Annals of Oncology

abstracts
respectively. Giemsa staining revealed tumor cells in 60% (15/25) at baseline and in
67% (8/12) after 3 rd cycle. PD-1 expression was observed in 71.4% (10/14) and 10% (1/
10) (p = 0.044) of the CTC-positive patients at baseline and after the 3 rd , respectively.
Conversely, PD-L1 was observed in 42,9% (6/14) and 50% (5/10) (p = 0.311) of the
CTC-positive patients at baseline and after the 3 rd cycle. Among the total number of
detected CTCs, 47.8% were PD-1-positive at baseline and 30% after the 3 rd cycle
whereas, 35.7% and 50% at baseline and after the 3 rd cycle, respectively, were
PD-L1-positive.
Conclusions: PD-1- and PD-L1 positive CTCs can be observed during the treatment of
metastatic NSCLC, suggesting that they can be used as a potential biomarker to
monitor the expression of PD-L1 on tumor cells during the clinical phases of the
disease and understand the mechanisms of tumor immune escape.
Legal entity responsible for the study: N/A
Funding: Laboratory of Translational Oncology, School of Medicine, University of Crete
Disclosure: All authors have declared no conflicts of interest.
Methods: Peripheral blood was collected from 124 pts with diverse staging and
histology at three clinical sites prior to diagnostic biopsy, with some having follow-up
draws. All nucleated cells were plated onto glass slides and circulating cells of interest
identified by immunofluorescence and morphological features. Prognostic capacity of
PD-L1(+) cells (CK + /-, CD45-, PD-L1 + , malignant nuclear morphology) were
assessed with Kaplan-Meier and Cox Proportional Hazard (PH) models.
Results:
Table: 75P
Annals of Oncology
AJCC Stage n = 124 Baseline n = 27 Follow-Up
I 53 7
II 18 4
III 30 8
IV 22 8
74P
The level of soluble programmed death ligand-1 in lung cancer:
An exploratory biomarker study
R. Geng 1 ,L.Pan 1 , S. Guo 2 , X.J. Jing 3 , F.F. Shen 1 , J.J. Xu 1 , X. Zhang 1 ,
D.X. Zhang 4 , X. Song 1
1 Department of Pulmonary Oncology, Shanxi Tumor Hospital, Taiyuan, China,
2 Department of Molecular Biology, Shanxi Tumor Hospital, Taiyuan, China,
3 Department of Etiology and Tumor, Shanxi Tumor Hospital, Taiyuan, China,
4 School of Medicine and Public Health, Newcastle Private Oncology Centre,
Newcastle, Australia
Background: A new approach to immunotherapy based on programmed death 1
(PD-1) and programmed death ligand-1 (PD-L1) pathway represents a remarkable
innovation in lung cancer treatment. There is growing evidence that lung cancer cells
exploit the PD-L1 to cause local immune-suppression. The aim of this prospective
study was to investigate the prevalence and prognostic roles of soluble PD-L1(sPD-L1 )
protein in the blood of patients with lung cancer.
Methods: A total of 159 patients with lung cancer who were diagnosed by
histopathology or cytopathology between July 2013 to October 2015 were enrolled.
Blood samples plasma were collected at the time of diagnosis. 85 samples of healthy
subjects matching in sex and age from the Health care Center of the hospital were also
studied as control. The level of sPD-L1 protein in the blood was measured using an
enzyme-linked immunosorbentassay (ELISA). 64 cases of lung cancer patients who
were treated with platinum based chemotherapy for 4-6 cycles were followed up. The
median follow-up duration since the time of diagnosis was 18.6 months (range, 4-26.6
months). The associations between the level of sPD-L1 expression and
clinicopathologic features and prognosis were statistically analyzed.
Results: Expression of sPD-L1 in lung cancer patients was significantly up-regulated
compared with health people( P < 0.001). A cut-off value of 2.37ng/ml was
distinguished in patients according to Receiver operating characteristic curve(ROC).
The expression of sPD-L1 was associated with abdominal organ metastasis (P = 0.015).
A high sPD-L1 expression had a worse prognosis than a low expression in patients
(13.4 months vs 19.8 months, P = 0.001).
Conclusions: Our results indicated that plasma sPD-L1 protein was elevated in lung
cancer patients and was associated with a poor prognosis. Plasma sPD-L1 protein is a
potent predicting biomarker in lung cancer and may may play a pivotal role in tumor
immune evasion.
Legal entity responsible for the study: N/A
Funding: N/A
Disclosure: All authors have declared no conflicts of interest.
75P
PD-L1 expression on circulating CD45(-) cells is an
independent prognostic factor for overall survival (OS) in
patients (Pts) across all stages of treatment-naïve lung cancer
in a prospective, multicenter study
R. Graf 1 ,D.Lu 1 , R. Krupa 1 , J. Louw 1 , L. Dugan 1 , A. Jendrisak 1 ,S.Orr 1 ,
K. Bethel 1 ,Y.Wang 1 , M. Suraneni 1 , M. Landers 1 , D. Boffa 2 , J. Nieva 3 ,
L. Bazhenova 4 , M. Salazar 2 , S. Makani 4 , M. Magana 4 , R. Dittamore 1
1 Translational Research, Epic Sciences, Inc, San Diego, CA, USA, 2 Surgery:
Thoracic Surgery, Yale New Haven Health System, New Haven, CT, USA,
3 Department of Medicine, University of Southern California Norris Comprehensive
Cancer Center, Los Angeles, CA, USA, 4 Department of Medicine, Moores Cancer
Center, San Diego, CA, USA
Background: Biopsies are currently utilized for profiling (histologic, molecular) of lung
cancer prior to treatment. Profiling tumors from circulating markers could avoid
invasive procedures and enable more frequent, kinetic disease monitoring. PD-L1
expression on lung cancer biopsy correlates with efficacy of immune checkpoint
inhibitors. Using the Epic Sciences PD-L1 assay, we sought to correlate patient
outcome with PD-L1(+) circulating CD45(-) cells, prior to its evaluation as a predictive
biomarker for immune checkpoint inhibitors.
