Abstract P3-07-19: Progesterone receptor positivity is an independent predictor of long-term benefit from adjuvant tamoxifen treatment of estrogen receptor positive breast cancer

Introduction:The expression of estrogen receptor (ER) and progesterone receptor (PgR) predicts the response to endocrine therapy of breast cancer. Nearly all PgR positive tumors are also ER positive. The independent predictive information of PgR has been questioned after an overview by the EBCTCG. However, the studies in the overview were performed before modern PgR immunohistochemistry (IHC) was developed.

Purpose: We aim to investigate the independent predictive value of PgR determined by IHC in ER positive tumors.

Materials and methods: Between 1976 and 1990 the Stockholm Breast Cancer Study Group conducted a randomized trial comparing adjuvant tamoxifen versus control. We evaluated 618 patients with ER-positive "low-risk" breast cancer ( tumor size≤ 30 mm and lymph node-negative) for whom PgR was determined by immunohistochemistry. The median follow-up was 17 years. Hazard ratios (HRs) and 95 % confidence intervals (CIs) were estimated using the Cox's proportional hazards model.

Results: Patients with ER+/PgR+ tumors receiving tamoxifen had a reduced recurrence risk compared with those who were not treated with tamoxifen (HR= 0.40, 95% CI 0.27 – 0.59, p< 0.001). For patients with ER+/PgR- tumors the difference between tamoxifen vs. no tamoxifen treatment was not statistically significant (HR= 0.88, 95% CI 0.51 – 1.52, p= 0.65). P for interaction between the groups was 0.02.

Tam vs. controlPgR (IHC)HR (95% CI)P valueP for interactionRecurrence-free survival≥ 10 %0.40 (0.27 - 0.59)< 0.0010.02 < 10 %0.88 (0.51 - 1.52)0.65 Distant recurrence-free survival≥ 10 %0.41 (0.25 - 0.65)< 0.0010.08 < 10 %0.80 (0.44 - 1.47)0.47 Breast-cancer specific survival≥ 10 %0.35 (0.21 - 0.60)< 0.0010.11 < 10 %0.70 (0.37 - 1.33)0.28 

Conclusion: Our results indicate that the PgR expression adds predictive value to the ER expression regarding benefit from tamoxifen treatment.

Citation Format: Fohlin H, Nordenskjöld A, Fornander T, Löfdahl B, Skoog L, Stål O. Progesterone receptor positivity is an independent predictor of long-term benefit from adjuvant tamoxifen treatment of estrogen receptor positive breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-19.

Abstract A54: Met and its ligand HGF predict radiotherapy response in premenopausal breast cancer patients

Post-operative radiotherapy effectively decreases the risk for loco-regional recurrence in breast cancer. However, some patients display signs of radioresistance. There are few biomarkers used in the clinic today to predict response to radiotherapy, and patients continue to receive unnecessary treatment. Studies propose a role for the receptor tyrosine kinase Met and its ligand HGF in radioresistance. Therefore, it was aimed in this study to determine MET and HGF copy numbers, Met and HGF expression, and phosphorylated Met expression in breast cancers to elucidate Met and HGF's role in radiotherapy response. MET and HGF copy numbers were determined by digital droplet PCR in 205 pre-menopausal patients, randomized to receive either radio- or chemotherapy. Immunohistochemical staining of Met, phosphorylated Met, and HGF could be performed on 228 tumor tissue samples in this cohort. Increased MET and HGF copy numbers, more than two copies, were detected in 33% and 21% of the tumors, respectively. MET and HGF amplification, more than three copies, was detected in 8% and 7% of the tumors, respectively. Interestingly, patients with tumours with MET amplification tended to relapse at a higher rate than patients without amplification. This was more prominent in patients with triple-negative breast cancer, where both MET amplification and increased copy number were correlated with a shorter recurrence-free survival. High stromal HGF expression, but not HGF copy number, was also shown to be correlated with shorter survival. Both high cytoplasmic phosphorylated Met and high cytoplasmic HGF predicted better response to radiotherapy, compared with low expression. Similar results were seen for MET and HGF increased copy number. A tendency of opposite results were obtained with total membranous Met and stromal HGF. Patients with tumors expressing low levels of these proteins had more benefit from radiotherapy. This suggests that MET and HGF copy gain is not enough for a favorable radiotherapy response, the status of the resulting proteins is additionally of importance.

