cfDNA Characteristics Research Articles

Plasma Cell-Free DNA Concentration and Fragmentomes Predict Neoadjuvant Chemotherapy Response in Cervical Cancer Patients.

Cervical cancer remains one of the most lethal gynecological malignancies. However, biomarkers for more precise patient care are an unmet need. Herein, the concentration of 285 plasma cell-free DNA (cfDNA) samples are analyzed from 84 cervical patients and the clinical significance of cfDNA fragmentomic characteristics across the neoadjuvant chemotherapy (NACT) treatment. Patients with poor NACT response exhibit a significantly greater escalation in cfDNA levels following the initial cycle of treatment, in comparison to patients with a favorable response. Distinctive end motif profiles and promoter coverages of cfDNA in initial plasma are observed between patients with differing NACT responses. Notably, the DNASE1L3 analysis further demonstrates the intrinsic association between cfDNA characteristics and chemotherapy resistance. The cfDNA and motif ratios show a good discriminative capacity for predicting non-responders from responders (area under the curve (AUC) > 0.8). In addition, transcriptional start sites (TSS) coverages around promoters discern the alteration of biological processes associated with chemotherapy resistance and reflect the potential value in predicting chemotherapy response. These findings in predictive biomarkers may optimize treatment selection, minimize unnecessary treatment, and assist in establishing personalized treatment strategies for cervical cancer patients.

Multi-dimensional cell-free DNA-based liquid biopsy for sensitive early detection of gastric cancer

BackgroundGastric cancer is the fifth most common cancer type. Most patients are diagnosed at advanced stages with poor prognosis. A non-invasive assay for the detection of early-stage gastric cancer is highly desirable for reducing associated mortality.MethodsWe collected a prospective study cohort of 110 stage I–II gastric cancer patients and 139 non-cancer individuals. We performed whole-genome sequencing with plasma samples and profiled four types of cell-free DNA (cfDNA) characteristics, fragment size pattern, copy number variation, nucleosome coverage pattern, and single nucleotide substitution. With these differential profiles, we developed an ensemble model to detect gastric cancer signals. Further, we validated the assay in an in-house first validation cohort of 73 gastric cancer patients and 94 non-cancer individuals and an independent second validation cohort of 47 gastric cancer patients and 49 non-cancer individuals. Additionally, we evaluated the assay in a hypothetical 100,000 screening population by Monte Carlo simulation.ResultsOur cfDNA-based assay could distinguish early-stage gastric cancer from non-cancer at an AUROC of 0.962 (95% CI: 0.942–0.982) in the study cohort, 0.972 (95% CI: 0.953–0.992) in the first validation cohort and 0.937 (95% CI: 0.890–0.983) in the second validation cohort. The model reached a specificity of 92.1% (128/139) and a sensitivity of 88.2% (97/110) in the study cohort. In the first validation cohort, 91.5% (86/94) of non-cancer individuals and 91.8% (67/73) of gastric cancer patients were correctly identified. In the second validation cohort, 89.8% (44/49) of non-cancer individuals and 87.2% (41/47) of gastric cancer patients were accurately classified.ConclusionsWe introduced a liquid biopsy assay using multiple dimensions of cfDNA characteristics that could accurately identify early-stage gastric cancer from non-cancerous conditions. As a cost-effective non-invasive approach, it may provide population-wide benefits for the early detection of gastric cancer.Trial registrationThis study was registered on ClinicalTrials.gov under the identifier NCT05269056 on March 7, 2022.

Multi-dimensional cell-free DNA-based liquid biopsy for sensitive detection of head and neck squamous cell carcinomas.

