A comparability study of 5 commercial KRAS tests.
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 The assay used by Invitek is no longer commercially available and has been replaced by an alternative technique.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 kappa 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 (kappa = 0.95), Genzyme (kappa = 0.94), and Agencourt (kappa = 0.94) were in almost perfect agreement with these results, and the results from Gentris were in substantial agreement with the results from Amgen (kappa = 0.75). The Invitek allele-specific assay demonstrated slight agreement (kappa = 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.
Oliner
Kelly
K
Department of Molecular Sciences, Amgen Inc., Thousand Oaks, CA, USA.
Juan
Todd
T
Suggs
Sid
S
Wolf
Michael
M
Sarosi
Ildiko
I
Freeman
Daniel J
DJ
Gyuris
Tibor
T
Baron
Will
W
Bakker
Andreas
A
Parker
Alex
A
Patterson
Scott D
SD
D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D003062:Codon; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D004252:DNA Mutational Analysis; D005260:Female; D005404:Fixatives; D005557:Formaldehyde; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D015588:Observer Variation; D016612:Paraffin Embedding; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D016707:Tissue Fixation; D018631:ras Proteins / Q000235:genetics*
D003062:Codon; D005404:Fixatives; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D011933:Reagent Kits, Diagnostic; D005557:Formaldehyde; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins
J Mol Diagn. 2010 Jan;12(1):35-42
20007841
J Clin Oncol. 2009 Mar 1;27(7):1130-6
19124802
J Clin Oncol. 2008 Apr 1;26(10):1626-34
18316791
Clin Chem. 2000 Dec;46(12):1929-38
11106325
Clin Chem. 2009 Apr;55(4):641-58
19246620
J Clin Oncol. 2009 Apr 20;27(12):2091-6
19188670
Fam Med. 2005 May;37(5):360-3
15883903
Adv Anat Pathol. 2010 Jan;17(1):23-32
20032635
Virchows Arch. 2008 Nov;453(5):417-31
18802721
Nat Med. 2006 Jul;12(7):852-5
16799556
Nucleic Acids Res. 2007;35(19):e130
17932070
N Engl J Med. 2007 Nov 15;357(20):2040-8
18003960
Nat Biotechnol. 1999 Aug;17(8):804-7
10429248
J Mol Diagn. 2009 Nov;11(6):543-52
19815694
Br J Cancer. 2001 Sep 1;85(5):692-6
11531254
J Clin Oncol. 2007 May 1;25(13):1658-64
17470858
Nature. 2005 Sep 15;437(7057):376-80
16056220
J Natl Cancer Inst. 1998 May 6;90(9):675-84
9586664