cfDNA Next-generation Sequencing Research Articles

Abstract 6079: Comparison of FIT and cell-free DNA analyses for detection of individuals with colorectal cancer in population based screening

Abstract Background The fecal immunochemical test (FIT) is widely used in population based colorectal cancer (CRC) screening programs. Recently, circulating cell-free DNA (cfDNA) analyses have emerged as a new avenue for early cancer detection. The performance of cfDNA methods in comparison with FIT is currently unknown. The present study compared pre-operative cfDNA analyses to FIT for detection of patients with CRC who participated in a population-based screening program. Methods In the Dutch national CRC screening program, individuals aged 55-75 years are biennially invited to perform a single FIT. The database of the Dutch CRC screening program was queried to identify individuals with FIT data who also participated in two cfDNA studies, PLCRC-MEDOCC and PLCRC-PROVENC3 (AACR abstract C. Rubio Alarcón). Sensitivities with 95% confidence intervals (CI) for detecting individuals with CRC were determined for FIT, tumor-informed cfDNA analyses, as well as both tests combined. For FIT, sensitivities were determined at 20 µg and 47 µg hemoglobin (Hb)/g feces positivity cut-offs as these represent the most commonly used international and Dutch cut-offs, respectively. Liquid biopsy analyses were performed using next generation sequencing of cfDNA. Tumor-specific alterations were identified through parallel next generation sequence analysis of resected tumor tissues. Results The query identified 120 individuals with stage I (n=3, 2.5%), stage II (n= 57, 47.5%) and stage III (n=60, 50.0%) CRC who had participated in the Dutch CRC screening program and either PLCRC-MEDOCC or PLCRC-PROVENC3. All FIT samples were collected at a median time of 38 days before diagnosis (IQR 27-112 days). FIT sensitivity for detection of individuals with CRC was 83.3% (100/120 CRCs, 95% CI 75.4-89.5%) at a 20 µg Hb/g feces cut-off and 80.0% (96/120, 95% CI 71.7-86.7%) at a 47 µg Hb/g feces cut-off. Tumor-informed cfDNA analyses detected 75.8% (91/120, 95% CI 67.2-83.2%) of individuals with CRC in this population. The combination of cfDNA analyses and and FIT (20 µg Hb/g feces cut-off) identified almost all individuals with CRCs (119/120, sensitivity 99.2%, 95% CI 97.0-100%). The individual who was missed had a cancer that was a T3N0 microsatellite stable moderately differentiated adenocarcinoma in the ascending colon. Discussion While both FIT and cfDNA analyses identified most CRC cases (75-83%) in this series, both tests also demonstrated a substantial level of complementarity, indicating that in principle combining FIT with cell-free DNA testing would allow to increase sensitivity of CRC screening. Since the cell-free DNA tests used here are tumor-informed, which in real life screening practice is not feasible, it remains to be determined to what extent this result can be reached using non-tumor-informed approaches. Citation Format: Pieter Henk Abraham Wisse, Carmen Rubio-Alarcon, Suzanna J. Schraa, Adria C. Mosquera, Mark Sausen, Remond J. Fijneman, Geraldine R. Vink, Meike de Wit, Jillian Phallen, Victor E. Velculescu, Beatriz Carvalho, Gerrit A. Meijer. Comparison of FIT and cell-free DNA analyses for detection of individuals with colorectal cancer in population based screening [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 6079.

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< 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.

Identification of Potential Genomic Alterations Using Pan-Cancer Cell-Free DNA Next-Generation Sequencing in Patients With Gastric Cancer.

Molecular cancer profiling may lead to appropriate trials for molecularly targeted therapies. Cell-free DNA (cfDNA) is a promising diagnostic and/or prognostic biomarker in gastric cancer (GC). We characterized somatic genomic alterations in cfDNA of patients with GC. Medical records and cfDNA data of 81 patients diagnosed as having GC were reviewed. Forty-nine and 32 patients were tested using the Oncomine Pan-Cancer Cell-Free Assay on the Ion Torrent platform and AlphaLiquid 100 kit on the Illumina platform, respectively. Tier I or II alterations were detected in 64.2% (52/81) of patients. Biomarkers for potential targeted therapy were detected in 55.6% of patients (45/81), and clinical trials are underway. ERBB2 amplification is actionable and was detected in 4.9% of patients (4/81). Among biomarkers showing potential for possible targeted therapy, TP53 mutation (38.3%, 35 variants in 31 patients, 31/81) and FGFR2 amplification (6.2%, 5/81) were detected the most. Next-generation sequencing of cfDNA is a promising technique for the molecular profiling of GC. Evidence suggests that cfDNA analysis can provide accurate and reliable information on somatic genomic alterations in patients with GC, potentially replacing tissue biopsy as a diagnostic and prognostic tool. Through cfDNA analysis for molecular profiling, it may be possible to translate the molecular classification into therapeutic targets and predictive biomarkers, leading to personalized treatment options for patients with GC in the future.