Citation Format: Cynthia Veenstra, Gizeh Pérez-Tenorio, Bo Nordensköljd, Tommy Fornander, Olle Stål. Met and its ligand HGF predict radiotherapy response in premenopausal breast cancer patients. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr A54.

Loss of TGFβ Receptor Type 2 Expression Impairs Estrogen Response and Confers Tamoxifen Resistance

One third of the patients with estrogen receptor α (ERα)-positive breast cancer who are treated with the antiestrogen tamoxifen will either not respond to initial therapy or will develop drug resistance. Endocrine response involves crosstalk between ERα and TGFβ signaling, such that tamoxifen nonresponsiveness or resistance in breast cancer might involve aberrant TGFβ signaling. In this study, we analyzed TGFβ receptor type 2 (TGFBR2) expression and correlated it with ERα status and phosphorylation in a cohort of 564 patients who had been randomized to tamoxifen or no-adjuvant treatment for invasive breast carcinoma. We also evaluated an additional four independent genetic datasets in invasive breast cancer. In all the cohorts we analyzed, we documented an association of low TGFBR2 protein and mRNA expression with tamoxifen resistance. Functional investigations confirmed that cell cycle or apoptosis responses to estrogen or tamoxifen in ERα-positive breast cancer cells were impaired by TGFBR2 silencing, as was ERα phosphorylation, tamoxifen-induced transcriptional activation of TGFβ, and upregulation of the multidrug resistance protein ABCG2. Acquisition of low TGFBR2 expression as a contributing factor to endocrine resistance was validated prospectively in a tamoxifen-resistant cell line generated by long-term drug treatment. Collectively, our results established a central contribution of TGFβ signaling in endocrine resistance in breast cancer and offered evidence that TGFBR2 can serve as an independent biomarker to predict treatment outcomes in ERα-positive forms of this disease.

Androgen receptor expression predicts beneficial tamoxifen response in oestrogen receptor-α-negative breast cancer

Background:

Although the androgen receptor (AR) is frequently expressed in breast cancer, its relevance in the disease is not fully understood. In addition, the relevance of AR in determining tamoxifen treatment efficiency requires evaluation.

Purpose:

To investigate the tamoxifen predictive relevance of the AR protein expression in breast cancer.

Methods

Patients were randomised to tamoxifen 40 mg daily for 2 or 5 years or to no endocrine treatment. Mean follow-up was 15 years. Hazard ratios were calculated with recurrence-free survival as end point.

Results:

In patients with oestrogen receptor (ER)-negative tumours, expression of AR predicted decreased recurrence rate with tamoxifen (hazard ratio (HR)=0.34; 95% confidence interval (CI)=0.14–0.81; P=0.015), whereas the opposite was seen in the AR− group (HR=2.92; 95% CI=1.16–7.31; P=0.022). Interaction test was significant P<0.001. Patients with triple-negative and AR+ tumours benefitted from tamoxifen treatment (HR=0.12; 95% CI=0.014–0.95 P=0.044), whereas patients with AR− tumours had worse outcome when treated with tamoxifen (HR=3.98; 95% CI=1.32–12.03; P=0.014). Interaction test was significant P=0.003. Patients with ER+ tumours showed benefit from tamoxifen treatment regardless of AR expression.

Conclusions:

AR can predict tamoxifen treatment benefit in patients with ER− tumours and triple-negative breast cancer.

