209P - Clinical validation of a novel multiplex kit for all RAS mutations in colorectal cancer: Results of RASKET(RAS KEy Testing) prospective multicenter...

Date 28 September 2014
Event ESMO 2014
Session Poster Display session
Topics Biomarkers
Colon Cancer
Rectal Cancer
Translational Research
Presenter Kensei Yamaguchi
Citation Annals of Oncology (2014) 25 (suppl_4): iv58-iv84. 10.1093/annonc/mdu326
Authors K. Yamaguchi1, K. Akagi2, K. Muro3, H. Taniguchi4, T. Nishina5, T. Kajiwara5, T. Denda6, S. Hironaka7, T. Kudo8, T. Satoh9, W. Okamoto10, T. Yoshino11
  • 1Division Of Gasteroenterology, Saitama Cancer Center, 362-0806 - Saitama/JP
  • 2Division Of Molecular Diagnosis And Cancer Prevention, Saitama Cancer Center, Saitama/JP
  • 3Clinical Oncology, Aichi Cancer Center Hospital, 464-8681 - Nagoya/JP
  • 4Department Of Clinical Oncology, Aichi Cancer Center Hospital, 464-8681 - Nagoya/JP
  • 5Dept. Of Gastroenterology, Shikoku Cancer Center, 791-0280 - Matsuyama/JP
  • 6Gastroenterology, Chiba Cancer Center Hospital, 260-8717 - Chiba/JP
  • 7Clinical Trial Promotion Centre, Chiba Cancer Center Hospital, 260-8717 - Chiba/JP
  • 8Frontier Science For Cancer And Chemotherapy, Osaka University, 565-0871 - Osaka/JP
  • 9Frontier Science For Cancer And Chemotherapy, Osaka University Graduate School of Medicine, 565-0871 - Osaka/JP
  • 10Division Of Translational Research, National Cancer Center Hospital East, 277-8577 - Kashiwa/JP
  • 11Gastroenterology & Gastrointestinal Oncology, National Cancer Center Hospital East, 277-8577 - Kashiwa/JP

Abstract

Aim

It is increasingly important to diagnose all RAS statuses in KRAS and NRAS among patients with advanced colorectal cancer (CRC), and to administer anti-epidermal growth factor receptor antibodies. Although direct sequencing (DS) with manual microdissection (MMD) is a widely used approach, a quality-controlled diagnostic kit that simultaneously and rapidly detects RAS mutations (MTs) is needed. In this study, we evaluate a novel multiplex kit using a Luminex (xMAP) assay to detect 48 MTs reported in the PRIME study (NEJM 2013;369:1023-34) or with >0.1% incidence in the COSMIC database in all RAS of exon (ex) 2 (codon 12/13), ex 3 (codon 59/61), and ex 4 (codon 117/146) and with 1-5% sensitivity in a single reaction using 50-100 ng of DNA from formalin-fixed paraffin-embedded (FFPE) tissue without MMD.

Methods

Samples were taken from patients with histologically confirmed colorectal adenocarcinoma and sufficient archived FFPE; the patients provided written informed consent. The primary endpoint was the concordance rate (CR) of all RAS MTs between the results of the kit and the two reference methods (DS with MMD and TheraScreen KRAS Mutation Kit). The secondary endpoints included the concordance of minor RAS MTs other than KRAS ex 2 for the KRAS ex 2 wild-type (WT) population and the concordance of each genotype for the overall population.

Results

309 samples from six institutes were registered. For the reference methods, 307 FFPE were analyzable and 140 RAS MTs (46%) were detected, with 111 KRAS ex 2 and 29 minor RAS MTs. The kit detected 143 RAS MTs (47%) with 114 KRAS ex 2 and 29 minor RAS MTs. Each assay in the kit was performed using 50-100 ng of template DNA, with an overall hands-on time of 4.5h per each 96-specimen-set. The CR between the two methods was 97% (95% CI, 94 to 98%). In the KRAS ex 2 WT population (n = 191), minor RAS MTs were detected in 15%, and the CR was 98% (95% CI, 96 to 100%). The concordance of each genotype for the overall population was 100% (95% CI, 97 to 100%).

Conclusions

The clinical validity of the multiplex kit was demonstrated. The kit allows for the rapid and exact detection of all RAS MTs in ex 2, ex 3, and ex 4 from an FFPE of CRC.(Study ID: UMIN000011784).

Disclosure

All authors have declared no conflicts of interest.