Tissue-agnostic efficacy of trastuzumab deruxtecan (T-DXd) in advanced solid tumors with HER2 amplification identified by plasma cell-free DNA (cfDNA) testing: Results from a phase 2 basket trial (HERALD/EPOC1806).

3014 Background: HER2 ( ERBB2) gene amplification (amp) is a potential therapeutic target beyond breast and gastric cancers. HER2 amp can be detected in plasma cfDNA which may be an alternative to tissue biopsy. HERALD/EPOC1806 was a multicenter, investigator-initiated phase 2 trial of T-DXd for patients with HER2-amplified advanced solid tumors identified by cfDNA testing. Methods: We enrolled adults with advanced solid tumors harboring HER2 amp detected by next-generation sequencing of cfDNA (Guardant360) in the GOZILA study (UMIN000029315). We excluded breast or gastric cancer patients with HER2 overexpression (IHC 3+ or IHC 2+/ISH+). Patients received T-DXd 5.4 mg/kg every 3 weeks until disease progression or unacceptable toxicity. The primary endpoint was investigator-assessed objective response rate (ORR). Results: From December 2019 to January 2022, 4,734 patients were screened by cfDNA in the GOZILA study. Among 252 with HER2 amp, 62 with 16 cancer types were enrolled in HERALD. Median baseline plasma HER2 copy number (CN) was 8.55 (range, 2.4–73.9). All patients but 3 (all with salivary gland cancer) received prior anti-cancer therapy (median, 3 lines; range, 0–8). At a median follow-up of 8.9 months (data cut-off: July 17, 2022), the confirmed ORR was 56.5% (95% CI, 43.3–69.0%), statistically higher than the threshold value of 5%. Responses were observed for 13 cancer types, including KRAS-mutant colorectal (1/3), PIK3CA-mutant endometrial (5/6), and tissue HER2-negative gastric cancers (1/2). Plasma HER2 CN above vs. below the baseline median value did not impact response (ORR: 58.1% vs. 54.8%); however, the clearance vs. persistence of HER2 amp in cfDNA on Cycle 2 Day 1 corresponded to higher response (ORR: 88.0% vs. 22.7%). ORR by independent review was 58.1% (95% CI, 44.8–70.5%), and the disease control rate was 90.3% (95% CI, 80.1–96.4%). Median progression-free survival was 7.0 (95% CI, 4.9–9.7) months, and the median duration of response was 8.8 months (95% CI, 5.8–11.2). Most adverse events were mild to moderate. Interstitial lung diseases occurred in 16 patients (25.8%, G1/G2/G3; 14/1/1). Conclusions: T-DXd achieved a high ORR, durable response with a manageable safety profile in patients with advanced solid tumors and HER2 amp detected in cfDNA. Clinical trial information: JapicCTI-194707 .[Table: see text]

A comparative analysis of next-generation sequencing based on plasma cfDNA and tumor tissue DNA in patients with advanced lung cancer.

e21021 Background: Although liquid biopsy based on plasma cell-free DNA (cfDNA) provides a non-invasive detection method for cancer patients, tissue biopsy is still the gold standard for molecular subtyping. The concordance of these two techniques has been evaluated in certain cohorts. The comparison of plasma cfDNA and tissue DNA NGS ina large Chinese cancer cohort is yet to be analyzed. Methods: We retrospectively reviewed HaploX's genomic sequencing data from July 2021 to December 2022 to assess the concordance between plasma cfDNA and cancer tissue DNA. A total of 589 advanced lung cancer patients with matched tissue and plasma sample were included in the study. Tissue and peripheral blood was collected at the same time during surgical operation or biopsy. Tissue DNA and plasma cfDNA were isolated and prepared for the NGS with commercially available kits. The positive percent agreement (PPA) between plasma cfDNA sequencing and tissue sequencing, the negative percent agreement (NPA), positive predictive value (PPV), negative predictive value (NPV), and overall percent agreement (OPA) were calculated and compared. Results: The positive percent agreement (PPA) of plasma cfDNA sequencing compared with tissue sequencing were 78% (EGFR, 82%; KRAS, 71%; HER2 mutation, 76%; BRAF V600E mutation, 75%; ALK fusion, 74%; RET fusion, 60%; ROS1 fusion,33.3%; MET exon14 skipping, 50%). EGFR mutations included EGFR p.L858R,19del, p.C797S, p.L861Q, p.T790M, KRAS mutations included p.G12X and p.Q61X.， HER2 mutations included gain-of-function mutations；NPA was 92.4%，PPV was 93.8%，NPV was 74.4%，OPA was 84%. Conclusions: The positive mutation detection consistency of plasma cfDNA sequencing and tissue sequencing in advanced lung cancer patients is 78%, indicating that liquid biopsy based on plasma cfDNA is reliable in most advanced lung cancer patients, but there are some limitations in gene fusion and MET exon 14 jumping detection. Liquid biopsy based on plasma cfDNA can meet most clinical genomic testing needs in general, especially when tissue is not available, but physicians need to be more cautious with negative results. Keywords: Liquid biopsy, Next-generation sequencing (NGS), Concordance Analysis, Lung Cancer.

