is quantifiable, applicable to FFPE tissues with no technical failures, and has potential for significant impact on DLBCL research and clinical trial development.

Abstract 3072: Prospective study of genetic mutations in matched tumor and plasma specimens in advanced cancer patients referred to phase I trials

Abstract Background: Circulating free DNA (cfDNA) represents a minimally-invasive resource for detecting mutations in advanced cancer patients. The primary objective of this study was to determine if cfDNA is representative of tumor tissue for multiplex mutation detection utilizing Sequenom MassARRAY. Methods: Metastatic colorectal, breast, melanoma and ovary cancer patients referred to the Drug Development Unit at the Royal Marsden Hospital between 9/09-8/10 gave their consent to provide DNA from matched archival formalin fixed paraffin embedded (FFPE) tumor and plasma. Samples mutation genotyping using the Sequenom MassARRAY technology and the OncoCartaTM Panel allowed the parallel analysis of 238 simple and complex mutations across 19 selected key oncogenes. Dilutions (10ng/µl to 0.01ng/µl) of HCT116 DNA containing KRAS G13D mutation were used to determine assay sensitivity and specificity. Results: Serial dilution spiking experiments revealed that the KRAS G13D mutation was reproducibly detectable to 40ng/ml of HCT116 DNA; 74 patient samples were then analyzed. The median quantity of cfDNA was 305ng/ml (range 10-32000). Of the 25 colorectal patients, the median quantity of cfDNA was 361ng/ml (range 189-4603); KRAS, BRAF and PIK3CA mutations were detected in 8 (31%), 3 (12%) and 3 (12%) tumor specimens respectively; concordant data for matched plasma tumor DNA was found in 88% of patients for KRAS, 100% for BRAF mutations and 33% for PIK3CA (1 patient had a PIK3CA mutation in primary and plasma; one patient had a mutation detected only in the primary; one patient had no mutation in the primary or plasma, but a mutation detected in a metastatic liver deposit). The recently reported oncogenic AKT1 E17K mutation was detected in 1 colorectal patient in tissue and plasma. Of the 19 breast cancer patients, the median cfDNA concentration was 354ng/ml (range 10-32000); PIK3CA H1047R mutation was detected in 4 (21%) FFPE tumor specimens; concordance between matched FFPE and cfDNA was 75% (3 out of 4 patients). The AKT1 E17K mutation was detected in 1 patient in both tissue and plasma. In 15 melanoma patients the median cfDNA concentration was 141ng/ml (range 46-1002); BRAF V600E, NRAS codon 61 and MET R970C mutations were detected in 4 (27%), 3 (20%) and 1 (7%) FFPE tumor specimens respectively. Concordance between matched FFPE and cfDNA was 50% for BRAF, 75% for NRAS and 100% for MET mutations. Another MET mutation, T992I, was found in plasma but not in tissue for one patient. Of the 15 ovary patients, the median cfDNA concentration was 261ng/ml (range 79-957). Two KRAS mutations and 1 PIK3CA H1047R mutation were detected in FFPE, but no mutation was found in any plasma sample. Conclusions: A high concordance in detected mutations was observed between FFPE tumor and matched cfDNA. cfDNA is representative of tumor DNA and may be used for the prospective selection of cancer patients for targeted therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3072. doi:10.1158/1538-7445.AM2011-3072

Prospective study of genetic mutations in matched tumor and plasma specimens in colorectal cancer patients.

