Liquid Biopsies: Miracle Diagnostic or Next New Fad?
Article Jun 28, 2016
GATCLIQUID is the world's first service line for comprehensive liquid biopsy analysis. The plasma-based tests offer sensitive and cost-efficient detection of mutations in circulating tumour DNA. The services advance cancer research and diagnostics through detailed assessment of the tumour exome, of selected cancer drivers or by monitoring of single mutations.
" Highly sensitive methods are essential, to detect cancer specific SNPs in ctDNA with high confidence. Therefore, we offer unique services, which can be used to get a deeper understanding of cancer and its dynamics."
Dr Tobias Paprotka – Director Research & Development at GATC Biotech
Droplet Digital™PCR (ddPCR™ technology has emerged as the clearest path for liquid biopsy to the clinic. Its superior precision, sensitivity, and rapid time to results in detecting and quantifying low abundance DNA targets have allowed laboratories to develop tests for monitoring residual disease, tracking treatment efficacy, and identifying disease recurrence earlier and more confidently than ever before.
" Bio-Rad is advancing liquid biopsy analysis through our comprehensive offering of ddPCR mutation detection assays and reagents. We are also committed to achieving regulatory clearance for our ddPCR systems and solutions."
Viresh Patel, Marketing Director, Digital Biology Group, Bio-Rad Laboratories
QIAGEN’s liquid biopsy solutions empower you to sensitively, specifically and rapidly reveal meaningful insights from your samples with an efficient, streamlined and complete workflow for analyzing circulating cell-free DNA, exosomes and CTCs for PCR and NGS applications, giving you the first step towards uncovering valuable biomarkers in your samples.
" Our mission is to provide you with the best-in-class solutions from Sample to Insight in the emerging field of Liquid Biopsy that has the potential to transform biomarker research and healthcare."
Michael Kazinski, Senior Director, Molecular Preanalytic Technology, QIAGEN
Diagnosing, monitoring, and managing cancer through blood tests has been a decades-long goal of medical diagnostics. Complete blood counts, protein biomarkers, and cancer antigen tests (e.g. for prostate-specific antigen) provide clues regarding disease status, but do not always render definitive diagnoses.
Liquid biopsies (LBs) are an emerging, disparate group of technologies that seek to broaden the scope and sensitivity of blood-based cancer diagnosis. Since they usually require only a blood sample (vs. solid tissue) LBs are primarily non-invasive. And thanks to the development of highly specific gene-amplification and sequencing technologies LBs access more biomarkers relevant to more cancers than ever before.
Traditional tissue biopsies range in cost from $15,000 to $60,000 U.S. dollars, depending on whether invasive surgery is required, the level of sample preparation, pathology services, and follow-on genetic tests. Because so many hands are in play, traditional biopsies have a failure rate of approximately 25%. Additionally, biopsy tissue from tumors is simply not available for monitoring patient response over the course of treatment, when liquid biopsies become the only feasible option.
LBs seek out two major targets: circulating cancer cells (CTCs) and cell-free tumor DNA (cfDNA). CTC analysis focuses on isolating and expanding populations of rare cells for downstream analysis. cfDNA LBs identify multiple circulating tumor gene mutants at multiple time points.
LBs have generated great attention for their ease of use and applications across many different diseases and health conditions, such as noninvasive prenatal testing, transplant medicine, and oncology – far and away the most commercially lucrative market.
It’s in the Genes
“Liquid biopsies will provide clinicians with faster, cheaper, broader, less invasive ways to assess cancer patients’ clinical status, and help to deliver the right treatment for the right target without delay,” says Dr. Chen-Hsiung Yeh, Chief Scientific Officer at Circulogene Theranostics (Birmingham, Alabama, USA). Yeh believes DNA-based liquid biopsies for multiple mutation profiles could become the gold standard for next-generation cancer management and precision medicine. “Clinical tests employing cfDNA are inherently specific, sensitive, and capture both intra- and inter-tumor heterogeneity in real time,” he adds.
Table 1: Comparison of liquid biopsy and tissue biopsy. Note that these benefits apply to liquid biopsies based on CTCs.
|Key Characteristics||Liquid Biopsy||Tissue Biopsy|
|Suitability throughout the disease process||Yes||No|
|Ex vivo sample stability||Yes (less so for CTCs)||Stable when processed|
|Provides longitudinal disease monitoring||Yes||No|
|Processing Time||Short||Long (involvement of tissue sectioning, staining and pathologists)|
|Rejection/Failure rates||Low||High due to insufficient sample or unidentified tumor|
|Starting material for multiple testing||Ample||Scarce|
Source: Circulogene Theranostics
Circulating cfDNA is highly fragmented and exists at very low concentrations, making its isolation from blood challenging. Isolation efficiency using silica membrane/bead techniques is extremely low due to the unavoidable losses during gene binding, washing, and elution. Circulogene’s cfDNA enrichment technology enables nearly full-recovery of cfDNA from both necrotic and apoptotic cells.
Detection of such mutations has potential for monitoring tumor progression before lesions reach a size amenable for diagnostic imaging. PET scans, for example, cannot visualize solid tumors containing fewer than 6 million cells in one location. Analysis beyond a single mutation could also uncover tumor heterogeneity that might influence treatment decision-making.
“Liquid biopsies are not as spatially limited as tissue biopsies, and display a global spectrum of mutations that occur throughout cancer development,” Yeh says. Nevertheless, the sensitivity of conventional Sanger sequencing is not sufficient for detecting low-frequency variants. Advanced next-generation sequencing bioinformatics, for example developed by Guardant Health, provides a cost-effective, highly sensitive alternative for high-throughput analysis of multiple mutations. Additionally PCR-based amplification techniques from RainDance, Bio-Rad, Qiagen, Thermo Fisher, Transgenomic, Sysmex Inostics and Trovagene, allow single-molecule amplification and/or selective enrichment of tumor-specific cfDNA.
Immersed as he is in this new industry, Yeh believes that larger prospective trials are needed to confirm the clinical utility of cfDNA testing. “Future studies must demonstrate whether cfDNA-derived mutation profiles from blood samples can contribute to improved treatment outcomes in cancer patients.”
Table 2: Advanced technologies employed for circulating cell-free DNA in oncology
|ARMS-PCR (Amplification Refractory Mutation System)||1 %||Treatment decision; Resistance|
|Suitability throughout the disease process||0.1–1 %||Treatment decision; Resistance|
|Clamping PCR||Yes (less so for CTCs)||Stable when processed|
|castPCR (Competitive Allele-Specific TaqMan PCR)||0.1–1 %||Treatment decision; Resistance|
|ICE COLD-PCR (Improved & Complete Enrichment CO-amplification at Lower Denaturation temperature)||0.1-1 %||Treatment decision; Resistance|
|BEAMing Digital PCR (Beads, Emulsions, Amplification and Magnetics)||0.01 %||Treatment decision; Resistance|
|Droplet Digital PCR||< 0.1 %||Treatment decision; Resistance|
|NGS (Next-Generation Sequencing)||1-5 %||Treatment decision; Metastasis; Resistance; Recurrence|
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