1316 - Feasibility and usefulness of determining EGFR and KRAS mutations in cytological samples and CNB of NSCLC using an automated real-time PCR system

Date 28 September 2012
Event ESMO Congress 2012
Session Publication Only
Topics Non-Small-Cell Lung Cancer, Metastatic
Translational Research
Presenter Maria Lozano
Authors M.D. Lozano1, T. Labiano1, M. Montañana1, J.I. Echeveste1, A. Gurpide2, J.L. Pérez - Gracia2, F. Shieh3, T. Ramos4, J. Zulueta5, S. Martin Algarra6
  • 1Pathology, University of Navarra, 31080 - Pamplona/ES
  • 2Clinical Oncology, Clinica Universitaria de Navarra, 31008 - Pamplona/ES
  • 3Roche Molecular System, Roche Molecular System, 94588 - Pleasanton/US
  • 4Roche Diagnostics, Roche Diagnostics, Barcelona/ES
  • 5Pulmonary Medicine, Clinica Universidad de Navarra, 31008 - Pamplona/ES
  • 6Clinica Universitaria de Navarra, 31008 - Pamplona/ES

Abstract

Background

EGFR and KRAS gene mutations guide treatment selection in non-small cell lung cancer (NSCLC) patients. About 70%-80% of these patients are diagnosed at advanced stage, and mutational analysis has to be performed in small samples: core needle biopsy (CNB) and fine needle aspiration (FNA) cytology. Cobas® EGFR Mutation Test has been CE-IVD marked for the detection of 41 mutations in formalin-fixed-paraffin-embedded (FFPE) NSCLC specimens. No validation studies have been performed using cytological samples. Determining the feasibility of cobas® test on such samples is an important step to extend the benefits of molecular targeted therapy.

Methods

EGFR and KRAS mutations were studied in 64 non-selected samples from NSCLC patients: 31 CNB and 33 FNA. DNA was extracted directly from stained smears in FNA samples and from 4-micron sections in CNB. All samples contained at least 50% of tumor cells. All cases were studied using the cobas® test, and FNA samples were also analyzed by direct sequencing. DNA was extracted using the cobas® DNA Sample Preparation Kit. DNA concentration and DNA ratio of sample absorbance at 260/280nm (A260/280) were registered. U Mann Whitney test was used.

Results

CNB diagnosis was: 23 SqCC, 6 AC, 1 BAC, and 1 NSCLC-NOS. FNA diagnosis was: 26 AC, 3 SqCC, 1 BAC, 1 LCC, and 2 NSCLC-NOS. Mean DNA concentration from CNB was 23.07ng/ul ± 20.99, and from FNA samples 12.41ng/ul ± 20.04 (p < 0.001). However A260/280 was 1.61 ± 0.26 and 1.71 ± 0.55 respectively (p = 0.666). Mutational analysis results from all 31 CNB and from 19 FNA cases are shown in Table 1. Sanger sequencing in all FNA cases rendered concordant results. Updated results will be presented.

FNA CNB
EGFR WT 6 28
EXON 19 DEL 2 1
EXON 20 INS 0 1
INVALID 1 1
KRAS WT 9 26
12/13 MUTATED 9 4
INVALID 1 1

Conclusions

Assessment of EGFR and KRAS mutations in FNA and CNB samples using cobas® EGFR and KRAS test is feasible and reliable. Quality of DNA (A260/280) using cobas® DNA Sample Preparation Kit in FNA samples is similar to those from CNB. Molecular results from FNA samples using cobas® test and direct sequencing are concordant, though cobas® tests are simpler, faster and easier to use.

Disclosure

All authors have declared no conflicts of interest.