Amplicon-based Next-generation Sequencing Research Articles

Investigating somatic variants and pathways in mismatch repair-deficient (dMMR) colorectal carcinoma in South Africa

AimsColorectal carcinoma (CRC) is a common cause of morbidity and mortality worldwide, and an emerging public health problem in sub-Saharan Africa. Several authors have described an increased frequency of mismatch...

Pepper mild mottle virus intended for use as a process indicator for drinking water treatment: Present forms and quantitative relations to norovirus and rotavirus in surface water

Pepper mild mottle virus (PMMoV) has been proposed as a potential indicator of human enteric viruses in environmental water and for viral removal during drinking water treatment. To investigate the occurrence and present forms of PMMoV and quantitative relations to norovirus GII and rotavirus A (RVA) in surface waters, 147 source water samples were collected from 21 drinking water treatment plants (DWTPs) in Japan between January 2018 and January 2021, and the concentrations of viruses in suspended and dissolved fractions were measured using real-time RT-PCR. PMMoV was detected in 81–100 % of samples in each sample month and observed concentrations ranged from 3.0 to 7.0 log10 copies/L. The concentrations of PMMoV were higher in dissolved fraction compared to suspended fractions, while different partitioning was observed for NoV GII depending on seasons. The concentrations of PMMoV were basically higher than those of norovirus GII (1.9−5.3 log10 copies/L) and RVA (1.9−6.6 log10 copies/L), while in 18 samples, RVA presented higher concentrations than PMMoV. Partial regions of VP7, VP4, and VP6 of the RVA in the 18 samples were amplified using nested PCR, and the genotypes were determined using an amplicon-based next-generation sequencing approach. We found that these source water samples included not only human RVA but also various animal RVA and high genetic diversity due to the existence of animal RVA was associated with a higher RVA concentration than PMMoV. Our findings suggest that PMMoV can be used as an indicator of norovirus GII and human RVA in drinking water sources and that the indicator performance should be evaluated by comparing to zoonotic viruses as well as human viruses.

Concurrent molecular characterization of sand flies and Leishmania parasites by amplicon-based next-generation sequencing

Concurrent molecular characterization of sand flies and Leishmania parasites by amplicon-based next-generation sequencing

Development of an automated amplicon-based next-generation sequencing pipeline for rapid detection of bacteria and fungi directly from clinical specimens.

To our knowledge, this represents the first application of an automated sequencing and bioinformatics pipeline in an exclusively pediatric population. Next-generation sequencing is time-consuming, labor-intensive, and requires experienced personnel; perhaps contributing to hesitancy among clinical laboratories to adopt such a test. Here, we report a strong case for use by removing these barriers through near-total automation of our sequencing pipeline.

Harnessing Next-Generation Sequencing as a Timely and Accurate Second-Tier Screening Test for Newborn Screening of Inborn Errors of Metabolism.

In this study, we evaluated the implementation of a second-tier genetic screening test using an amplicon-based next-generation sequencing (NGS) panel in our laboratory during the period of 1 September 2021 to 31 August 2022 for the newborn screening (NBS) of six conditions for inborn errors of metabolism: citrullinemia type II (MIM #605814), systemic primary carnitine deficiency (MIM #212140), glutaric acidemia type I (MIM #231670), beta-ketothiolase deficiency (#203750), holocarboxylase synthetase deficiency (MIM #253270) and 3-hydroxy-3-methylglutaryl-CoA lyase deficiency (MIM # 246450). The custom-designed NGS panel can detect sequence variants in the relevant genes and also specifically screen for the presence of the hotspot variant IVS16ins3kb of SLC25A13 by the copy number variant calling algorithm. Genetic second-tier tests were performed for 1.8% of a total of 22,883 NBS samples. The false positive rate for these six conditions after the NGS second-tier test was only 0.017%, and two cases of citrullinemia type II would have been missed as false negatives if only biochemical first-tier testing was performed. The confirmed true positive cases were citrullinemia type II (n = 2) and systemic primary carnitine deficiency (n = 1). The false positives were later confirmed to be carrier of citrullinemia type II (n = 2), carrier of glutaric acidemia type I (n = 1) and carrier of systemic primary carnitine deficiency (n = 1). There were no false negatives reported. The incorporation of a second-tier genetic screening test by NGS greatly enhanced our program's performance with 5-working days turn-around time maintained as before. In addition, early genetic information is available at the time of recall to facilitate better clinical management and genetic counseling.

