210P - Detection of KRAS mutations in codons other than 12 and 13 in FFPET samples of colorectal cancer and non-small cell lung cancer

Date 28 September 2014
Event ESMO 2014
Session Poster Display session
Topics Colon and Rectal Cancer
Thoracic Malignancies
Pathology/Molecular Biology
Translational Research
Basic Scientific Principles
Basic Principles in the Management and Treatment (of cancer)
Presenter Sung Lee
Citation Annals of Oncology (2014) 25 (suppl_4): iv58-iv84. 10.1093/annonc/mdu326
Authors S.C. Lee, J. Cao, T. May, N. Lee, Y. Wu, V. Brophy, S. Soviero
  • Development, Roche Molecular Systems, 94588 - Pleasanton/US

Abstract

Aim

KRAS mutation testing is mandatory prior to prescribing anti-EGFR antibodies to colorectal cancer (CRC) patients. KRAS is also the most frequently mutated oncogene in non-small cell lung cancer (NSCLC). There is an increasing body of evidence that detecting KRAS mutations other than the predominant mutations in codons 12 and 13 of exon 2 can be important in the management of CRC and NSCLC patients. We describe the extensive detection of KRAS mutations by a real-time PCR assay (cobas® KRAS Mutation Test) that detects 19 single mutations in codons 12, 13 (exon 2) and 61 (exon 3). In addition, the cobas® KRAS Mutation Test detects single mutations in the flanking regions of prevalent mutation sites as well as double or complex mutations in codons 12 and 13.

Methods

Nineteen (19) single mutations in codons 12, 13, and 61 were tested using formalin-fixed paraffin-embedded tissue (FFPET) and plasmid samples by the cobas® KRAS Mutation Test. In addition, mutations reported in the flanking regions of codons 12, 13, and 61 (i.e., mutations in codons 11, 14, 15, 59, 60, 62 and 63) as well as double or complex mutations in codons 12 and 13 were tested using FFPET and plasmid samples.

Results

The cobas® KRAS Mutation Test detected all of the 19 single mutations in codons 12, 13, and 61 at ≥ 5% mutant sequences: 6 mutations in codon 12 (p.G12C, p.G12V, p.G12D, p.G12A, p.G12S, and p.G12R), 6 mutations in codon 13 (p.G13C, p.G13D, p.G13S, p.G13R, p.G13A, and p.G13V), and 7 mutations in codon 61 (p.Q61Hc, p.Q61Ht, p.Q61R, p.Q61L, p.Q61K, p.Q61E, and p.Q61P). In addition, 11 other rare mutations in the flanking regions (p.A11P, p.V14I, p.G15D, p.A59S, p.A59T, p.A59E, p.A59G, p.G60A, p.E62D, p.E63K, and p.E63del) were also detected at ≥ 5% mutant sequences. Furthermore, the cobas® KRAS Mutation Test detected 8 rare double or complex mutations in codons 12 and 13 (p.G12Y, p.G12N, p.G12I, p.G13I, p.G13N, p.G13D + p.V14I, p.G12fs*3, and p.G12_G13insG) at ≥ 5% mutant sequences.

Conclusions

The cobas® KRAS Mutation Test detects 19 KRAS mutations in codons 12, 13 and 61 plus at least 19 flanking, double, or complex mutations, including codon 59, at ≥ 5% mutant sequences.

Disclosure

All authors have declared no conflicts of interest.