Journal Thoracic Oncology

Abstracts Journal of Thoracic Oncology • Volume 12 Issue S1 January 2017
patients happening acquired EGFR-TKI resistance in Zhejiang cancer hospital
from December 2014 to December 2015. Extracted ctDNA was analyzed using
two platforms (Droplet Digital PCR and ARMS [dPCR]). And the associations
between progression free survival (PFS) starting from initial TKI treatment
and the T790M ctDNA status detected in plasma were analyzed. Results: A
total of 108 patients were enrolled in this study. 108 patient plasma samples
were detected by ddPCR and 75 were detected by ARMS. And 16 patients
experienced re-biopsy were detected T790M status by ARMS method. 43.7%
(47/108) had acquired T790M mutation by ddPCR. In 75 patient plasma
samples, comparing ddPCR with ARMS, the rates of T790M mutation were
46.7% (35/75) and 25.3% (19/75) by ddPCR and ARMS, respectively. Of all, 16
patients both had tumor and plasma samples, the T790M mutation rates were
56.3% (9/16) by ARMS in tissue and 50.5% (8/16) by ddPCR in plasma ctDNA.
Among them, there were two ctDNA T790M mutations by ddPCR but T790M
gene negative in tumor tissue by ARMS method. For all patients, the median
PFS and OS were 12.3 months and 32.8 months, respectively. The patients
with T790M-positive tumors had a longer time to disease progression after
treatment with EGFR-TKIs (median, 13.1 months vs 10.8 months; P=0.010) and
overall survival (median, 35.3 months vs 30.3 months; P=0.214) compared with
those with T790M-negative patients. Conclusion: Our study demonstrates
dPCR assay provide feasibility and sensitive method in detecting EGFR T790M
status in plasma samples from NSCLC patients with acquired EGFR-TKI
resistance.And T790M-positive patients have better clinical outcomes to
EGFR-TKIs than patients with T790M negative.
Keywords: EGFR, ddPCR, T790M,non-small cell lung cancer
POSTER SESSION 3 – P3.02B: ADVANCED NSCLC & CHEMOTHERAPY/TARGETED THERAPY/
IMMUNOTHERAPY
EGFR BIOMARKERS –
WEDNESDAY, DECEMBER 7, 2016
P3.02B-041 GENOME-WIDE SCREEN OF DNA METHYLATION
CHANGES REVEALS GABBR2 AS A NOVEL POTENTIAL TARGET FOR
EGFR 19 DELETION ADENOCARCINOMA WITH ERLOTINIB
Xiaomin Niu 1 , Fatao Liu 2 , Yi Zhou 3 , Zhen Zhou 1 , Yun Liu 4 , Zhiwei Chen 1 , Shun
Lu 1
1 Department of Shanghai Lung Cancer Center, Shanghai Chest Hospital, Shanghai
Jiao Tong University, Shanghai/China, 2 Department of General Surgery, Xinhua
Hospital Affiliated To Shanghai Jiao Tong University School of Medicine, Shanghai/
China, 3 Institute for Nutritional Sciences, Shanghai Institutes for Biological
Sciences, Chinese Academy of Sciences, Shanghai, Shanghai/China, 4 Institutes of
Biomedical Sciences, Fudan University, Shanghai, Shanghai/China
Background: Lung cancer is the leading cause of cancer related death
around the world. The last decade has witnessed the rapid development of
epidermal growth factor receptor (EGFR) directly targeted therapies that
have significantly changed the treatment of non-small-cell lung cancer
(NSCLC). However, the challenge of acquired resistance to EGFR tyrosine
kinase inhibitors (TKIs) has been an issue when talking with activating EGFR
mutations, which makes it crucial to elucidate the mechanism of EGFR-TKI
targeted drug resistance. Methods: Methyl-sensitive cut counting sequencing
(MSCC), one of the most commonly used whole-genome DNA methylation
sequencing technology, was applied to investigate the changes of paired
tissue DNA methylation before and after TKI (erlotinib) treatment lasting
two cycles with partial response (PR) for stage IIIa (N2) lung adenocarcinoma
patients (N=2) with activating EGFR 19 deletion. Sequenom EpiTYPER assay
method was further analyzed to double confirm the changed methylated
candidate genes in these two patients, through comparing the methylated
changes in paired tissues before and after TKI treatment. Western blotting,
cell cycle and apoptosis analysis by the up/down regulation of a candidate