e18054 Background: Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer type worldwide. The mortality from HNSCC is closely linked to stage. However, the majority of HNSCC patients were diagnosed at an advanced stage. Therefore, a non-invasive assay for the early detection of HNSCCs is highly desirable for reducing the associated mortality. Methods: We collected a study cohort of 281 participants including 140 pathologically confirmed with head and neck squamous cell carcinomas (HNSCCs) and 141 with non-cancerous conditions. A plasma sample was collected from each participant along with general health screening examinations before any invasive examinations. We performed low-pass whole-genome sequencing with plasma samples and profiled three types of cell-free DNA (cfDNA) characteristics, fragment size pattern (FSP), copy number variation (CNV), and single nucleotide substitution (SNS). We developed an ensemble model with these differential profiles to identify HNSCC patients from non-cancer individuals. We further collected a validation cohort consisting of 90 HNSCC patients and 95 non-cancer individuals to validate the cfDNA-based assay. Results: The liquid biopsy assay that incorporated three types of cfDNA characteristics was able to identify HNSCC patients from non-cancer individuals at an AUROC of 0.989 in the study cohort and 0.984 in the validation cohort. At a specificity of 95.7% (135/141), it achieved a sensitivity of 95.7% (134/140) in the study cohort. With this threshold (0.580), in the validation cohort, 93.7% (89/95) of non-cancer individuals and 93.3% (84/90) of HNSCC patients were correctly identified. Specifically, the sensitivities in early stage (I&II) HNSCCs were 94.5 % (52/55) and 87.5% (28/32) in the study and validation cohort, respectively. Of note, the inferred probabilities of cancer showed consistent trends to increase with pathological stages in both cohorts (P=0.032 and 0.047, respectively). On the contrary, the differentiation grades and sub-locations did not significantly affect the performance of the assay. Conclusions: We introduced a liquid biopsy assay using multiple dimensions of cfDNA characteristics that could accurately identify HNSCCs from non-cancerous conditions. As a cost-effective non-invasive approach, it may be conveniently incorporated into annual general physical examinations to provide supplementary information about the risk of HNSCCs.

Use of Enzymatically Converted Cell-Free DNA (cfDNA) Data for Copy Number Variation-Linked Fragmentation Analysis Allows for Early Colorectal Cancer Detection.

The use of non-invasive liquid biopsy-based cell-free DNA (cfDNA) analysis is an emerging method of cancer detection and intervention. Different analytical methodologies are used to investigate cfDNA characteristics, resulting in costly and long analysis processes needed for combining different data. This study investigates the possibility of using cfDNA data converted for methylation analysis for combining the cfDNA fragment size with copy number variation (CNV) in the context of early colorectal cancer detection. Specifically, we focused on comparing enzymatically and bisulfite-converted data for evaluating cfDNA fragments belonging to chromosome 18. Chromosome 18 is often reported to be deleted in colorectal cancer. We used counts of short and medium cfDNA fragments of chromosome 18 and trained a linear model (LDA) on a set of 2959 regions to predict early-stage (I-IIA) colorectal cancer on an independent test set. In total, 87.5% sensitivity and 92% specificity were obtained on the enzymatically converted libraries. Repeating the same workflow on bisulfite-converted data yielded lower accuracy results with 58.3% sensitivity, implying that enzymatic conversion preserves the cancer fragmentation footprint in whole genome data better than bisulfite conversion. These results could serve as a promising new avenue for the early detection of colorectal cancer using fragmentation and methylation approaches on the same datasets.

A review on the impact of single-stranded library preparation on plasma cell-free diversity for cancer detection.

In clinical oncology, cell-free DNA (cfDNA) has shown immense potential in its ability to noninvasively detect cancer at various stages and monitor the progression of therapy. Despite the rapid improvements in cfDNA liquid biopsy approaches, achieving the required sensitivity to detect rare tumor-derived cfDNA still remains a challenge. For next-generation sequencing, the perceived presentation of cfDNA is strongly linked to the extraction and library preparation protocols. Conventional double-stranded DNA library preparation (dsDNA-LP) focuses on assessing ~167bp double-stranded mononucleosomal (mncfDNA) and its other oligonucleosomal cell-free DNA counterparts in plasma. However, dsDNA-LP methods fail to include short, single-stranded, or nicked DNA in the final library preparation, biasing the representation of the actual cfDNA populations in plasma. The emergence of single-stranded library preparation (ssDNA-LP) strategies over the past decade has now allowed these other populations of cfDNA to be studied from plasma. With the use of ssDNA-LP, single-stranded, nicked, and ultrashort cfDNA can be comprehensively assessed for its molecular characteristics and clinical potential. In this review, we overview the current literature on applications of ssDNA-LP on plasma cfDNA from a potential cancer liquid biopsy perspective. To this end, we discuss the molecular principles of single-stranded DNA adapter ligation, how library preparation contributes to the understanding of native cfDNA characteristics, and the potential for ssDNA-LP to improve the sensitivity of circulating tumor DNA detection. Additionally, we review the current literature on the newly reported species of plasma ultrashort single-stranded cell-free DNA plasma, which appear biologically distinct from mncfDNA. We conclude with a discussion of future perspectives of ssDNA-LP for liquid biopsy endeavors.

Hypobaric hypoxia modulated structural characteristics of circulating cell-free DNA in high-altitude pulmonary edema.

