Related Experiment Video
Updated: May 19, 2026
CRISPR-Cas-mediated Multianalyte Synthetic Urine Biomarker Test for Portable Diagnostics
Published on: December 8, 2023
Study of KRAS new predictive marker in a clinical laboratory
Inmaculada Bando1, Lourdes Cillero, Julián Sanz-Ortega
1Laboratorio de Oncología Molecular, Planta Baja Sur, Hospital Clínico San Carlos, C/Martín Lagos s/n, Madrid, Spain.
Background:
The presence of somatic mutations in the KRAS gene has been identified as a reliable strong negative predictor for the response to targeting the epidermal growth factor receptor (EGFR), in patients with metastatic colorectal cancer and the use of anti-EGFR monoclonal antibodies such as Cetuximab and Panitumumab is now restricted to patients with no detectable KRAS mutations. Between 30 and 40 % of colorectal cancers contain a mutated KRAS oncogene. The aim of this study was to evaluate concordance between three methods to analyze KRAS mutational status in regard to clinical testing.
Methods:
We analyzed KRAS mutations in codons 12 and 13 of exon 2 in one hundred formalin-fixed paraffin-embedded (FFPE) colorectal cancer samples by three different methods: Direct Sequencing and two commercial kits on allele-specific oligonucleotide hybridization (KRAS StripAssay, Vienna Lab.) and Amplification Refractory Mutation System/Scorpions (ARMS/S; TheraScreen KRAS Mutation kit DxS) based on q-PCR.
Results:
We have found similar frequencies of KRAS mutations by TheraScreen and Strip-Assay (44 and 48 %), with a κ value of 0.90, indicating almost perfect agreement between methods. The frequency by direct sequencing was much lower (26 %) and the κ values were 0.67 (compared to TheraScreen) and 0.57 (compared to Strip-Assay) indicating low sensitivity.
Conclusions:
On analyzing KRAS mutation in FFPE tumor samples, direct sequencing sensitivity is too low to be used in a clinical setting. Choosing between ARMS/S; TheraScreen KRAS Mutation kit DxS and KRAS StripAssay, Vienna Lab, will depend on laboratory facilities and expertise.
Insights
Direct sequencing shows low sensitivity for KRAS mutation detection in colorectal cancer. Commercial kits like TheraScreen and Strip-Assay offer high concordance, making them suitable for clinical use.
Area of Science:
- Oncology
- Molecular Diagnostics
- Genetics
Background:
- KRAS mutations are key negative predictors for anti-EGFR therapy response in metastatic colorectal cancer (CRC).
- Approximately 30-40% of CRC cases harbor KRAS oncogene mutations.
- Current clinical practice restricts anti-EGFR antibody use to patients without detectable KRAS mutations.
Purpose of the Study:
- To evaluate the concordance of three distinct methods for analyzing KRAS mutational status.
- To assess the suitability of different KRAS testing methods for clinical application.
Main Methods:
- Analysis of KRAS mutations (codons 12 and 13, exon 2) in 100 FFPE CRC samples.
- Comparison of Direct Sequencing with two commercial kits: KRAS StripAssay and TheraScreen (ARMS/S) based on q-PCR.
Main Results:
- TheraScreen and Strip-Assay showed high concordance (κ=0.90), detecting mutations in 44% and 48% of samples, respectively.
- Direct sequencing identified mutations at a lower frequency (26%) with lower concordance (κ=0.67 and κ=0.57).
- Direct sequencing demonstrated significantly lower sensitivity compared to the commercial kits.
Conclusions:
- Direct sequencing lacks the required sensitivity for clinical KRAS mutation analysis in FFPE tumor samples.
- Both TheraScreen (ARMS/S) and KRAS StripAssay are reliable methods, with the choice depending on laboratory resources and expertise.
