Abstract 2412: Assessment of clinical applications of circulating tumor DNA using an enhanced TAm-Seq platform
1
Citation
0
Reference
10
Related Paper
Citation Trend
Abstract:
Abstract Novel biomarkers are required to assess tumor burden and response in cancer as conventional biopsies are invasive, costly and only provide a snapshot of the mutational profile at a given time and location. A promising biomarker is the detection of genomic material released from tumors into the blood plasma of patients, known as circulating tumor DNA (ctDNA). ctDNA has been detected in plasma for a wide range of solid tumors and can be distinguished from other (germline) cell-free DNA by the presence of tumor-specific DNA alterations or known hotspot mutations. However, the potential of ctDNA as a biomarker has not yet been fully realized due to technical challenges associated with its detection and analysis, including the short fragment sizes (140-170 bp), small number of amplifiable copies and low/variable allele fractions of ctDNA. We have developed an enhanced platform for tagged-amplicon deep sequencing (TAm-Seq™). Using a combination of improved library preparation and bespoke data analysis methods, this platform can be used to sequence established cancer hotspots and the entire coding regions of selected genes, while preserving high levels of specificity and sensitivity. Using this approach, we have developed an assay that analyzes ∼20 kb of the genome (including regions of interest in more than 30 genes) with sensitivity down to a few mutant copies. Performance of this assay has been demonstrated using spike-in experiments, dilution series and clinical sample cohorts. Proof of concept studies have shown the potential of ctDNA to be used to assess tumor mutation status, monitor tumor dynamics, assess response to treatment and identify mutations associated with acquired drug resistance and disease progression. This non-invasive approach - a “liquid biopsy” - offers a revolution in how cancer can be detected, monitored and treated. Citation Format: Andrew RJ Lawson, Vincent Plagnol, Abdelaziz Fahem, Tim Forshew, James D. Brenton, Davina Gale, Nitzan Rosenfeld. Assessment of clinical applications of circulating tumor DNA using an enhanced TAm-Seq platform. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2412. doi:10.1158/1538-7445.AM2015-2412Keywords:
Amplicon
Liquid biopsy
Circulating tumor DNA
Highly sensitive technologies are available for the molecular characterization of solid tumors, including digital PCR (dPCR). Liquid biopsy, based on the analysis of cell-free DNA (cfDNA), is often used to assess EGFR or RAS alterations in lung and colorectal cancers. Our study aimed to compare the results of two different dPCR platforms for the detection of mutations in cfDNA.Plasma samples from lung and colorectal cancer patients collected as per routine procedures have been tested. cfDNA Was extracted from plasma, and samples were screened on the droplet digital PCR (ddPCR, BioRad) and solid dPCR QIAcuity (Qiagen).A total of 42 samples were analyzed, obtained from 20 Non-Small Cell Lung Cancer (NSCLC) patients carrying an EGFR or a KRAS mutation on tissue at diagnosis, and from 22 samples of colorectal cancer (CRC) patients, 10 of which presenting a KRAS mutation. EGFR mutation detection was 58.8% for ddPCR and 100% for dPCR (κ = 0.54; 95% CI, 0.37-0.71), compared to tissue results. The detection rate for RAS mutations was 72.7% for ddPCR and 86.4% for dPCR (κ = 0.34; 95% CI, 0.01-0.68), compared to tissue results.This study showed moderate agreement between dPCR and ddPCR. Sampling effect or threshold settings may potentially explain the differences in the cfDNA data between the two different platforms.
Liquid biopsy
Cite
Citations (15)
The "sample-to-answer" integration and automation of circulating tumor DNA (ctDNA)-based liquid biopsy using digital PCR (dPCR) has been hampered by the complicated operations of liquids with volumes ranging from milliliter samples to nanoliter droplets. On the basis of a "3D extensible" design paradigm proposed previously, an integrated droplet digital PCR (IddPCR) microdevice was successfully developed to automate the entire process of liquid biopsy, from the extraction of ctDNA in 2 mL of plasma using magnetic beads to the generation, amplification, and screening of over 30 000 droplets for detection. A series of reagent mixing structures, including macro-, meso-, and micromixers, was designed to enable efficient reagent handling and mixing at different volume scales. The volume thresholds of the microscale and macroscale in the IddPCR device were calculated to be 40 and 100 μL, respectively, based on the fluid dynamics and sizes of the device structures, so that different mixers can be selected according to the reagent volumes. The DNA extraction efficiency obtained on the device was determined to be ∼60%, and the on-chip ddPCR demonstrated a high correlation with an R2 of 0.9986 between the readouts and the estimations by a Poisson distribution. Finally, the IddPCR microdevice was able to detect rare tumor mutations (T790M) with an occurring frequency as low as ∼1% from 2 mL of human plasma in a "sample-to-answer" manner. This work offers a feasible solution for the automation of liquid biopsy and paves the way for its broad applications in clinics.
