Annual Meeting Proceedings Part 1 - American Society of Clinical ...
Annual Meeting Proceedings Part 1 - American Society of Clinical ...
Annual Meeting Proceedings Part 1 - American Society of Clinical ...
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62s Breast Cancer—Triple-Negative/Cytotoxics/Local Therapy<br />
1052 General Poster Session (Board #21C), Sat, 8:00 AM-12:00 PM<br />
Effect <strong>of</strong> therapeutic targeting <strong>of</strong> the oncogene EMP2 in triple-negative<br />
breast cancer on tumor load. Presenting Author: Madhuri Wadehra,<br />
DGSOM at UCLA, Los Angeles, CA<br />
Background: Understanding tumor induced angiogenesis is a challenging<br />
problem with important consequences for the diagnosis and treatment <strong>of</strong><br />
cancer. In this study we define a novel function for the tetraspan epithelial<br />
membrane protein-2 (EMP2) in the control <strong>of</strong> neoangiogenesis. EMP2 is an<br />
oncogene whose expression has been shown to correlate with tumor<br />
progression and survival in a number <strong>of</strong> human cancers including triple<br />
negative breast, ovarian, and endometrial tumors. In breast cancer, EMP2<br />
is highly expressed on the majority <strong>of</strong> invasive tumors examined, and in<br />
particular 70% <strong>of</strong> triple negative breast tumors showed surface expression<br />
<strong>of</strong> this marker. In this study, we examine the control <strong>of</strong> EMP2 on the tumor<br />
microenvironment and further characterize its therapeutic efficacy in<br />
breast cancer. Methods: A number <strong>of</strong> cancer cell lines were utilized both in<br />
vitro and in vivo to determine if EMP2 expression levels altered the tumor<br />
microenvironment. Cells were tested for their expression <strong>of</strong> pro-angiogenic<br />
proteins HIF-1a and VEGF-A as well as for their ability to induce endothelial<br />
cell migration and capillary like tube formation. Cells with modulated<br />
EMP2 levels were also tested in vivo for tumor formation and examined for<br />
histological changes in the tumor microenvironment. In addition, we<br />
recently constructed a fully human EMP2 IgG1 and determined its<br />
therapeutic efficacy in a number <strong>of</strong> triple negative breast cancer cells.<br />
Results: In vitro, upregulation <strong>of</strong> EMP2 promoted VEGF expression through<br />
a HIF-1a dependent pathway and resulted in successful capillary-like tube<br />
formation. In contrast, reduction <strong>of</strong> EMP2 correlated with reduced HIF-1a<br />
and VEGF expression with the net consequence <strong>of</strong> poorly vascularized<br />
tumors in vivo. Treatment <strong>of</strong> breast cancer cells with EMP2 IgG1 reduced<br />
tumor load with a significant improvement in survival. Conclusions: <strong>Clinical</strong>ly,<br />
EMP2 has been shown to correlate with poor survival, and these<br />
results suggest that this occurs in part through its control on tumor<br />
vasculature. In addition, we provide additional evidence on the potent<br />
cytotoxic effects <strong>of</strong> EMP2 treatment in vivo.<br />
1054 General Poster Session (Board #21E), Sat, 8:00 AM-12:00 PM<br />
Biomarkers <strong>of</strong> response to Akt inhibitor MK-2206 in breast cancer.<br />
Presenting Author: Takafumi Sangai, University <strong>of</strong> Texas M. D. Anderson<br />
Cancer Center, Houston, TX<br />
Background: Akt significantly contributes to cancer pathogenesis. PTEN, a<br />
negative regulator <strong>of</strong> PI3K/Akt signaling, is mutated or decreased, and<br />
PIK3CA is frequently mutated in multiple cancer lineages. We hypothesized<br />
that MK-2206, an allosteric Akt inhibitor, would inhibit Akt<br />
signaling thus blocking cancer cell growth, and PTEN and/or PIK3CA<br />
mutations may confer MK-2206 sensitivity in breast cancer. Methods: After<br />