The Common and Unique Microbiota in Sabah’s Traditional Rice Wine Starter Cultures (SASAD)

Rice wine is an alcoholic beverage produced through the fermentation of cereal grains, mainly rice, with microbial starters consisting of fungi and bacteria. However, the microbes in the rice wine starter cultures have never been documented comprehensively except for a few studies that looked into culturable microbes. Hence, their exact core microbiota contents especially those unculturable microbes remained unknown. Therefore, this research aimed to identify the fungal and bacterial communities in sasad through ribosomal amplicon-based next-generation sequencing and analysis that captured both the culturable and unculturable microbiota. The results showed that two fungal phyla (Mucoromycota and Ascomycota) with five genera (Mucor, Rhizopus, Saccharomycopsis, Wickerhamomyces, and Kodamaea) and two bacterial phyla (Proteobacteria and Firmicutes) with 10 genera (Kosakonia, Weissella, Enterobacter, Lactococcus, Pseudomonas, Bacillus, Chromobacterium, Paludibacterium, Enterococcus, and Gluconobacter) were identified as the core microbiota (relative abundance > 1.00%) in the sasad samples. Some of these microbes have been reported in other starter cultures, but some are unique to the sasad (Chromobacterium and Paludibacterium). Hence, this research provides the first comprehensive report on the microbes in sasad and provides important insights into the potential roles of core microbiota. These data may be used to facilitate the development of starter cultures with defined microbial compositions for the consistent production of safe and high-quality rice wines in the future.

Taxonomic Variations of Bacterial and Fungal Communities depending on Fermentation Temperature in Traditional Korean Fermented Soybean Food, Doenjang.

Meju, a fermented soybean brick, is a key component in soybean foods like doenjang and ganjang, harboring a variety of microorganisms, including bacteria and fungi. These microorganisms significantly contribute to the nutritional and sensory characteristics of doenjang and ganjang. Amplicon-based next-generation sequencing was applied to investigate how the microbial communities of meju fermented at low and high temperatures differ and how this variation affects the microbial communities of doenjang, a subsequently fermented soybean food. Our metagenomic data showed distinct patterns depending on the fermentation temperature. The microbial abundance in the bacterial community was increased under both temperatures during the fermentation of meju and doenjang. Weissella was the most abundant genus before the fermentation of meju, however, it was replaced by Bacillus at high temperature-fermented meju and lactic acid bacteria such as Weissella and Latilactobacillus at low temperature-fermented meju. Leuconostoc, Logiolactobacillus, and Tetragenococcus gradually took over the dominant role during the fermentation process of doenjang, replacing the previous dominant microorganisms. Mucor was dominant in the fungal community before and after meju fermentation, whereas Debaryomyces was dominant under both temperatures during doenjang fermentation. The dominant fungal genus of doenjang was not affected regardless of the fermentation temperature of meju. Strong correlations were shown for specific bacteria and fungi linked to specific fermentation temperatures. This study helps our understanding of meju fermentation process at different fermentation temperatures and highlights different bacteria and fungi associated with specific fermentation periods which may influence the nutritional and organoleptic properties of the final fermented soybean foods doenjang.

Next-Generation Sequencing-Based Identification of Enterobacter hormaechei as Causative Agent of High Mortality Disease in NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) Mice.

NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice, lacking many components of a mature immune system, are at increased risk of disease. General understanding of potential pathogens of these mice is limited. We describe a high mortality disease outbreak caused by an opportunistic bacterial infection in NSG mice. Affected animals exhibited perianal fecal staining, dehydration, and wasting. Histopathologic lesions included a primary necrotizing enterocolitis, with inflammatory and necrotizing lesions also occurring in the liver, kidneys, heart, and brain of some mice. All affected individuals tested negative for known opportunistic pathogens of immunodeficient mice. We initially identified a member of Enterobacter cloacae complex (ECC) in association with the outbreak by traditional diagnostics. ECC was cultured from extraintestinal organs, both with and without histopathologic lesions, suggesting bacteremia. Infrared spectroscopy and MALDI-TOF mass spectrometry demonstrated that isolates from the outbreak shared molecular features and likely a common origin. We subsequently hypothesized that advanced sequencing methods would identify a single species of ECC associated with clinical disease. Using a novel targeted amplicon-based next-generation sequencing assay, we identified Enterobacter hormaechei in association with this outbreak. Knowledge of this organism as a potential opportunistic pathogen in NSG mice is critical for preclinical studies to prevent loss of animals and confounding of research.

Performance of non-formalin fixed paraffin embedded samples in hybrid capture and amplicon next-generation sequencing panels.

Genomic profiling using next-generation sequencing (NGS) is fundamental for driving prognostic and therapy in cancer. Formalin-fixed paraffin embedded (FFPE) tissue is the widely used material, whereas non-FFPE may represent an alternative. However, studies comparing the NGS performance of non-FFPE materials to FFPE are still lacking in the literature. The objective of this study was to characterize in non-FFPE preparations the nucleic acid yield and NGS performance on both a capture-based and an amplicon-based NGS platform. NGS quality metrics obtained from non-FFPE preparations were compared to FFPE. We analyzed the cellularity and nucleic acid yield in 111 tumors from non-FFPE preparations. In addition, comprehensive hybrid capture panel sequencing metrics obtained from DNA and RNA libraries were compared between independent non-FFPE and FFPE samples. A paired comparison between non-FFPE and FFPE samples was performed to analyze concordance in mutant allele detection using an amplicon panel. The mean target coverage from DNA libraries was 2× higher in non-FFPE samples than in FFPE. The detection of exogenous DNA was 2.5× higher in non-FFPE than in FFPE. Conversely, a lower performance was observed in non-FFPE RNA libraries in comparison to FFPE DNA libraries with no impact in minimum standard cutoffs. The variant allele detection in non-FFPE was found to be comparable to that of FFPE tumor samples in matched samples. Non-FFPE was demonstrated to be a suitable material for DNA and RNA library preparations using a comprehensive NGS panel. This is the first study reporting library quality metrics according to the TSO500 analysis pipeline.

Detection of zoonotic Cryptosporidium spp. in small wild rodents using amplicon-based next-generation sequencing

Rodents may serve as reservoirs of zoonotic species of Cryptosporidium; however, data from molecular surveys in support of this hypothesis are still scarce. In this study, we screened faeces and rectal content from murid and cricetid rodents (N = 58) caught around three farms in Zealand, Denmark, for Cryptosporidium spp. by amplicon-based next-generation sequencing (NGS) of ribosomal genes. Selected samples were further examined using nested conventional PCR targeting SSU rRNA, gp60, and actin genes. Cryptosporidium-specific DNA was identified in 40/58 (69%) samples, and in 12 (30%) of the 40 positive animals, mixed cryptosporidial infections were observed. Cryptosporidium ditrichi was the species most commonly identified, found in 28 (48%) of the animals. Cryptosporidium parvum was identified in 4 (7%) of the animals, all of which were co-infected with C. ditrichi. The present study is the first to utilize NGS-based screening for Cryptosporidium species in wild rodents. Moreover, it is the first study to provide molecular data on Cryptosporidium in rodents sampled in Denmark and to detect DNA of C. ditrichi in Mus musculus, Myodes glareolus, and Microtus agrestis. The NGS approach was successfully applied to yield new knowledge, and the results showed that zoonotic species of Cryptosporidium are common in murid and cricetid rodents in Zealand, Denmark.

