scholarly journals Clinical advantage of targeted sequencing for unbiased tumor mutational burden estimation in samples with low tumor purity

2020 ◽  
Vol 8 (2) ◽  
pp. e001199
Author(s):  
Tae Hee Hong ◽  
Hongui Cha ◽  
Joon Ho Shim ◽  
Boram Lee ◽  
Jongsuk Chung ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Predictive Ability ◽  
Progression Free Survival ◽  
Superior Performance ◽  
Enhanced Sensitivity ◽  
Mutational Burden ◽  
Tumor Purity ◽  
Whole Exome ◽  
Tumor Mutational Burden

BackgroundTumor mutational burden (TMB) measurement is limited by low tumor purity of samples, which can influence prediction of the immunotherapy response, particularly when using whole-exome sequencing-based TMB (wTMB). This issue could be overcome by targeted panel sequencing-based TMB (pTMB) with higher depth of coverage, which remains unexplored.MethodsWe comprehensively reanalyzed four public datasets of immune checkpoint inhibitor (ICI)-treated cohorts (adopting pTMB or wTMB) to test each biomarker’s predictive ability for low purity samples (cut-off: 30%). For validation, paired genomic profiling with the same tumor specimens was performed to directly compare wTMB and pTMB in patients with breast cancer (paired-BRCA, n=165) and ICI-treated patients with advanced non-small-cell lung cancer (paired-NSCLC, n=156).ResultsLow tumor purity was common (range 30%–45%) in real-world samples from ICI-treated patients. In the survival analyzes of public cohorts, wTMB could not predict the clinical benefit of immunotherapy when tumor purity was low (log-rank p=0.874), whereas pTMB could effectively stratify the survival outcome (log-rank p=0.020). In the paired-BRCA and paired-NSCLC cohorts, pTMB was less affected by tumor purity, with significantly more somatic variants identified at low allele frequency (p<0.001). We found that wTMB was significantly underestimated in low purity samples with a large proportion of clonal variants undetected by whole-exome sequencing. Interestingly, pTMB more accurately predicted progression-free survival (PFS) after immunotherapy than wTMB owing to its superior performance in the low tumor purity subgroup (p=0.054 vs p=0.358). Multivariate analysis revealed pTMB (p=0.016), but not wTMB (p=0.32), as an independent predictor of PFS even in low-purity samples. The net reclassification index using pTMB was 21.7% in the low-purity subgroup (p=0.016).ConclusionsOur data suggest that TMB characterization with targeted deep sequencing might have potential strength in predicting ICI responsiveness due to its enhanced sensitivity for hard-to-detect variants at low-allele fraction. Therefore, pTMB could act as an invaluable biomarker in the setting of both clinical trials and practice outside of trials based on its reliable performance in mitigating the purity-related bias.

scholarly journals Analysis of tumor mutational burden: correlation of five large gene panels with whole exome sequencing

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Carina Heydt ◽  
Jan Rehker ◽  
Roberto Pappesch ◽  
Theresa Buhl ◽  
Markus Ball ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Large Gene ◽  
Mutational Burden ◽  
Whole Exome ◽  
Tumor Mutational Burden ◽  
Gene Panels

scholarly journals Cancer-Specific Thresholds Adjust for Whole Exome Sequencing–Based Tumor Mutational Burden Distribution

2019 ◽  
pp. 1-12
Author(s):  
Evan M. Fernandez ◽  
Kenneth Eng ◽  
Shaham Beg ◽  
Himisha Beltran ◽  
Bishoy M. Faltas ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Disease Stage ◽  
Cancer Type ◽  
Primary Tumors ◽  
Mutational Burden ◽  
Whole Exome ◽  
Significant Difference ◽  
Tumor Mutational Burden ◽  
Pan Cancer

PURPOSE To understand the clinical context of tumor mutational burden (TMB) when comparing a pan-cancer threshold and a cancer-specific threshold. MATERIALS AND METHODS Using whole exome sequencing data from primary tumors in The Cancer Genome Atlas (n = 3,534) and advanced and/or metastatic tumors from Weill Cornell Medicine Advanced (n = 696), TMB status was determined using a pan-cancer and cancer-specific threshold. Survival curves, number of samples classified as TMB high, and predicted neoantigens were used to evaluate the differences between thresholds. RESULTS The distribution of TMB varied dramatically among cancer types. A cancer-specific threshold was able to adjust for the different TMB distributions, whereas the pan-cancer threshold was often too stringent. The dynamic nature of the cancer-specific threshold resulted in more tumors being classified as TMB high compared with the static pan-cancer threshold. In addition, no significant difference in survival outcomes was found with the cancer-specific threshold compared with the pan-cancer threshold. Furthermore, the cancer-specific threshold maintained higher predicted neoantigen load for the TMB-high samples compared with the TMB-low samples, even when the threshold was lower than the pan-cancer threshold. CONCLUSION TMB is determined within the context of cancer type, metastatic state, and disease stage. Compared with a pan-cancer threshold, a cancer-specific threshold classifies more patients as TMB high while maintaining clinical outcomes that are not significantly different. Furthermore, the cancer-specific threshold identifies patients with a high number of predicted neoantigens. Because of the potential impact in the care of patients with cancer, TMB status should be determined in a cancer-specific manner.

