Annual Meeting Proceedings Part 1 - American Society of Clinical ...

10553 General Poster Session (Board #44B), Mon, 1:15 PM-5:15 PM
Activation of and dependence on ataxia telangiectasia mutated kinase in
PTEN-deficient tumor cells. Presenting Author: Nuala McCabe, Almac
Diagnostics, Craigavon, United Kingdom
Background: Loss of PTEN function has been widely reported to cause
up-regulation of the PI3K/AKT signalling pathway resulting in increased
cell growth, proliferation and survival. More recently it has been reported
that PTEN null cells demonstrate genomic instability and have increased
production of reactive oxygen species (ROS) and oxidative stress induced
DNA damage. Ataxia Telangiectasia Mutated (ATM) is the primary response
kinase, which responds to stalled DNA replication and DNA double strand
breaks due to oxidative DNA damage. Methods: A metagene representing
ATM activation was generated from cell line data and used to perform
hierarchical clustering analysis of public DNA microarray profiling datasets
of breast cancer, ovarian cancer and glioblastoma with known PTEN
IHC/mutation status. Furthermore, we ask if ATM activation may be
therapeutically exploited in PTEN null tumours using ATM specific siRNA
and compounds in 2 PTEN isogenic cell line model systems. Results: We
show that PTEN null cells have elevated levels of ROS, DNA damage and
have endogenous activation of ATM, an enzyme important in responding to
DNA damage resulting from oxidative stress. We hypothesised that PTEN
deficient tumours may rely on ATM enzyme for survival. To investigate this
we generated a 189-gene list representing ATM activation and used this to
perform hierarchical clustering analysis of a breast cancer DNA microarray
dataset. This list was able to significantly cluster tumours with known loss
of PTEN expression (p�0.004). Furthermore, this gene list was able to
segregate PTEN null/mutant tumours from PTEN wild-type tumours in 2
independent datasets of glioblastoma and ovarian cancer (p�0.015 and
p�0.012). In addition, we found that inhibition of ATM using the selective
inhibitor KU-55933 caused DNA damage, cell cycle arrest and apoptosis
specifically in PTEN deficient cells when compared to PTEN wild-type
cells. Conclusions: These observations suggest that ATM may represent a
therapeutic target in PTEN deficient tumours and furthermore ATM
activation may be the basis of a biomarker of PTEN status in human
cancers.
10555 General Poster Session (Board #44D), Mon, 1:15 PM-5:15 PM
Topoisomerase II alpha gene status, HER2, and microtubule-associated
protein tau as predictors of pathologic complete response after neoadjuvant
chemotherapy. Presenting Author: Agust Barnadas, Hospital de la Santa
Creu i Sant Pau, Medical Oncology Department, Barcelona, Spain
Background: There is growing evidence that topoisomerase II-alpha
(TOPOII�) is a marker for anthracycline-, and microtubule-associated
protein tau (MAPT) for taxane sensitivity. HER2 has been described as a
marker of both anthracycline and taxane sensitivity.The goal of our study
was to examine the predictive and prognostic value of TOPOII�, MAPT and
HER2 expression in breast cancer patients (pts) who received neoadjuvant
chemotherapy (NAC) based on anthracycline-taxane regimens. We analyzed
the relationship between these biomarkers and pathological complete
response (pCR), disease-free survival (DFS) and overall survival (OS).
Methods: Between November 1993-2009, 140 pts (mean age 52 years)
with locally advanced breast cancer (T1-4, N0-3, M0) were retrospectively
studied. The study contained 2 groups: group A included 85 pts who
received NAC with an anthracycline-taxane regimen and group B included
the last 55 pts who received NAC with only an anthracycline-based
regimen. HER2 was tested by immunohistochemistry (IH) or FISH, TOPOII�
by CISH and MAPT by IH. Expression of these proteins was evaluated in
core needle breast biopsy. Results: Overall, 12 pts (8.5%) had a pCR.
TOPOII� was amplified in 6 (4%) of the tumors. Among pts without
amplification, 6 (4%) had deletion of the TOPOII�, and 10 (7%) polysomia
of chromosome 17. TOPOII� gene aberrations (amplification, deletion,
polysomia), which was present in 22 (25%) of the tumors, was a strong
predictive factor for pCR (p�0.018) but showed no direct association with
prognostic outcome in multivariate analysis. HER2 amplification, which
was present in 16% (21) of the tumors, show no direct association with
pCR, DFS or OS. Finally, differences by treatment arm or pCR in low versus
high MAPT expression groups were not observed, indicating that MAPT is
not a useful predictive marker for taxane-based chemotherapy. In multivariate
analysis high MAPT expression was associated with longer DFS
(p�0.002). Conclusions: TOPOII� gene aberrations but not HER2 are
highly predictive of pCR for anthracycline-based regimen. MAPT is not
associated with response to taxanes but has a prognostic value.