Revealing Different Roles of the mTOR-Targets S6K1 and S6K2 in Breast Cancer by Expression Profiling and Structural Analysis

Background

The AKT/mTORC1/S6K pathway is frequently overstimulated in breast cancer, constituting a promising therapeutic target. The benefit from mTOR inhibitors varies, likely as a consequence of tumour heterogeneity, and upregulation of several compensatory feed-back mechanisms. The mTORC1 downstream effectors S6K1, S6K2, and 4EBP1 are amplified and overexpressed in breast cancer, associated with a poor outcome and divergent endocrine treatment benefit. S6K1 and S6K2 share high sequence homology, but evidence of partly distinct biological functions is emerging. The aim of this work was to explore possible different roles and treatment target potentials of S6K1 and S6K2 in breast cancer.

Materials and methods

Whole-genome expression profiles were compared for breast tumours expressing high levels of S6K1, S6K2 or 4EBP1, using public datasets, as well as after in vitro siRNA downregulation of S6K1 and/or S6K2 in ZR751 breast cancer cells. In silico homology modelling of the S6K2 kinase domain was used to evaluate its possible structural divergences to S6K1.

Results

Genome expression profiles were highly different in S6K1 and S6K2 high tumours, whereas S6K2 and 4EBP1 profiles showed significant overlaps, both correlated to genes involved in cell cycle progression, among these the master regulator E2F1. S6K2 and 4EBP1 were inversely associated with IGF1 levels, and their prognostic value was shown to be restricted to tumours positive for IGFR and/or HER2. In vitro, S6K1 and S6K2 silencing resulted in upregulation of genes in the mTORC1 and mTORC2 complexes. Isoform-specific silencing also showed distinct patterns, e.g. S6K2 downregulation lead to upregulation of several cell cycle associated genes. Structural analyses of the S6K2 kinase domain showed unique structure patterns, deviating from those of S6K1, facilitating the development of isoform-specific inhibitors. Our data support emerging proposals of distinct biological features of S6K1 and S6K2, suggesting their importance as separate oncogenes and clinical markers, where specific targeting in different breast cancer subtypes could facilitate further individualised therapies.

Physics at the [Formula: see text] linear collider

A comprehensive review of physics at an [Formula: see text] linear collider in the energy range of [Formula: see text] GeV-3 TeV is presented in view of recent and expected LHC results, experiments from low-energy as well as astroparticle physics. The report focusses in particular on Higgs-boson, top-quark and electroweak precision physics, but also discusses several models of beyond the standard model physics such as supersymmetry, little Higgs models and extra gauge bosons. The connection to cosmology has been analysed as well.

HER4 tumor expression in breast cancer patients randomized to treatment with or without tamoxifen

The human epidermal growth factor receptor (HER) 4 is a relative of HER2 and has been associated to endocrine breast cancer and prediction of tamoxifen response. In addition to PI3K/Akt and MAPK pathway activation, ligand binding to HER4 triggers proteolytic cleavage and release of an intracellular receptor domain (4ICD) with signaling properties. The aim of the present study was to analyze HER4 protein expression and intracellular localization in breast cancer tissue from patients randomized to treatment with or without adjuvant tamoxifen. To investigate HER4 expression and localization in response to estradiol (E2) and 4-hydroxytamoxifen (4-OHT) exposure, we also performed in vitro studies. Cytoplasmic, nuclear and membrane expression of HER4 protein was evaluated by immunohistochemical staining in tumor tissue from 912 breast cancer patients. Three different breast epithelia cancer cell lines were exposed to E2 and 4-OHT and mRNA expression was analyzed using qPCR. Further, nuclear and cytoplasmic proteins were separated and analyzed with western blotting. We found an association between nuclear HER4 protein expression and ER-positivity (P=0.004). Furthermore, significant association was found between cytoplasmic HER4 and ER-negativity (P<0.0005), PgR-negativity (P<0.0005), tumor size >20 mm (P=0.001) and HER2-negativity (P=0.008). However, no overall significance of HER4 on recurrence-free survival was found. After E2 exposure, HER4 mRNA and protein expression had decreased in two cell lines in vitro yet no changes in nuclear or cytoplasmic protein fractions were seen. In conclusion, nuclear HER4 seem to be co-located with ER, however, we did not find support for overall HER4 expression in independently predicting response of tamoxifen treatment. The possible influence of separate isoforms was not tested and future studies may further evaluate HER4 significance.

