Targeted Next-generation Sequencing Assay Research Articles

The Advantage of Targeted Next-Generation Sequencing over qPCR in Testing for Druggable EGFR Variants in Non-Small-Cell Lung Cancer.

The emergence of targeted therapies in non-small-cell lung cancer (NSCLC), including inhibitors of epidermal growth factor receptor (EGFR) tyrosine kinase, has increased the need for robust companion diagnostic tests. Nowadays, detection of actionable variants in exons 18-21 of the EGFR gene by qPCR and direct DNA sequencing is often replaced by next-generation sequencing (NGS). In this study, we evaluated the diagnostic usefulness of targeted NGS for druggable EGFR variants testing in clinical NSCLC material previously analyzed by the IVD-certified qPCR test with respect to DNA reference material. We tested 59 NSCLC tissue and cytology specimens for EGFR variants using the NGS 'TruSight Tumor 15' assay (Illumina) and the qPCR 'cobas EGFR mutation test v2' (Roche Diagnostics). The sensitivity and specificity of targeted NGS assay were evaluated using the biosynthetic and biological DNA reference material with known allelic frequencies (VAF) of EGFR variants. NGS demonstrated a sufficient lower detection limit for diagnostic applications (VAF < 5%) in DNA reference material; all EGFR variants were correctly identified. NGS showed high repeatability of VAF assessment between runs (CV% from 0.02 to 3.98). In clinical material, the overall concordance between NGS and qPCR was 76.14% (Cohen's Kappa = 0.5933). The majority of discordant results concerned false-positive detection of EGFR exon 20 insertions by qPCR. A total of 9 out of 59 (15%) clinical samples showed discordant results for one or more EGFR variants in both assays. Additionally, we observed TP53 to be a frequently co-mutated gene in EGFR-positive NSCLC patients. In conclusion, targeted NGS showed a number of superior features over qPCR in EGFR variant detection (exact identification of variants, calculation of allelic frequency, high analytical sensitivity), which might enhance the basic diagnostic report.

Development of custom amplicon-based test systems for detecting KRAS, NRAS, and BRAF gene mutations in colorectal cancer using next-generation sequencing (NGS).

e15061 Background: Polymerase chain reaction (PCR)-based mutation diagnostics in colorectal cancer is widely available. However, PCR has limitations in identifying rare mutations and precise mutation coordinates. Targeted sequencing, though promising, often incurs high costs and longer research durations, demanding higher DNA sample quality. Our study demonstrates the benefits of using a customized amplicon test system for diagnosing somatic mutations in tumor tissue, including detecting rare mutations not captured by PCR, requiring less input biomaterial, and similar research costs. Methods: A targeted NGS assay system was developed using region-specific primers for KRAS (exons 2, 3, and 4), NRAS (exons 2, 3, and 4), and BRAF (exon 15). Library preparation involved a three-step PCR process: Target PCR incorporating Illumina overhang adapter sequences, Index PCR introducing multiplexing indices and sequencing adapters, and PCR cleanup using magnetic beads. Sequencing utilized MiSeq v2 reagents with paired 300‐bp reads, generating high-quality, full-length reads. Validation included re-testing known samples. Tumor cell percentages in FFPE specimens were determined, and DNA was extracted using the QIAamp DNA FFPE Tissue Kit. Data analysis utilized proprietary software. Results: Out of 1234 samples, 1133 were tested, with mutations detected in 685 samples (60.45%). KRAS mutations were found in 548 (48.36%), NRAS mutations in 40 (3.5%), and BRAF mutations in 88 (7.7%) samples. Double mutations were observed in 9 samples (0.79%). Data on rare and double mutations are presented in the table. Conclusions: The developed test system accurately identifies essential mutations in colorectal cancer, including rare and potentially clinically significant variants. The required DNA amount ranged from 10 to 30 ng in 5 μl, nearly ten times less than well-known commercial PCR test systems like COBAS (Roche) and therascreen (QIAGEN). The cost of the study is comparable to PCR with a minimum study duration of 4 days. [Table: see text]

Exploratory biomarker analysis in the phase III L-MOCA study of olaparib maintenance therapy in patients with platinum-sensitive relapsed ovarian cancer.

The prospective phase III multi-centre L-MOCA trial (NCT03534453) has demonstrated the encouraging efficacy and manageable safety profile of olaparib maintenance therapy in the Asian (mainly Chinese) patients with platinum-sensitive relapsed ovarian cancer (PSROC). In this study, we report the preplanned exploratory biomarker analysis of the L-MOCA trial, which investigated the effects of homologous recombination deficiency (HRD) and programmed cell death ligand 1 (PD-L1) expression on olaparib efficacy. HRD status was determined using the ACTHRD assay, an enrichment-based targeted next-generation sequencing assay. PD-L1 expression was assessed by SP263 immunohistochemistry assay. PD-L1 expression positivity was defined by the PD-L1 expression on ≥ 1% of immune cells. Kaplan-Meier method was utilised to analyse progression-free survival (PFS). This exploratory biomarker analysis included 225 patients and tested HRD status [N = 190; positive, N = 125 (65.8%)], PD-L1 expression [N = 196; positive, N = 56 (28.6%)], and BRCA1/2 mutation status (N = 219). The HRD-positive patients displayed greater median PFS than the HRD-negative patients [17.9 months (95% CI: 14.5-22.1) versus 9.2 months (95% CI: 7.5-13.8)]. PD-L1 was predominantly expressed on immune cells. Positive PD-L1 expression on immune cells was associated with shortened median PFS in the patients with germline BRCA1/2 mutations [14.5 months (95% CI: 7.4-18.2) versus 22.2 months (95% CI: 18.3-NA)]. Conversely, positive PD-L1 expression on immune cells wasassociated with prolonged median PFS in the patients with wild-type BRCA1/2 [20.9 months (95% CI: 13.9-NA) versus 8.3 months (95% CI: 6.7-13.8)]. HRD remained an effective biomarker for enhanced olaparib efficacy in the Asian patients with PSROC. Positive PD-L1 expression was associated with decreased olaparib efficacy in the patients with germline BRCA1/2 mutations but associated with improved olaparib efficacy in the patients with wild-type BRCA1/2. NCT03534453. Registered at May 23, 2018.

