[ Title ]
- Ultra-Sensitive Detection of the Pretreatment EGFR T790M Mutation in
Non-Small Cell Lung Cancer Patients with an EGFR-Activating Mutation
Using Droplet Digital PCR
[ Journal ]
- CLINICAL CANCER RESEARCH
[ Author ]
- Watanabe, M
Kawaguchi, T
Isa, S
Ando, M
Tamiya, A
Kubo, A
Saka, H
Takeo, S
Adachi, H
Tagawa, T
Kakegawa, S
Yamashita, M
Kataoka, K
Ichinose, Y
Takeuchi, Y
Sakamoto, K
Matsumura, A
Koh, Y
[ Abstract ]
- The resistance to the EGFR tyrosine kinase inhibitors (TKI) is
a major concern in non-small cell lung cancer (NSCLC) treatment. T790M
mutation in EGFR accounts for nearly 50% of the acquired resistance to
EGFR-TKIs. Earlier studies suggested that T790M mutation was also
detected in TKI-naive NSCLCs in a small cohort. Here, we use an
ultra-sensitive droplet digital PCR (ddPCR) technique to address the
incidence and clinical significance of pretreatment T790M in a larger
cohort.
Experimental Design: ddPCR was established as follows: wildtype or T790M
mutation-containing DNA fragments were cloned into plasmids. Candidate
threshold was identified using wild-type plasmid, normal human genomic
DNA, and human A549 cell line DNA, which expresses wild type. Surgically
resected tumor tissues from 373 NSCLC patients with EGFR-activating
mutations were then examined for the presence of T790M using ddPCR.
Results: Our data revealed a linear performance for this ddPCR method
(R-2 = 0.998) with an analytical sensitivity of approximately 0.001%.
The overall incidence of the pretreatment T790M mutation was 79.9%
(298/373), and the frequency ranged from 0.009% to 26.9%. The T790M
mutation was detected more frequently in patients with a larger tumor
size (P = 0.019) and those with common EGFR-activating mutations (P =
0.022), as compared with the others.
Conclusions: The ultra-sensitive ddPCR assay revealed that pretreatment
T790M was found in the majority of NSCLC patients with EGFR-activating
mutations. ddPCR should be utilized for detailed assessment of the
impact of the low frequency pretreatment T790M mutation on treatment
with EGFR-TKIs.
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