Tumor Biology
669s
10554 General Poster Session (Board #44C), Mon, 1:15 PM-5:15 PM
Central review of discordant samples for microarray based on ER, PR, and
HER2 and local IHC/FISH assessment worldwide from 827 patients.
Presenting Author: Jelle Wesseling, Netherlands Cancer Institute - Antoni
van Leeuwenhoek Hospital, Amsterdam, Netherlands
Background: Differences in fixation and IHC and subjective interpretation
can substantially affect the accuracy and reproducibility of estrogen
receptor (ER), progesterone receptor (PR) and HER2 expression. The
commercially available TargetPrint test measures the mRNA expression
level of ER, PR and HER2 and is 98% concordant with centrally assessed
ER as presented by Viale et al, SABCS 2011. This study compares results
from the microarray-based TargetPrint with IHC and FISH (for HER2
IHC2�) generated by local standard procedures. Methods: Fresh tumor
samples (core needle biopsies or surgical) were collected for 831 patients
diagnosed with breast cancer stage I to IV (Feb 2008 - Jan 2011) from 22
hospitals from Europe, New Zealand, Japan and US. The results of the
IHC/FISH assessments performed according to the local standards at the
hospitals were compared to the quantitative gene expression readouts with
TargetPrint. Discordant cases were centrally reviewed for IHC/FISH assessment.
Results: Of the 831 samples, IHC assessment was unknown for 4 ER/
PR samples; HER2 was unknown for 12 samples. Comparison of IHC and
gene expression read out by TargetPrint showed a concordance of 95% for
ER; 83% for PR and 94% for HER2. In this study, 3% of all IHC ER positive
samples were classified negative by microarray, and 11% of IHC PR
positive samples were classified negative by microarray. For HER2, 4% of
IHC/FISH HER2 positive samples were classified negative by microarray
and 2% of IHC/FISH HER2 negative samples were classified positive by
microarray. Most notably, all available 5 ER IHC negative/TargetPrint
positive samples turned out to be positive with central re-assessment.
HER2 IHC2� samples with discordant classifications for TargetPrint and
local assessment are currently being reviewed for FISH/SISH assessment.
Conclusions: Microarray based readout of ER, PR and HER2 status using
TargetPrint is fairly comparable to local IHC and FISH analysis in 827
analyzed samples in various hospitals worldwide. However, re-assessment
of discordant cases –especially IHC ER-/TargetPrint ER� cases- confirms
TargetPrint to be a useful high quality second opinion for local IHC/FISH
assessment.
10556 General Poster Session (Board #44E), Mon, 1:15 PM-5:15 PM
ALK amplification and crizotinib sensitivity in non-small cell lung cancer
cell lines and patients report. Presenting Author: Kalai Khadija, Institut
Gustave Roussy, Villejuif, France
Background: ALK high copy number (HCN) seems to be a frequent event,
described in 13-17% of Non-small cell lung cancer (NSCLC). The goal of
this study was to describe ALK genomic aberrations on NSCLC patients and
cell lines, to explore the ALK HCN response to crizotinib through in vitro
assays and to report three patients case. Methods: 191 Paraffin embedded
specimens from advanced NSCLC patients and 27 NSCLC cancer cell lines
were screened for ALK copy number by fluorescent in situ hybridization
(FISH). Crizotinib sensitivity was evaluated in 9 cell lines through WST1
assays and clonogenic tests. Three patients exhibiting ALK HCN were
assessed for response to crizotinib. Results: EML4-ALK translocation was
present in 22 pts (11.5%). 21 pts (11%) exhibited over 6 copies of ALK.6
(22%) cell lines displayed more than 5 copies of ALK, 19 (70%) presented
a gain of 3 or 4 ALK copy number, only one cell line exhibited normal ALK
copies and one harbored EML4-ALK translocation. FISH with CEP2
revealed a polysomy of chromosome 2 in cases with ALK HCN.Out of the 9
cell lines tested, 4 ALK HCN cell lines (H661, A427, BEN, H1299)
exhibited increased sensitivity for crizotinib vs. 3 low ALK copy number
(LCN) cell lines (H1975, H1651, H1650) with a low sensitivity. Median
IC50 with crizotinib values was1750 nM [300-2800nM] in ALK HCN cell
lines vs 4500 nM [800-8000nM] in ALK LCN cell lines, p�0.35. 3
patients with ALK HCN tumor received crizotinib ( in 4th , 5th and 6th -line
therapy) for 2, 3 and 5 months with stable disease as best response and
clinical benefit in 2 pts. Conclusions: ALK HCN may predict sensitivity to
crizotinib. A clinical study is planned in ALK HCN pts.
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