Abstract GS03-10: Allosteric PI3K-alpha inhibition overcomes on-target resistance to orthosteric inhibitors mediated by secondary PIK3CA mutations

Abstract Background: PIK3CA mutations occur in ~40% of HR-positive breast cancers, where alpelisib, an orthosteric PI3Kα inhibitor, is FDA-approved in combination with fulvestrant. Although prior studies have identified potential resistance mechanisms, such as PTEN loss, clinical acquired resistance to orthosteric PI3Kα inhibitors and the role of next-generation allosteric PI3Kα inhibitors remain poorly understood. Methods: To identify on-target and off-target alterations potentially mediating resistance to PI3Kα inhibitors, we used a targeted next-generation sequencing assay (Guardant360; Guardant Health) to analyze ctDNA in serially collected plasma samples from 32 patients with PIK3CA-mutated advanced HR-positive, HER2-negative breast cancer treated with alpelisib and inavolisib. In addition, we performed whole exome sequencing (WES) of 100 tissue samples collected from 8 autopsy series from patients with metastatic, PIK3CA-mutant HR-positive, HER2-negative breast cancer previously treated with PI3Kα inhibitors. Acquired alterations were prioritized through a combination of structural modeling and free-energy perturbation simulation and validated in genomically engineered PIK3CA mutant breast cancer cell lines T47D (PIK3CA H1047R-mutant) or MCF7 (PIK3CA E545K-mutant). Results: We observed that 50% of patients acquire genomic alterations within the PI3K-pathway, including PTEN loss and activating AKT1 mutations. Notably, while secondary PIK3CA mutations were previously reported to increase sensitivity to PI3Ka-inhibitors, we identified emergent secondary resistance mutations in PIK3CA that alter the inhibitor binding pocket including PIK3CA Q859K and PIK3CA W780R. Some mutations had differential effects on PI3Ka-selective vs. pan-PI3K inhibitors, but resistance induced by all mutations could be overcome by the novel allosteric pan-mutant-selective PI3Ka-inhibitor RLY-2608. Conclusion: In one of the largest patient cohorts analyzed to date, this study defines the clinical landscape of acquired resistance to PI3Ka inhibitors. Genomic alterations within the PI3K pathway represent a major mode of resistance and identify a novel class of secondary PIK3CA resistance mutations that can be overcome by an allosteric PI3Ka inhibitor. Together, these findings provide insights to guide strategies to overcome resistance in PIK3CA-mutated cancers. Citation Format: Andreas Varkaris, Ferran Fece de la Cruz, Elizabeth Martin, Bryanna Nordern, Nicholas Chevalier, Ignaty Leshchiner, Anastasia Stavridi, Janice Kim, Alkistis Papatheodoridi, Hakan Gunaydin, Brian Danysh, Laxmi Parida, Ioannis Sanidas, Yongli Ji, Kayao Lau, Gerburg Wulf, Aditya Bardia, Laura Spring, Steven Isakoff, Jochen Lennerz, Levi Pierce, Ermira Pazolli, Gad Getz, Ryan Corcoran, Dejan Juric. Allosteric PI3K-alpha inhibition overcomes on-target resistance to orthosteric inhibitors mediated by secondary PIK3CA mutations [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr GS03-10.

Abstract 6570: HLA genotyping and HLA-based clinical trial matching using MSK-IMPACT, a targeted next-generation sequencing assay

Abstract Purpose: Performing tumor next-generation sequencing (NGS) and human leukocyte antigen (HLA) typing in a single test can maximize the likelihood of matching patients with cancer to clinical trials. We investigated the utility of a clinical-grade NGS assay for this purpose. Methods: HLA class I genotypes were determined on an investigational basis by MSK-IMPACT (FDA-authorized hybrid-capture, tumor and matched normal DNA-based NGS) using POLYSOLVER for patients with cancers of any histology between March 2014 and September 2023. Patient HLA genotype matches for phase I clinical trials were identified; for a subset of patients, concordance between HLA genotyping was compared to a CLIA-certified laboratory test. Results: 60,565 patients successfully underwent complete class I HLA genotyping (two alleles each of HLA-A, HLA-B, and HLA-C). The median age at diagnosis was 64 years old and most patients were female (55%) and white (76%). The most common genotypes were HLA-A*02:01 (42%, n=25,457), HLA-C*04:01 (28%, n=17,274), HLA-A*01:01 (25%, n=14,867), HLA-C*07:01 (24%, n=14,538), HLA-A*03:01 (21%, n=12,668), HLA-C*07:02 (21%, n=12,493), and HLA-B*07:02 (16%, n=9,787). Most patients (96%, n=58,287) were HLA genotype eligible [HLA-A*02:01 (n=28), HLA-A*11:01 (n=3), HLA-A*01:01 (n=1), and HLA-C*07:02 (n=1)] for ≥1 of 33 active early phase adoptive T cell therapy or T cell receptor bispecific trials on Clinicialtrials.gov. 280 patients with HLA class I matches were screened for phase I trial candidacy by the MSK phase I group. 117 were candidates for confirmatory HLA and neoantigen testing, of whom 43 patients were enrolled on a trial after additional screening. 72 patients had HLA genotyping both by MSK-IMPACT and an outside CLIA-certified laboratory; 100% (72/72) of these subjects had concordant genotypes. Conclusions: MSK-IMPACT successfully determined class I HLA genotypes in a large, multi-ethnic population of patients. A substantial proportion of patients were identified as potential candidates for HLA-matched trials, supporting local trial enrollment. Citation Format: Monica F. Chen, Michael V. Gormally, Anne Marie Noronha, Kristalla Panageas, Maggie Reynolds, Kaelyn Kohlasch, Bryan Novak, Tatiana Kee-Velez, Nikeysha Clarke, Chrisann Kyi, Claire Friedman, Sandra D'Angelo, Mark G. Kris, Christopher A. Klebanoff, Ronak Shah, Michael Berger, Chaitanya Bandlamudi, Alexander Drilon, Mark T. Donoghue. HLA genotyping and HLA-based clinical trial matching using MSK-IMPACT, a targeted next-generation sequencing assay [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 6570.