The utility of cell-free (cf) DNA has extended as a surrogate or clinical biomarker for various diseases. However, a more profound and expanded understanding of the diverse cfDNA population and its correlation with physiological phenotypes and environmental factors is imperative for using its full potential. The high-altitude (HA; altitude > 2,500 m above sea level) environment characterized by hypobaric hypoxia offers an observational case-control design to study the differential cfDNA profile in patients with high-altitude pulmonary edema (HAPE) (number of subjects, n = 112) and healthy HA sojourners (n = 111). The present study investigated cfDNA characteristics such as concentration, fragment length size, degree of integrity, and subfractions reflecting mitochondrial-cfDNA copies in the two groups. The total cfDNA level was significantly higher in patients with HAPE, and the level increased with increasing HAPE severity (P = 0.0036). A lower degree of cfDNA integrity of 0.346 in patients with HAPE (P = 0.001) indicated the prevalence of shorter cfDNA fragments in circulation in patients compared with the healthy HA sojourners. A significant correlation of cfDNA characteristics with the peripheral oxygen saturation levels in the patient group demonstrated the translational relevance of cfDNA molecules. The correlation was further supported by multivariate logistic regression and receiver operating characteristic curve. To our knowledge, our study is the first to highlight the association of higher cfDNA concentration, a lower degree of cfDNA integrity, and increased mitochondrial-derived cfDNA population with HAPE disease severity. Further deep profiling of cfDNA fragments, which preserves cell-type specific genetic and epigenetic features, can provide dynamic physiological responses to hypoxia.NEW & NOTEWORTHY This study observed altered cell-free (cf) DNA fragment patterns in patients with high-altitude pulmonary edema and the significant correlation of these patterns with peripheral oxygen saturation levels. This suggests deep profiling of cfDNA fragments in the future may identify genetic and epigenetic mechanisms underlying physiological and pathophysiological responses to hypoxia.

Abstract C015: FGFR1 and RB1 genetic alteration impair clinical benefit of CDK4/6 inhibitors plus endocrine therapy in HR+/HER2- advanced breast cancer

Abstract Background: One of the great challenges for HR+/HER2- advanced breast cancer (ABC) is to determine who respond poorly to cyclin-dependent kinase 4/6 inhibitors (CDK4/6i). Chemotherapy is still used in HR+/HER2- patients. We aimed to explore cfDNA biomarkers for CDK4/6i plus endocrine therapy (ET), and compare its efficacy with chemotherapy in subgroups stratified by clinical and cfDNA characteristics. Method: Patients diagnosed with HR+/HER2- advanced breast cancer underwent first-line CDK4/6i plus ET or chemotherapy in Peking University Cancer Hospital from January 2018 to June 2022 were enrolled in this study. Baseline blood samples of patients were collected before first-line treatment for cfDNA sequencing. Results: Among all the 125 patients included in this study, the median PFS (mPFS) of CDK4/6i plus ET group (n=51) was significantly longer than patients treated with chemotherapy(n=74) (22.0 vs. 16.0 months, P = 0.025). In multivariate analysis, RB1 loss (Hazard ratio [HR] = 6.4, adjusted P = 0.031), FGFR1 gain (HR: 4.9, adjusted P = 0.030) were associated with shorter PFS of patients treated with CDK4/6i plus ET. A better efficacy of CDK4/6i plus ET was observed in patients with visceral metastasis, higher Ki-67 (≥20%) and smaller SLD (< 35mm) than chemotherapy. In subgroup analysis, interaction effects were found between RB1 loss (P interaction = 0.028), FGFR1 gain (P interaction = 0.004) and first-line treatment. Conclusion: This study revealed that FGFR1 gain and RB1 loss are independent prognostic factors for PFS of CDK4/6i plus ET, and chemotherapy was not superior to CDK4/6i plus ET in the absence of FGFR1 gain and RB1 loss, which might improve selection of patients for CDK4/6 inhibitors. Citation Format: Jianxin Zhong, Bin Shao, Hanfang Jiang, Huiping Li. FGFR1 and RB1 genetic alteration impair clinical benefit of CDK4/6 inhibitors plus endocrine therapy in HR+/HER2- advanced breast cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C015.

