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

40s Breast Cancer—HER2/ER
635 General Poster Session (Board #13F), Sat, 8:00 AM-12:00 PM
Effect of heterogeneity of HER2 expression on brain metastases of breast
cancer. Presenting Author: Mari Hosonaga, Division of Gene Regulation,
Institute for Advanced Medical Research, Keio University, Tokyo, Japan
Background: HER2-overexpressing or triple-negative [ER(-)/PR(-)/HER2(-)]
breast cancers are associated with increased risk of brain metastases. The
mechanisms leading to metastasis in each subtype are not well known.
Methods: We introduced the wild-type HER2 gene into MDA-MB-231-luc-
D3H2LN (231-Luc) cells, which are triple-negative breast cancer cells,
and established HER2-expressing (63.2%) cells as 231-Luc-HER2 cells.
We investigated the tumor formation following orthotopic inoculation and
brain metastasis following intracardiac injection into nude mice. Metastasis
was detected by bioluminescence imaging and confirmed in H&E
staining and immunohistochemistry of vimentin and HER2 expressions.
Flow cytometry analysis was used to detect the proportion of CD44�/CD24cells,
a maker for stem-like breast cancer cells. Results: 231-Luc-HER2
cells formed larger tumors in orthotopic xenograft models compared to
231-Luc cells, however, no significant difference was observed in proliferation
in vitro. Neither 231-Luc-HER2 nor 231-Luc metastasized in the brain
from the breast after orthotopic inoculation. After intracardiac injections of
the 231-Luc-HER2 cells, brain metastasis developed (7/13 mice, 53.8%).
Immunohistochemical analysis revealed that most metastasized cells
expressed HER2, although we had injected a mixture of HER2-positive and
HER2-negative cancer cells. Interestingly, administering Lapatinib, a dual
EGFR and HER2 tyrosine kinase inhibitor, effectively prevented HER2positive
cells to colonize the brain. However, the HER2-negative 231-Luc-
HER2 cells developed into brain metastases. In fact, the 231-Luc cells,
which are HER2-negative, also metastasized in the brain (10/16 mice,
62.5%). Flow cytometry analysis of the 231-Luc-HER2 cells showed that
HER2-positive cells decreased the population of CD44�/CD24- (HER2�/
CD44�/CD24-: 86.8% and HER2-/CD44�/CD24-: 96.3%). Conclusions:
The mechanism of brain metastases of HER2-positive breast cancer cells is
different from that of HER2-negative breast cancer cells. It is therefore
important to consider an additional therapeutic approach when dealing
with HER2-negative cells in tumors having the heterogeneity of HER2
expression.
637 General Poster Session (Board #13H), Sat, 8:00 AM-12:00 PM
The effects of lapatinib and neratinib on HER2 protein levels in breast
cancer cell lines. Presenting Author: Denis Collins, National Institute for
Cellular Biotechnology, Dublin City University, Dublin, Ireland
Background: HER2, a member of the c-erbB receptor tyrosine kinase family,
is over-expressed (HER2 gene amplification/IHC 3�, �30% cells) in
approx. 25% of breast cancers. Pre-clinical studies have shown that the
HER2-targeted small molecule tyrosine kinase inhibitor (TKI) lapatinib
(LAP) can increase HER2 levels in cell line models and can potentiate
trastuzumab-mediated antibody dependent cell-mediated cytotoxicity. To
assess the potential effects of the next generation TKI neratinib (NER) on
expression of HER2 in breast cancer, this study compares the effects of
LAP and NER on HER2 protein levels in the HER2-amplified SKBR3 and
HER2-non-amplified T47D cell lines in vitro. Methods: SKBR3 and T47D
were treated with LAP or NER (0.2, 1 and 2 �M) for 12, 24 and 48
hours.HER2 protein levels were determined by ELISA, immunoblotting and
high content analysis (HCA). HER2 protein was examined using two
antibodies targeting the extracellular domain (ECD) and the intracellular
domain (ICD) of HER2. pHER2, EGFR/pEGFR, MAPK/pMAPK and AKT/
pAKT levels were determined by immunoblotting. Proliferation studies
utilized an acid phosphatase-based assay. Results: ELISA analysis confirmedsignificantly
lower HER2 expression in T47D (44 �/- 17 pg/�g)
compared to SKBR3 (748 �/- 296 pg/�g), p � 0.015. NER proved a more
potent inhibitor of pHER2 and pEGFR as analyzed by immunoblotting and
in proliferation studies (NER IC50 - SKBR3 0.03 �/- 0.01 nM, T47D 199
�/- 70 nM, LAP IC50 - SKBR3 20 �/- 1 nM, T47D 1.2 �/- 0.2 �M). LAP
induced an increase in both ECD and ICD-containing HER2 protein levels
in SKBR3 and T47D cells. No increase in HER-2 levels was observed with
NER treatment, as determined by HCA and immunoblotting. EGFR protein
levels increased in response to lapatinib in both cell lines. Conclusions: Our
results suggest that LAP and NER have differing effects on HER2 protein
levels in the models examined. NER provides greater inhibition of HER2
signaling activity but does not increase HER2 protein levels as was
observed with LAP. Further pre-clinical assessment of combinations of LAP
and NER with HER2 and EGFR monoclonal antibody therapies is warranted
in HER2-amplified, HER2-non-amplified and EGFR-expressing breast
cancer models.