Comparison of an amplicon-based large panel next generation sequencing (NGS) assay with conventional testing methods for MET and HER2 amplification in lung and breast cancers

The frequency of MET and HER2 amplification being detected by next generation sequencing (NGS) is increasing due to NGS being increasingly adopted for molecular profiling of cancers. However, the accuracy of NGS in detecting these gene amplifications remains uncertain due to conflicting reports in the scientific literature. We studied the accuracy of an amplicon-based large panel NGS assay in detecting MET and HER2 amplification in lung and breast cancers, respectively, by comparing it against conventional testing methods. Amongst 48 lung cancers, four of five cancers that were MET amplified on fluorescence in situ hybridisation (FISH) were classified as amplified on NGS while 42 of the remaining 43 non-amplified cancers were classified as non-amplified on NGS, giving a sensitivity of 80%, specificity of 97.7% and overall concordance of 95.8%. Of the 46 breast cancers tested, only six of the nine cancers that were HER2-positive on immunohistochemistry (IHC)/FISH were HER2-positive on NGS, while all the remaining HER2-negative cases were negative on NGS, giving a sensitivity of 66.7%, specificity of 100% and overall concordance of 93.5%. All the false-negative cases had low level gene amplification (MET:CEP7 or HER2:CEP17 FISH ratio of <3). The low sensitivity for HER2 amplification may be confounded by the small sample size and disproportionate number of cases with low level amplification. In summary, the NGS assay has good concordance with conventional testing methods but may be less sensitive in detecting low level gene amplification.

Reshaping MRD Detection Strategies: Next-Generation Sequencing and High DNA Input Identify Previously Missed Measurable Residual Disease in Peripheral Blood of B-Cell Precursor Acute Lmyphoblastic Leukemia

Background: In acute lymphoblastic leukemia (ALL), measurable residual disease (MRD) is the most important prognostic factor. MRD is traditionally quantified in bone marrow aspirates (BM) using real-time quantitative polymerase chain reaction (RQ-PCR) according to EuroMRD standards. Since the emergence of modern molecular methods, it has been a continuous effort to enable MRD assessment from peripheral blood (PB). The less invasive material collection would allow closer MRD monitoring and solve technical challenges of BM aspiration, such as skewed or non-representative MRD values due to hemodilution and unequal distribution of leukemic cells. While several studies demonstrated comparable MRD values of BM and PB in T-ALL, in B-cell precursor ALL (BCP-ALL) MRD determination from PB is still a challenge. Mean MRD levels in PB are considerably lower than in BM and frequently escape detection. Additionally, paired samples show a highly variable MRD level ratio in both pediatric and adult cases (Kotrova et al, Leukemia 2020). Objective: BCP-ALL cases with known MRD positivity in the BM likely also harbor MRD positive cells in the PB, even when missed by traditional methods. With more sensitive assays, either by increased DNA input or by application of amplicon-based next generation sequencing (NGS), MRD detection from PB may improve in these cases. Methods: We retrospectively selected PB - BM sample pairs of 74 BCP-ALL patients with BM MRD positivity (43 with quantifiable MRD positivity and 31 with positivity below quantitative range) and sufficient leftover DNA from a cohort of patients treated according to GMALL protocols, where conventional RQ-PCR of clonal immunoglobuline heavy chain (IGH) VJ/DJ gene rearrangements failed to detect PB MRD. MRD had been determined by standard RQ-PCR with 1.5 µg DNA in BM and PB, respectively, according to the EuroMRD guidelines (van der Velden et al, Leukemia 2007). PB samples were re-tested for MRD with high DNA input RQ-PCR using 6.6 µg DNA and amplicon-based NGS, each using 6.6 µg DNA, as well as standard input NGS. NGS analyses of corresponding PB and BM samples were performed with the EuroClonality amplicon-based NGS assay (Brüggemann et al, Leukemia 2019). Identification and quantification of leukemia-derived clonotypes was done using ARResT/Interrogate. Results: In total, 74 BCP-ALL patients with pre/c-B-ALL (n=60) and pro-B-ALL (n=14) were included. Patient age ranged from 19 - 71 years with a median of 44.5. In all included samples (56 in first-line therapy and 18 salvage treatment), BM was MRD positive and PB was MRD negative in standard RQ-PCR at a sensitivity of at least 10 -4. To assess the effect of high DNA input alone, RQ-PCR was repeated in PB with high DNA input for 59 patients and 63 IGH VJ/DJ markers. At least one positive signal was detected in 19/59 patients (32%) and 20/63 markers (32%) (FIGURE 1A). NGS was performed for 73 PB samples and 84 markers using standard and high DNA input. With standard DNA input, MRD could be detected for 19/73 patients (26%) and 21/84 markers (25%) (FIGURE 1A). In the high input approach, MRD was detected in 36/73 patients (49%) and 40/84 markers (48%) (FIGURE 1A). A quantifiable MRD value was identified in 17 patients and 19 markers. All markers with quantifiable NGS MRD positivity in PB showed higher MRD values in the corresponding BM sample and MRD values below 10 -4 (FIGURE 1B). No correlation of MRD in paired samples could be demonstrated (Pearson correlation coefficient: 0.09) (FIGURE 1B). Conclusion: In BCP-ALL, MRD detection from PB is challenging with conventional methods. Increased DNA input and amplicon-based NGS allowed detection of MRD in a subset of PB samples that were negative in standard RQ-PCR. With identical DNA input, NGS showed a higher sensitivity than RQ-PCR and best results were achieved when high DNA input and NGS were combined, identifying MRD in nearly half of the PB samples. These results demonstrate that PB can be a valuable tool for early MRD detection in BCP-ALL when adjusting traditional MRD assessment strategies. However, in half of the samples, MRD was still missed by high input NGS. Even with assays improved for sensitivity, PB therefore cannot fully replace BM for MRD assessment in BCP-ALL yet and should rather be considered to complement BM analyses or in cases where BM is not accessible.