Next-generation sequencing (NGS) of circulating cell-free DNA (cfDNA) in advanced pancreatic neuroendocrine neoplasms (PanNENs).

653 Background: PanNENs represent 1-2% of all pancreatic neoplasms. The genomic landscape derived from PanNEN tumor tissue has been described previously. There are little data detailing the frequency of genetic alterations identified in cfDNA in an advanced PanNEN population, the plasma-tissue concordance of detected alterations, and the clinical utility of cfDNA. Methods: Patients (pts) with metastatic PanNENs underwent collection of cfDNA for NGS using the MSK-IMPACT 505 gene assay between March 2017 and April 2020. Matched tissue based NGS with the FDA authorized MSK-IMPACT gene assay was completed when tumor tissue was available. For some pts, plasma and tumor tissue were sequenced at multiple time points. Clinical actionability of sequence variants was annotated by OncoKB. Clinicopathologic characteristics were extracted, and data are herein reported. Results: 25 unique pts with metastatic PanNENs had 32 plasma samples analyzed. The majority had well differentiated (22/25; 88%), intermediate grade disease (13/25; 52%). 6 (24%) pts had well differentiated high grade disease and 3 (12%) had poorly differentiated neuroendocrine carcinomas. After extraction, median cfDNA yield per sample was 23.98ng (range: 3.2 to 500.1). Mutations were detected in 21(66%) of 32 samples (10 pre systemic therapy, 10 at progression, 12 post response to therapy or while stable on therapy). The most frequently mutated genes occurring in >10% of patients were DAXX (28%), TSC2 (24%), MEN1 (24%), ARID1B (20%), ARID1A (12%) and ATRX (12%). 23 (92%) pts underwent tumor tissue sequencing with MSK-IMPACT with a median time of 6.9 (range: 0.5-33.4) months between tissue collection and time of plasma analysis. NGS of cfDNA identified the most common mutations observed in tumor tissue for: DAXX (5/6; 83%), TSC2 (3/6; 50%), MEN1 (5/12; 42%), ARID1A (3/5; 60%) and ATRX (3/6; 50%). In 21/23 (91%) paired samples, additional mutations not seen in tissue were detected in plasma and included TSC2, TP53, EGFR, VHL, and BRCA2. Potentially actionable mutations were identified in sequenced cfDNA in 8/25 (32%) patients including 4 TSC2 mutations (level 3b), 1 ATM mutation (level 3b), 2 ARID1A mutations (level 4) and 1 KRAS mutation (level 4). One patient who was treated with larotrectinib for an ETV6:NTRK3 fusion detected on tumor sequencing ultimately developed resistance with a NRTK3 G623R alteration identified through sequencing of cfDNA at radiographic disease progression. Conclusions: NGS of cfDNA in metastatic PanNENs, across the spectrum of WHO-defined tumor grade/differentiation, revealed tumor-associated genetic alterations in 66% of plasma samples. Clonal evolution, actionable alterations, and resistance mechanisms can be detected through circulating cfDNA genotyping and may serve as a powerful tool to better understand disease biology of a disease that often changes over time and through therapy.

High Yield of Pleural Cell-Free DNA for Diagnosis of Oncogenic Mutations in Lung Adenocarcinoma

Pleural cytology is currently used to assess targetable mutations in patients with advanced lung adenocarcinoma. However, it is fraught with low diagnostic yield. Can pleural cell-free DNA (cfDNA) be used to assess targetable mutations in lung adenocarcinoma patients with malignant pleural effusions (MPE)? Patients with lung adenocarcinoma MPE were recruited prospectively between January 2017 and September 2021. Oncogenic mutations were assessed by treating providers using pleural fluid cytology or lung cancer biopsies. Pleural and plasma cfDNA were used to assess the mutations using next generation sequencing (NGS). Fifty-four pleural fluid samples were collected from 42 patients. The diagnostic yield to detect oncogenic mutations for pleural cfDNA, pleural cytology, biopsy and plasma cfDNA was 49/54 (90.7%), 16/33 (48.5%), 22/25 (88%) and 24/32 (75%), respectively, P <0.001. The agreement of mutations in positive samples between pleural cfDNA and pleural cytology was 100% while the agreement of pleural cfDNA with biopsies was 89.4%. The median concentration (Q1-Q3) of pleural cfDNA was higher than plasma: 28,444 (4,957-67,051) vs. 2,966.5 (2,167-5,025) copies of amplifiable DNA per ml, P <0.01. Median of 5 ml (interquartile range, Q1-Q3, 4.5-5) of pleural fluid supernatant was adequate for cfDNA testing. The diagnostic yield of pleural cfDNA NGS for oncogenic mutations in lung adenocarcinoma patients is comparable to tumor biopsies and higher than pleural cytology and plasma cfDNA. The pleural cfDNA can be longitudinally collected, readily incorporated in clinical workflow and may decrease the need for additional biopsies.