determining sensitivity to MK-2206 in16 cell lines, the effect on Akt<br />
signaling was tested by reverse-phase protein array analysis and western<br />
blotting. The effect to cell cycle progression and cell death were analyzed<br />
by flow cytometry. Using RNA knockdown technique, the effect <strong>of</strong> PTEN,<br />
PIK3CA and Akt on MK2206 sensitivity was tested. Anti-tumor effect in<br />
vivo with or without paclitaxel was tested using PTEN-mutant ZR75-1<br />
breast cancer xenografts. Results: MK-2206 inhibited Akt signaling and<br />
cell cycle progression, and increased apoptosis in a dose-dependent<br />
manner in breast cancer cell lines. Cell lines with PTEN or PIK3CA<br />
mutations were more sensitive to MK-2206 (P�0.0337), however, a<br />
number <strong>of</strong> lines with PTEN/PIK3CA mutations were MK-2206-resistant.<br />
Small interfering RNA (siRNA) knockdown <strong>of</strong> PTEN in breast cancer cells<br />
increased Akt phosphorylation concordant with increased MK-2206 sensitivity.<br />
Stable transfection <strong>of</strong> PIK3CA E545K or H1047R mutant plasmids<br />
into normal-like MCF10A breast cells enhanced MK-2206 sensitivity. Cell<br />
lines that were less sensitive to MK-2206 had lower ratios <strong>of</strong> Akt1/Akt2 and<br />
had less growth inhibition with Akt siRNA knockdown. In ZR75-1 xenografts,<br />
MK-2206 treatment inhibited Akt signaling, cell proliferation, and<br />
tumor growth. In vitro, MK-2206 showed a synergistic interaction with<br />
paclitaxel in MK-2206-sensitive cell lines, and this combination had<br />
significantly greater antitumor efficacy than either agent alone in vivo.<br />
Conclusions: MK-2206 has antitumor activity alone and in combination<br />
with chemotherapy. This activity may be greater in tumors with PTEN loss<br />
or PIK3CA mutation, providing a strategy for patient enrichment in clinical<br />
trials. However, not all tumors with PIK3CA/PTEN aberrations are MK-2206sensitive,<br />
emphasizing the need for additional markers <strong>of</strong> response.<br />
1053 General Poster Session (Board #21D), Sat, 8:00 AM-12:00 PM<br />
<strong>Clinical</strong> characteristics and chemotherapy options <strong>of</strong> triple-negative breast<br />
cancer: Role <strong>of</strong> classical CMF regimen. Presenting Author: Min Hee Hur,<br />
Department <strong>of</strong> Surgery, Kwandong University College <strong>of</strong> Medicine, Cheil<br />
General Hospital, Seoul, South Korea<br />
Background: Triple-negative breast cancer is a high risk breast cancer that<br />
lacks the benefit <strong>of</strong> specific targeted therapy. We investigated the clinicopathologic<br />
characteristics between triple-negative breast cancers (TNBC)<br />
and non-TNBC. And we also analyzed the effect <strong>of</strong> chemotherapy options<br />
such as classical CMF regimen, anthracycline-based, or taxane-based<br />
chemotherapy. Methods: A total <strong>of</strong> 826 invasive breast cancer patients were<br />
evaluated from March 2003 to December 2008. We investigated them<br />
retrospectively, who had the median follow-up for 88 months. We examined<br />
the differences between TNBC compared with non-TNBC in relation to the<br />
clinicopathologic parameters, chemotherapy regimen, overall survival (OS).<br />
Results: 156 (18.9%) cases among 826 patients were triple negative breast<br />
cancers. There were significantly positive associations with younger age<br />
(below 35 years), large tumor (�2cm), high stage, poorly differentiated<br />
nuclear grade, poorly histologic grade in TNBC. Positive lymph node,<br />
lymphovascular invasion were not significantly different between TNBC and<br />
non- TNBC. A total <strong>of</strong> 677 patients were treated with chemotherapy. In<br />
TNBC patients, 142 (93.4%) patients were treated with chemotherapy<br />