S6 kinase signaling: tamoxifen response and prognostic indication in two breast cancer cohorts

Detection of signals in the mammalian target of rapamycin (mTOR) and the estrogen receptor (ER) pathways may be a future clinical tool for the prediction of adjuvant treatment response in primary breast cancer. Using immunohistological staining, we investigated the value of the mTOR targets p70-S6 kinase (S6K) 1 and 2 as biomarkers for tamoxifen benefit in two independent clinical trials comparing adjuvant tamoxifen with no tamoxifen or 5 years versus 2 years of tamoxifen treatment. In addition, the prognostic value of the S6Ks was evaluated. We found that S6K1 correlated with proliferation, HER2 status, and cytoplasmic AKT activity, whereas high protein expression levels of S6K2 and phosphorylated (p) S6K were more common in ER-positive, and low-proliferative tumors with pAKT-s473 localized to the nucelus. Nuclear accumulation of S6K1 was indicative of a reduced tamoxifen effect (hazard ratio (HR): 1.07, 95% CI: 0.53-2.81, P=0.84), compared with a significant benefit from tamoxifen treatment in patients without tumor S6K1 nuclear accumulation (HR: 0.42, 95% CI: 0.29-0.62, P<0.00001). Also S6K1 and S6K2 activation, indicated by pS6K-t389 expression, was associated with low benefit from tamoxifen (HR: 0.97, 95% CI: 0.50-1.87, P=0.92). In addition, high protein expression of S6K1, independent of localization, predicted worse prognosis in a multivariate analysis, P=0.00041 (cytoplasm), P=0.016 (nucleus). In conclusion, the mTOR-activated kinases S6K1 and S6K2 interfere with proliferation and response to tamoxifen. Monitoring their activity and intracellular localization may provide biomarkers for breast cancer treatment, allowing the identification of a group of patients less likely to benefit from tamoxifen and thus in need of an alternative or additional targeted treatment.

Abstract P1-12-17: Mature data (&gt; 25 years) on 2 years adjuvant tamoxifen treatment in premenopausal women with breast cancer: Time to re-emphasize the progesterone receptor as predictive factor?

Background

In 2011 The Early Breast Cancer Trialists' Collaborative Group (EBCTCG) reported that five years of adjuvant tamoxifen (TAM) significantly reduces the 15-year risks of breast cancer recurrence and death. Moreover, the estrogen receptor (ER) was considered the clinically most relevant predictive factor for efficacy of TAM treatment. In premenopausal patients participating in a randomized trial of 2 years of adjuvant TAM, we have previously reported on increased recurrence free survival in patients with ER- and PR-positive disease and a trend for increased overall survival in patients with PR-positive tumors. The median follow-up time was 13.9 years for patients without events. Since the effect on mortality may increase beyond year 10, we investigated more mature of data.

Aims

To investigate the long-term effect of 2 years adjuvant TAM in premenopausal patients choosing cumulative mortality (CM) and cumulative breast cancer mortality (CBCM) as end-points.

Methods

Premenopausal patients (n=564) with stage II breast cancer were included in a Swedish randomized multicenter trial between 1986-1991 and allocated to 2 years of TAM (n=276) or no treatment (n=288). The hormone receptor status of the tumor was known for 541 (96%) of the patients included, determined by immunohistochemistry or cytosol-based methods. Less than 2% were treated with adjuvant chemotherapy and they were equally distributed between the two groups. Median follow-up time was 26.3 years (22.7-29.7). Mortality data was obtained from the Swedish Cause of Death Register.