Liquid biopsy
Circulating tumor DNA
Cite
Citations (50)
Amplicon
Viremia
Serial dilution
Cite
Citations (140)
Abstract Droplet digital PCR provides superior accuracy in nucleic acid quantitation. The requirement of microfluidics to generate and analyze the emulsions, however, is a barrier to its adoption, particularly in low resource or clinical settings. Here, we report a novel method to prepare ddPCR droplets by vortexing and readout the results by bulk analysis of recovered amplicons. We demonstrate the approach by accurately quantitating SARS-CoV-2 sequences using entirely bulk processing and no microfluidics. Our approach for quantitating reactions should extend to all digital assays that generate amplicons, including digital PCR and LAMP conducted in droplets, microchambers, or nanoliter wells. More broadly, our approach combines important attributes of ddPCR, including enhanced accuracy and robustness to inhibition, with the high-volume sample processing ability of quantitative PCR.
Amplicon
Robustness
Digital Microfluidics
Amplicon sequencing
Cite
Citations (2)
Circulating tumor DNA (ctDNA) is a component of the "naked" DNA found in blood. It can be isolated from plasma and represents combined genetic material from the primary tumor and metastases. Quantitative and qualitative information about a cancer, including mutations, can be derived using digital polymerase chain reaction and other technologies. This "liquid biopsy" is quicker and more easily repeated than tissue biopsy, yields real-time information about the cancer, and may suggest therapeutic options. All stages of cancer therapy have the ability to benefit from ctDNA, starting with screening for cancer before it is clinically apparent. During treatment of metastatic disease, it is useful to predict response and monitor disease progression. Currently, ctDNA is used in the clinic to select patients who may benefit from epidermal growth factor receptor-targeted therapy in non-small cell lung cancer. In the future, ctDNA technology promises useful applications in every part of clinical oncology care.
Liquid biopsy
Circulating tumor DNA
Circulating tumor cell
Cite
Citations (87)
Opportunities and challenges in translational application of ctDNA along with recent developments in chip-based ctDNA detection technologies have been reviewed.
Liquid biopsy
Cite
Citations (269)
Droplet digital PCR provides superior accuracy for nucleic acid quantitation. The requirement of microfluidics to generate and analyze the emulsions, however, is a barrier to its adoption, particularly in low resource settings or clinical laboratories. Here, we report a novel method to prepare ddPCR droplets by vortexing and readout of the results by bulk analysis of recovered amplicons. We demonstrate the approach by accurately quantitating SARS-CoV-2 sequences using entirely bulk processing and no microfluidics. Our approach for quantitating reactions should extend to all digital assays that generate amplicons, including digital PCR and LAMP conducted in droplets, microchambers, or nanoliter wells. More broadly, our approach combines important attributes of ddPCR, including enhanced accuracy and robustness to inhibition, with the high-volume sample processing ability of quantitative PCR.
Amplicon
Digital Microfluidics
Robustness
Cite
Citations (22)
Liquid biopsy allows the identification of targetable cancer mutations in a minimally invasive manner. In patients with advanced non-small cell lung cancer (NSCLC), droplet digital PCR (ddPCR) is increasingly used to genotype the epidermal growth factor receptor (EGFR) gene in circulating cell-free DNA (cfDNA). However, the sensitivity of this method is still under debate. The aim of this study was to implement and assess the performance of a ddPCR assay for detecting the EGFR T790M mutation in liquid biopsies.A ddPCR assay was optimized to detect the EGFR T790M mutation in plasma samples from 77 patients with NSCLC in progression.Our ddPCR assay enabled the detection and quantification of the EGFR T790M mutation at cfDNA allele frequency as low as 0.5%. The mutation was detected in 40 plasma samples, corresponding to a positivity rate of 52%. The number of mutant molecules per mL of plasma ranged from 1 to 6,000. A re-biopsy was analyzed for 12 patients that had a negative plasma test and the mutation was detected in 2 cases. A second liquid biopsy was performed for 6 patients and the mutation was detected in 3 cases.This study highlights the value of ddPCR to detect and quantify the EGFR T790M mutation in liquid biopsies in a real-world clinical setting. Our results suggest that repeated ddPCR tests in cfDNA may obviate tissue re-biopsy in patients unable to provide a tumor tissue sample suitable for molecular analysis.
T790M
Liquid biopsy
Cell-free fetal DNA
Cite
Citations (20)
The use of liquid biopsy is of potential high importance for children with high grade (HGG) and diffuse midline gliomas (DMG), particularly where surgical procedures are limited, and invasive biopsy sampling not without risk. To date, however, the evidence that detection of cell-free DNA (cfDNA) or circulating tumor DNA (ctDNA) could provide useful information for these patients has been limited, or contradictory.
Liquid biopsy
Circulating tumor DNA
Cell-free fetal DNA
Cite
Citations (57)