more than in 535 (61.4%) <strong>of</strong> non- TNBC patients. The chemotherapy in<br />
TNBC patients was composed <strong>of</strong> classical CMF (47.9%), anthracyclinebased<br />
regimen (25.4%), taxane-based regimen (26.8%). 19 cases (12%)<br />
<strong>of</strong> TNBC experienced locoregional or systemic metastases. 48 (7.2%)<br />
patients <strong>of</strong> non- TNBC did local or systemic metastases. Patients with<br />
TNBC had worse 5-year OS than with non-TNT (95.7% vs 98.6%,<br />
p�0.01). Interestingly, patients treated with CMF regimen were better<br />
5-year OS than with anthracycline-based, or taxane-based regimen in<br />
TNBC (100% vs 96.9% vs 89.2%, p�0.001). There was no survival<br />
difference among chemotherapy regimens in non-TNBC patients.<br />
Conclusions: Patients with TNBC have poor prognosis compared with<br />
non-TNBC. Classical CMF regimen for TNBC patients may be more<br />
effective than anthracycline-based or taxane-based regimens.<br />
1055 General Poster Session (Board #21F), Sat, 8:00 AM-12:00 PM<br />
Preclinical evaluation <strong>of</strong> selective inhibitors <strong>of</strong> nuclear export (SINE) in<br />
basal-like breast cancer (BLBC). Presenting Author: Dilara McCauley,<br />
Karyopharm Therapeutics, Boston, MA<br />
Background: Basal-like breast cancers (BLBC) compose up to 15% <strong>of</strong> breast<br />
cancer (BC) and are usually triple negative characterized by lack <strong>of</strong> ER, PR,<br />
and HER-2 amplification. In addition, most BRCA1-associated BCs are<br />
BLBC and TNBC, expressing basal cytokeratins and EGFR. BLBC is<br />
characterized by an aggressive phenotype, high histological grade, and poor<br />
clinical outcomes: high recurrence and metastasis rates. CRM1 (XPO1) is<br />
the exclusive nuclear exporter <strong>of</strong> multiple Tumor Suppressor Proteins (TSP)<br />
including p53, p21, BRCA1&2, pRB, FOXO. CRM1 inhibition forces<br />
nuclear accumulation <strong>of</strong> TSPs, inducing apoptosis in cancer cells. KPT-<br />
SINE are novel, small molecule, irreversible inhibitors <strong>of</strong> CRM1 with potent<br />
anti cancer activity. Methods: The Cancer Genome Atlas (TCGA) and BC cell<br />
line databases were used for mRNA analyses. MTT assay was used to<br />
determine the cytotoxic effect <strong>of</strong> KPT-SINE (KPT-185 and KPT-330) on 44<br />
breast cell lines including luminal A, luminal B, HER2 positive, BLBC and<br />
TNBC cells. The effect <strong>of</strong> KPT-330 treatment on tumor growth was tested<br />
in vivo in the TNBC model MDA-MB-468 xenograft. Results: Analyses <strong>of</strong><br />
nuclear pore complex (NPC)-related mRNA levels (including CRM1)<br />
showed clear separation <strong>of</strong> BCs into high and low NPC expression. BLBC<br />
subtype was enriched with high NPC transcripts while luminal BC was<br />
enriched in low NPC levels (p�1.53e-20). High NPC levels had higher<br />
mutation levels in BRCA2 (cor�0.33, p�1.83e-8) and ABL1. NPC<br />
expression was inversely correlated with ER mRNA expression (cor�-0.58,<br />
p�1.37e-7). KPT-SINE showed potent cytotoxicity on �75% <strong>of</strong> the cell<br />
lines (IC50 values �1 �M). Only three <strong>of</strong> 24 TNBC cell lines displayed IC50 values �1.5 �M upon KPT-SINE treatment. Genomic analyses on all BC<br />
lines indicated that p53, PI3K/AKT and BRCA1 or 2 status did not affect<br />
cytotoxicity. In MDA-MB-468 xenograft, KPT-330 displayed efficacy in a<br />
dose-dependent manner inhibiting nearly 100% <strong>of</strong> tumor growth compared<br />
with vehicle treated animals, and was well tolerated. Conclusions: These<br />
data show that NPC/CRM1 mRNAs are overexpressed in BLBC/TNBC and<br />
that CRM-1 mediated nuclear export inhibition by SINE represents a<br />
potentially novel and well tolerated therapy for BLBC / TNBC.<br />
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