Pan-Cancer assessment of tumor mutational burden using a comprehensive genomic profiling assay.

2018 ◽  
Vol 36 (5_suppl) ◽  
pp. 157-157 ◽  
Author(s):  
Donna Nichol ◽  
Siân Jones ◽  
Samuel V. Angiouli ◽  
Laurel Keefer ◽  
Monica Nesselbush ◽  
...  
Keyword(s):  
Microsatellite Instability ◽  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Dynamic Range ◽  
Predictive Biomarkers ◽  
Clinical Biomarkers ◽  
Mutational Burden ◽  
Whole Exome ◽  
Tumor Mutational Burden ◽  
Tumor Types

157 Background: Checkpoint inhibitors (CPIs) have been approved for frontline or subsequent therapies in several indications over the last few years. While patient response can be remarkably durable, many patients do not benefit. Current clinical biomarkers of response to CPIs include microsatellite instability (MSI) and PD-L1 expression. While a proportion of many solid tumors display microsatellite instability, the prevalence is often very low. Similarly, while clinically informative, PD-L1 expression alone is not sufficient to predict therapeutic outcomes with high accuracy. The lack of predictive biomarkers for response highlights the need for improved biomarkers with greater prevalence across tumor types to predict response to CPIs. Multiple clinical studies have revealed that high tumor mutational burden (TMB) is associated with improved clinical response. Methods: Here, we describe the development of a method that can be used to accurately infer mutational burden from a discrete set of targeted regions of interest across the exome. Initially, we performed an assessment of the accuracy across multiple bioinformatics methods for identification of individual sequence mutations (SBS/indels) using orthogonally validated data together with publicly available TCGA whole-exome sequencing data. The targeted regions were then isolated from these datasets to demonstrate analytical performance across several different solid tumor types. Finally, we evaluated independent non-small cell lung cancer (NSCLC) and colorectal carcinoma (CRC) cohorts to demonstrate the analytical accuracy of the assay and bioinformatics approach for determination of mutational burden when compared to whole exome sequencing. Results: In summary, high concordance was observed across a large dynamic range of mutations per megabase of coding sequence. Conclusions: Our data indicate that the assay can be used to accurately determine mutational burden in a range of tumor types, across a spectra of potential mutational burden cut-offs using automated, complex mutation identification algorithms.

scholarly journals Estimating tumor mutational burden across multiple cancer types using whole-exome sequencing

2021 ◽  
Vol 0 (0) ◽  
pp. 0-0
Author(s):  
Chuang Zhou ◽  
Song Chen ◽  
Fei Xu ◽  
Jinwang Wei ◽  
Xiaoyu Zhou ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Multiple Cancer ◽  
Mutational Burden ◽  
Whole Exome ◽  
Tumor Mutational Burden ◽  
Cancer Types

scholarly journals Sequential filtering for clinically relevant variants as a method for clinical interpretation of whole exome sequencing findings in glioma

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Ege Ülgen ◽  
Özge Can ◽  
Kaya Bilguvar ◽  
Cemaliye Akyerli Boylu ◽  
Şirin Kılıçturgay Yüksel ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Clinical Analysis ◽  
Clinical Interpretation ◽  
Germline Variants ◽  
Whole Exome ◽  
Gene Level ◽  
Analysis Workflow ◽  
Tumor Mutational Burden ◽  
Diffuse Gliomas

Abstract Background In the clinical setting, workflows for analyzing individual genomics data should be both comprehensive and convenient for clinical interpretation. In an effort for comprehensiveness and practicality, we attempted to create a clinical individual whole exome sequencing (WES) analysis workflow, allowing identification of genomic alterations and presentation of neurooncologically-relevant findings. Methods The analysis workflow detects germline and somatic variants and presents: (1) germline variants, (2) somatic short variants, (3) tumor mutational burden (TMB), (4) microsatellite instability (MSI), (5) somatic copy number alterations (SCNA), (6) SCNA burden, (7) loss of heterozygosity, (8) genes with double-hit, (9) mutational signatures, and (10) pathway enrichment analyses. Using the workflow, 58 WES analyses from matched blood and tumor samples of 52 patients were analyzed: 47 primary and 11 recurrent diffuse gliomas. Results The median mean read depths were 199.88 for tumor and 110.955 for normal samples. For germline variants, a median of 22 (14–33) variants per patient was reported. There was a median of 6 (0–590) reported somatic short variants per tumor. A median of 19 (0–94) broad SCNAs and a median of 6 (0–12) gene-level SCNAs were reported per tumor. The gene with the most frequent somatic short variants was TP53 (41.38%). The most frequent chromosome-/arm-level SCNA events were chr7 amplification, chr22q loss, and chr10 loss. TMB in primary gliomas were significantly lower than in recurrent tumors (p = 0.002). MSI incidence was low (6.9%). Conclusions We demonstrate that WES can be practically and efficiently utilized for clinical analysis of individual brain tumors. The results display that NOTATES produces clinically relevant results in a concise but exhaustive manner.

