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Detection and Monitoring of Tumor Associated Circulating DNA in Patient Biofluids
Published on: June 8, 2019
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Direct circulating tumor DNA detection from unpurified plasma using a digital PCR platform
David Sefrioui1, Ludivine Beaussire2, Anne Perdrix3
1Normandie Univ, UNIROUEN, Inserm U1245, IRON group, Rouen University Hospital, Normandy Centre for Genomic and Personalized Medicine, Department of Hepatogastroenterology, F 76000 Rouen, France.
Clinical Biochemistry
|June 25, 2017
Summary
Directly analyzing circulating tumor DNA (ctDNA) from plasma using digital PCR (dPCR) is feasible. This method shows high concordance with traditional isolation techniques, especially for samples with higher mutant allelic frequencies (MAF).
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Circulating tumor DNA (ctDNA) analysis typically requires a plasma isolation step.
- The necessity of this isolation step for ultrasensitive technologies like digital PCR (dPCR) is uncertain.
- Investigating direct ctDNA detection from plasma versus post-isolation analysis is crucial for optimizing pre-analytical workflows.
Purpose of the Study:
- To evaluate the efficacy of ctDNA detection using a dPCR platform directly from plasma (plasma group, PG).
- To compare ctDNA detection performance between direct plasma analysis (PG) and analysis after a DNA isolation step (isolation group, IG).
- To assess the impact of plasma processing on ctDNA detection rates and mutant allelic frequencies (MAF).
Main Methods:
- Analysis of 43 blood samples from 17 metastatic colorectal cancer patients.
- Comparison of ctDNA detection with and without a plasma isolation step using dPCR.
- Detection of KRAS, NRAS, and BRAF mutations following a pre-amplification step.
Main Results:
- ctDNA detection rates were 93% for the isolation group (IG) and 88% for the plasma group (PG).
- High concordance (91%) in ctDNA detection between IG and PG, with discrepancies mainly in samples with low MAF (<0.5%).
- Strong correlation (r²=0.82) in mutant allelic frequencies (MAF) between the two methods, with no significant difference in mean MAF values.
Conclusions:
- Direct detection of ctDNA from unpurified plasma is a viable approach.
- This direct method is particularly effective for samples with higher mutant allelic frequencies (MAF >0.5%).
- The findings suggest potential simplification of pre-analytical procedures for ctDNA analysis.
