ACB-PCR Quantification of K-<i>RAS</i>Codon 12 GAT and GTT Mutant Fraction in Colon Tumor and Non-Tumor Tissue

Parsons, Barbara L.; Marchant-Miros, Kathryn E.; Delongchamp, Robert R.; Verkler, Tracie L.; Patterson, Tucker A.; McKinzie, Page B.; Kim, Lawrence T.

doi:10.3109/07357901003630975

Cited by 26 publications

(34 citation statements)

References 32 publications

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“…These findings have other important clinical implications. They also suggest that the use of RAF inhibitors might be pointless and even deleterious in normal tissues especially in cells harboring a RAS mutation, as it can be found in lung and colon tissue, for example (40,41). Indeed, we cannot exclude the hypothesis that RAF inhibitors could promote cell transformation and/or proliferation in these wtBRAF cells with RAS activation and lead to internal tumors.…”

Section: A B C D E F G H Discussionmentioning

confidence: 87%

Skin Tumors Induced by Sorafenib; Paradoxic RAS–RAF Pathway Activation and Oncogenic Mutations of HRAS, TP53, and TGFBR1

Arnault

Mateus

Escudier

et al. 2012

Clinical Cancer Research

114

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Purpose: The emergence of skin tumors in patients treated with sorafenib or with more recent BRAF inhibitors is an intriguing and potentially serious event. We carried out a clinical, pathologic, and molecular study of skin lesions occurring in patients receiving sorafenib.Experimental Design: Thirty-one skin lesions from patients receiving sorafenib were characterized clinically and pathologically. DNA extracted from the lesions was screened for mutation hot spots of HRAS, NRAS, KiRAS, TP53, EGFR, BRAF, AKT1, PI3KCA, TGFBR1, and PTEN. Biological effect of sorafenib was studied in vivo in normal skin specimen and in vitro on cultured keratinocytes.Results: We observed a continuous spectrum of lesions: from benign to more inflammatory and proliferative lesions, all seemingly initiated in the hair follicles. Eight oncogenic HRAS, TGFBR1, and TP53 mutations were found in 2 benign lesions, 3 keratoacanthomas (KA) and 3 KA-like squamous cell carcinoma (SCC). Six of them correspond to the typical UV signature. Treatment with sorafenib led to an increased keratinocyte proliferation and a tendency toward increased mitogen-activated protein kinase (MAPK) pathway activation in normal skin.Sorafenib induced BRAF-CRAF dimerization in cultured keratinocytes and activated CRAF with a dosedependent effect on MAP-kinase pathway activation and on keratinocyte proliferation.Conclusion: Sorafenib induces keratinocyte proliferation in vivo and a time-and dose-dependent activation of the MAP kinase pathway in vitro. It is associated with a spectrum of lesions ranging from benign follicular cystic lesions to KA-like SCC. Additional and potentially preexisting somatic genetic events, like UV-induced mutations, might influence the evolution of benign lesions to more proliferative and malignant tumors.

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Section: A B C D E F G H Discussionmentioning

confidence: 87%

Skin Tumors Induced by Sorafenib; Paradoxic RAS–RAF Pathway Activation and Oncogenic Mutations of HRAS, TP53, and TGFBR1

Arnault

Mateus

Escudier

et al. 2012

Clinical Cancer Research

114

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“…22,26,33,[41][42][43][44] Approximately 50% of people do not have RAS mutations and are classified as RAS WT.…”

Section: -40mentioning

confidence: 99%

The clinical effectiveness and cost-effectiveness of cetuximab (review of technology appraisal no. 176) and panitumumab (partial review of technology appraisal no. 240) for previously untreated metastatic colorectal cancer: a systematic review and economic evaluation