Multi-faceted attributes of salivary cell-free DNA as liquid biopsy biomarkers for gastric cancer detection

BackgroundRecent advances in circulating cell-free DNA (cfDNA) analysis from biofluids have opened new avenues for liquid biopsy (LB). However, current cfDNA LB assays are limited by the availability of existing information on established genotypes associated with tumor tissues. Certain cancers present with a limited list of established mutated cfDNA biomarkers, and thus, nonmutated cfDNA characteristics along with alternative biofluids are needed to broaden the available cfDNA targets for cancer detection. Saliva is an intriguing and accessible biofluid that has yet to be fully explored for its clinical utility for cancer detection.MethodsIn this report, we employed a low-coverage single stranded (ss) library NGS pipeline “Broad-Range cell-free DNA-Seq” (BRcfDNA-Seq) using saliva to comprehensively investigate the characteristics of salivary cfDNA (ScfDNA). The identification of cfDNA features has been made possible by applying novel cfDNA processing techniques that permit the incorporation of ultrashort, ss, and jagged DNA fragments. As a proof of concept using 10 gastric cancer (GC) and 10 noncancer samples, we examined whether ScfDNA characteristics, including fragmentomics, end motif profiles, microbial contribution, and human chromosomal mapping, could differentiate between these two groups.ResultsIndividual and integrative analysis of these ScfDNA features demonstrated significant differences between the two cohorts, suggesting that disease state may affect the ScfDNA population by altering nuclear cleavage or the profile of contributory organism cfDNA to total ScfDNA. We report that principal component analysis integration of several aspects of salivary cell-free DNA fragmentomic profiles, genomic element profiles, end-motif sequence patterns, and distinct oral microbiome populations can differentiate the two populations with a p value of < 0.0001 (PC1).ConclusionThese novel features of ScfDNA characteristics could be clinically useful for improving saliva-based LB detection and the eventual monitoring of local or systemic diseases.

Neutrophil extracellular traps-associated markers in malignant neoplasms of the female reproductive system after surgical treatment and adjuvant chemotherapy

Introduction. Studies evidence about a relation between increased circulating free DNA (cfDNA) concentrations and chemotherapy, the majority of which have been focused on considering a tumor as a source of cfDNA. It has been suggested that neutrophils also contribute to this process, as cancer-related cfDNA characteristics resemble those of neutrophil extracellular traps (NETs). Therefore, the elevated concentration of cfDNA observed in chemotherapy patients may be associated with NETosis.Aim: assessment of NETosis markers in surgical treatment and adjuvant chemotherapy of patients with malignant neoplasms of the female reproductive system.Materials and Methods. A prospective non-randomized interventional controlled study was carried out by enrolling 111 patients with malignant breast diseases and female genital organs of various localizations and stages hospitalized for elective surgical treatment or chemotherapy course. The control group included 33 healthy women. 69 patients underwent surgical treatment. Adjuvant chemotherapy with paclitaxel and carboplatin was performed in 25 patients with ovarian cancer and 17 patients with breast cancer. In cancer patients, citrullinated histone H3 (citH3) and myeloperoxidase (MPO) were chosen as NETosis biomarkers allowing to distinguish NETs from other tumor-derived cfDNA thereby improving quality of research study. The concentration of NETosis markers was assessed before surgery or onset of chemotherapy upon admission to hospital and 14 days after surgery or 14 days after the second course of chemotherapy.Results. In all patients, the concentrations of NETosis markers before the start of therapy were significantly increased compared to the control group as well as 14 days after surgical treatment and 14 days after the second course of chemotherapy. However, in surgical patients, no significantly increased concentration of NETosis markers postvs. pre-surgery magnitude was observed. Upon that, patients underwent 2 courses of chemotherapy vs. baseline level were found to have significantly elevated magnitude of NETosis markers.Conclusion. The study revealed the relationship between administration of paclitaxel-containing chemotherapy in patients with ovarian cancer and breast cancer and a rise in NETs level. Chemotherapy is an essential component for management of patients with malignant neoplasms of the female reproductive system, therefore, development of new strategies to lower a risk of thrombosis and resistance to it is of crucial importance.

Multi-dimensional cell-free DNA-based liquid biopsy and early detection of gastric cancer.

