Elsevier

Lung Cancer

Volume 90, Issue 3, December 2015, Pages 509-515
Lung Cancer

EGFR mutation detection in ctDNA from NSCLC patient plasma: A cross-platform comparison of leading technologies to support the clinical development of AZD9291

https://doi.org/10.1016/j.lungcan.2015.10.004Get rights and content
Under a Creative Commons license
open access

Highlights

  • Multiple platforms were compared for detection of EGFR mutations in plasma ctDNA.

  • Digital and traditional PCR assays were assessed using plasma from AZD9291 trials.

  • Multiple platforms enabled robust detection of common EGFR-sensitizing mutations.

  • cobas® and BEAMing assays showed >70% sensitivity for plasma T790M detection.

  • Genomic heterogeneity of T790M may explain most plasma-tissue discordance.

Abstract

Objectives

To assess the ability of different technology platforms to detect epidermal growth factor receptor (EGFR) mutations, including T790M, from circulating tumor DNA (ctDNA) in advanced non-small cell lung cancer (NSCLC) patients.

Materials and methods

A comparison of multiple platforms for detecting EGFR mutations in plasma ctDNA was undertaken. Plasma samples were collected from patients entering the ongoing AURA trial (NCT01802632), investigating the safety, tolerability, and efficacy of AZD9291 in patients with EGFR-sensitizing mutation-positive NSCLC. Plasma was collected prior to AZD9291 dosing but following clinical progression on a previous EGFR-tyrosine kinase inhibitor (TKI). Extracted ctDNA was analyzed using two non-digital platforms (cobas® EGFR Mutation Test and therascreen™ EGFR amplification refractory mutation system assay) and two digital platforms (Droplet Digital™ PCR and BEAMing digital PCR [dPCR]).

Results

Preliminary assessment (38 samples) was conducted using all four platforms. For EGFR-TKI-sensitizing mutations, high sensitivity (78–100%) and specificity (93–100%) were observed using tissue as a non-reference standard. For the T790M mutation, the digital platforms outperformed the non-digital platforms. Subsequent assessment using 72 additional baseline plasma samples was conducted using the cobas® EGFR Mutation Test and BEAMing dPCR. The two platforms demonstrated high sensitivity (82–87%) and specificity (97%) for EGFR-sensitizing mutations. For the T790M mutation, the sensitivity and specificity were 73% and 67%, respectively, with the cobas® EGFR Mutation Test, and 81% and 58%, respectively, with BEAMing dPCR. Concordance between the platforms was >90%, showing that multiple platforms are capable of sensitive and specific detection of EGFR-TKI-sensitizing mutations from NSCLC patient plasma.

Conclusion

The cobas® EGFR Mutation Test and BEAMing dPCR demonstrate a high sensitivity for T790M mutation detection. Genomic heterogeneity of T790M-mediated resistance may explain the reduced specificity observed with plasma-based detection of T790M mutations versus tissue. These data support the use of both platforms in the AZD9291 clinical development program.

Abbreviations

ARMS
amplification refractory mutation system
BEAM
beads, emulsions, amplification, and magnetics
CR
complete response
ctDNA
circulating tumor DNA
dPCR
digital polymerase chain reaction
ddPCR
Droplet Digital PCR
EGFR
epidermal growth factor receptor
M1a/M0
disease confined to the thoracic cavity
M1b
extra-thoracic metastatic disease
NSCLC
non-small cell lung cancer
PCR
polymerase chain reaction
PR
partial response
SD
stable disease
TKI
tyrosine kinase inhibitor

Keywords

Non-small cell lung cancer
Circulating tumor DNA
Epidermal growth factor receptor mutation
T790M
AZD9291

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