Abstract 3493: Read-level methylation pattern extraction for high-multiplex large-scale targeted NGS assay

Abstract The abnormal changes in DNA methylation are linked to the early stages of carcinogenesis. Identifying these epigenetic changes in circulating tumor DNA (ctDNA) can reveal potential biomarkers for the early diagnosis of various cancers. However, analyzing such data poses bioinformatics challenges due to the lack of sensitivity in detecting the low abundance ctDNA signals in biopsy samples, which are often overwhelmed by the complexity of libraries containing hundreds of targeted regions. Read-level methylation analysis holds the promise of more in-depth DNA methylation detection due to the wide coverage and high sensitivity of rare signals. However, this approach is hindered by the absence of a standardized workflow capable of generating interpretable reports suitable for both bench scientists and professional bioinformaticians. Here, we present a bioinformatics workflow that examines next-generation sequencing (NGS) data and characterizes the read-level methylation patterns of amplicons. Compared to other currently available tools, our method is designed to work with high-multiplex, large-scale targeted assays. It effectively eliminates the undesired noise derived from sequencing byproducts such as false CpG calls, dimers, and off-target alignments. Additionally, to accommodate the substantial volume of data generated by state-of-the-art NGS platforms, the workflow enables parallel processing of samples compatible with both cloud-based and on-premises computing resources. This workflow provides a comprehensive per-sample visualization of DNA methylation patterns and reports read-level methylation results in a “pattern-as-a-feature” table. In this table, the occurrence of an amplicon epiallelic haplotype (pattern) for every sample is represented as a “feature column” and is aggregated with all patterns discovered in the experiment. These read-level patterns, along with other information, can be used to develop machine learning algorithms to reiteratively harvest true predictive features and penalize confounding signals in predicting cancer diagnosis. Citation Format: Mingda Jin, Masatomo Kaneko, Steven Cen, Hongtao Li, Wei Guo, Xinyi Zhou, Atsuko Fujihara, Tsuyoshi Iwata, Lorenzo Storino Ramacciotti, Divyangi Paralkar, Giovanni E Cacciamani, Manju Aron, Osamu Ukimura, Inderbir S. Gill, Gangning Liang, Andre L. Abreu, Jeffrey Bhasin, Xiaojing Yang, Xi-Yu Jia. Read-level methylation pattern extraction for high-multiplex large-scale targeted NGS assay [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 3493.

Targeted Next-Generation Sequencing Assay for Direct Detection and Serotyping of Salmonella from Enrichment

In this study, an automated, targeted next-generation sequencing (tNGS) assay to detect and serotype Salmonella from sample enrichments was evaluated. The assay generates millions of reads to detect multiple Salmonella-specific genes and serotype-specific alleles, detecting all Salmonella spp. tested to date, and serotyping 62 common Salmonella serotypes. Accuracy was tested on 291 pure reference cultures (251 Salmonella, 40 non-Salmonella), 21 artificially contaminated poultry carcass rinse samples, and 363 naturally contaminated poultry environmental samples. Among the 291 pure reference cultures, the automated tNGS assay resulted in 100% detection accuracy, 100% serotyping accuracy for the claimed serotypes, and 0% false positives. The limit of detection was estimated at 5 × 104 CFU/mL by testing enumerated cultures of strains representative of six serotypes. In cocontamination studies with mixtures of two serotypes (Enteritidis, Typhimurium, Kentucky, Infantis, and Newport) at a 1:1 ratio, tNGS detected both serotypes with 100% accuracy. The assay demonstrated 100% accuracy in artificially contaminated poultry carcass rinse sample enrichments. Targeted NGS was highly effective in detecting Salmonella in samples collected from poultry production facilities. Results demonstrated that tNGS could detect Salmonella and provide accurate serotyping information consistent with conventional serology. These findings highlight the reliable and efficient performance of a fully automated tNGS Salmonella assay in detecting and identifying Salmonella strains in complex matrices, reducing the time to results from 4 to 5 days required by the traditional isolation and serotyping to 10–12 h for tNGS after primary enrichment.

Targeted next-generation sequencing assay to detect 3 Moraxella spp. directly from bovine ocular swabs.

Infectious bovine keratoconjunctivitis (IBK) is associated with 2 species of Moraxella: M. bovis and M. bovoculi. A third novel Moraxella spp., designated tentatively as M. oculi, has been identified from the eyes of cattle with and without pinkeye. These 3 Moraxella spp. can be found in various combinations within the same clinical sample, making speciation of this genus directly from a sample impossible with Sanger sequencing. Assessing Moraxella diversity found in IBK- and non-IBK-affected cattle eyes, independent of culture, may provide additional information about IBK by avoiding the selectivity bias of culturing. We developed a targeted NGS panel to detect and speciate these 3 Moraxella spp. directly from bovine ocular swabs. Our targeted panel amplifies bacterial essential genes and the 16S-23S ribosomal RNA intergenic spacer region (ITS) of the 3 Moraxella spp. and speciates based on these sequences. Our panel was able to differentiate the 3 species directly from DNA extracted from 13 swabs (6 from healthy animals, 7 from animals with IBK), and every swab except one (clinically healthy eye) had the 3 Moraxella spp. Targeted NGS with sequencing of Moraxella spp. housekeeping genes appears to be a suitable method for speciation of Moraxella directly from ocular swabs.

Measurable Residual FLT3-ITD before Allogeneic Transplant for Acute Myeloid Leukemia

