Clinical performance and utility of a comprehensive next-generation sequencing DNA panel for the simultaneous analysis of variants, TMB and MSI for myeloid neoplasms

Updates on germline predisposition in pediatric hematologic malignancies: What is the role of flow cytometry?

Hematologic neoplasms with germline predisposition have been increasingly recognized as a distinct category of tumors over the last few years. As such, this category was added to the World Health Organization (WHO) 4th edition as well as maintained in the WHO 5th edition and International Consensus Classification (ICC) 2022 classification systems. In practice, these tumors require a high index of suspicion and confirmation by molecular testing. Flow cytometry is a cost-effective diagnostic tool that is routinely performed on peripheral blood and bone marrow samples. In this review, we sought to summarize the current body of research correlating flow cytometric immunophenotype to assess its utility in diagnosis of and clinical decision making in germline hematologic neoplasms. We also illustrate these findings using cases mostly from our own institution. We review some of the more commonly mutated genes, including CEBPA, DDX41, RUNX1, ANKRD26, GATA2, Fanconi anemia, Noonan syndrome, and Down syndrome. We highlight that flow cytometry may have a role in the diagnosis (GATA2, Down syndrome) and screening (CEBPA) of some germline predisposition syndromes, although appears to show nonspecific findings in others (DDX41, RUNX1). In many of the others, such as ANKRD26, Fanconi anemia, and Noonan syndrome, further studies are needed to better understand whether specific flow cytometric patterns are observed. Ultimately, we conclude that further studies such as large case series and organized data pipelines are needed in most germline settings to better understand the flow cytometric immunophenotype of these neoplasms.

Combining germline, tissue and liquid biopsy analysis by comprehensive genomic profiling to improve the yield of actionable variants in a real-world cancer cohort

BACKGROUND

Comprehensive next-generation sequencing is widely used for precision oncology and precision prevention approaches. We aimed to determine the yield of actionable gene variants, the capacity to uncover hereditary predisposition and liquid biopsy appropriateness instead of, or in addition to, tumor tissue analysis, in a real-world cohort of cancer patients, who may benefit the most from comprehensive genomic profiling.

METHODS

Seventy-eight matched germline/tumor tissue/liquid biopsy DNA and RNA samples were profiled using the Hereditary Cancer Panel (germline) and the TruSight Oncology 500 panel (tumor tissue/cfDNA) from 23 patients consecutively enrolled at our center according to at least one of the following criteria: no available therapeutic options; long responding patients potentially fit for other therapies; rare tumor; suspected hereditary cancer; primary cancer with high metastatic potential; tumor of unknown primary origin. Variants were annotated for OncoKB and AMP/ASCO/CAP classification.

RESULTS

The overall yield of actionable somatic and germline variants was 57% (13/23 patients), and 43.5%, excluding variants previously identified by somatic or germline routine testing. The accuracy of tumor/cfDNA germline-focused analysis was demonstrated by overlapping results of germline testing. Five germline variants in BRCA1, VHL, CHEK1, ATM genes would have been missed without extended genomic profiling. A previously undetected BRAF p.V600E mutation was emblematic of the clinical utility of this approach in a patient with a liver undifferentiated embryonal sarcoma responsive to BRAF/MEK inhibition.

CONCLUSIONS

Our study confirms the clinical relevance of performing extended parallel tumor DNA and cfDNA testing to broaden therapeutic options, to longitudinally monitor cfDNA during patient treatment, and to uncover possible hereditary predisposition following tumor sequencing in patient care.

Systematic comparison of variant calling pipelines of target genome sequencing cross multiple next-generation sequencers

Targeted genomic sequencing (TS) greatly benefits precision oncology by rapidly detecting genetic variations with better accuracy and sensitivity owing to its high sequencing depth. Multiple sequencing platforms and variant calling tools are available for TS, making it excruciating for researchers to choose. Therefore, benchmarking study across different platforms and pipelines available for TS is imperative. In this study, we performed a TS of Reference OncoSpan FFPE (HD832) sample enriched by TSO500 panel using four commercially available sequencers, and analyzed the output 50 datasets using five commonly-used bioinformatics pipelines. We systematically investigated the sequencing quality and variant detection sensitivity, expecting to provide optimal recommendations for future research. Four sequencing platforms returned highly concordant results in terms of base quality (Q20 > 94%), sequencing coverage (>97%) and depth (>2000×). Benchmarking revealed good concordance of variant calling across different platforms and pipelines, among which, FASTASeq 300 platform showed the highest sensitivity (100%) and precision (100%) in high-confidence variants calling when analyzed by SNVer and VarScan 2 algorithms. Furthermore, this sequencer demonstrated the shortest sequencing time (∼21 h) at the sequencing mode PE150. Through the intersection of 50 datasets generated in this study, we recommended a novel set of variant genes outside the truth set published by HD832, expecting to replenish HD832 for future research on tumor variant diagnosis. Besides, we applied these five tools to another panel (TargetSeq One) for Twist cfDNA Pan-cancer Reference Standard, comprehensive consideration of SNP and InDel sensitivity, SNVer and VarScan 2 performed best among them. Furthermore, SNVer and VarScan 2 also performed best for six cancer cell lines samples regarding SNP and InDel sensitivity. Considering the dissimilarity of variant calls across different pipelines for datasets from the same platform, we recommended an integration of multiple tools to improve variant calling sensitivity and accuracy for the cancer genome. Illumina and GeneMind technologies can be used independently or together by public health laboratories performing tumor TS. SNVer and VarScan 2 perform better regarding variant detection sensitivity for three typical tumor samples. Our study provides a standardized target sequencing resource to benchmark new bioinformatics protocols and sequencing platforms.