Results

Death from any cause was recorded among 312 (55%) of the patients, and 265 (47%) of the deaths were due to breast cancer. Two years of TAM decreased CM and CBCM in all patients irrespective of hormonal receptor status (n=564) (CM: HR 0.81; 95% CI: 0.65-1.02, p=0.070; CBCM: HR 0.79; 95% CI: 0.61-1.01, p=0.058), as well as in patients with ER-positive disease (n=346) (CM: HR 0.77; 95% CI: 0.57-1.03, p=0.077; CBCM: HR 0.72; 95% CI: 0.52-1.01, p=0.051), however not strictly significant. Importantly, in patients with PR-positive tumors, TAM significantly reduced CM and CBCM (CM: HR 0.73; 95% CI: 0.55-0.98, p=0.037; CBCM: HR 0.68; 95% CI: 0.49-0.94, p=0.020). Moreover, in patients with ER- and PR positive tumors TAM decreased CM (HR 0.74; 95% CI: 0.55-1.01, p=0.057) and CBCM (HR 0.69; 95% CI: 0-49-0.97, p=0.033), whereas there was no effect of TAM in patients with ER-positive and PR-negative tumors (p=0.97 and p=0.99, respectively).

Conclusions

The present study demonstrates that 2 years of adjuvant TAM as monotherapy significantly reduced CM and CBCM in premenopausal women with PR-positive tumors as well as CBCM in ER- and PR-positive tumors, after &gt; 25 years of follow-up. Five years of adjuvant TAM have been proven to reduce mortality rates at 15 years, but we herein show that also 2 years of TAM yields a survival benefit at 25 years.

In the latest meta-analysis from EBCTCG, PR did not add predictive information in patients with ER-positive tumors, but according to our results the significance of PR, as a predictive factor for TAM efficacy, should be re-emphasized in premenopausal women.

Citation Format: Maria Ekholm, Pär-Ola Bendahl, Mårten Fernö, Bo Nordenskjöld, Olle Stål, Lisa Rydén. Mature data (&gt; 25 years) on 2 years adjuvant tamoxifen treatment in premenopausal women with breast cancer: Time to re-emphasize the progesterone receptor as predictive factor? [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-12-17.

Proteomics profiling identify CAPS as a potential predictive marker of tamoxifen resistance in estrogen receptor positive breast cancer

Background

Despite the success of tamoxifen since its introduction, about one-third of patients with estrogen (ER) and/or progesterone receptor (PgR) - positive breast cancer (BC) do not benefit from therapy. Here, we aim to identify molecular mechanisms and protein biomarkers involved in tamoxifen resistance.

Results

Using iTRAQ and Immobilized pH gradient-isoelectric focusing (IPG-IEF) mass spectrometry based proteomics we compared tumors from 12 patients with early relapses (<2 years) and 12 responsive to therapy (relapse-free > 7 years). A panel of 13 proteins (TCEAL4, AZGP1, S100A10, ALDH6A1, AHNAK, FBP1, S100A4, HSP90AB1, PDXK, GFPT1, RAB21, MX1, CAPS) from the 3101 identified proteins, potentially separate relapse from non-relapse BC patients. The proteins in the panel are involved in processes such as calcium (Ca²⁺) signaling, metabolism, epithelial mesenchymal transition (EMT), metastasis and invasion. Validation of the highest expressed proteins in the relapse group identify high tumor levels of CAPS as predictive of tamoxifen response in a patient cohort receiving tamoxifen as only adjuvant therapy.

Conclusions

This data implicate CAPS in tamoxifen resistance and as a potential predictive marker.

Electronic supplementary material

The online version of this article (doi:10.1186/s12014-015-9080-y) contains supplementary material, which is available to authorized users.

Abstract 3819: Clinical potential of the Eph/ephrin profile in breast cancer

The Eph receptors belong to a large family of receptors tyrosine kinase. The Ephs and their ligands ephrins are aberrantly expressed in cancer. However, due their complex signaling and promiscuous interactions, a wide screening of the entire family will be important to determine their clinical value. Purpose: The Eph receptor tyrosine kinase family has been implicated in breast cancer but their role in tumor progression remains elusive. Therefore we aimed to profile the Eph receptors and their ligands ephrins in breast cancer samples to define them as potential clinical markers or therapeutic targets.