Clinical utility of a plasma-based comprehensive genomic profiling test in patients with non-small cell lung cancer in Korea

Objectives: Plasma-based comprehensive circulating cell-free DNA (cfDNA) next generation sequencing (NGS) has shown utility in advanced non-small cell lung cancer (aNSCLC). The aim of this study was to determine the feasibility of cfDNA-based NGS to identify actionable gene alterations in patients with aNSCLC.Patients and methods: This single-center non-interventional retrospective study evaluated Korean patients with biopsy-confirmed stage III/IV non-squamous aNSCLC. Tissue biopsy samples were collected at baseline, and/or at progression and analysed with Standard of Care (SOC) testing; cfDNA was analyzed by NGS in some patients concurrently.Results: aNSCLC patients with cfDNA test results (n = 405) were categorized into three groups: treatment naïve (n = 182), progressive aNSCLC after chemotherapy and/or immunotherapy (n = 157), and progressive aNSCLC after tyrosine kinase inhibitors (TKIs) (n = 66). Clinically informative driver mutations were identified for 63.5% of patients which were classified as OncoKB Tiers 1 (44.2%), 2 (3.4%), tier 3 (18.9%), and 4 (33.5%). Concordance between cfDNA NGS and tissue SOC methods for concurrently collected tissue samples (n = 221) with common EGFR mutations or ALK/ROS1 fusions was 96.9%. cfDNA analysis identified tumor genomic alterations in 13 patients that were unidentified with tissue testing, enabling initiation of targeted treatment.Conclusions: In clinical practice, results of cfDNA NGS are highly concordant with those of tissue SOC testing in aNSCLC patients. Plasma analysis identified actionable alterations that were missed or not evaluated by tissue testing, enabling the initiation of targeted therapy. Results from this study add to the body of evidence in the support routine use of cfDNA NGS for patients with aNSCLC.

319. Clinical accuracy and utility of plasma microbial cell free DNA NGS for the diagnosis of invasive aspergillosis in patients with hematologic malignancy and COVID-19

Abstract Background Invasive aspergillosis (IA) is a great threat to the severely immunocompromised and patients with coronavirus disease (COVID-19). However, diagnosis of IA is often difficult due to need for invasive biopsy and low sensitivity of other diagnostic tests. Next-generation sequencing (NGS) of plasma cell free DNA (cfDNA) can be a novel non-invasive diagnostic modality. We evaluated the clinical accuracy and utility of microbial cfDNA NGS for the diagnosis of IA in patients with hematologic malignancy (HM) and COVID-19. Methods A single-center prospective study of plasma microbial cfDNA NGS was conducted in a tertiary-care hospital in South Korea. We enrolled adult patients with HM and COVID-19, who suspected IA and performed conventional diagnostic tests for IA. The results of NGS were compared with the diagnosis of IA through conventional methods. IA cases were diagnosed according to EORTC/MSG definitions in patients with HM, and modified AspICU criteria in patients with COVID-19. (Figure 1). Figure 1.Flow chart for the participant selection method used in this study Results Between March 2021 and January 2022, a total of 33 participants (22 [64.7%] male, median age 66.0 [50.5, 72.0]) were enrolled;19 participants with HM and 15 with COVID-19 were analyzed (Figure1 and Table1). In participants with HM, aspergillus cfDNA was detected in 100% of both proven (1/1) and probable (12/12) IA cases, and 33.3% of both possible (1/3) and no IA (1/3) cases. In participants with COVID-19, 46.2% of probable IA (6/13) showed positive aspergillus cfDNA. Detection rate of aspergillus cfDNA was significantly higher in proven/probable IA cases in participants with HM compared to participants with COVID-19. (100% vs 46.2%, p=0.005) (Figure 2). As shown in Table 2, among proven/probable IA cases, participants with positive aspergillus cfDNA showed significantly higher rate of having uncontrolled hematologic disease, receiving stem cell transplantation and recent chemotherapy. In three participants with HM, non-aspergillus strains confirmed by cfDNA NGS were in accordance with pathogens identified through conventional culture methods. Table 1.Baseline characteristics of participants suspected of invaisve aspergillosis performing microbial cell free DNA NGSFigure 2.cfDNA detection rate in participants with suspected fungal infection according to the EORTC/MSG or modified AspICU diagnostic criteria Conclusion Detection of aspergillus cfDNA showed high concordance in the results of conventional diagnostic methods in proven/probable IA of patients with HM and could be a helpful non-invasive approach to IA diagnosis in those populations. Disclosures All Authors: No reported disclosures.

Matched Molecular Profiling of Cell-Free DNA and Tumor Tissue in Patients With Advanced Clear Cell Renal Cell Carcinoma.