Background: In the past year, multiple studies have demonstrated the drastically increased risk of relapse and death in patients with Acute Myeloid Leukemia (AML) who have persistent FLT3 internal tandem duplication (ITD) mutations detectable in clinical remission by next generation sequencing (NGS). Translating this evidence into a change in clinical practice requires both widely available testing and a clear understanding of the clinical implications of FLT3-ITD detection at defined threshold levels. In the largest of the recent studies (Pre-MEASURE, PMID: 36881031), we performed FLT3-ITD MRD detection in blood DNA collected from 608 patients at the time of first remission (CR1) prior to allogeneic hematopoietic cell transplant (alloHCT). To evaluate cross-assay comparability and the impact of residual disease burden levels, we performed analysis on this cohort using a commercially available FLT3-ITD MRD NGS assay. Methods: Of the 608 patients aged 18 or older from the Pre-MEASURE study who received an alloHCT for FLT3-ITD mutated AML during CR1 at a CIBMTR reporting site in the USA between the years of 2013-2019, patients not experiencing non-relapse mortality and with sufficient DNA from pretransplant blood available were included in this analysis. A commercially available testing kit (IVS, Invivoscribe, San Diego, CA), which can detect FLT3-ITD MRD by NGS for up to 21 patients on one Illumina MiSeq flow cell, was used to establish a workflow following clinical testing standards and validated to detect ITDs down to a variant allele fraction (VAF) of at least 0.005%. Results were compared to those previously reported using an anchored multiplex PCR-based (AMP) targeted NGS assay. Overall survival (OS) and cumulative incidence of relapse were estimated with the day of transplant as time 0 using Kaplan-Meier estimation (log-rank tests) and Cox proportional hazards models. Results: A total of 451 patients were included in this study, of which 173 (38%) experienced relapse (median: 5.2 months; range 0.7-52.1) and 133 (29%) died (median: 10.7 months; range 2-53.8) post-alloHCT. The IVS assay identified 232 FLT3-ITD variants with a median VAF of 0.005% (range 0.0002-44%) and length of 51bp (range 5-228). IVS positive patients had a median of 1 FLT3-ITD variant (range 1-15) and median maximum VAF of 0.01% (range 0.0003-44%). Utilizing the same VAF cutoff of 0.01% for MRD positivity for the IVS test as used in the Pre-MEASURE study, patients testing positive prior to alloHCT exhibited higher rates of relapse (79% vs 31%, p&amp;lt;0.0001) and decreased survival (29% vs 77%, p&amp;lt;0.0001) at 3 years compared to testing negative. These results closely align with those previously reported using the AMP assay (Figure A). The IVS test has a superior limit of detection compared with the AMP test, allowing investigation of alternative VAF thresholds. In total, 151 patients (33.5%) were FLT3-ITD MRD positive by IVS of which only 75 (17%) had VAF ≥0.01%. A threshold-free approach for the IVS test improved the ability to identify patients at risk of relapse, predicting 63% of relapses within 6 months of transplant compared to 43% with the 0.01% cutoff, but resulted in decreased specificity as 42% of all positive patients relapsed within 6 months vs. 57% with the 0.01% VAF cutoff. In multivariable analysis, IVS FLT3-ITD MRD status was associated with both relapse and overall survival (Figure B). Additionally, stratifying patients by their level of residual FLT3-ITD disease burden prior to alloHCT revealed a dose-dependent increase in risk for death (Figure B) and relapse. Any detectable level of residual FLT3-ITD over 0.001% VAF exhibited increased risk, with VAFs ≥0.01% being the highest. Conclusions: In this analysis of patients with AML from the Pre-MEASURE study, we show cross-assay evidence that the detection of residual FLT3-ITD variants in pre-transplant blood during CR1 is associated with significantly increased risk of relapse and death after alloHCT. The highly sensitive assay used in this study could identify ~2/3 of patients who relapsed within 6 months and demonstrated that a dose-dependent correlation between residual FLT3-ITD level and adverse clinical outcomes exists, with VAF ≥0.01% representing the highest risk. This evidence provides strong justification for NGS-based AML MRD clinical testing for persistent FLT3-ITD prior to alloHCT to identify patients at high risk of post-transplant relapse and death.

Evaluation of the Thermo Fisher Oncomine Myeloid MRD DNA Assay on the Ion Torrent Platform

Introduction Malignant myeloid diseases are a group of blood cancers that arise from genetic changes in hematopoietic cells in the bone marrow or peripheral blood. The presence of measurable residual disease (MRD), or detection of abnormal cells in the body following completion of therapy, is associated with a higher risk of disease relapse, and decreased overall survival (Schuurhuis 2018). Next-generation sequencing (NGS) can be leveraged as a high-sensitivity, minimally invasive method for detection of MRD. The Ion Torrent Oncomine Myeloid MRD Assay (Myeloid MRD) is a targeted NGS assay designed for the detection of single nucleotide variants (SNVs) and insertions/deletions in a curated selection of clinically relevant myeloid disease-related genes at low limits of detection. Assay performance was evaluated using normal and diseased clinical blood and bone marrow samples and NGS reference materials. Methods The Myeloid MRD DNA panel targets hotspot regions across 33 genes and uses Ion AmpliSeq HD technology with unique molecular tagging to suppress sequencing artifacts and improve analytical sensitivity. Briefly, DNA was extracted from whole blood or bone marrow samples and 120 ng of nucleic acid was used as input for the assay. The DNA was divided between 2 polymerase chain reactions (PCR), where it served as the template for target amplifications, before combining reaction products by sample. Library preparation followed the standard Ion AmpliSeq HD protocol, where amplicons were partially enzymatically digested, and a second round of amplification was performed using barcoded primers. Following bead purification, the final library was measured by quantitative PCR (qPCR) to inform final library loading onto the sequencer. Six libraries were pooled and sequenced on an Ion 550 chip using the Ion GeneStudio S5 System. Primary and secondary analyses were performed using the Torrent Suite software, and results were exported to the Ion Reporter software for variant calling. From the variant calling results, a probit model was utilized to determine the variant allele frequency (VAF) at which the assay achieved 90% power to call an expected variant, defining the limit of detection (LoD). Other parameters evaluated included analytical sensitivity, analytical specificity, positive predictive value (PPV), accuracy, and precision. Results Overall, consistent, high quality on-target reads were observed across 22 sequencing runs with a median Ion Sphere Particle (ISP) loading of 90%, usable sequence of 59%, and over 130 million total reads per chip. When evaluating individual samples according to the vendor-recommended number of mapped reads (&amp;gt; 10 million), 98.3% of samples tested passed quality control (QC). Additional sample QC metrics established during assay validation included thresholds of &amp;gt; 80% reads on-target, &amp;gt; 80% uniformity of base coverage, and a mean read length of at least 80 base pairs. The estimated LoD for the assay was 0.1% VAF for small variants (SNVs, insertions/deletions).Above the LoD, the assay demonstrated 96.03% sensitivity, 99.89% accuracy of base-calling, 100% specificity, and 98.83% PPV.Additionally,a comparison was performed usingmatched whole blood and bone marrow samples collected from patients with acute myeloid leukemia (AML) to evaluate the concordance of variant calling. It was determined that the same variants were identified across both sample types, although at higher allele frequency in bone marrow compared to whole blood. Conclusion This evaluation of the Myeloid MRD assay demonstrates that it is a precise and accurate assay with sensitivity that is acceptable for MRD analysis. Notably, variant detection was concordant between whole blood and bone marrow sample types collected from AML patients, with bone marrow providing improved sensitivity for low-frequency variant detection. The user-friendly workflow and integrated informatics pipeline offer opportunities for streamlined testing and interpretation of results. The Ion Torrent Myeloid MRD DNA assay is a powerful new tool for MRD detection across a growing myeloid disease target landscape.