Huxley

Crathorne

Varley-Campbell

et al. 2017

Health Technol Assess

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BackgroundColorectal cancer is the fourth most commonly diagnosed cancer in the UK after breast, lung and prostate cancer. People with metastatic disease who are sufficiently fit are usually treated with active chemotherapy as first- or second-line therapy. Targeted agents are available, including the antiepidermal growth factor receptor (EGFR) agents cetuximab (Erbitux®, Merck Serono UK Ltd, Feltham, UK) and panitumumab (Vecitibix®, Amgen UK Ltd, Cambridge, UK).ObjectiveTo investigate the clinical effectiveness and cost-effectiveness of panitumumab in combination with chemotherapy and cetuximab in combination with chemotherapy for rat sarcoma (RAS) wild-type (WT) patients for the first-line treatment of metastatic colorectal cancer.Data sourcesThe assessment included a systematic review of clinical effectiveness and cost-effectiveness studies, a review and critique of manufacturer submissions, and a de novo cohort-based economic analysis. For the assessment of effectiveness, a literature search was conducted up to 27 April 2015 in a range of electronic databases, including MEDLINE, EMBASE and The Cochrane Library.Review methodsStudies were included if they were randomised controlled trials (RCTs) or systematic reviews of RCTs of cetuximab or panitumumab in participants with previously untreated metastatic colorectal cancer withRASWT status. All steps in the review were performed by one reviewer and checked independently by a second. Narrative synthesis and network meta-analyses (NMAs) were conducted for outcomes of interest. An economic model was developed focusing on first-line treatment and using a 30-year time horizon to capture costs and benefits. Costs and benefits were discounted at 3.5% per annum. Scenario analyses and probabilistic and univariate deterministic sensitivity analyses were performed.ResultsThe searches identified 2811 titles and abstracts, of which five clinical trials were included. Additional data from these trials were provided by the manufacturers. No data were available for panitumumab plus irinotecan-based chemotherapy (folinic acid + 5-fluorouracil + irinotecan) (FOLFIRI) in previously untreated patients. Studies reported results forRASWT subgroups. First-line treatment with anti-EGFR therapies in combination with chemotherapy appeared to have statistically significant benefits for patients who areRASWT. For the independent economic evaluation, the base-case incremental cost-effectiveness ratio (ICER) forRASWT patients for cetuximab plus oxaliplatin-based chemotherapy (folinic acid + 5-fluorouracil + oxaliplatin) (FOLFOX) compared with FOLFOX was £104,205 per quality-adjusted life-year (QALY) gained; for panitumumab plus FOLFOX compared with FOLFOX was £204,103 per QALY gained; and for cetuximab plus FOLFIRI compared with FOLFIRI was £122,554 per QALY gained. The ICERs were sensitive to treatment duration, progression-free survival, overall survival (resected patients only) and resection rates.LimitationsThe trials includedRASWT populations only as subgroups. No evidence was available for panitumumab plus FOLFIRI. Two networks were used for the NMA and model, based on the different chemotherapies (FOLFOX and FOLFIRI), as insufficient evidence was available to the assessment group to connect these networks.ConclusionsAlthough cetuximab and panitumumab in combination with chemotherapy appear to be clinically beneficial forRASWT patients compared with chemotherapy alone, they are likely to represent poor value for money when judged by cost-effectiveness criteria currently used in the UK. It would be useful to conduct a RCT in patients withRASWT.Study registrationThis study is registered as PROSPERO CRD42015016111.FundingThe National Institute for Health Research Health Technology Assessment programme.

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“…First, the frequencies of spontaneous tumor-associated mutations are higher than expected based on neutral reporter gene mutant frequencies. Second, when the mutations most strongly associated with particular tumor types are measured in tumor tissue by ACB-PCR, tumor subpopulations are observed [Verkler et al, 2008a;Parsons et al, 2010].…”

Section: Lessons Learned During Initial Validation Of Oncomutation Asmentioning

confidence: 99%

Oncomutations as biomarkers of cancer risk

Parsons

Myers

Meng

et al. 2010

Environ and Mol Mutagen

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Cancer risk assessment impacts a range of societal needs, from the regulation of chemicals to achieving the best possible human health outcomes. Because oncogene and tumor suppressor gene mutations are necessary for the development of cancer, such mutations are ideal biomarkers to use in cancer risk assessment. Consequently, DNA-based methods to quantify particular tumor-associated hotspot point mutations (i.e., oncomutations) have been developed, including allele-specific competitive blocker-PCR (ACB-PCR). Several studies using ACB-PCR and model mutagens have demonstrated that significant induction of tumor-associated oncomutations are measureable at earlier time points than are used to score tumors in a bioassay. In the particular case of benzo[a]pyrene induction of K-Ras codon 12 TGT mutation in the A/J mouse lung, measurement of tumor-associated oncomutation was shown to be an earlier and more sensitive endpoint than tumor response. The measurement of oncomutation by ACB-PCR led to two unexpected findings. First, oncomutations are present in various tissues of control rodents and "normal" human colonic mucosa samples at relatively high frequencies. Approximately 60% of such samples (88/146) have mutant fractions (MFs) >10(-5), and some have MFs as high as 10(-3) or 10(-4). Second, preliminary data indicate that oncomutations are present frequently as subpopulations in tumors. These findings are integrated into a hypothesis that the predominant preexisting mutations in particular tissues may be useful as generic reporters of carcinogenesis. Future research opportunities using oncomutation as an endpoint are described, including rodent to human extrapolation, dose-response assessment, and personalized medicine.

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ACB-PCR Quantification of K-RASCodon 12 GAT and GTT Mutant Fraction in Colon Tumor and Non-Tumor Tissue

Cited by 26 publications

References 32 publications

Skin Tumors Induced by Sorafenib; Paradoxic RAS–RAF Pathway Activation and Oncogenic Mutations of HRAS, TP53, and TGFBR1

Skin Tumors Induced by Sorafenib; Paradoxic RAS–RAF Pathway Activation and Oncogenic Mutations of HRAS, TP53, and TGFBR1

The clinical effectiveness and cost-effectiveness of cetuximab (review of technology appraisal no. 176) and panitumumab (partial review of technology appraisal no. 240) for previously untreated metastatic colorectal cancer: a systematic review and economic evaluation

Oncomutations as biomarkers of cancer risk

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