When detected, PD-L1 subcellular localization was primarily membranous. Pts with >1
PD-L1(+) cell/mL in baseline samples had worse overall survival (OS) (n = 22/124,
mOS: 17.2 months vs. not reached, HR = 3.22, p = 0.0015) and follow-up (n = 5/22
mOS = 2.1 months vs. not reached, HR = 4.25, p = 0.0302). High baseline PD-L1(+)
cell burden was additive and independent to AJCC staging in Cox PH models
(HR = 2.32, p = 0.0447). Single-cell sequencing is underway.
Conclusions: In a multicenter cohort, circulating PD-L1(+)/CD45(-) cell burden
predicted worse OS in pre-biopsy and follow-up lung cancer blood samples. This
warrants prospective investigation as a predictive biomarker to PD-1 axis immune
checkpoint inhibitors.
Clinical trial identification: HHSN261201200049C
Legal entity responsible for the study: National Cancer Institute, Epic Sciences
Funding: National Cancer Institute, Epic Sciences
Disclosure: R. Graf, D. Lu, R. Krupa, J. Louw, L. Dugan, A. Jendrisak, S. Orr, K. Bethel,
Y. Wang, M. Landers, R. Dittamore: Epic Sciences Employee. All other authors have
declared no conflicts of interest.
76P
Molecular characterization of PDL1 status of circulating tumor
cells (CTCs) isolated with a novel label-free inertial microfluidic
system from patients (pts) with advanced cancers
J. Fraser-Fish 1 , Z. Ahmad 1 , R. Kumar 2 , B. Ebbs 1 , G. Fowler 1 , P. Flohr 1 ,
M. Crespo 1 , M. Ahmed 2 , S. Popat 2 , J. Bhosle 2 , U. Banerji 3 ,M.O’Brien 2 , J.S. de
Bono 3 , T.A. Yap 3
1 Cancer Biomarkers Laboratory, The Institute of Cancer Research, London, UK,
2 Lung Cancer Unit, Royal Marsden Hospital NHS Foundation Trust, London, UK,
3 Drug Development Unit, Royal Marsden Hospital and Division of Clinical Studies,
The Institute of Cancer Research, London, UK
Background: The ClearCell® FX system (FX) is a novel label-free inertial microfluidic
CTC isolation platform, in contrast to the EpCAM-based CELLSEARCH® system (CS).
We hypothesise that label-free CTC capture will lead to more accurate assessment of
CTCs, including PD-L1 expression, and capture CTCs that have undergone
epithelial-mesenchymal transition, which is prevalent in advanced cancers.
Methods: CellTracker TM labelled EpCAM-high and EpCAM-low cell lines were spiked
into healthy volunteer (HV) blood, prior to recovery on FX or CS platforms for initial
validation studies. Blood samples were then obtained from pts with advanced
non-small cell lung (NSCLC), prostate, ovarian, rectal and breast cancers for CTC
isolation on FX and CS. CTCs captured on FX were assessed with 5-color
immunofluorescence (IF) (CK, CD45, DAPI, PD-L1, as well as TTF-1 [lung
adenocarcinoma], androgen receptor [AR; prostate cancer] or EpCAM [other
cancers]). HV blood samples were assessed on FX and CS as controls.
Results: FX and CS captured similar counts in EpCAM-high cell lines (FX 67% ± 11 vs
CS 74% ± 10 [p = 0.11]). In contrast, higher cell counts were seen with EpCAM-low
cell lines with FX vs CS [62% ± 8 vs 32% ± 9 [p < 0.0001]). Of 36 pts, CTC counts were
higher with FX vs CS in 31 (86%) pts: 19/21 NSCLC, 7/10 prostate, 3/3 ovarian, 1/1
rectal and 1/1 breast cancer pts. No CTCs were detected in HV blood (N = 10) on FX
and CS. 19/19 NSCLC, 8/9 prostate, 3/3 ovarian, 1/1 rectal and 1/1 breast cancer pts
had ≥1 PD-L1+ CTCs. Heterogeneity in PD-L1 expression was observed. While 19/20
NSCLC pts had ≥1 PD-L1+ TTF-1+ CTCs, only 10 of these 19 pts had 100% PD-L1+
TTF-1+ CTCs. 5/10 prostate cancer pts had ≥1 PD-L1+ AR+ CTCs, but only 4 of these
5 pts had 100% PD-L1+ AR+ CTCs. All 3 ovarian cancer pts had ≥1 PD-L1+ EpCAM
+ CTCs, with no PD-L1- EpCAM+ CTCs detected. 1/1 rectal and 1/1 breast cancer pts
had 100% PD-L1+ EpCAM+ CTCs.
Conclusions: Higher CTC counts were isolated with FX vs CS in 86% of pts. CTC
PD-L1 heterogeneity was observed and may in part explain differences in antitumor
responses to PD-1/PD-L1 inhibitors. Clinical qualification of this 5-color IF PD-L1
CTC assay is ongoing in a PD-1 inhibitor NSCLC trial.
Clinical trial identification: CCR-2472 study opened 2nd August 2004 CCR-3171
study opened 22nd May 2009
vi22 | abstracts Volume 27 | Supplement 6 | October 2016