356 Background: Circulating free DNA (cfDNA) represents a minimally-invasive resource for detecting mutations in advanced cancer patients. The primary objective of this study was to determine if cfDNA is representative of tumor tissue for multiplex mutation detection utilizing Sequenom MassARRAY. Methods: Samples were spiked with dilutions (10ng/μl to 0.01ng/μl) of HCT116 DNA containing KRAS G13D mutations to determine assay sensitivity and specificity. Metastatic colorectal cancer patients referred to the Drug Development Unit at the Royal Marsden Hospital between 9/09-8/10 gave their consent to provide DNA from matched archival formalin fixed paraffin-embedded (FFPE) tumor and plasma. Samples had ∼200 described gene mutations genotyped using Sequenom MassARRAY (OncoCarta Panel). Results: Serial dilution spiking experiments revealed that the KRAS G13D mutation was reproducibly detectable to 40ng/mL of HCT116 DNA; 26 patient samples were then analyzed. KRAS, BRAF and PIK3CA mutations were detected in 8 (31%), 3 (12%) and 3 (12%) tumor specimens respectively; 100% concordance for KRAS status was observed between multiple FFPE biopsies from the same patient and analysis by Amplification Refractory Mutation System (ARMS)-Scorpion PCR. The median quantity of cfDNA was 353ng/ml (range 106-4603). Concordance between matched FFPE and cfDNA was 88% for KRAS and 100% for BRAF mutations. No patients with wildtype KRAS or BRAF tumor genotypes had mutations in their respective cfDNA confirming the high specificity of cfDNA analysis. Three patients had detectable PIK3CA mutations; 1 patient had a E346K mutation detected in both FFPE tissue and plasma; 1 patient had E545K detected only in FFPE and the other had E542K detected in a liver metastasis but not in the colorectal primary or plasma. The recently reported oncogenic AKT1 E17K mutation was detected in 1 patient in tissue and plasma. No mutations in any of the other tested oncogenes studied were detected. Conclusions: A high concordance in detected mutations was observed between FFPE tumor and matched cfDNA. cfDNA is representative of tumor DNA and may be used for the prospective selection of cancer patients for treatment with targeted therapeutics. No significant financial relationships to disclose.

Whole-Genome Gene Expression Profiling of Formalin-Fixed, Paraffin-Embedded Tissue Samples

BackgroundWe have developed a gene expression assay (Whole-Genome DASL®), capable of generating whole-genome gene expression profiles from degraded samples such as formalin-fixed, paraffin-embedded (FFPE) specimens.Methodology/Principal FindingsWe demonstrated a similar level of sensitivity in gene detection between matched fresh-frozen (FF) and FFPE samples, with the number and overlap of probes detected in the FFPE samples being approximately 88% and 95% of that in the corresponding FF samples, respectively; 74% of the differentially expressed probes overlapped between the FF and FFPE pairs. The WG-DASL assay is also able to detect 1.3–1.5 and 1.5–2 -fold changes in intact and FFPE samples, respectively. The dynamic range for the assay is ∼3 logs. Comparing the WG-DASL assay with an in vitro transcription-based labeling method yielded fold-change correlations of R2 ∼0.83, while fold-change comparisons with quantitative RT-PCR assays yielded R2∼0.86 and R2∼0.55 for intact and FFPE samples, respectively. Additionally, the WG-DASL assay yielded high self-correlations (R2>0.98) with low intact RNA inputs ranging from 1 ng to 100 ng; reproducible expression profiles were also obtained with 250 pg total RNA (R2∼0.92), with ∼71% of the probes detected in 100 ng total RNA also detected at the 250 pg level. When FFPE samples were assayed, 1 ng total RNA yielded self-correlations of R2∼0.80, while still maintaining a correlation of R2∼0.75 with standard FFPE inputs (200 ng).Conclusions/SignificanceTaken together, these results show that WG-DASL assay provides a reliable platform for genome-wide expression profiling in archived materials. It also possesses utility within clinical settings where only limited quantities of samples may be available (e.g. microdissected material) or when minimally invasive procedures are performed (e.g. biopsied specimens).

Accurate Classification of Diffuse Large B Cell Lymphoma Into Germinal Center and Activated B Cell Subtypes Using a Nuclease Protection Assay On Formalin Fixed Paraffin Embedded Tissue: A Study From the Lymphoma and Leukemia Molecular Profiling Project.