Clinical Utility of Optical Genome Mapping and 523-Gene Next Generation Sequencing Panel for Comprehensive Evaluation of Myeloid Cancers

The standard-of-care (SOC) for genomic testing of myeloid cancers primarily relies on karyotyping/fluorescent in situ hybridization (FISH) (cytogenetic analysis) and targeted gene panels (usually ≤54 genes) that harbor hotspot pathogenic variants (molecular genetic analysis). Despite this combinatorial approach, ~50% of myeloid cancer genomes remain cytogenetically normal, and the limited sequencing variant profiles obtained from targeted panels are unable to resolve the molecular etiology of many myeloid tumors. In this study, we evaluated the performance and clinical utility of combinatorial use of optical genome mapping (OGM) and a 523-gene next-generation sequencing (NGS) panel for comprehensive genomic profiling of 30 myeloid tumors and compared it to SOC cytogenetic methods (karyotyping and FISH) and a 54-gene NGS panel. OGM and the 523-gene NGS panel had an analytical concordance of 100% with karyotyping, FISH, and the 54-gene panel, respectively. Importantly, the IPSS-R cytogenetic risk group changed from very good/good to very poor in 22% of MDS (2/9) cases based on comprehensive profiling (karyotyping, FISH, and 54-gene panel vs. OGM and 523-gene panel), while additionally identifying six compound heterozygous events of potential clinical relevance in six cases (6/30, 20%). This cost-effective approach of using OGM and a 523-gene NGS panel for comprehensive genomic profiling of myeloid cancers demonstrated increased yield of actionable targets that can potentially result in improved clinical outcomes.

Optical genome mapping in acute myeloid leukemia: a multicenter evaluation

Detection of hallmark genomic aberrations in acute myeloid leukemia (AML) is essential for diagnostic subtyping, prognosis, and patient management. However, cytogenetic/cytogenomic techniques used to identify those aberrations, such as karyotyping, fluorescence in situ hybridization (FISH), or chromosomal microarray analysis (CMA), are limited by the need for skilled personnel as well as significant time, cost, and labor. Optical genome mapping (OGM) provides a single, cost-effective assay with a significantly higher resolution than karyotyping and with a comprehensive genome-wide analysis comparable with CMA and the added unique ability to detect balanced structural variants (SVs). Here, we report in a real-world setting the performance of OGM in a cohort of 100 AML cases that were previously characterized by karyotype alone or karyotype and FISH or CMA. OGM identified all clinically relevant SVs and copy number variants (CNVs) reported by these standard cytogenetic methods when representative clones were present in >5% allelic fraction. Importantly, OGM identified clinically relevant information in 13% of cases that had been missed by the routine methods. Three cases reported with normal karyotypes were shown to have cryptic translocations involving gene fusions. In 4% of cases, OGM findings would have altered recommended clinical management, and in an additional 8% of cases, OGM would have rendered the cases potentially eligible for clinical trials. The results from this multi-institutional study indicate that OGM effectively recovers clinically relevant SVs and CNVs found by standard-of-care methods and reveals additional SVs that are not reported. Furthermore, OGM minimizes the need for labor-intensive multiple cytogenetic tests while concomitantly maximizing diagnostic detection through a standardized workflow.