636 General Poster Session (Board #13G), Sat, 8:00 AM-12:00 PM
Adjuvant treatment of early-stage HER2� elderly breast cancer patients: A
retrospective, multicenter French study. Presenting Author: Philippe Barthelemy,
Hôpitaux Universitaires de Strasbourg, Strasbourg, France
Background: Trastuzumab (T) is the standard of care for the adjuvant
treatment of early stage, HER2� breast cancer (BC). However, few data are
available for elderly HER2� breast cancer patients in this setting. In this
current study, the patterns of care for elderly HER2� early stage BC in 7
French cancer centres was evaluated. Methods: Medical records of all
consecutive early stage HER2� BC patients over 70 years old treated
between 2006 and 2011 among participating centres were retrospectively
reviewed. Specific factors such as age, comorbidities, tumor stage, grade,
ER/PR and HER2 status, treatment characteristics, follow-up and cardiotoxicity
data were analysed. Results: One hundred and two patients were
identified, median age 75.4 (range 70-95). Elderly patients presented
mostly (57%) large tumors (pT �2), and positive lymph node involvement
(n�61). Trastuzumab-based adjuvant treatment was administered in 62%
of patients (n�63). 54% of patients (n�55) received adjuvant chemotherapy
whereas five patients received neoadjuvant chemotherapy. Chemotherapy
without T was administered in 2 additional patients. Anthracyclines
(A)-Taxanes (Ta) combination-based chemotherapy was given in 27% of
patients (n�16), whereas 38% received a Ta-based chemotherapy (n�23),
35% (n�19) an A-based chemotherapy. Five patients received singleagent
T. Treatment delays for T were required in 37% of patients (n�23)
among whom 15 and 8 permanently or temporarily stopped T, respectively.
The most frequent reason for interrupting or delaying therapy was cardiotoxicity
(n�12) as well as patients refusal (n�7). A � 10% decrease in LVEF
was observed in 18/63 (29%) of patients, among whom T was stopped in
12. After a median 33 months follow-up, the median progression-free
survival was not reached in patients receiving T-based therapy. The 2 and
3-year PFS rate were 94 and 89.5%, respectively. Conclusions: In routine
practice only 62% of elderly early stage HER2� BC patients are treated
with a neoadjuvant or adjuvant T-based regimen. However, less than 50%
of all patients completed their therapy. A-based chemotherapy was
administered in around 60% of treated patients, and could explain
cardiotoxicity in this setting.
638 General Poster Session (Board #14A), Sat, 8:00 AM-12:00 PM
Lapatinib or trastuzumab? Which anti-HER2 treatment is more effective in
the treatment of patients with HER2-positive breast cancer with brain
metastases? An Anatolian Society of Medical Oncology Study. Presenting
Author: Muhammet Ali Kaplan, Dicle Univercity Scholl of Medicine,
Diyarbakir, Turkey
Background: In the present study, we investigate that which treatment
choice is more effective in the human epidermal growth factor receptor 2
(HER2) positive breast cancer patients with brain metastases. Methods: Of
405 metastatic breast cancer patients with brain metastases at referral
centers in Turkey, 111 patients treated with lapatinib or trastuzumab after
brain metastases eligible for the analyses were identified. Patients received
both drugs consecutively or sequentially were excluded from the study.
Results: Median age was 44 years (27-76) and 46 of the 111 patients
(41.5%) had received lapatinib. Median time to development of brain
metastases was 12.2 months (0-71). Sixteen patients (14.4%) had
undergone surgery, 33 (29.7%) radiosurgery, and 108 (97.2%) whole
brain radiation therapy (WBRT). Median overall survival (OS) after brain
metastases was 15 months(95% confidence interval (CI): 12.3-17.6).
Lapatinib usage was prolonged OS over trastuzumab alone (19.1 months vs
12 months, p�0.039).Other parameters affecting the survival were Karnofsky
performance score (KPS, �70), number of brain metastases (�3),
extracranial metastases (�2), performed neurosurgery, and received radiosurgery.
After correction for potential confounders, lapatinib therapy
remained an independent positive predictor for survival [Odds ratio (OR),
0.57; p�0.02). Conclusions: Although this retrospective multi-center study
had several limitations, study results suggest that the usage of lapatinib
after brain metastases prolonged survival compared to the usage of
trastuzumab. This result should be support with prospective studies.
Visit abstract.asco.org and search by abstract for the full list of abstract authors and their disclosure information.