The clinical utility of cell-free DNA (cfDNA) as a biomarker for advanced clear cell renal cell carcinoma (ccRCC) remains unclear. We evaluated the validity of cfDNA-based genomic profiling in a large cohort of patients with ccRCC with matched next-generation sequencing (NGS) from primary tumor tissues. We performed paired NGS of tumor DNA and plasma cfDNA using the MSK-IMPACT platform in 110 patients with metastatic ccRCC. Tissues were profiled for variants and copy number alterations with germline comparison. Manual cross-genotyping between cfDNA and tumor tissue was performed. Deep sequencing with a higher sensitivity platform, MSK-ACCESS, was performed on a subset of cfDNA samples. Clinical data and radiographic tumor volumes were assessed to correlate cfDNA yield with treatment response and disease burden. Tumor tissue MSK-IMPACT testing identified 582 genomic alterations (GAs) across the cohort. Using standard thresholds for de novo variant calling in cfDNA, only 24 GAs were found by MSK-IMPACT in cfDNA in 7 of 110 patients (6%). With manual cross-genotyping, 210 GAs were detectable below thresholds in 74 patients (67%). Intrapatient concordance with tumor tissue was limited, including VHL (31.6%), PBRM1 (24.1%), and TP53 (52.9%). cfDNA profiling did not identify 3p loss because of low tumor fractions. Tumor volume was associated with cfDNA allele frequency, and VHL concordance was superior for patients with greater disease burden. cfDNA-based NGS profiling yielded low detection rates in this metastatic ccRCC cohort. Concordance with tumor profiling was low, even for truncal mutations such as VHL, and some findings in peripheral blood may represent clonal hematopoiesis. Routine cfDNA panel testing is not supported, and its application in biomarker efforts must account for these limitations.

Reliability of Cell-Free DNA and Targeted NGS in Predicting Chromosomal Abnormalities of Patients With Myeloid Neoplasms

IntroductionCytogenetic analysis is important for stratifying patients with various neoplasms. We explored the use of targeted next generation sequencing (NGS) in detecting chromosomal structural abnormalities or copy number variations (CNVs) in patients with myeloid neoplasms.MethodsPlasma cell-free DNA (cfDNA) from 2821 myeloid or lymphoid neoplasm patients were collected. cfDNA was sequenced using a 275 gene panel. CNVkit software was used for analyzing and visualizing CNVs. Cytogenetic data from corresponding bone marrow (BM) samples was available on 89 myeloid samples.ResultsOf the 2821 samples, 1539 (54.5%) showed evidence of mutations consistent with the presence of neoplastic clones in circulation. Of these 1539 samples, 906 (59%) showed abnormalities associated with myeloid neoplasms and 633 (41%) with lymphoid neoplasms. Chromosomal structural abnormalities in cfDNA were detected in 146 (16%) myeloid samples and 76 (12%) lymphoid samples. Upon comparison of the myeloid samples with 89 BM patients, NGS testing was able to reliably detect chromosomal gain or loss, except for fusion abnormalities. When cytogenetic abnormalities were classified according to prognostic classes, there was a complete (100%) concordance between cfDNA NGS data and cytogenetic data.ConclusionsThis data shows that liquid biopsy using targeted NGS is reliable in detecting chromosomal structural abnormalities in myeloid neoplasms. In specific circumstances, targeted NGS may be reliable and efficient to provide adequate information without the need for BM biopsy considering broad mutation profiling can be obtained through adequate sequencing within the same test. Overall, this study supports the use of liquid biopsy for early diagnosis and monitoring of patients with myeloid neoplasms.

Up-front cell-free DNA next generation sequencing improves target identification in UK first line advanced non-small cell lung cancer (NSCLC) patients

BackgroundGenomic sequencing is necessary for first-line advanced non-small cell lung cancer (aNSCLC) treatment decision-making. Tissue next generation sequencing (NGS) is standard but tissue quantity, quality, and time-to-results remains problematic. Here, we compare upfront cell-free-DNA (cfDNA) NGS clinical utility against routine tissue testing in patients with aNSCLC. MethodscfDNA-NGS was performed in consecutive, newly identified aNSCLC patients between December 2019–October 2021 alongside routine tissue genotyping. Variants were interpreted using AMP/ASCO/CAP guidelines. The primary endpoint was tier-1 variants detected on cfDNA-NGS. cfDNA-NGS results were compared to tissue results. ResultsOf 311 patients, 282 (91%) had an informative cfDNA-NGS test; 118 (38%) patients had a tier-1 variant identified by cfDNA-NGS. Of 243 patients with paired tissue-cfDNA tests, 122 (50%) tissue tests were informative; 85 (35%) tissue tests identified a tier-1 variant. cfDNA-NGS detected 39 additional tier-1 variants compared to tissue alone, increasing the tier-1 detection rate by 46% (from 85 to 124). The sensitivity of cfDNA-NGS relative to tissue was 75% (25% tissue tier-1 variants were not detected on cfDNA-NGS); 33% of cfDNA tier-1 variants were not identified on tissue tests. Median time from request-to-report was shorter for cfDNA-NGS versus tissue (8 versus 22 days; p < 0.0001).A total of 245 (79%) patients received first-line systemic-therapy: 49 (20%) with cfDNA-NGS results alone. Median time from sampling-to-commencement of first-line treatment was shorter for cfDNA-NGS blood draw versus first tissue biopsy (16 versus 35 days; p < 0.0001). ConclusionscfDNA-NGS increased the tier-1 variant detection rate with high concordance with tissue, and halves time-to-treatment. ‘Plasma-first’ upfront cfDNA-NGS use should be considered routinely for aNSCLC.