Detection of Isolated Extramedullary AML Using Next-Generation Sequencing of Cell-Free DNA

Introduction Isolated extramedullary (IEM) manifestation of AML is a recurrent event especially after allogenic hematopoietic cell transplantation (alloHCT). To date, measurable residual disease (MRD) assessment for early detection and monitoring of this difficult-to-treat patient cohort has not been established. Using cell-free DNA (cfDNA) from plasma or serum for MRD measurement shows comparable sensitivity to bone marrow mononuclear cells (BMMCs) and improved sensitivity over peripheral blood mononuclear cells (PBMCs) in medullary AML (Nakamura et al., Blood, 2019). Here, we evaluate next-generation sequencing (NGS) for MRD assessment of cfDNA in a cohort of patients with IEM AML. Methods We retrospectively collected tumor tissue and matched BMMC/PBMCs and cfDNA serum or plasma samples from IEM AML patients at our institution. BMMC/PBMCs and IEM tumor tissue were sequenced with 35- to 48-gene panels at diagnosis and relapse. Amplicon-based NGS-MRD (sensitivity 0.01%) of matched cfDNA and BMMC/PBMCs was quantified at time of IEM manifestation and in all available samples collected up to 12 months before IEM manifestation using the known mutations from IEM AML tissue. Amplicon-based NGS and bioinformatic error-correction was conducted and analyzed as previously described (Thol et al., Blood, 2018). Results We identified a cohort of 15 IEM AML patients at our institution. One patient was diagnosed with IEM AML at first diagnosis, 14 patients suffered from IEM relapse. For three patients, matched BMMC/PBMCs and cfDNA samples were collected from a second IEM AML relapse during the disease course. 15 of 18 IEM AML episodes (83%) occurred as relapse after alloHCT. 42 AML-related mutations were identified in the IEM AML tissue with a median of three mutations per patient (range 1-5). 33 of 39 mutations (85%) found in IEM relapse tissue had been already present at first diagnosis. All mutations were then evaluated in cfDNA and BMMCs at the time of the IEM manifestation by sensitive NGS-MRD analysis for all 18 IEM AML episodes. For two IEM episodes, BMMCs were not available and PBMCs were used instead. 17 of 18 (94%) cfDNA samples were NGS-MRD positive at the time of IEM manifestation, while only 8 of 18 (44%) BMMC/PBMC samples were positive. 20 of 53 mutations (38%) at first and second IEM episode could only be detected using cfDNA, 15 mutations (28%) were detected in both cfDNA and BMMC/PBMCs and only one mutation was solely found in BMMCs. 17 mutations (32%) could not be detected by either method (Figure 1). The variant allele frequency (VAF) of mutations detected by both methods was significantly higher using cfDNA with a median VAF of 2.45% (range 0.12 - 24%) compared to BMMC/PBMCs with a median VAF of 0.048% (range 0.13 - 10%; p &amp;lt; 0.01). Median VAF of mutations that were only found in cfDNA was 0.63% (range 0.017 - 39.6) and did not significantly differ from the cfDNA VAF of mutations that were found by both methods (p=0.43), indicating that these mutations represented the major clone. However, no correlation was found between IEM tumor VAF and cfDNA VAF (r=0.01; p=0.95). For ten IEM episodes from nine patients at least one cfDNA sample was available within 12 months before IEM relapse. In six IEM episodes (60%) cfDNA samples were MRD positive, one at 6 months, one at 5 months, two at 3 months and two at 2 months before IEM relapse. In four IEM episodes (40%) cfDNA samples were MRD negative, one at 10 months, one at 5 months and two at 2 months before IEM relapse. Conclusion In summary, cfDNA analysis from serum or plasma of AML patients can identify the molecular characteristics of a large proportion of patients with IEM AML. More than one third of clinically relevant mutations could only be detected using cfDNA and were missed by NGS-MRD of BMMC/PBMCs. Our data suggest that MRD monitoring from cfDNA detects IEM relapse earlier than routine monitoring from PB or BM in a significant proportion of patients.