4060 Background: Gastric cancer is one of the most common cancer types. Most patients were diagnosed at advanced stages and experienced poor prognosis. A non-invasive assay for the detection of early-stage gastric cancer is highly desirable for reducing the gastric cancer-associated mortality. Methods: We prospectively collected a study cohort of 249 participants including 110 pathologically confirmed with stage I-II gastric cancer and 139 with non-cancerous conditions. A plasma sample was collected from each patient before conventional screening modalities for gastric cancer. We performed whole-genome sequencing with plasma samples and profiled four types of cell-free DNA (cfDNA) characteristics, fragment size pattern, copy number variation, nucleosome coverage pattern, and single nucleotide substitution. We used these differential profiles to develop an ensemble model to identify gastric cancer patients from non-cancer individuals. We further collected a validation cohort consisting of 73 gastric cancer patients and 94 non-cancer individuals to validate the cfDNA-based assay. Additionally, we compared the performance of our assay and conventional gastroscopy in a hypothetical 100,000 screening population by Monte Carlo simulation. Results: The liquid biopsy assay that incorporated four types of cfDNA characteristics was able to identify early-stage gastric cancer patients from non-cancer individuals at an AUROC of 0.962 in the study cohort and 0.972 in the validation cohort. At a specificity of 92.1% (128/139), it achieved a sensitivity of 88.2% (97/110) in the study cohort. With this threshold, in the validation cohort, 91.5% (86/94) of healthy individuals and 91.8% (67/73) of gastric cancer patients were correctly identified. In both study and validation cohorts, the inferred probabilities of cancer showed consistent trends to increase with pathological stages in the cancer group and disease statuses in the non-cancer group. Of note, our approach detected all gastric tumors located in the cardia and fundus (100.0%, 19/19), which could be challenging for gastroscopic examination. Additionally, through in-silico simulations, we showed that our cfDNA-based non-invasive assay may detect 96.3% more gastric cancer cases than conventional gastroscopy owing to higher sensitivity and anticipated better participant compliance in a large hypothetical screening population. Conclusions: We introduced a liquid biopsy assay using multiple dimensions of cfDNA characteristics that could accurately identify early-stage gastric cancer from non-cancerous conditions. As a cost-effective non-invasive approach, it may provide population-wide benefits for the early detection of gastric cancer.

Quantitative Analysis of Plasma Cell-Free DNA and Its DNA Integrity and Hypomethylation Status as Biomarkers for Tumor Burden and Disease Progression in Patients with Metastatic Neuroendocrine Neoplasias.

Simple SummaryNeuroendocrine neoplasias (NEN) are a heterogeneous group of frequent slow-progressing malignant tumors for which a reliable marker for tumor relapse and progression is still lacking. Previously, circulating cell-free DNA and its global methylation status and fragmentation rate have been proposed to be valuable prognostic tumor markers in a variety of malignancies. In the current study, we compared plasma cell-free DNA (cfDNA) properties of NEN patients with a healthy control group and a group of surgically cured patients. Our results revealed significantly higher plasma cfDNA concentrations with increased fragmentation and hypomethylation in patients with advanced metastatic NEN, which was strongly associated with tumor load and could help to differentiate between metastasized disease and presumably cured patients. This suggests that the combined analysis of plasma cfDNA characteristics is a potent and sensitive prognostic and therapeutic biomarker for tumor burden and disease progression in patients with neuroendocrine neoplasias.Background: Neuroendocrine neoplasia (NEN) encompasses a diverse group of malignancies marked by histological heterogeneity and highly variable clinical outcomes. Apart from Chromogranin A, specific biomarkers predicting residual tumor disease, tumor burden, and disease progression in NEN are scant. Thus, there is a strong clinical need for new and minimally invasive biomarkers that allow for an evaluation of the prognosis, clinical course, and response to treatment of NEN patients, thereby helping implement individualized treatment decisions in this heterogeneous group of patients. In the current prospective study, we evaluated the role of plasma cell-free DNA concentration and its global hypomethylation and fragmentation as possible diagnostic and prognostic biomarkers in patients with neuroendocrine neoplasias. Methods: The plasma cfDNA concentration, cfDNA Alu hypomethylation, and LINE-1 cfDNA integrity were evaluated prospectively in 63 NEN patients with presumably cured or advanced metastatic disease. The cfDNA characteristics in NEN patients were compared to the results of a group of 29 healthy controls and correlated with clinical and histopathological data of the patients. Results: Patients with advanced NEN showed a significantly higher cfDNA concentration and percentage of Alu hypomethylation and a reduced LINE-1 cfDNA integrity as compared to the surgically cured NET patients and the healthy control group. The increased hypomethylation and concentration of cfDNA and the reduced cfDNA integrity in NEN patients were strongly associated with tumor burden and poor prognosis, while no correlation with tumor grading, differentiation, localization, or hormonal activity could be found. Multiparametric ROC analysis of plasma cfDNA characteristics was able to distinguish NEN patients with metastatic disease from the control group and the cured NEN patients with AUC values of 0.694 and 0.908, respectively. This was significant even for the group with only a low tumor burden. Conclusions: The present study, for the first time, demonstrates that the combination of plasma cfDNA concentration, global hypomethylation, and fragment length pattern has the potential to serve as a potent and sensitive prognostic and therapeutic “liquid biopsy” biomarker for tumor burden and disease progression in patients with neuroendocrine neoplasias.