Longitudinal Shifts of Solid Tumor and Liquid Biopsy Sequencing Concordance in Metastatic Breast Cancer.

PURPOSETissue-based next-generation sequencing (NGS) in metastatic breast cancer (mBC) is limited by the inability to noninvasively track tumor evolution. Cell-free DNA (cfDNA) NGS has made sequential testing feasible; however, the relationship between cfDNA and tissue-based testing in mBC is not well understood. Here, we evaluate concordance between tissue and cfDNA NGS relative to cfDNA sampling frequency in a large, clinically annotated mBC data set.METHODSTempus LENS was used to analyze deidentified records of mBC cases with Tempus xT (tissue) and xF (cfDNA) sequencing results. Then, various metrics of concordance were assessed within overlapping probe regions of the tissue and cfDNA assays (104 genes), focusing on pathogenic variants. Variant allele frequencies of discordant and concordant pathogenic variants were also compared. Analyses were stratified by mBC subtype and time between tests.RESULTSRecords from 300 paired tissue and liquid biopsies were analyzed. Median time between tissue and blood collection was 78.5 days (standard deviation = 642.99). The median number of pathogenic variants/patient was one for cfDNA and two for tissue. Across the cohort, 77.8% of pathogenic tissue variants were found in cfDNA and 75.7% of pathogenic cfDNA variants were found in tissue when tests were ≤ 7 days apart, which decreased to 50.3% and 51.8%, respectively, for > 365 days. Furthermore, the median patient-level variant concordance was 67% when tests were ≤7 days apart and 30%-37% when > 30 days. The median variant allele frequencies of discordant variants were generally lower than those of concordant variants within the same time frame.CONCLUSIONWe observed high concordances between tissue and cfDNA results that generally decreased with longer durations between tests. Thus, cfDNA NGS reliably measures tissue genomics and is likely beneficial for longitudinal monitoring of molecular changes in mBC.

Detection of homologous recombination deficiency (HRD) in cell-free DNA (cfDNA) using an amplicon-based next-generation sequencing (NGS) assay.

3042 Background: Homologous recombination (HR) deficiency is characterized by tumor genomic instability, often due to alterations in BRCA1/2 and other HR-related genes. HRD predicts sensitivity to PARP inhibitors (PARPi) in prostate, ovarian and breast cancers. For the subset of cancers that have genomic instability without detectable alterations in HR genes, profiling biomarkers of HRD such as loss of heterozygosity (LOH) could identify additional HRD positive (HRD+) patients that may benefit from PARPi. Here, we present a novel cfDNA NGS assay that can detect tumor LOH non-invasively to improve assessment of HRD+ status. Methods: An amplicon-based HRD NGS assay covering &gt; 1000 SNPs was developed to detect LOH both globally and on the gene level in cfDNA. Analytical validation was done using LOH+ BRCA-mutant cell lines in limiting dilution admixtures. Clinical performance was assessed by benchmarking findings from 46 tumor tissue DNA samples against results from an orthogonal NGS-based genomic scarring assay. Clinical utility of the HRD assay was evaluated in 75 cfDNA samples, including 72% (54/75) from BRCA-associated cancers (36 breast, 12 prostate, 4 ovarian, 2 pancreatic) and 28% from other cancer types. All cfDNA samples were previously clinically tested by an NGS assay that included BRCA1/2 (LiquidHALLMARK). A subset of cfDNA samples identified as HRD+ were further assessed for alterations in 26 key HR genes ( ARID1A, ATM, ATR, ATRX, BAP1, BARD1, BRCA1, BRCA2, BRIP1, CDK12, CHEK1, CHEK2, FANCA, FANCC, FANCG, FANCL, MRE11, NBN, PALB2, PTEN, RAD51, RAD51B, RAD51C, RAD51D, RAD54L, and XRCC2). Results: In analytical validation, the assay could detect HRD in admixtures with as low as 18% tumor fraction. In tissue samples, overall concordance of HRD status with the orthogonal test was 91.3% (42/46), with a positive percent agreement of 94.4% (34/36) and negative percent agreement of 80.0% (8/10). In cfDNA, 26.7% (20/75) of samples were HRD+, including 29.6% of BRCA-associated cancers (16/54; 12 breast, 2 prostate, 1 ovarian, and 1 pancreatic) and 19.1% (4/21) of other cancer types. In the three HRD+ breast cancers with pathogenic BRCA mutations, the assay also identified BRCA-specific LOH. Nine HRD+ breast cancers (two BRCA+ and seven BRCA-) were further analyzed for alterations in 26 HR genes. Of the two BRCA+ HRD+ breast cancers, one harbored an additional PTEN loss-of-function (LOF) mutation. Of the seven BRCA- HRD+ breast cancers, one harbored biallelic PALB2 and CDK12 LOF mutations, while another harbored a CDK12 LOF mutation. Conclusions: LOH detection in cfDNA provides additional diagnostic yield of HRD+ status in multiple cancer types, even in the absence of pathogenic HR gene alterations. Further clinical studies to evaluate the utility of HRD detection in cfDNA using LOH and to determine concordance with tumor tissue are ongoing.