Development and validation of a next-generation sequencing assay with open-access analysis software for detecting resistance-associated mutations in CMV.

Cytomegalovirus (CMV) resistance testing by targeted next-generation sequencing (NGS) allows for the simultaneous analysis of multiple genes. We developed and validated an amplicon-based Ion Torrent NGS assay to detect CMV resistance mutations in UL27, UL54, UL56, and UL97 and compared the results to standard Sanger sequencing. NGS primers were designed to generate 83 overlapping amplicons of four CMV genes (~10 kb encompassing 138 mutation sites). An open-access software plugin was developed to perform read alignment, call variants, and interpret drug resistance. Plasmids were tested to determine NGS error rate and minor variant limit of detection. NGS limit of detection was determined using the CMV WHO International Standard and quantified clinical specimens. Reproducibility was also assessed. After establishing quality control metrics, 185 patient specimens previously tested using Sanger were reanalyzed by NGS. The NGS assay had a low error rate (<0.05%) and high accuracy (95%) for detecting CMV-associated resistance mutations present at ≥5% in contrived mixed populations. Mutation sites were reproducibly sequenced with 40× coverage when plasma viral loads were ≥2.6 log IU/mL. NGS detected the same resistance-associated mutations identified by Sanger in 68/69 (98.6%) specimens. In 16 specimens, NGS detected 18 resistance mutations that Sanger failed to detect; 14 were low-frequency variants (<20%), and six would have changed the drug resistance interpretation. The NGS assay showed excellent agreement with Sanger and generated high-quality sequence from low viral load specimens. Additionally, the higher resolution and analytic sensitivity of NGS potentially enables earlier detection of antiviral resistance.

Identification of causative gene variants for patients with known monogenic diabetes using a targeted next-generation sequencing panel in a single-center study.