Peritoneal Effluent Cell-Free DNA Sequencing in Peritoneal Dialysis Patients With and Without Peritonitis

Rationale & ObjectiveConventional culture can be insensitive for the detection of rare infections and for the detection of common infections in the setting of recent antibiotic usage. Patients receiving peritoneal dialysis (PD) with suspected peritonitis have a significant proportion of negative conventional cultures. This study examines the utility of metagenomic sequencing of peritoneal effluent cell-free DNA (cfDNA) for evaluating the peritoneal effluent in PD patients with and without peritonitis.Study DesignProspective cohort study.Setting & ParticipantsWe prospectively characterized cfDNA in 68 peritoneal effluent samples obtained from 33 patients receiving PD at a single center from September 2016 to July 2018.OutcomesPeritoneal effluent, microbial, and human cfDNA characteristics were evaluated in culture-confirmed peritonitis and culture-negative peritonitis.Analytical ApproachDescriptive statistics were analyzed and microbial cfDNA was detected in culture-confirmed peritonitis and culture-negative peritonitis.ResultsMetagenomic sequencing of cfDNA was able to detect and identify bacterial, viral, and eukaryotic pathogens in the peritoneal effluent from PD patients with culture-confirmed peritonitis, as well as patients with recent antibiotic usage and in cases of culture-negative peritonitis.LimitationsParallel cultures were not obtained in all the peritoneal effluent specimens.ConclusionsMetagenomic cfDNA sequencing of the peritoneal effluent can identify pathogens in PD patients with peritonitis, including culture-negative peritonitis.

Cell-free DNA (cfDNA) and Exosome Profiling from a Year-Long Human Spaceflight Reveals Circulating Biomarkers.

SummaryLiquid biopsies based on cell-free DNA (cfDNA) or exosomes provide a noninvasive approach to monitor human health and disease but have not been utilized for astronauts. Here, we profile cfDNA characteristics, including fragment size, cellular deconvolution, and nucleosome positioning, in an astronaut during a year-long mission on the International Space Station, compared to his identical twin on Earth and healthy donors. We observed a significant increase in the proportion of cell-free mitochondrial DNA (cf-mtDNA) inflight, and analysis of post-flight exosomes in plasma revealed a 30-fold increase in circulating exosomes and patient-specific protein cargo (including brain-derived peptides) after the year-long mission. This longitudinal analysis of astronaut cfDNA during spaceflight and the exosome profiles highlights their utility for astronaut health monitoring, as well as cf-mtDNA levels as a potential biomarker for physiological stress or immune system responses related to microgravity, radiation exposure, and the other unique environmental conditions of spaceflight.

Comparison of the cell-free DNA genomics in patients with metastatic breast cancer (MBC) who develop brain metastases versus those without brain metastases.

1094 Background: The genomics of patients with metastatic breast cancer (MBC) who develop brain metastases (BM) is not well understood given the difficulty in obtaining brain tumor for genotyping. We compared tumor genotyping results via cell-free DNA (cfDNA) collected at MBC diagnosis in patients who developed BM after MBC diagnosis with those who did not develop BM (non-BM). Methods: Patients at an academic institution who had cfDNA testing (Guardant 360/Next generation sequencing, 73 gene assay) at MBC diagnosis between 1/2016-12/2017, with ≥ 6 months of follow-up post testing, were identified. A chart review was done to identify tumor subtype, demographics, cfDNA results, and development of BM at or after MBC diagnosis. Pearson’s chi-squared and Wilcoxon rank sum tests were used to determine differences in clinical and cfDNA characteristics in BM vs. non-BM (p&lt;0.05 for statistical significance). Results: CfDNA results were available for 49 patients, of whom 13 (27%) developed BM (4 with BM at MBC diagnosis). The median time to BM development was 11 months. While patients with BM were younger at MBC diagnosis than non-BM (median age BM 53 vs. non-BM 61, p=0.05), they had similar subtype (BM vs. non-BM: HR+/HER2- 62% vs. 69%, HER2+ 8% vs. 14%, TNBC 23% vs. 17%, unknown 8% vs. 0%, p=0.3), de-novo vs. recurrent disease (BM vs. non-BM: de-novo 8% vs. 14%, recurrent 92% vs. 86%, p=0.6), and visceral disease (BM vs. non-BM: 77% vs. 56%, p=0.2) distributions. All patients with BM had ≥1 detectable cfDNA mutation vs. 88% of non-BM. While the median mutant allele frequency of the most common mutation was similar in BM vs. non-BM (2.4% vs. 3.7%, p=0.5), the mutation pattern varied. Patients with BM more often had mutations in BRCA1 (15% vs. 3%, p=0.1), APC (15% vs. 0%, p=0.02), and CDKN2A (15% vs. 0%, p=0.02), compared to non-BM. In 4 patients with BM at MBC diagnosis, mutations in APC (50%), CDKN2A (50%), and BRCA 1/2 (25%) were noted; 1 had coexisting APC and BRCA1/2 mutations and another had coexisting APC and CDKN2A mutations. Conclusions: Patients with MBC who develop BM may have different cfDNA genomics, particularly BRCA1, APC, and CDKN2A mutations. Further research is needed to determine the predictive value of cfDNA at MBC diagnosis in the identification of patients at higher risk of developing BM. [Table: see text]