Identification of an optimal circulating tumor DNA (ctDNA) shedding threshold to detect actionable driver mutations in colorectal and pancreatic adenocarcinoma.

3571 Background: In colorectal cancer (CRC), mutations in KRAS, NRAS, and BRAF predict resistance to anti-EGFR therapies. In pancreatic ductal adenocarcinoma (PDAC), ~90% of patients harbor KRAS mutations, while KRAS wild-type tumors often have clinically actionable fusion alterations. Thus, in both cancers, the accurate ascertainment of RAS and BRAF driver status is essential. Sequencing of cell-free DNA (cfDNA) from plasma allows convenient assessment of a tumor’s molecular profile, but sensitivity can be limited by low ctDNA shedding. We sought to establish a ctDNA shedding threshold at which actionable driver mutations can be reliably detected. Methods: Molecular reports and matched clinical data were obtained from the Duke Molecular Registry of Tumors and the SCRUM-Japan GOZILA and GI-SCREEN. CRC or PDAC patients with a pathogenic KRAS, NRAS, or BRAF activating point mutation (“driver”) present on tissue next-generation sequencing (NGS) assays and who also had cfDNA assay available were included. Tissue NGS included Foundation One CDx and Oncomine Comprehensive Assay. Guardant 360 (G360) was the sole plasma cfDNA assay. 131 CRC and 24 PDAC cases with 189 total G360 assays met criteria and were included. Samples were analyzed according to detection of the driver mutation and the maximum mutant allele frequency (MAF) of non-driver mutations on G360. An optimal cut-point for max MAF was explored among the CRC and PDAC patients using a maximally selected Wilcoxon rank statistic method. Results: 76.8% of driver mutations were in KRAS, 22.6% in BRAF, and 1.9% in NRAS with an overlap of 1 BRAF and 1 NRAS mutation with a KRAS mutation. Overall sensitivity of G360 for drivers was 83.0% for CRC and 54.2% for PDAC. No variants were detected on G360 in 9.1% of CRC and 37.5% of PDAC. Sensitivity for driver mutations increased with higher maximum non-driver MAF, with MAF &gt; 1% predicting sensitivity &gt; 98% (Table). Optimal cut-point analysis identified MAF of &gt; 0.34% (p &lt; 0.0001), above which the driver was identified in 97% of patients and below which only 27%. Conclusions: In our study, non-driver MAF &gt; 1% on cfDNA NGS predicts high sensitivity for RAS and BRAF mutations and thus is adequate to guide clinical decisions such as anti-EGFR therapy in CRC, evaluation for fusions in PDAC, and validity in clinical trials. MAF ≤0.34% is a clear threshold to consider an assay inadequate and thus seek alternative testing. Sensitivity rises for MAF between 0.35 and 1% but will require greater patient numbers to establish clinically relevant sensitivity thresholds. These results will be updated with additional data for final presentation. [Table: see text]

Quantitative PCR–Based Method to Assess Cell-Free DNA Quality, Adjust Input Mass, and Improve Next-Generation Sequencing Assay Performance

Cell-free (cf)DNA-based testing has undergone increasingly wide adoption, including assays for the detection of circulating tumor DNA. Due to nucleosome protection, cfDNA has a distinctive fragment size of 160 to 180 bp. However, cfDNA can be contaminated with high molecular weight genomic DNA from blood cells released in plasma during sample collection. Such contamination can lead to decreased sensitivity or inconsistent results in cfDNA next-generation sequencing assays. This article describes a technical advancement in which a quantitative PCR method is used for high molecular weight contamination assessment and input mass adjustment, and has been demonstrated to improve consistency of performance in a circulating tumor DNA next-generation sequencing workflow.

The genomic characteristics of RET fusion positive tumors in Chinese non-small cell lung cancer (NSCLC) patients

BackgroundApproximately 1–2% of non-small cell lung cancer (NSCLC) patients harbor RET (rearranged during transfection) fusions. The oncogenic RET fusions could lead to constitutive kinase activation and oncogenesis.Methods1746 Chinese NSCLC patients were analyzed in this study. Tumor tissues were collected, and were formalin fixed, paraffin-embedded (FFPE) and archived. Peripheral blood (PB) samples were also collected from each patient as control. In addition, we selected 17 of them for cfDNA NGS testing and 14 tumor samples for immunohistochemistry testing using PD-L1 rabbit monoclonal antibody, clones 28-8 (Abcam, Cambridge, UK).ResultsOf the 1746 NSCLC cases, RET rearrangements were identified in 25 cases (1.43%) with locally advanced or metastatic NSCLC, of which 20 (80%) were female. We found that 14 out of 25 patients had an KIF5B-RET fusion, with KIF5B exon15-RET exon12, KIF5B exon23-RET exon12, and KIF5B exon24-RET exon11 detected in 14, 3, and 1 patients, respectively. We also identified one novel RET fusion partner PLCE1 and 4 intergenic-breakpoint fusions.ConclusionIn this study, using the hybrid capture based next generation sequencing (NGS) techniques, we revealed the genomic profiling for the patients with RET fusion-positive NSCLC. To the best of our knowledge, this is the first study that exhibited the detailed breakpoints of Chinese NSCLC patients with RET rearrangement, and we found a novel new partner PLCE1. The results provided genomic information for patients with RET fusion which is significant for personalized clinical management in the era of precision medicine.

