KRAS and NRAS mutational analysis in plasma ctDNA from patients with metastatic colorectal cancer by real-time PCR and digital PCR
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Published on: March 14, 2019
Manuela Pinheiro1, Ana Peixoto1,2, Patricia Rocha1,2
1Cancer Genetics Group, IPO Porto Research Center (CI-IPOP), Portuguese Oncology Institute of Porto, Rua Dr. António Bernardino Almeida, 4200-072, Porto, Portugal.
Purpose:
Mutations in the KRAS and NRAS (RAS) genes are negative predictors of response to anti-EGFR therapy in metastatic colorectal cancer (mCRC). The detection of mutations in circulating tumor DNA (ctDNA) has emerged as a less invasive strategy to assess the molecular profile of mCRC patients. We aimed to perform RAS mutational analysis in ctDNA from mCRC patients using BEAMing Digital PCR (OncoBEAM) and Idylla ctDNA qPCR and evaluate the concordance rate with RAS mutational status in tumor tissue and between these two methodologies with different limits of detection.
Methods:
Blood samples were collected from 47 mCRC patients previously tested for RAS mutations in tumor tissue. DNA was extracted from plasma using the QIAamp Circulating Nucleic Acid Kit, and RAS mutation analysis was conducted using OncoBEAM RAS CRC and Idylla ctRAS assays.
Results:
The overall agreement between tumor tissue and ctDNA analyses was 83% and 78.7% using the OncoBEAM and Idylla assays, respectively, with the concordance being 96.2% and 88.5% in naive treatment patients. The overall agreement between OncoBEAM and Idylla ctDNA analyses was 91.7%.
Conclusions:
Analysis of ctDNA is a viable strategy for clinical management of mCRC patients. Although the OncoBEAM assay sensitivity is somewhat higher, the fully automated Idylla platform also has good performance, while being cheaper and much less labor-intensive, for the detection of RAS mutations in plasma, either at diagnosis or after progression when considering anti-EGFR treatment rechallenge.
Insights
Circulating tumor DNA (ctDNA) analysis is a viable strategy for managing metastatic colorectal cancer (mCRC). Both BEAMing Digital PCR and Idylla assays show good concordance with tumor tissue RAS mutation status, supporting ctDNA
Area of Science:
- Oncology
- Molecular Diagnostics
- Genetics
Background:
- RAS gene mutations (KRAS and NRAS) are key negative predictors of anti-EGFR therapy response in metastatic colorectal cancer (mCRC).
- Circulating tumor DNA (ctDNA) analysis offers a less invasive method for assessing mCRC molecular profiles.
- Accurate RAS mutation detection is crucial for guiding treatment decisions in mCRC.
Purpose of the Study:
- To evaluate RAS mutational analysis in ctDNA from mCRC patients using BEAMing Digital PCR (OncoBEAM) and Idylla ctDNA qPCR.
- To assess the concordance of ctDNA RAS mutation status with tumor tissue analysis.
- To compare the concordance between OncoBEAM and Idylla methodologies, considering their different limits of detection.
Main Methods:
- Blood samples were collected from 47 mCRC patients with known tumor tissue RAS mutation status.
- DNA was extracted from plasma using the QIAamp Circulating Nucleic Acid Kit.
- RAS mutation analysis was performed using OncoBEAM RAS CRC and Idylla ctRAS assays.
Main Results:
- Overall agreement between tumor tissue and ctDNA RAS mutation status was 83% for OncoBEAM and 78.7% for Idylla.
- Concordance in naive treatment patients was 96.2% (OncoBEAM) and 88.5% (Idylla).
- The overall agreement between the OncoBEAM and Idylla ctDNA assays was 91.7%.
Conclusions:
- ctDNA analysis is a feasible approach for the clinical management of mCRC patients.
- While OncoBEAM shows higher sensitivity, the automated Idylla platform offers a cost-effective and less labor-intensive alternative for RAS mutation detection in plasma.
- Both methods support the use of ctDNA for RAS mutation assessment at diagnosis or during progression for anti-EGFR treatment decisions.