Biological Fragmentation of Circulating Cell-free DNA Alters Genetic Representation

High-throughput sequencing of circulating cell-free DNA (cfDNA) as liquid biopsy has revolutionized tumor genome profiling by providing a more accurate, longitudinal, real-time and non-invasive mean for precision and personalized medicine. Current knowledge on cfDNA characteristics revealed that it exists mainly as double-stranded molecules, resulting from biological fragmentation into both short (<1 kb) and long segments (>10 kb) [1,2]. Short fractions are mostly derived from apoptosis via the activation of cellular endonucleases leading to the cleavage of chromatin DNA into inter-nucleosomal fragments [3], whereas necrosis generates relatively long fragments of DNA.

Baseline cfDNA characteristics and evolution of cfDNA profile during treatment with selective FGFR inhibitor TAS-120.

3056 Background: There is an increasing role for cfDNA in monitoring response and mechanisms of resistance. We performed cfDNA analysis in a subset of patients enrolled on a Phase I trial with an irreversible, selective FGFR1-4 inhibitor, TAS-120. Methods: 58 plasma samples from 17 patients (13 with cholangiocarcinoma) were analyzed on a 73-gene, next-generation sequencing panel. Selected patients(pts) had longitudinal samples. Results: At least one alteration was detected in 46 cfDNA samples, in 16 (94%) of 17 pts – a pt with GBM had no alterations detected. 14 pts had alterations in FGFR2/3 by genomic testing of archival tumor samples, comprising 20 total alterations (18 unique). 10 of 20 FGFR2/3 alterations were also detected by cfDNA testing: 4/5 SNVs, 1/2 amplifications, 5/13 fusions. Three pts had FGFR/FGF alterations not included (thus not detected) in the cfDNA panel: 2 with FGF ligand amplification, and one FGFR4 mutation. 6 pts (35%) had PR, 5 (29%) had SD and 6 (35%) PD as a best response to TAS-120. Four pts had prior FGFRi: 2 had a PR, 1 SD, and 1 PD on TAS-120. Baseline cfDNA mutations became undetectable during treatment in 4/6 pts with PR. 4 of 6 PD pts had other driver mutations at baseline including mutations in PIK3CA, KRAS, IDH1, BRCA2, or amplifications in PIK3CA, PDGFR. 9 pts with cfDNA available at progression after SD/PR: 3 had acquired FGFR2 mutations (one each of V564L, V564F, or N549K). Two also acquired alterations in other candidate resistance genes ( PTEN and MAP2K1). Another pt had low variant allele frequency (VAF) NRAS G12D and BRAF A694T pretreatment and had SD. At progression, cfDNA revealed an increase in NRAS VAF and mutations acquired in the MAPK pathway . One pt with prior FGFRi acquired FGFR2 V564I and V564K detected by cfDNA prior to initiation of TAS-120, and had a PR on TAS-120. There was a drop in FGFR2 V564I VAF with response that subsequently increased with progression. The patient also acquired a FGFR2 V564L mutation at progression. Conclusions: FGFR alterations can be detected by cfDNA. cfDNA may detect potential resistance mechanisms, including PI3K or MAPK pathway alterations and acquired FGFR2 mutations. Patients with gatekeeper mutations in cfDNA at baseline may still respond to TAS-120. Further study is needed to determine the impact of FGFR2 mutations and co-alterations on TAS-120 sensitivity.

Abstract P4-01-17: Aggressive subgroups of metastatic triple-negative breast cancer: Inflammatory breast cancer and young patients in the Dana-Farber cell-free DNA cohort