Experimental design: Gene expression of Eph/ephrins was quantified by RT-PCR using a TaqMan® Micro Fluidics Cards Microarray custom designed for 21 Eph/ephrin family members: EphA1-A8, EphB1-B4 and EphB6, ephrinA1-A5, ephrinB1-B3 and 2 endogenous controls: GAPDH and HPRT1 in 70 breast cancer tumors.

Results: We found that high expression of EphBs, and particularly EphB2, was associated to worse outcome among postmenopausal patients with lymph node infiltration. Additionally high EphB2 expression correlated with HER2 positive status.

Conclusions: Our results suggest that the EphB receptor family may have prognostic value for postmenopausal breast cancer patients with lymph nodal infiltration. We will continue this study in a larger patient material in order to better evaluate the therapeutic impact of this family.

Citation Format: Gizeh Perez-Tenorio, Anna-Maria Husa, Olle Stål. Clinical potential of the Eph/ephrin profile in breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3819. doi:10.1158/1538-7445.AM2014-3819

Abstract 3295: S6 kinase signaling in prognosis and tamoxifen response in two randomized breast cancer cohorts

Detecting signals in the mammalian target of rapamycin (mTOR), and the estrogen receptor (ER) pathways for prediction of treatment response may be a future clinical tool in primary breast cancer. Here, we investigated the validity and value of the mTOR targets p70-S6 kinase (S6K) 1 and 2 as biomarkers for tamoxifen sensitivity in vitro and in two independent tamoxifen randomized postmenopausal breast cancer cohorts. In addition, the prognostic value of the S6Ks was evaluated.

We found S6K1 to correlate with HER2 and cytoplasmic Akt activity, whereas S6K2 and phosphorylated S6K were closer connected with ER positivity, low proliferation and nucleic p-Akt. Treatment prediction and prognosis were evaluated by immunohistochemical staining. Nuclear accumulation of S6K1 was indicative of a reduced tamoxifen treatment effect, compared with a significant benefit from tamoxifen treatment in patients without tumor S6K1 nuclear accumulation. Patients with a combination of S6K1 nuclear accumulation and S6K2 cytoplasmic accumulation in the tumor cells had no tamoxifen benefit. Also, S6K1 and S6K2 activation, indicated by p-S6K-t389 expression, was associated with low benefit from tamoxifen compared with untreated patients. In addition, high protein expression of S6K1, independent of localization, predicted worse prognosis. This was not evident for variations in S6K2 or p-S6K-t389 expression.

In conclusion, the mTOR targeted kinases S6K1 and S6K2 interfere with proliferation and response to tamoxifen. Monitoring their activity and intracellular localization may provide biomarkers for breast cancer treatment, allowing for identification of a group of patients less likely to benefit from tamoxifen and thus in need of an alternative or additional treatment.

Citation Format: Josefine Bostner, Elin Karlsson, Cecilia Bivik, Gizeh Perez-Tenorio, Tommy Fornander, Olle Stål. S6 kinase signaling in prognosis and tamoxifen response in two randomized breast cancer cohorts. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3295. doi:10.1158/1538-7445.AM2014-3295

The mTOR effectors 4EBP1 and S6K2 are frequently coexpressed, and associated with a poor prognosis and endocrine resistance in breast cancer: a retrospective study including patients from the randomised Stockholm tamoxifen trials

Introduction

mTOR and its downstream effectors the 4E-binding protein 1 (4EBP1) and the p70 ribosomal S6 kinases (S6K1 and S6K2) are frequently upregulated in breast cancer, and assumed to be driving forces in tumourigenesis, in close connection with oestrogen receptor (ER) networks. Here, we investigated these factors as clinical markers in five different cohorts of breast cancer patients.