gene (GABBR2) were performed in three lung adenocarcinoma cell lines, A549
(EGFR wild type), HCC4006 (EGFR 19 deletion, DelL747-E749) and HCC827
(EGFR 19 deletion, DelE746-A750), to elucidate the mechanism of GABBR2
gene in the regulation of EGFR-TKI treatment. Results: Sixty aberrant
methylated genes were firstly discovered using MSCC method in these
two patients harboring EGFR 19 del mutation treated with erlotinib. Two
aberrant methylated genes, CBFA2T3 and GABBR2, were clearly validated
by the Sequenom EpiTYPER assay subsequently. GABBR2 was significantly
down regulated in HCC4006 and HCC827 cells harboring EGFR 19 mutations
but remained conservative in A549 cells with EGFR wild-type after erlotinib
treatment by Western blotting. The phenomenon was in line with the obvious
apoptosis of HCC4006 and HCC827 cell lines after erlotinib treatment,
but not in A549 cells. GABBR2 was further induced down regulation after
erlotinib exposure through apoptosis method silenced by siRNA using RNAi
technology. Meanwhile, GABBR2 gene was demonstrated up regulation
rescued the apoptosis significantly, when overexpressing GABBR2 in
HCC827 cell lines along with erlotinib treatment. Conclusion: Genome-wide
screen of DNA methylation changes demonstrated that GABBR2 gene
might be as a novel potential treatment target for stage IIIa (N2) EGFR 19
deletion adenocarcinoma with erlotinib treatment. Our research provides
a new theoretical basis for the epigenetic study of EGFR mutated lung
adenocarcinoma treatment.
Keywords: epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor
(TKI), lung adenocarcinoma, methyl-sensitive cut counting sequencing
(MSCC), methylation
POSTER SESSION 3 – P3.02B: ADVANCED NSCLC & CHEMOTHERAPY/TARGETED THERAPY/
IMMUNOTHERAPY
EGFR BIOMARKERS –
WEDNESDAY, DECEMBER 7, 2016
P3.02B-042 REDUCTION IN PERIPHERAL BLOOD CYTOKINE LEVELS
OBSERVED IN EGFR MUTANT (EGFRM) PATIENTS TREATED WITH
ERLOTINIB
Aaron Lisberg 1 , John Horton 1 , Jonathan W. Goldman 1 , Brian Wolf 1 , D. Andrew
Tucker 1 , James Carroll 1 , Phillip Abarca 1 , Jennifer Strunck 1 , Maria Velez 1 , Sina
Famenini 1 , Jamie Hunt 1 , Krikor Bornazyan 1 , Timothy Ellis-Caleo 1 , Xinkai Zhou 2 ,
Tristan Grogan 2 , David Elashoff 2 , Patricia Young 1 , Richard Pietras 1 , Steven
Dubinett 3
1 Translational Oncology Research Laboratory, UCLA Medical Center, Santa Monica/
CA/United States of America, 2 University of California, Los Angeles, Los Angeles/
CA/United States of America, 3 David Geffen School of Medicine at UCLA, Los
Angeles/CA/United States of America
Background: A retrospective analysis of EGFRm non-small cell lung cancer
(NSCLC) patients enrolled on the KEYNOTE-001 trial at UCLA showed a
significantly lower objective response rate for those treated with a tyrosine
kinase inhibitor (TKI) prior to pembrolizumab than those who were TKI naïve
(Garon et al, WCLC 2015). Since nivolumab treated squamous NSCLC patients
that had high baseline cytokine levels had a median overall survival almost
three times longer than those with low baseline levels (Lena et al, ELCC
2016), we used multiplex cytokine analysis to assess effects of an EGFR TKI
on peripheral blood cytokine concentrations. Methods: Paired baseline and
cycle 2 day 1 samples were evaluated in 60 stage IIIb or IV NSCLC patients
[EGFRm=12, EGFR wild type (wt)=33, unknown EGFR=15] enrolled on a clinical
trial of erlotinib +/- fulvestrant for 30 cytokines [Bio-Rad Bio-Plex Human
Cytokine 27-plex and Bio-Plex Pro TGF 3-plex (M500KCAF0Y, 171W4001M)].
Cytokine concentration values were compared between EGFR groups with
GEE models. In these models, cytokine values were log-transformed and
terms for treatment, EFGR status, and their interaction were included. Age
(continuous), sex (binary), smoking status (ever/never), and tumor stage
(binary) were also included in the model. R software was used for analyses.
A p-value