Abstract 620Classification of DLBCL into cell-of-origin (COO) subtypes based on gene expression profiles has well-established prognostic value. These subtypes, termed Germinal Center B cell (GCB) and Activated B cell (ABC) also have different genetic alterations and over-expression of different pathways that may serve as therapeutic targets. Thus, accurate classification is essential for analysis of clinical trial results and planning new trials using targeted agents. The gold standard for COO classification uses gene expression profiling (GEP) of snap frozen tissues, and a Bayesian predictor algorithm utilizing the expression levels of 14 key genes (G. Wright et al PNAS 2003). An immunohistochemistry (IHC) classification scheme by C. Hans et al (Blood 2004), based on 3 antibodies, is widely used as a substitute for GEP classification, however does not completely correlate with GEP. We recently described a qNPA assay (ArrayPlateR, High ThroughPut Genomics, Tucson, AZ) with excellent correlation between frozen and formalin fixed paraffin embedded (FFPE) tissues (R. Roberts et al, Lab Invest 2007). In this study, we investigated whether this technique could be used for accurate classification of COO using FFPE tissues. We expanded the previous gene probe repertoire of the DLBCL-ArrayPlateR assay to include the 14 genes (represented by 17 probe sets) most pertinent to COO classification. 52 cases of R-CHOP treated DLBCL that had undergone GEP using the Affymetrix U133 Plus 2.0 microarray and had matching FFPE blocks were analyzed with qNPA in duplicate. The genes included CD10, LRMP, CCND2, ITPKB, PIM1, IL16, IRF4, FUT8, BCL6, PTPN1, LM02, CD39, MYBL1, IGHM. Results were evaluated using the previously published algorithm with a leave-one-out cross validation scheme to classify cases into GCB or ABC subtypes. These results were compared to COO classification based on frozen tissue GEP profiles. All 14 genes in all 52 cases were successfully analyzed with no missing data points. For each case, a probability statistic was generated indicating the likelihood that the classification using qNPA was accurate. Of the 54 cases, 25 were GCB, 27 were ABC and 4 were unclassifiable by GEP. Of the GCB cases, 23/25 (92%) were classified correctly by qNPA with a confidence cut-off of >0.9 and 25/25 (100%) classified correctly with a confidence cut-off of >0.8. Of the ABC cases, 25/27 (93%) were correctly classified as ABC using qNPA with a confidence cut-off of >0.9 and 27/27 (100%) classified correctly with a confidence cut-off of >0.8. In summary, the qNPA technique accurately categorized DLBCL into GCB and ABC subtypes, as defined by GEP. There were no technical difficulties with any of the pathological materials although they were collected retrospectively from a variety of institutions and countries with different fixation methods. This approach represents a substantial improvement over previously published IHC methods and is applicable to FFPE tissues, therefore overcoming the need for snap frozen materials. This technically robust classification method has potential to have a significant impact on future DLBCL research and clinical trial development. Disclosures:Rimsza:High Throughput Genomics: HTG provided the assays at no charge to Dr. Rimsza's lab. Schwartz:High Throughput Genomics: Employment. Gascoyne:Roche Canada: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Microarray analysis of RNA extracted from formalin-fixed, paraffin-embedded and matched fresh-frozen ovarian adenocarcinomas

BackgroundGene expression profiling of formalin-fixed, paraffin-embedded (FFPE) samples represents a valuable approach for advancing oncology diagnostics and enhancing retrospective clinical studies; however, at present, this methodology still requires optimization and thus has not been extensively used. Here, we utilized thorough quality control methods to assess RNA extracted from FFPE samples and then compared it to RNA extracted from matched fresh-frozen (FF) counterparts. We preformed genome-wide expression profiling of FF and FFPE ovarian serous adenocarcinoma sample pairs and compared their gene signatures to normal ovary samples.MethodsRNA from FFPE samples was extracted using two different methods, Ambion and Agencourt, and its quality was determined by profiling starting total RNA on Bioanalyzer and by amplifying increasing size fragments of beta actin (ACTB) and claudin 3 (CLDN3) by reverse-transcriptase polymerase chain reaction. Five matched FF and FFPE ovarian serous adenocarcinoma samples, as well as a set of normal ovary samples, were profiled using whole genome Agilent microarrays. Reproducibility of the FF and FFPE replicates was measured using Pearson correlation, whereas comparison between the FF and FFPE samples was done using a Z-score analysis.ResultsData analysis showed high reproducibility of expression within each FF and FFPE method, whereas matched FF and FFPE pairs demonstrated lower similarity, emphasizing an inherent difference between the two sample types. Z-score analysis of matched FF and FFPE samples revealed good concordance of top 100 differentially expressed genes with the highest correlation of 0.84. Genes characteristic of ovarian serous adenocarcinoma, including a well known marker CLDN3, as well as potentially some novel markers, were identified by comparing gene expression profiles of ovarian adenocarcinoma to those of normal ovary.ConclusionConclusively, we showed that systematic assessment of FFPE samples at the RNA level is essential for obtaining good quality gene expression microarray data. We also demonstrated that profiling of not only FF but also of FFPE samples can be successfully used to identify differentially expressed genes characteristic of ovarian carcinoma.