Validation of targeted next-generation sequencing of cell-free DNA from archival cerebrospinal fluid specimens for the detection of somatic variants in cancer involving the leptomeninges: Cytopathologic and radiographic correlation.

Leptomeningeal metastases occur across multiple solid and lymphoid cancers, and patients typically undergo cytopathologic assessment of cerebrospinal fluid (CSF) in this setting. For patients diagnosed with metastatic cancer, the detection of actionable somatic mutations in CSF can provide clinically valuable information for treatment without the need for additional tissue collection. The authors validated a targeted next-generation sequencing assay for the detection of somatic variants in cancer (OncoPanel) on cell-free DNA (cfDNA) isolated from archival CSF specimens in a cohort of 25 patients who had undergone molecular testing of a prior tumor specimen. CSF storage time and volume had no impact on cfDNA concentration or mean target coverage of the assay. Previously identified somatic variants in CSF cfDNA were detected in 88%, 50%, and 27% of specimens diagnosed cytologically as positive, suspicious/atypical, and negative for malignancy, respectively. Somatic variants were identified in 81% of CSF specimens from patients who had leptomeningeal enhancement on magnetic resonance imaging compared with 31% from patients without such enhancement. These data highlight the stability of cfDNA in CSF, which allows for cytopathologic evaluation before triage for next-generation sequencing assays. For a subset of cases in which clinical suspicion is high but cytologic or radiographic studies are inconclusive, the detection of pathogenic somatic variants in CSF cfDNA may aid in the diagnosis of leptomeningeal metastases.

Abstract 4294: Bridging the gap between targeted NGS and FISH gene-level CNV detection capabilities in hematologic malignancies

Abstract Background: Copy Number Variations (CNVs) are prominent features of cancer cells. From a clinical standpoint, their accurate detection at a low cost is a priority. With regular increases in the number of markers to be tested, the cost effectiveness and practicality of gold standard techniques like Fluorescence In Situ Hybridization (FISH) are slowly decreasing. Cost-efficient Next Generation Sequencing (NGS) targeted gene panels can be scaled up but accurately detecting CNVs from the resulting data remains challenging. We demonstrate large amounts of data and machine learning can help bridge the gap between the two techniques. Methods: We collected the sequencing data of 6,277 patients tested using a custom amplicon based NGS assay designed to detect somatic alterations in 297 hematological cancer relevant genes such that at least one concurrent FISH test was also performed. FISH results were used to infer the gain, loss, or normality information for each corresponding gene. The annotated genes were then used to curate a training set by extracting 20 features per gene from the alignment results. A 3-class random forest classifier was trained using this dataset. The selected model was evaluated on a distinct set of 2,738 patients. Results: Evaluation results are provided in Table 1 for 8 genes for which the FISH probe used to infer the gain, loss, or normality information directly spanned the gene region. The predicted CNVs are almost a perfect match with FISH for 6 of these genes with a limit of detection at 20% abnormal cells. In most cases, the model reduces discordant calls by over 50% compared to using existing CNV detection software only. Conclusion: We show the CNV detection capabilities of a targeted NGS assay can closely match the gold-standard FISH technique by analytically correcting the biases introduced by the targeting procedures. The model presented here is used to detect CNVs in ALL patients after a successful formal validation in our laboratory. Table 1. Evaluation results. Gene FISH Positive Cases (Gain/Loss) FISH Negative Cases (Normal) All FISH Cases Total Concordant Sensitivity Total Concordant Specificity Total Concordant Accuracy ATM 72 72 100.00% 641 629 98.13% 713 701 98.32% CBFB 23 22 95.65% 517 506 97.87% 540 528 97.78% EGR1 171 169 98.83% 1,541 1,538 99.81% 1,712 1,707 99.71% KMT2A 27 25 92.59% 474 472 99.58% 501 497 99.20% MET 113 113 100.00% 1,593 1,582 99.31% 1,706 1,695 99.36% NF1 15 15 100.00% 908 908 100.00% 923 923 100.00% TERT 10 10 100.00% 1,723 1,709 99.19% 1,733 1,719 99.19% TP53 76 73 96.05% 1,567 1,556 99.30% 1,643 1,629 99.15% Citation Format: Christophe N. Magnan, Hyunjun Nam, Shashikant Kulkarni, Segun C. Jung. Bridging the gap between targeted NGS and FISH gene-level CNV detection capabilities in hematologic malignancies. [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 4294.

Clinical Targeted Next-Generation Panel Sequencing Reveals MYC Amplification Is a Poor Prognostic Factor in Osteosarcoma.

Osteosarcoma risk stratification, on the basis of the presence of metastatic disease at diagnosis and histologic response to chemotherapy, has remained unchanged for four decades, does not include genomic features, and has not facilitated treatment advances. We report on the genomic features of advanced osteosarcoma and provide evidence that genomic alterations can be used for risk stratification. In a primary analytic patient cohort, 113 tumor and 69 normal samples from 92 patients with high-grade osteosarcoma were sequenced with OncoPanel, a targeted next-generation sequencing assay. In this primary cohort, we assessed the genomic landscape of advanced disease and evaluated the correlation between recurrent genomic events and outcome. We assessed whether prognostic associations identified in the primary cohort were maintained in a validation cohort of 86 patients with localized osteosarcoma tested with MSK-IMPACT. In the primary cohort, 3-year overall survival (OS) was 65%. Metastatic disease, present in 33% of patients at diagnosis, was associated with poor OS (P = .04). The most frequently altered genes in the primary cohort were TP53, RB1, MYC, CCNE1, CCND3, CDKN2A/B, and ATRX. Mutational signature 3 was present in 28% of samples. MYC amplification was associated with a worse 3-year OS in both the primary cohort (P = .015) and the validation cohort (P = .012). The most frequently occurring genomic events in advanced osteosarcoma were similar to those described in prior reports. MYC amplification, detected with clinical targeted next-generation sequencing panel tests, is associated with poorer outcomes in two independent cohorts.