Abstract Background: Relative to other metastatic breast cancer subtypes, metastatic triple-negative breast cancer (mTNBC) has a shorter duration of response to therapy and worse overall survival. Within mTNBCs, there is a prevailing belief that inflammatory breast cancer and young women tend to have among the most aggressive phenotypes. We investigated clinical and cell-free DNA (cfDNA) characteristics of inflammatory-mTNBC and young-mTNBC. We hypothesized that inflammatory-mTNBC may have distinct clinical and cfDNA characteristics, offering potential novel biomarker and therapeutic strategies. Methods: 164 patients from the Dana-Farber metastatic triple-negative cell-free DNA cohort (Stover DG, et al J Clin Oncol 2018) were included in this secondary analysis. Patients were stratified into three groups: 1) inflammatory breast cancer ('IBC'); 2) non-IBC patients aged 45 years (yr) or younger at primary diagnosis ('non-IBC young'); and 3) non-IBC patients over age 45 yr at diagnosis. For each subset population, we evaluated clinicopathologic characteristics, sites of metastasis, survival outcomes, and cfDNA 'tumor fraction' – the fraction of DNA in circulation derived from tumor. Those patients with adequate cfDNA tumor content for high confidence copy number calls (n=101) were included in an analysis of copy number alterations. Results: Among 164 patients with metastatic TNBC, 13.4% (22/164) had IBC, 37.8% (62/164) were non-IBC young, and 48.8% (80/164) were non-IBC and over 45 yr. Race and primary receptor status were similar. IBC patients were diagnosed at a higher stage (Chi-square p=0.0009) while non-IBC young patients were significantly more likely to harbor a BRCA mutation (Chi-square p=0.03). Analysis of metastatic sites revealed that IBC patients had significantly greater frequency of ipsilateral and contralateral breast chest wall recurrences (p=0.04 and p=0.046, respectively) while non-IBC young patients had the most frequent lung metastases (p=0.002). There were no significant differences in frequency of bone, brain, or liver metastases. cfDNA analyses showed that cfDNA 'tumor fraction' was highest in non-IBC young patients (ANOVA p=0.03 for maximum tumor fraction). Median overall survival from metastatic diagnosis was 22.9 months. IBC and non-IBC young patients had a worse prognosis relative to non-IBC patients over 45 yr (hazard ratio IBC=1.97, 95% CI 1.09-3.57; HR non-IBC young=1.60 95% CI 1.07-2.41; log-rank p=0.023). By subgroup, median overall survival from metastatic diagnosis for IBC was 15.2 months, non-IBC young 21.2 months, and non-IBC over 45 yr 31.2 months. Analyses of genome-wide copy number alterations from cell-free DNA will be presented. Conclusions: Among metastatic TNBCs, IBC patients and non-IBC young patients have a significantly worse overall survival compared with non-IBC patients over 45 yr of age. Young patients have more frequent lung metastases and higher 'tumor fraction' of cfDNA. Confirmation of the reported findings is limited due to cohort size and may reflect referral bias. Citation Format: Singh J, Asad S, Nock W, Zhang Y, Adams E, Damicis A, Parsons HA, Adalsteinsson VA, Winer EP, Lin NU, Partridge AH, Overmoyer B, Stover DG. Aggressive subgroups of metastatic triple-negative breast cancer: Inflammatory breast cancer and young patients in the Dana-Farber cell-free DNA cohort [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-01-17.

CFDNA characteristics in transitional cell carcinoma (TCC) patients who achieved complete response to checkpoint inhibitors (CPI).

e16589Background: cfDNA Transitional Cell Carcinoma patients who achieve complete response (CR) represent a rare population whose disease monitoring with radiographic evaluation remains challenging...

Cell-free DNA in a three-dimensional spheroid cell culture model: A preliminary study

BackgroundInvestigating the biological functions of cell-free DNA (cfDNA) is limited by the interference of vast numbers of putative sources and causes of DNA release into circulation. Utilization of three-dimensional (3D) spheroid cell cultures, models with characteristics closer to the in vivo state, may be of significant benefit for cfDNA research. MethodsCfDNA was isolated from the growth medium of C3A spheroid cultures in rotating bioreactors during both normal growth and treatment with acetaminophen. Spheroid growth was monitored via planimetry, lactate dehydrogenase activity and glucose consumption and was related to isolated cfDNA characteristics. ResultsChanges in spheroid growth and stability were effectively mirrored by cfDNA characteristics. CfDNA characteristics correlated with that of previous two-dimensional (2D) cell culture and human plasma research. Conclusions3D spheroid cultures can serve as effective, simplified in vivo-simulating “closed-circuit” models since putative sources of cfDNA are limited to only the targeted cells. In addition, cfDNA can also serve as an alternative or auxiliary marker for tracking spheroid growth, development and culture stability. Biological significance3D cell cultures can be used to translate “closed-circuit” in vitro model research into data that is relevant for in vivo studies and clinical applications. In turn, the utilization of cfDNA during 3D culture research can optimize sample collection without affecting the stability of the growth environment. Combining 3D culture and cfDNA research could, therefore, optimize both research fields.