We aimed to verify the usefulness of targeted next-generation sequencing (NGS) technology for diagnosing monogenic diabetes in a single center. We designed an amplicon-based NGS panel targeting 34 genes associated with known monogenic diabetes and performed resequencing in 56 patients with autoantibody-negative diabetes mellitus diagnosed at < 50years who had not been highly obese. By bioinformatic analysis, we filtered significant variants based on allele frequency (< 0.005 in East Asians) and functional prediction. We estimated the pathogenicity of each variant upon considering the family history. Overall, 16 candidate causative variants were identified in 16 patients. Among them, two previously known heterozygous nonsynonymous single-nucleotide variants associated with monogenic diabetes were confirmed as causative variants: one each in the GCK and WFS1 genes. The former was found in two independent diabetes-affected families. Two novel putatively deleterious heterozygous variants were also assumed to be causative from the family history: one frameshift and one nonsynonymous single-nucleotide variant in the HNF4A gene. Twelve variants remained as candidates associated with the development of diabetes. Targeted NGS panel testing was useful to diagnose various forms of monogenic diabetes in combination with familial analysis, but additional ingenuity would be needed for practice. The online version contains supplementary material available at 10.1007/s13340-023-00669-3.

BIOM-06. LONGITUDINAL CEREBROSPINAL FLUID LIQUID BIOPSY IN PHASE 0/2 TRIAL OF NIRAPARIB FOR NEWLY-DIAGNOSED GLIOBLASTOMA

Abstract INTRODUCTION Effective drug development in glioblastoma (GBM) requires visualization of tumor evolution in response to experimental therapy. Today, genetic and epigenetic mechanisms of tumor resistance are undetected in clinical trials. Here, we establish the feasibility of a liquid biopsy paradigm in tracking tumor evolution in response to a novel therapeutic using an intra-cavitary reservoir for serial cerebrospinal fluid (CSF) collection. METHODS We conducted a Phase 0/2 clinical trial of niraparib, a potent PARP1/2 inhibitor, in newly-diagnosed GBM patients (NCT05076513). Intra-cavitary reservoirs were placed in select patients following tumor resection. Monthly outpatient CSF samples were collected to longitudinally examine cell-free tumor DNA (cfDNA) using a 293-gene amplicon-based next-generation sequencing (NGS) panel and circulating tumor cells using single cell RNA-sequencing (scRNA-seq). Concordance analysis was performed using paired tumor tissue samples against multiple liquid biopsies. RESULTS Tumor-derived cfDNA and circulating tumor cells were successfully isolated from intra-cavitary reservoirs at regular intervals for the duration of the clinical trial. Twelve patients so far have been implanted with the reservoirs for CSF collection. Among 55 CSF samples, 53 (94%) has detectable cfDNA. Radiographic tumor burden is associated with concentration of cfDNA (ng/ml, p&amp;lt; 0.01). No adverse events were observed during liquid biopsy acquisition. CSF sequencing data was highly concordant with NGS analyses of tumor tissue. cfDNA and single-cell analyses from serial CSF samples reflected the disparate evolution of GBM patient tumors in the face of PARP1/2 inhibition. CONCLUSION This is the first reported experience of serial CSF liquid biopsy to monitor DNA- and RNA-based tumor evolution in the context of an experimental therapy. Our data demonstrate the feasibility of cfDNA NGS and scRNA-seq using longitudinal CSF sampling of clinical trial patients. This new strategy for serial tumor profiling will be an important component of future drug development efforts targeting the moving biology of glioblastoma.

219P Multicentric evaluation of amplicon-based next-generation sequencing solution for local comprehensive molecular tumor profiling

219P Multicentric evaluation of amplicon-based next-generation sequencing solution for local comprehensive molecular tumor profiling

B-253 Performance Characteristics and Validation of Next-Generation Sequencing for Human Leucocyte Antigen Typing