Prevalence and Impact of Clonal Hematopoiesis in Therapy Related Myeloid Neoplasms Occurring in the Context of Low-Grade Follicular Lymphoma Treated with Radioisotope Therapy

Background: Clonal hematopoiesis (CH) is defined by the acquisition of somatic mutations (MT) in hematopoietic stem cells with the propensity to expand over time. While CH is ubiquitous with aging, context-specific development of CH is heterogeneous and dependent on clonal pressures. Retrospective series have documented the role of CH in the development of therapy-related myeloid neoplasms (t-MN). In recent times, radioisotope-based therapies have advanced cancer management. Ibritumomab tiuxetan (Zevalin) is a radioimmunoconjugate approved for the treatment of relapsed low-grade follicular lymphoma (FL) and more recently, lutetium Dotatate has been used in neuroendocrine tumors and prostate cancer. Reports of accelerated t-MN with these therapies have generated concern. We studied a large cohort of relapsed FL patients treated with Zevalin to assess the prevalence and impact of CH. Method: After IRB approval, we identified patients with FL treated with Zevalin who had stored DNA for CH assessment at any time point before or after therapy. DNA was extracted from mononuclear cells and subjected to a customized, targeted next-generation sequencing assay covering 220 CH-related genes (~ 1000x). Bone marrow (BM) sequencing was carried out in a subset at t-MN diagnosis. We compared clinical characteristics, MT patterns, variant allele fraction (VAF), and outcomes of those with and without t-MN. All statistical calculations were performed using R 4.0.1. Results: Fifty-eight patients with relapsed FL were included, with a median age of 48.5 (IQR: 42-61.8) years, and 23 (40%) were females. The median follow-up duration was 17.8 (IQR: 15.7-21.9) years. At the last follow-up, 14 (24%) patients developed t-MN, and 23 (40%) deaths were documented. The median latency to t-MN after Zevalin exposure was 8.8 (IQR: 6.7-12.6) years, and the median overall survival (OS) after t-MN diagnosis was 0.9 (IQR: 0.24-2.2) years. There were no significant differences in baseline demographics, FL stage, grade, FLIPI scores, and the number of prior therapies (median, 4 in both groups) between the t-MN vs. non-t-MN groups (all p>0.5; Table 1). At the time of Zevalin administration, all patients had a normal karyotype, and 46% (17/37) had prevalent CH, with 60% (35/58) having CH at any time point. In total, 97 variants were identified, 27 (28%) in t-MN and 70 (72%) in the non-t-MN group. Common variants seen in the t-MN group included PPM1D (n=7, 28%), DNMT3A (n=3, 11%), and TP53 (n=2, 8%), and in the non-t-MN group included DNMT3A (n=16, 23%), PPM1D (n=15, 21%), KMT2D (n=7, 10%), and TP53 (n=6, 9%). The prevalence of CH was not significantly different between the t-MN (64%) and non-t-MN (59%) groups (p=0.97). However, the t-MN group had a higher CH diversity (p=0.03), with a trend towards higher median VAF for driver MTs (26% vs. 2%, p=0.09) and a trend towards higher numbers of co-mutations (89% vs. 54%, p=0.06). The presence of CH prior to Zevalin therapy or post-therapy was not associated with a higher risk of t-MN (p=0.6 and 0.73, respectively). No other risk factors, including CH or biological CH groupings, were associated with t-MN. Paired pre- and post- Zevalin exposure samples were available in 24 patients (37 MTs in 16 patients). Among 15 evaluable patients, 10 (67%) had CH at both time points and 5 (33%) had CH at the second time point only. The median annual change in VAF for DNMT3A (n=15) was 2% (range: -8% to 14%), and for DDR MTs (n=8) was 4.5% (range: 2% to 19%) (Figure 1). Four patients developed t-MN in this subset, 3 with CH and 1 without. Thirteen of 14 evaluable patients who developed t-MN (7 each with t-MDS and t-AML) had an abnormal karyotype; 7 (50%) monosomal, 4 with chromosome 17 abnormalities. All 7 sequenced t-MN BM samples demonstrated new clones (n=15) at t-MN diagnosis. Common MT gained at t-MN transformation were TP53 (n=5, 33%), PPM1D and SETBP1 (both n=3, 20%), with 3 patients with biallelic TP53 inactivations. Conclusion: We demonstrate the high prevalence of CH (60%) and t-MN (24%) in this heavily pretreated FL population who received Zevalin therapy. The spectrum of CH differed from age-related CH, with a high prevalence of MTs involving the DDR pathway, with no spliceosomal and a paucity of signaling MT, including at t-MN diagnosis. The median time between FL diagnosis to t-MN was 8 years and the mere presence of CH did not correlate with t-MN, highlighting the need to determine other mechanisms of clonal progression. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Development and Assessment of a Novel Whole-Gene-Based Targeted Next-Generation Sequencing Assay for Detecting the Susceptibility of Mycobacterium tuberculosis to 14 Drugs.