scholarly journals Mesenchymal Stromal Cells (MSCs) from Myelodysplastic Syndromes (MDS) Are Not Clonally Mutated I n Vivo

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1514-1514
Author(s):  
Johann-Christoph Jann ◽  
Maximilian Mossner ◽  
Vladimir Riabov ◽  
Eva Altrock ◽  
Nanni Schmitt ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Myelodysplastic Syndromes ◽  
Research Funding ◽  
Ex Vivo ◽  
Mutational Burden ◽  
Bm Niche ◽  
Whole Exome ◽  
Validation Experiments

Abstract Introduction There is increasing evidence for an active role of the bone marrow (BM) microenvironment in the pathogenesis of Myelodysplastic Syndromes (MDS). Genetically engineered murine models have shown that isolated mutations in the BM niche can disrupt the non-mutated hematopoietic compartment and induce MDS-like phenotypes. However, it is still unclear whether primary MDS in humans may possibly be associated with acquired mutations non-hematopoietic BM stroma cells. Although chromosomal aberrations and mutations have been described in in ex vivo expanded MSC cultures from MDS and AML patients, little validation has been performed to address whether such molecular lesions were not clonal outgrowths resulting from the strenuous and massively expansive cell culture procedures. Materials and Methods We performed whole exome sequencing on paired ex vivo expanded MSCs and native BM samples of n=98 MDS and associated myeloid neoplasia cases treated at the Department of Hematology and Oncology of the Medical Faculty Mannheim, Heidelberg University, Germany (median age 73 years, range 44-86). As controls, we included a cohort of n=28 samples from healthy subjects (median age 75 years, range 36-84). MSCs were expanded adherently on plastic dishes by seeding 5x10e6 mononuclear cells in StemMACS MSC Expansion Medium XF (Miltenyi Biotec) for a median of 34 days, (95% confidence interval 22-50d). Whole exome sequencing was carried out using Nextera DNA Flex Tagmentation kit (Illumina) with IDT xGene Research probe v1 at a median coverage at 88x with BM MNC as germline control accounting for possible LOH in the BM sample. Validation experiments were performed by deep re-sequencing of single CFU-F colonies (n=4 patients), sequencing of serial cultures (n=7 patients) and re-sequencing of primary sorted native bone marrow MSCs from n=9 patients. Results In the exome sequencing analyses of ex vivo expanded MSCs we discovered multiple recurrent mutations in MSCs of MDS patients including but not limited to genes such as ZFX (n=8/98) and RANK (n=5/98). MSCs from MDS patients displayed an overall higher mutational burden and increased replicative stress as determined by gH2AX and RPA staining, which correlated with the mutational burden and shorter telomeres as compared to healthy controls. The analysis of mutational signatures revealed that MDS MSCs were distinct compared to healthy MSCs. Furthermore, we found that MDS MSCs displayed increased senescence assessed by flow bGAL staining and associated inflammatory gene expression determined by IL6 qPCR/ELISA for n=32 cases. To investigate whether acquired mutations in MSCs were driven by the ex vivo expansion we performed individualized amplicon based deep re-sequencing of serial culture passages and different BM aspirations for n=7 patients as well as single colony re-sequencing in n=4 patient cases. Furthermore, we re-sequenced primary sorted CD45-,CD235a-,CD31+/-,CD271+/- BM cells of n=9 cases. All of these validation experiments indicated that the discovered mutations were associated with expansion in culture and but not present in clonally relevant cell populations in the primary BM in vivo. Discussion Together with previously published data of the BM niche of myeloid neoplasms, our results add to the notion that MSCs in MDS are molecularly and functionally altered. Nevertheless, our current comprehensive sequencing analyses leave little doubt that if acquired mutations in the stroma of MDS patients play a role in MDS disease initiation at all, then at such a low clonal and possibly locally confined level, that they are not detectable with currently feasible sample acquisition and methodology. In our current study, we discovered no evidence for acquired mutations in BM derived MSCs in MDS. Disclosures Schmitt: Affimed GmbH: Research Funding. Flach: Gilead: Current Employment. Hofmann: BMS: Honoraria; Amgen: Honoraria; Novartis: Honoraria. Nowak: Pharmaxis: Current holder of individual stocks in a privately-held company, Research Funding; Celgene: Honoraria; AbbVie: Other: Investigator on funded clinical trial; Tolero Pharma, Pharmaxis, Apogenix: Research Funding; Affimed: Research Funding; Takeda: Honoraria.

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