Clinical Validation and Diagnostic Utility of Optical Genome Mapping for Enhanced Cytogenomic Analysis of Hematological Neoplasms

The current standard-of-care cytogenetic techniques for the analysis of hematological malignancies include karyotyping, fluorescence in situ hybridization, and chromosomal microarray, which are labor intensive and time and cost prohibitive, and they often do not reveal the genetic complexity of the tumor, demonstrating the need for alternative technology for better characterization of these tumors. Herein, we report the results from our clinical validation study and demonstrate the utility of optical genome mapping (OGM), evaluated using 92 sample runs (including replicates) that included 69 well-characterized unique samples (59 hematological neoplasms and 10 controls). The technical performance (quality control metrics) resulted in 100% first-pass rate, with analytical performance (concordance) showing a sensitivity of 98.7%, a specificity of 100%, and an accuracy of 99.2%. OGM demonstrated robust technical, analytical performance, and interrun, intrarun, and interinstrument reproducibility. The limit of detection was determined to be at 5% allele fraction for aneuploidy, translocation, interstitial deletion, and duplication. OGM identified several additional structural variations, revealing the genomic architecture in these neoplasms that provides an opportunity for better tumor classification, prognostication, risk stratification, and therapy selection. Overall, OGM has outperformed the standard-of-care tests in this study and demonstrated its potential as a first-tier cytogenomic test for hematologic malignancies.

RB1-deficient squamous cell carcinoma: the proposed source of combined Merkel cell carcinoma

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine (NE) carcinoma arising from integration of Merkel cell polyomavirus (MCPyV) DNA into a host cell or from ultraviolet light-induced genetic damage (proportions vary geographically). Tumors in the latter group include those with "pure" NE phenotype and those "combined" with other elements, most often squamous cell carcinoma (SCC). We performed comprehensive genomic profiling (CGP) of MCPyV+ and MCPyV- (pure and combined) tumors, to better understand their mutational profiles and shed light on their pathogenesis. Supplemental immunohistochemistry for Rb expression was also undertaken. After eliminating low quality samples, 37 tumors were successfully analyzed (14 MCPyV+, 8 pure MCPyV- and 15 combined MCPyV-). The SCC and NE components were sequenced separately in 5 combined tumors. Tumor mutational burden was lower in MCPyV+ tumors (mean 1.66 vs. 29.9/Mb, P < 0.0001). MCPyV- tumors featured frequent mutations in TP53 (95.6%), RB1 (87%), and NOTCH family genes (95.6%). No recurrently mutated genes were identified in MCPyV+ tumors. Mutational overlap in the NE and SCC components of combined tumors was substantial ('similarity index' >24% in 4/5 cases). Loss of Rb expression correlated with RB1 mutational (P < 0.0001) and MCPyV- status (P < 0.0001) in MCCs and it was observed more frequently in the SCC component of combined MCC than in a control group of conventional cutaneous SCC (P = 0.0002). Our results (i) support existing evidence that MCPyV+ and MCPyV- MCCs are pathogenetically distinct entities (ii) concur with earlier studies linking the NE and SCC components of combined MCCs via shared genetic profiles and (iii) lend credence to the proposal that an Rb-deficient subset of SCC's is the source of phenotypically divergent combined MCCs.

Diagnostic Validation of a Comprehensive Targeted Panel for Broad Mutational and Biomarker Analysis in Solid Tumors

The use of targeted Next Generation Sequencing (NGS) for the diagnostic screening of somatic variants in solid tumor samples has proven its high clinical value. Because of the large number of ongoing clinical trials for a multitude of variants in a growing number of genes, as well as the detection of proven and emerging pan-cancer biomarkers including microsatellite instability (MSI) and tumor mutation burden (TMB), the currently employed diagnostic gene panels will become vastly insufficient in the near future. Here, we describe the validation and implementation of the hybrid capture-based comprehensive TruSight Oncology (TSO500) assay that is able to detect single-nucleotide variants (SNVs) and subtle deletions and insertions (indels) in 523 tumor-associated genes, copy-number variants (CNVs) of 69 genes, fusions with 55 cancer driver genes, and MSI and TMB. Extensive validation of the TSO500 assay was performed on DNA or RNA from 170 clinical samples with neoplastic content down to 10%, using multiple tissue and specimen types. Starting with 80 ng DNA and 40 ng RNA extracted from formalin-fixed and paraffine-embedded (FFPE) samples revealed a precision and accuracy >99% for all variant types. The analytical sensitivity and specificity were at least 99% for SNVs, indels, CNVs, MSI, and gene rearrangements. For TMB, only values around the threshold could yield a deviating outcome. The limit-of-detection for SNVs and indels was well below the set threshold of 5% variant allele frequency (VAF). This validated comprehensive genomic profiling assay was then used to screen 624 diagnostic samples, and its success rate for adoption in a clinical diagnostic setting of broad solid tumor screening was assessed on this cohort.

Targeted Therapies and Druggable Genetic Anomalies in Acute Myeloid Leukemia: From Diagnostic Tools to Therapeutic Interventions

Acute myeloid leukemia (AML) is a clonal disorder resulting from acquired somatic mutations in hematopoietic progenitor cells that lead to the dysregulation of differentiation and the proliferation of hematopoietic cells [...].