Targeted next-generation sequencing (tNGS) has emerged as an alternative method for detecting drug-resistant tuberculosis (DR-TB). To provide comprehensive drug susceptibility information and to address mutations missed by available commercial molecular diagnostics, we developed and evaluated a tNGS panel with 22 whole-gene targets using the Ion Torrent platform to predict drug resistance to 14 drugs, namely, rifampicin (RIF), isoniazid (INH), ethambutol (EMB), pyrazinamide (PZA), moxifloxacin (MFX), levofloxacin (LFX), amikacin (AMK), capreomycin (CM), kanamycin (KM), streptomycin (SM), bedaquiline (BDQ), clofazimine (CFZ), linezolid (LZD), and delamanid (DLM). We selected 50 and 35 Mycobacterium tuberculosis isolates with various DR profiles as the training set and the challenge set, respectively. Comparative variant analyses of the DR genes were performed using Sanger sequencing and whole-genome sequencing (WGS). Phenotypic drug susceptibility testing (pDST) results were used as gold standards. Regarding the limit of detection, the tNGS assay detected 2.9 to 3.8% minority variants in 4% mutant mixtures. The sensitivity and specificity of tNGS were 97.0% (95% confidence interval [CI] = 93.1 to 98.7%) and 99.1% (95% CI = 97.7 to 99.7%), respectively. The concordance of tNGS with pDST was 98.5% (95% CI = 97.2 to 99.2%), which was comparable to that of WGS (98.7%, 95% CI = 97.4 to 99.3%) and better than that of Sanger sequencing (96.9%, 95% CI = 95.3 to 98.0%). The agreement between tNGS and pDST was almost perfect for RIF, INH, EMB, MFX, LFX, AMK, CM, KM, SM, BDQ, and LZD (kappa value = 0.807 to 1.000) and substantial for PZA (kappa value = 0.791). Our customized novel whole-gene-based tNGS panel is highly consistent with pDST and WGS for comprehensive and accurate prediction of drug resistance in a strengthened and streamlined DR-TB laboratory program. IMPORTANCE We developed and validated a tNGS assay that was the first to target 22 whole genes instead of regions of drug resistance genes and comprehensively detected susceptibility to 14 anti-TB drugs, with great flexibility to include new or repurposed drugs. Notably, we demonstrated that our custom-designed Ion AmpliSeq TB research panel platform had high concordance with pDST and could significantly reduce turnaround time (by approximately 70%) to meet a clinically actionable time frame. Our tNGS assay is a promising DST solution for providing needed clinical information for precision medicine-guided therapies for DR-TB and allows the rollout of active pharmacovigilance.

Targeted Next-Generation Sequencing for Comprehensive Testing for Selected Vector-Borne Pathogens in Canines.

The standard for detecting vector-borne pathogens is real-time PCR (rtPCR). However, this requires many individual tests to obtain an accurate diagnosis. The purpose of this study was to develop and validate a targeted next-generation sequencing (NGS) assay for vector-borne pathogens. Pathogen target regions were amplified via PCR using two primer pools that were developed in conjunction with ThermoFisher Scientific, and barcoded DNA libraries were prepared and sequenced with the Ion Torrent S5 system. Data were assembled using SPAdes and mapped to a reference file containing sequences from the pathogens. The raw reads were analyzed to confirm the results. Test feasibility and analytical specificity were evaluated with type strains or validated positive clinical samples from dogs. The analytical sensitivity of the method was compared to Ct values obtained by rtPCR testing. Diagnostic sensitivity and specificity were assessed with a set of known positive and negative clinical samples based on rtPCR testing. Positive and negative percent agreements and Cohen’s kappa were calculated. The primer sets were specific for the intended targets, based on sequence analysis of the amplified products, and the method detected 17 different pathogens. Analytical sensitivity was equivalent to an rtPCR Ct value of approximately 35–36. The positive percent agreement was 92%, and the negative percent agreement was 88%. Cohen’s kappa was 0.804, which indicates almost perfect agreement between the rtPCR assays and the targeted NGS assay. Using a targeted method reduces the costs associated with NGS sequencing and allows for a 2–3 day turn-around time, making this a viable method for detection of vector-borne pathogens in canine whole blood samples.

High-Throughput Next-Generation Sequencing of the Kidd Blood Group: Unexpected Antigen Expression Properties of Four Alleles and Detection of Novel Variants

Background: The blood supply for patients with foreign ethnic backgrounds can be challenging, as they often have blood group and HPA patterns that differ from the variants prevalent in the German population. In addition, hemoglobinopathies requiring regular blood transfusion may be more common in such populations. High-throughput genotyping tests can facilitate the identification of the most compatible blood products, thereby reducing the risk of transfusion reactions. The present study reports the results of a molecular study for the Kidd (JK) blood group. Allele frequencies and antigen prevalence data are presented for >8,000 individuals of various origins. Material and Methods: More than 8,000 blood donors were genotyped for 22 blood group systems and 5 HPA genes using an amplicon-based next-generation sequencing (NGS) approach. As part of the test system, we focused on the JK system in more detail. Double-ARMS PCR analysis was performed for the haplotype phasing of the JK1/JK2 and two more common synonymous polymorphisms. We performed transcript analysis to detect potential alternative splice products. For a subset of samples, a comparison between serotype and red cell genotype was conducted. Allele frequencies were determined for geographically different panels of individuals. Results: We successfully genotyped the JK blood group for 99.6% of the samples. Haplotype phasing revealed 96 different alleles. For several alleles that carry one of the synonymous SNVs c.588A>G and c.810G>A, we could not confirm the reported JK phenotypes. We found a higher frequency of JK:1 alleles for all populations except Iraqis. JK*01W.01 alleles were more common in the Asian groups and sub-Saharan Africans. A variant of the allele JK*02N.01 was present exclusively in Southeast Asians. Conclusion: Genotyping for JK antigens with a targeted NGS assay can easily be performed in routine. The interpretation that c.588A>G leads to a weak phenotype and c.810G>A to a null phenotype is questionable. IDs as well as the descriptions of alleles carrying these SNVs should be revised in the ISBT JK table.

PAXgene Fixation for Pancreatic Cancer: Implications for Molecular and Surgical Pathology.

Genomic profiling of pancreatic cancer using small core biopsies has taken an increasingly prominent role in precision medicine. However, if not appropriately preserved, nucleic acids (NA) from pancreatic tissues are known to be susceptible to degradation due to high intrinsic levels of nucleases. PAXgene fixation (PreAnalytix, Switzerland) represents a novel formalin-free tissue preservation method. We sought to compare the NA and histomorphological preservation of pancreatic cancer tissues preserved with PAXgene-fixed paraffin-embedding (PFPE) and formalin-fixed paraffin-embedding (FFPE). Tissues from 19 patients were obtained prospectively from pancreaticoduodenectomy specimens and evaluated by four gastrointestinal pathologists. The extracted NA were quantified by Nanodrop and Qubit and assessed for quality by qPCR, targeted next-generation sequencing (NGS) assay, and RNA-sequencing. Our results demonstrated that, when assessed blindly for morphological quality, the four pathologists deemed the PFPE slides adequate for diagnostic purposes. PFPE tissues enable greater yields of less fragmented and more amplifiable DNA. PFPE tissues demonstrated significantly improved quality control (QC) metrics in a targeted NGS assay including Median Absolute Pair-wise Difference (MAPD) scores. Our results support the use of PAXgene fixative for the processing of specimens from pancreatic cancers with the potential benefits of improved yields for more amplifiable DNA in low-yield biopsy specimens and its ideal use for amplicon-based NGS assays.