Utility of liquid biopsy in diagnosing isolated cerebral phaeohyphomycosis: illustrative case.

BACKGROUNDCladophialophora bantiana is a dematiaceous, saprophytic fungus and a rare but reported cause of intracranial abscesses due to its strong neurotropism. Although it predominantly affects immunocompetent individuals with environmental exposure, more recently, its significance as a highly lethal opportunistic infection in transplant recipients has been recognized. Successful treatment requires timely but often challenging diagnosis, followed by complete surgical excision. Next-generation sequencing of microbial cell-free DNA (cfDNA) from plasma is a novel diagnostic method with the potential to identify invasive fungal infections more rapidly and less invasively than conventional microbiological testing, including brain biopsy.OBSERVATIONSThe authors described the case of a recipient of a liver transplant who presented with seizures and was found to have innumerable ring-enhancing intracranial lesions. The Karius Test, a commercially available method of next-generation sequencing of cfDNA, was used to determine the causative organism. Samples from the patient’s plasma identified C. bantiana 6 days before culture results of the surgical specimen, allowing optimization of the empirical antifungal regimen, which led to a reduction in the size of the abscesses.LESSONSThe authors’ findings suggest that microbial cfDNA sequencing may be particularly impactful in improving the management of brain abscesses in which the differential diagnosis is wide because of immunosuppression.

Cell-Free-DNA-Based Copy Number Index Score in Epithelial Ovarian Cancer-Impact for Diagnosis and Treatment Monitoring.

Simple SummaryThe prognosis of ovarian cancer is dependent on the tumor stage and the development of chemotherapy resistance. Using low-coverage cell-free tumor DNA sequencing, we were able to determine the chromosomal instability (CI) of tumors that are frequently found in patients with primary advanced and recurrent high-grade ovarian cancer from a blood sample. We were able to show that the CI could be used for the reliable detection of ovarian cancer in comparison to healthy controls. Moreover, we showed that the CI was significantly associated with the prognostic and predictive clinical measures in primary and recurrent ovarian cancer. The high diagnostic accuracy of the tumor CI derived from cfDNA analysis might lead to the optimization of main prognostic determinants in patients with ovarian cancer. As the CI is a characteristic feature in high-grade ovarian cancer, no upfront tumor tissue analysis is required to identify genomic alterations for targeted sequencing of cfDNA, if the herein described low-coverage sequencing and CNI-Score determination is used.Background: Chromosomal instability, a hallmark of cancer, results in changes in the copy number state. These deviant copy number states can be detected in the cell-free DNA (cfDNA) and provide a quantitative measure of the ctDNA levels by converting cfDNA next-generation sequencing results into a genome-wide copy number instability score (CNI-Score). Our aim was to determine the role of the CNI-Score in detecting epithelial ovarian cancer (EOC) and its role as a marker to monitor the response to treatment. Methods: Blood samples were prospectively collected from 109 patients with high-grade EOC. cfDNA was extracted and analyzed using a clinical-grade assay designed to calculate a genome-wide CNI-Score from low-coverage sequencing data. Stored data from 241 apparently healthy controls were used as a reference set. Results: Comparison of the CNI-Scores of primary EOC patients versus controls yielded sensitivities of 91% at a specificity of 95% to detect OC, respectively. Significantly elevated CNI-Scores were detected in primary (median: 87, IQR: 351) and recurrent (median: 346, IQR: 1891) blood samples. Substantially reduced CNI-Scores were detected after primary debulking surgery. Using a cut-off of 24, a diagnostic sensitivity of 87% for primary and recurrent EOC was determined at a specificity of 95%. CNI-Scores above this threshold were detected in 21/23 primary tumor (91%), 36/42 of platinum-eligible recurrent (85.7%), and 19/22 of non-platinum-eligible recurrent (86.3%) samples, respectively. Conclusion: ctDNA-quantification based on genomic instability determined by the CNI-Score was a biomarker with high diagnostic accuracy in high-grade EOC. The applied assay might be a promising tool for diagnostics and therapy monitoring, as it requires no a priori information about the tumor.

Reliability of Cell-Free DNA (cfDNA) Next Generation Sequencing in Predicting Chromosomal Structural Abnormalities and Cytogenetic-Risk Stratification of Patients with Myeloid Neoplasms

Reliability of Cell-Free DNA (cfDNA) Next Generation Sequencing in Predicting Chromosomal Structural Abnormalities and Cytogenetic-Risk Stratification of Patients with Myeloid Neoplasms