Relevance of BRAF and extended RAS mutational analyses for metastatic colorectal cancer patients (original) (raw)
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The Journal of Molecular Diagnostics, 2011
The analysis of KRAS mutations has become a prerequisite for anti-epidermal growth factor receptor therapy in patients with metastatic colorectal cancers. KRAS mutations are associated with resistance to treatment by monoclonal antibodies such as cetuximab and panitumumab and thus are correlated with a shorter progression-free survival. BRAF mutations also may play a role in treatment decisions. The widespread use of these targeted therapies has generated the need to develop cost-effective methods for routine KRAS and BRAF analysis. The aim of this study was to compare a multiplex SNaPshot assay with DNA sequencing and high-resolution melting analysis for identifying KRAS codons 12 and 13 and BRAF codon 600 mutations. Thus 110 routinely formalin-fixed and paraffin-embedded tissue blocks were tested by each method. The SNaPshot analysis detected KRAS and BRAF codon 600 mutations in, respectively, 34.5% (n ؍ 38) and 10% (n ؍ 11) of these tissue blocks. These results were confirmed by direct DNA sequencing and by high-resolution melting analysis. The costs and time constraints of each detection method were compared at the same time. In conclusion, our newly designed multiplex SNaPshot assay is a fast, inexpensive, sensitive, and robust technique for molecular diagnostic practices and patient selection.
Molecular cancer therapeutics, 2017
In metastatic colorectal cancer (mCRC) recent studies have shown the importance to accurately quantify low-abundance mutations of RAS pathway because anti-EGFR therapy may depend on certain mutation thresholds. We aimed to evaluate the added predictive value of extended RAS panel testing using two commercial assays and a highly sensitive and quantitative digital PCR (dPCR). Tumor samples from 583 mCRC patients treated with anti-EGFR (n=255) or bevacizumab (n=328) based therapies from several clinical trials and retrospective series from the TTD/RTICC Spanish network were analyzed by cobas®, therascreen® and dPCR. We evaluated concordance between techniques using Cohen's kappa index. Response rate, progression-free survival (PFS) and overall survival (OS) were correlated to the mutational status and the mutant allele fraction (MAF). Concordance between techniques was high when analyzing RAS and BRAF (Cohen's kappa index around 0.75). We observed an inverse correlation between...
Molecular Diagnosis & Therapy, 2013
Background and Objective The rapid development of molecular biology techniques allows for the introduction of real-time polymerase chain reaction (PCR) methods with a limit of mutation detection at 1 % in a background of wildtype DNA. Analysis of KRAS mutations in codons 12, 13, and 61, together with analysis of BRAF mutations in codon 600, are predictive biomarkers for anti-epidermal growth factor receptor (EGFR) treatment in colorectal cancer. Our aim was to compare PCR methods for KRAS mutations and BRAF mutation analysis using DNA isolated from tissue samples previously evaluated for presence of tumor cells using a quantitative scale and the percentage of tumor cells (PTC) scale. We addressed the question of whether a low number of tumor cells can be qualified for somatic mutation testing. Results Our study showed that PTC as low as 10 % was good enough to detect KRAS G12D, G13D, and Q61L mutations in formalin-fixed paraffin-embedded (FFPE) material. Furthermore, our results indicate that up to 20 % of colorectal cancer may carry mutations in the KRAS codon 61 and BRAF codon 600, which suggests the value of these mutation analyses because patients carrying them are unlikely to respond to cetuximab or panitumumab. A low level of KRAS somatic mutation detection has not been studied in depth in the context of clinical outcomes in patients; therefore, we compared new PCR methods, (KRBR-RT 50 Entrogen; ViennaLab StripAssay) and re-evaluated KRAS and BRAF status in patients with relapse after targeted therapy. Conclusions The importance of molecular results was confirmed by clinical observation of a patient with relapse who had qualified for targeted therapy with KRAS WT status (but was diagnosed by less sensitive single-stranded conformation polymorphisms method). Interestingly, during anti-EGFR treatment, it came to the selection of cells with KRAS G12C mutation which were present from the beginning in the tumor but at a low level (detected by PCR methods) only and led consequently to the metastasis. Taking into consideration the limit of detection, labor time, and assay cost, the real-time PCR method seems to be very promising especially for FFPE material with the PTC below 15 %.
Appropriate use of tumour biomarkers for treatment with innovative drugs: A retrospective study
Oncology Letters, 2015
Performing randomised clinical trials to address the clinical usefulness of predictive and prognostic tumour markers is a complex process for several reasons, and observational experiences may thus play an important role. The present study performed an observational retrospective analysis in Area Vasta Romagna, Italy, collecting information on tumour marker determination in 760 consecutive patients who started a new line of anticancer therapy between January and June 2010. The determination of well-known biomarkers was requested for all gastrointestinal stromal tumour (GIST) patients (n=13) and for almost all breast cancer patients (n=369), and targeted therapies were consequently prescribed. Conversely, Kirsten rat sarcoma viral oncogene homolog (KRAS) determination in colon cancer patients (n=177) was requested in ~50% of advanced cases, while epidermal growth factor receptor (EGFR) determination was required in slightly more than 30% of the same patients. EGFR and KRAS determinations were requested in only 15% and 7.5% of non-small cell lung cancer (NSCLC) patients (n=201), respectively. There would appear to be greater appropriateness of tumour marker determination for breast cancer and GISTs than for colon cancer and NSCLC. Resources can be further optimised by standardising tumour marker determinations in terms of the timing of requests and the consequent use of the results for tailored treatment planning.
Avances tecnológicos en nuevos marcadores en cáncer y en biología tumoral AACR
2012
Activated kinases that induce cell proliferation have been attractive targets for targeted cancer therapy development. Cancer cells could become dependent on tumor-specifi c activated kinases and this tendency has been coined oncogene addiction. Here, we investigated three activated kinase inhibitors: BRAF inhibitor, PLX-4032 analog, and the MEK inhibitors, CI1040 and PD0325901. We established a high throughput cellular approach to profi le 240 human tumor cell lines identifying genotype-correlated sensitivity or resistance. Proliferative, apoptotic and cell cycle arrest responses were measured using multiplexed high content screening with automated fl uorescence microscopy and image analysis based technology. Growth index was measured using nuclear dye. Activated caspase 3 antibodies were used for the apoptosis induction detection. Phospho-histone H3 antibodies were used to measure the cell cycle block. We generated cell line profi les to reveal drug sensitivity and resistance patterns that may correlate with the clinical genotype responses. Cell lines with BRAFV600E mutations showed overlapping sensitivity to all three MEK and BRAF inhibitors. RAS mutations confer resistance to the BRAF inhibitor and confer sensitivity to both MEK inhibitors. In addition, we used Alphascreen technology to measure phosphoERK across the 240 non-treated tumor cell line panel. We found that the majority of PLX-4032 sensitive cell lines expressed high levels of phosphoERK. In addition, we investigated BRAF, MEK and EGFR inhibitor combinations to evaluate potential synergies. This preclinical approach can be used to predict mechanisms of susceptibility or resistance to these agents which in turn could be used for the optimization of targeted cancer therapeutics.