Abstract 2293: Evaluation of multiple myeloma research samples by analysis of B cell heavy and light chain receptors in a single NGS assay

Abstract Introduction: B cell repertoire analysis by next-generation sequencing (NGS) is at the forefront of leukemia and lymphoma research. Some advantages provided by NGS-based techniques include a lower limit-of-detection and simpler paths to standardization compared to other methods. Importantly, in research of post-germinal B cell disorders, such as multiple myeloma (MM), NGS methods allow for the study of clonal lineage based on somatic hypermuation patterns. Current targeted NGS assays require multiple libraries to survey each B cell receptor chain (IGH, IgK, IgL), and this fact is highlighted when initial clonality detection fails due to mutations under primer binding sites. Methods: A B cell pan-clonality panel (Oncomine™ BCR Pan-Clonality Assay) targets the framework 3 (FR3) portion of the variable gene and the joining gene region of heavy- and light-chain loci (IGH, IgK, IgL) for all alleles found within the IMGT database, enabling readout of the complementary-determining region 3 (CDR3) sequence of each immunoglobulin chain. Primers are included to amplify rearrangements involving Kappa deletion element. Reproducibility studies and clonality assessment were conducted using gDNA from a total of 45 MM research samples. All MM cases examined in this work were confirmed clonal via flow cytometry or IHC/ISH in tissue sections. Sequencing and repertoire analyses were performed using the Ion GeneStudio S5 System and Ion Reporter 5.16 analysis software. Results: Clonality assessment of MM research samples show an 93% overall positive detection rate by an assay which combines the IGH, IgK, and IgL chains using published guidelines for clonality assignment. Thirty-four of 45 samples show positive detection of an IGH rearrangement, while 41 of 45 showed positive detection of at least one light chain receptor. Clonality results for this sample set are well correlated with orthogonal data from flow, IHC/ISH, or alternate NGS assays. A clonal lambda light chain was identified in 14 of 16 samples determined to be lambda restricted by flow cytometry. Estimates of somatic hypermutation rates were calculated using the BCR pan-clonality assay. Most MM samples contained somatic hypermutation with 6 of 45 samples showing mutation rates greater than 10%. Lineage analysis, based on somatic hypermuation signatures within each sample, identified 8 of 45 MM samples which contained 5 or more clones in the primary clonal lineage, with one case containing a lineage with 23 clones. Conclusions: These results demonstrate the utility of a novel assay for combined repertoire analysis of B cell receptor heavy and light chains in a single library preparation reaction. We expect this assay to simplify workflow and inclusion of analysis tools such as automated somatic hypermutation rate determination and clonal lineage identification to open new paths for research in B cell disorders. Citation Format: Geoffrey Marc Lowman, Landon Pastushok, Karen Mochoruk, Wayne Hill, Michelle Toro, Loni Pickle, Carolina Gonzalez, Stephanie Ostresh, Shrutii Sarda, Chenchen Yang, Julie Stakiw, Mark Bosch, Hadi Goubran, Ron Geyer, John DeCoteau. Evaluation of multiple myeloma research samples by analysis of B cell heavy and light chain receptors in a single NGS assay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2293.

Abstract 5668: DNA damage response gene mutations and their association with PD-L1 expression in sarcoma and bone tumor

Abstract Background For a long time, the use of immune checkpoint inhibitors(ICIs)has been limited in sarcomas and bone tumors, and is only recommended as second or later line therapy for patients who meet specific requirements such as dMMR/MSI-H. DNA damage response (DDR) pathways aim to protect cells against some acquired genome changes and monitor exogenous or endogenous DNA damage. Studies have reported that genomic instability caused by DDR gene mutations effects on the immune system, and may benefit from ICI treatment. Although some studies have reported that DDR gene mutations in solid tumors such as non-small cell lung cancer and bladder cancer predicted response to ICI and correlated with patient prognosis, reports are lacking in sarcomas and bone tumors. Methods Formalin-fixed, paraffin-embedded tissues and matched blood samples were collected from patients with sarcoma or bone tumor for targeted next-generation sequencing assay at OrigiMed (Shanghai, China), a College of American Pathologists accredited and Clinical Laboratory Improvement Amendments certified laboratory. PD-L1 expression was detected by immunohistochemistry using 22C3 antibody. Results Fifteen patients including 12 male and 3 female with a median age of 22 years were recruited. Among them, 9 patients had bone tumors with a median age of 17 years. PD-L1 was tested in 13 patients and 10 patients were positive.Genetic testing showed that TP53, BRCA1, and CCND3 were the most frequently mutated genes. The analysis of pathways showed that DDR (11/15), cell cycle (7/15), NOTCH (4/15), RTK.RAS (4\15) were the most affected pathways. The median TMB was 1.6 muts/Mb. In DDR genes, TP53 mutations occurred in 8 patients including 2 soft tissue sarcomas and 6 bone tumors. BRCA1 gene fusions occurred in 2 osteosarcoma patients, one is 7-year-old boy who carried 3 BRCA1 fusions with ASIC2, LUZP6 and OXCT1 fusion partners. The boy also carried TP53 germline pathogenic mutations. Another 17-year-old boy carried a BRCA1-TMEM271 fusion, and PTEN and STK11 DDR gene mutations. Among the 11 sarcoma patients with DDR mutations, 8 were PD-L1 positive and 1 was PD-L1 negative. PD-L1 testing was not performed in other 2 cases. Conclusion Our results showed that a proportion of sarcoma and bone tumor patients carried DDR gene mutations, especially in pediatric and adolescent osteosarcoma patients.The majority of sarcoma and bone tumor patients with DDR gene mutations in this cohort were PD-L1 positive. Since DDR gene mutation was associated with favorable response rate to ICIs, patients with DDR gene mutated sarcoma and bone tumor may benefit from ICIs therapy. Citation Format: Fanfei Meng, Qing Zhang, Fei Pang, Xiaoliang Shi. DNA damage response gene mutations and their association with PD-L1 expression in sarcoma and bone tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5668.