Abstract Background High-resolution human leukocyte antigen (HLA) typing is a crucial process in transplant matching. Sequencing-based typing (SBT) has been the gold standard method used in HLA-based clinical applications. Recently, next-generation sequencing (NGS) has been adopted in clinical laboratories for HLA typing. NGS HLA typing assays cover whole or near-whole target HLA genes, allowing the detection of genetic variants outside of key exons. Multiplex amplicon-based NGS is an efficient high-resolution HLA typing method with minimal ambiguity and a high throughput. Here, we report the performance and validation of NGS for HLA typing and compare the results obtained using NGS with those of SBT to identify any discrepancies between the 2 methods. Methods A total of 237 samples from 2019 to July 2022 were collected from Chang Gung Memorial Hospital, including 42 samples previously subjected to SBT sequencing for 4-digit HLA analysis. NGS was performed for 5 whole genes (HLA-A/B/C/DQA1/DPA1) and 3 near-whole genes (HLA-DRB1/DQB1/DPB1; excluding exon 1 and part of intron 1) by using the AllType NGS kit (One Lambda), Illumina MiSeq platform, and Type Steam Visual NGS analysis software (One Lambda). Results Our validation process comprised 34 NGS runs and 237 samples. In total, 42 samples were analyzed with an overall accuracy and precision of 100% and 100% reproducibility. The overall ambiguity rate was 0% in HLA-A/B/C compared with 56.9% for SBT. Two discrepant alleles of HLA-A and DRB1 were noted in NGS and Sanger sequencing. In accordance with additional SBT exon analyses, one of the results was corrected according to the NGS results. Conclusion NGS HLA typing is a high-throughput approach with high accuracy and precision and a low ambiguity and is promising for use in clinical HLA laboratories.

Association of IFNAR2 rs2236757 and OAS3 rs10735079 Polymorphisms with Susceptibility to COVID-19 Infection and Severity in Palestine.

The clinical course and severity of COVID-19 vary among patients. This study aimed to investigate the potential correlation between the gene polymorphisms of the interferon receptor (IFNAR2) rs2236757 and oligoadenylate synthetase 3 (OAS3) rs10735079 with the risk of COVID-19 infection and its severity among Palestinian patients. The study was conducted between April and May 2021 on 154 participants who were divided into three groups: the control group (RT-PCR-negative, n = 52), the community cases group (RT-PCR-positive, n = 70), and the critically ill cases (ICU group; n = 32). The genotyping of the investigated polymorphisms was performed using amplicon-based next-generation sequencing. The genotypes distribution for the IFNAR2 rs2236757 was significantly different among the study groups (P = 0.001), while no statistically significant differences were found in the distribution of genotypes for the OAS3 rs10735079 (P = 0.091). Logistic regression analysis adjusted for possible confounding factors revealed a significant association between the risk allele rs2236757A and critical COVID-19 illness (P < 0.025). Among all patients, those who carried the rs2236757GA were more likely to have a sore throat (OR, 2.52 (95% CI 1.02-6.24); P = 0.011); the presence of the risk allele rs2236757A was associated with an increased risk to dyspnea (OR, 4.70 (95% CI 1.80-12.27); P < 0.001), while the rs10735079A carriers were less likely to develop muscle aches (OR, 0.34 (95% CI 0.13-0.88); P = 0.0248) and sore throat (OR, 0.17 (95% CI 0.05-0.55); P < 0.001). In conclusion, our results revealed that the rs2236757A variant was associated with critical COVID-19 illness and dyspnea, whereas the rs10735079A variant was protective for muscle aches and sore throat.

Ultra-Fast Amplicon-Based Next-Generation Sequencing in Non-Squamous Non-Small Cell Lung Cancer.

The number of molecular alterations to be tested for targeted therapy of non-squamous non-small cell lung cancer (NS-NSCLC) patients has significantly increased these last few years. The detection of molecular abnormalities is mandatory for the optimal care of advanced or metastatic NS-NSCLC patients, allowing targeted therapies to be administrated with an improvement in overall survival. Nevertheless, these tumors develop mechanisms of resistance that are potentially targetable using novel therapies. Some molecular alterations can also modulate the treatment response. The molecular characterization of NS-NSCLC has to be performed in a short turnaround time (TAT), in less than 10 working days, as recommended by the international guidelines. In addition, the origin of the tissue biopsies for genomic analysis is diverse, and their size is continuously decreasing with the development of less invasive methods and protocols. Consequently, pathologists are being challenged to perform effective molecular technics while maintaining an efficient and rapid diagnosis strategy. Here, we describe the ultra-fast amplicon-based next-generation sequencing (NGS) workflow used in daily routine practice at diagnosis for NS-NSCLC patients. We showed that this system is able to identify the current molecular targets used in precision medicine in thoracic oncology in an appropriate TAT.