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A comparability study of 5 commercial KRAS tests

Kelly Oliner1, Todd Juan2, Sid Suggs1, Michael Wolf34, Ildiko Sarosi5, Daniel J Freeman6, Tibor Gyuris2, Will Baron2, Andreas Bakker7, Alex Parker8 and Scott D Patterson1*

Author Affiliations

1 Department of Molecular Sciences, Amgen Inc., Thousand Oaks, CA, USA

2 Department of Protein Sciences, Amgen Inc., Thousand Oaks, CA, USA

3 Department of Global Biostatistics & Epidemiology, Amgen Inc., Thousand Oaks, CA, USA

4 Department of Clinical Development, Amgen Inc., Thousand Oaks, CA, USA

5 Department of Pathology, Amgen Inc., Thousand Oaks, CA, USA

6 Department of Oncology Research, Amgen Inc., Thousand Oaks, CA, USA

7 Department of Global Technical Services, Amgen Inc., Thousand Oaks, CA, USA

8 Department of Molecular Sciences, Amgen Inc., Cambridge, MA, USA

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Diagnostic Pathology 2010, 5:23  doi:10.1186/1746-1596-5-23

Published: 16 April 2010

Abstract

Background

Activating mutations in the KRAS gene occur frequently in human tumors, including colorectal carcinomas; most mutations occur in codons 12 and 13. Mutations in KRAS have been associated with poor response to anti-epidermal growth factor receptor antibodies. Therefore, an accurate and readily available analysis of KRAS mutational status is needed. The aim of this study was to evaluate concordance between KRAS assays performed by 6 different laboratories.

Methods

Forty formalin-fixed paraffin-embedded colorectal cancer tumor samples were obtained. Sample sections were submitted for KRAS mutation analysis to 5 independent commercial laboratories (Agencourt, Gentris, Genzyme, HistoGeneX, and Invitek) and to the Amgen DNA Sequencing Laboratory for direct polymerase chain reaction sequencing. The assay used by Invitek is no longer commercially available and has been replaced by an alternative technique. Results from the commercial services were compared with those from Amgen direct sequencing by κ statistics.

Results

KRAS mutations were observed in codon 12 and/or 13 in 20 of 40 (50%) samples in Amgen direct sequencing assays. Results from HistoGeneX (κ = 0.95), Genzyme (κ = 0.94), and Agencourt (κ = 0.94) were in almost perfect agreement with these results, and the results from Gentris were in substantial agreement with the results from Amgen (κ = 0.75). The Invitek allele-specific assay demonstrated slight agreement (κ = 0.13).

Conclusions

This study provides data on the comparability of KRAS mutational analyses. The results suggest that most (but not all) commercial services provide analysis that is accurate and comparable with direct sequencing.