62P - Ultra-sensitive mass spectrometry allows 33% increased detection of somatic EGFR T790M mutation in plasma cfDNA samples

Date 10 October 2016
Event ESMO 2016 Congress
Session Poster display
Topics Translational Research
Basic Principles in the Management and Treatment (of cancer)
Presenter Raphael Saffroy
Citation Annals of Oncology (2016) 27 (6): 15-42. 10.1093/annonc/mdw363
Authors R. Saffroy1, V. Suybeng2, N. Bosselut2, J. Hamelin2, M. Becker2, P. Pham2, C. Khoja2, J. Morère3, A. Lemoine1
  • 1Oncogenetics And Biochemistry, Hopital Paul Brousse, 94800 - Villejuif/FR
  • 2Oncogenetics And Biochemistry, Hopital Paul Brousse, Villejuif/FR
  • 3Medical Oncology, Hopital Paul Brousse, Villejuif/FR

Abstract

Background

Epidermal growth factor receptor (EGFR) T790M has been considered to confer resistance to first generation anti-EGFR tyrosine kinase inhibitors (TKI) in patients with advanced non-small-cell lung cancer (NSCLC). Third-generation EGFR TKIs are active in EGFR-mutated NSCLC with T790M. Therefore, the EGFR T790M has become a challenging predictive biomarker. However, highly variable prevalence of EGFR T790M mutation have been found both in tissue from TKI-naïve patients (from 2.7% to 79%) and in tumor re-biopsies with acquired TKI resistance. Moreover, the detection sensitivity for T790M in cell free DNA (cfDNA) is lower than those observed for other EGFR mutations. This could be relied on the more indolent progression and relatively favorable prognosis of T790M positive tumors. The detection of T790M in tissue or cfDNA can be challenging due to a number of scientific and technical reasons. Its detection sensitivity could be increased by inhibiting the PCR amplification of the wild type allele and by utility of a highly sensitive technology: mass spectrometry has shown to detect the T790M at 31.5% compared to 2.7% with Sanger sequencing (Su et al, J Clin Oncol 2012).

Methods

We have used novel ultra-sensitive mutation detection using the MassARRAY® System with UltraSEEKTM technology (Agena Bioscience, Inc.). It allows targeting of the T790M mutated allele down to 0.1% frequency. We have compared the results to the classical iPlexTM chemistry (Agena Bioscience, Inc.) for tissue on the MassARRAY System. Here we studied cfDNA from 54 subjects with NSCLC with acquired resistance to EGFR TKIs, all of them had activating EGFR mutations in liquid biopsies (31 L858R, 22 bp deletions in exon 19, 1 G719X; 39 women, 15 males)

Results

Using the iPlex assay, we have identified 36% (18/54) of T790M. Using UltraSEEK on the same cfDNA samples 50% (27/54) were positive for T790M, increasing by 33% the detection of somatic EGFR T790M in cfDNA samples.

Conclusions

The MassARRAY System with UltraSEEK detects 50% T790M in cfDNA samples concomitantly with EGFR activating mutations in patients whose tumors had developed resistance to EGFR TKIs and could benefit from Osimertinib.

Clinical trial identification

NA

Legal entity responsible for the study

APHP, Oncogenetics and Biochemistry department Hop Paul Brousse Villejuif

Funding

APHP, Oncogenetics and Biochemistry department Hop Paul Brousse Villejuif

Disclosure

All authors have declared no conflicts of interest.