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RAS testing in metastatic colorectal cancer: advances in Europe
J Han J M Van Krieken1, Etienne Rouleau2, Marjolijn J L Ligtenberg3
1Department of Pathology, Radboud University Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, Netherlands. Han.vanKrieken@radboudumc.nl.
Abstract:
Personalized medicine shows promise for maximizing efficacy and minimizing toxicity of anti-cancer treatment. KRAS exon 2 mutations are predictive of resistance to epidermal growth factor receptor-directed monoclonal antibodies in patients with metastatic colorectal cancer. Recent studies have shown that broader RAS testing (KRAS and NRAS) is needed to select patients for treatment. While Sanger sequencing is still used, approaches based on various methodologies are available. Few CE-approved kits, however, detect the full spectrum of RAS mutations. More recently, "next-generation" sequencing has been developed for research use, including parallel semiconductor sequencing and reversible termination. These techniques have high technical sensitivities for detecting mutations, although the ideal threshold is currently unknown. Finally, liquid biopsy has the potential to become an additional tool to assess tumor-derived DNA. For accurate and timely RAS testing, appropriate sampling and prompt delivery of material is critical. Processes to ensure efficient turnaround from sample request to RAS evaluation must be implemented so that patients receive the most appropriate treatment. Given the variety of methodologies, external quality assurance programs are important to ensure a high standard of RAS testing. Here, we review technical and practical aspects of RAS testing for pathologists working with metastatic colorectal cancer tumor samples. The extension of markers from KRAS to RAS testing is the new paradigm for biomarker testing in colorectal cancer.
Insights
Broader RAS testing, including KRAS and NRAS mutations, is crucial for selecting effective anti-cancer treatments in metastatic colorectal cancer. Accurate and timely testing ensures personalized medicine approaches improve patient outcomes.
Area of Science:
- Oncology
- Molecular Diagnostics
- Personalized Medicine
Background:
- KRAS exon 2 mutations predict resistance to epidermal growth factor receptor-directed therapies in metastatic colorectal cancer.
- Personalized medicine aims to optimize anti-cancer treatment efficacy and minimize toxicity.
- Broader RAS (KRAS and NRAS) testing is increasingly recognized as necessary for patient selection.
Purpose of the Study:
- To review the technical and practical aspects of RAS testing for pathologists.
- To highlight the importance of extending biomarker testing from KRAS to RAS in colorectal cancer.
- To discuss methodologies and quality assurance for RAS mutation detection.
Main Methods:
- Review of current and emerging RAS testing methodologies, including Sanger sequencing and next-generation sequencing (NGS).
- Discussion of the potential role of liquid biopsy for tumor-derived DNA assessment.
- Emphasis on critical factors for accurate and timely testing: sampling, delivery, and turnaround processes.
Main Results:
- While Sanger sequencing is established, NGS offers high technical sensitivity for mutation detection.
- Few CE-approved kits cover the full spectrum of RAS mutations.
- Liquid biopsy presents a potential complementary tool for RAS evaluation.
Conclusions:
- RAS testing, encompassing both KRAS and NRAS, represents a new paradigm in colorectal cancer biomarker assessment.
- Efficient RAS testing processes and robust external quality assurance are vital for ensuring high standards.
- Implementing appropriate sampling and prompt evaluation is critical for timely and effective patient treatment.
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