Methods

The prognostic significance of 4EBP1, S6K1 and S6K2 mRNA expression was assessed with real-time PCR in 93 tumours from the treatment randomised Stockholm trials, encompassing postmenopausal patients enrolled between 1976 and 1990. Three publicly available breast cancer cohorts were used to confirm the results. Furthermore, the predictive values of 4EBP1 and p4EBP1_S65 protein expression for both prognosis and endocrine treatment benefit were assessed by immunohistochemical analysis of 912 node-negative breast cancers from the Stockholm trials.

Results

S6K2 and 4EBP1 mRNA expression levels showed significant correlation and were associated with a poor outcome in all cohorts investigated. 4EBP1 protein was confirmed as an independent prognostic factor, especially in progesterone receptor (PgR)-expressing cancers. 4EBP1 protein expression was also associated with a poor response to endocrine treatment in the ER/PgR positive group. Cross-talk to genomic as well as non-genomic ER/PgR signalling may be involved and the results further support a combination of ER and mTOR signalling targeted therapies.

Conclusion

This study suggests S6K2 and 4EBP1 as important factors for breast tumourigenesis, interplaying with hormone receptor signalling. We propose S6K2 and 4EBP1 as new potential clinical markers for prognosis and endocrine therapy response in breast cancer.

Clinical value of isoform-specific detection and targeting of AKT1, AKT2 and AKT3 in breast cancer

SUMMARY 

Overactivation of the PI3K/AKT signaling pathway is frequently reported in breast cancer, consequently inhibitors targeting this pathway are clinically useful. AKT constitutes a hub in the regulation of several cancer hallmarks, such as proliferation, survival and migration. Three AKT isoforms, named AKT1, AKT2 and AKT3, are identified in humans. AKT alterations, mainly upregulation of phosphorylated AKT in tumors may have prognostic and predictive value. Moreover, the AKT isoforms may possess partly divergent cellular functions and be upregulated in certain breast cancer subtypes, suggesting the importance of isoform-specific analyses. In conclusion, AKT isoform-specific detection and targeting in different tumor subtypes will hopefully result into a further developed personalized medicine.

VAV3 mediates resistance to breast cancer endocrine therapy

Introduction

Endocrine therapies targeting cell proliferation and survival mediated by estrogen receptor α (ERα) are among the most effective systemic treatments for ERα-positive breast cancer. However, most tumors initially responsive to these therapies acquire resistance through mechanisms that involve ERα transcriptional regulatory plasticity. Herein we identify VAV3 as a critical component in this process.

Methods

A cell-based chemical compound screen was carried out to identify therapeutic strategies against resistance to endocrine therapy. Binding to ERα was evaluated by molecular docking analyses, an agonist fluoligand assay and short hairpin (sh)RNA–mediated protein depletion. Microarray analyses were performed to identify altered gene expression. Western blot analysis of signaling and proliferation markers, and shRNA-mediated protein depletion in viability and clonogenic assays, were performed to delineate the role of VAV3. Genetic variation in VAV3 was assessed for association with the response to tamoxifen. Immunohistochemical analyses of VAV3 were carried out to determine its association with therapeutic response and different tumor markers. An analysis of gene expression association with drug sensitivity was carried out to identify a potential therapeutic approach based on differential VAV3 expression.

Results

The compound YC-1 was found to comparatively reduce the viability of cell models of acquired resistance. This effect was probably not due to activation of its canonical target (soluble guanylyl cyclase), but instead was likely a result of binding to ERα. VAV3 was selectively reduced upon exposure to YC-1 or ERα depletion, and, accordingly, VAV3 depletion comparatively reduced the viability of cell models of acquired resistance. In the clinical scenario, germline variation in VAV3 was associated with the response to tamoxifen in Japanese breast cancer patients (rs10494071 combined P value = 8.4 × 10⁻⁴). The allele association combined with gene expression analyses indicated that low VAV3 expression predicts better clinical outcome. Conversely, high nuclear VAV3 expression in tumor cells was associated with poorer endocrine therapy response. Based on VAV3 expression levels and the response to erlotinib in cancer cell lines, targeting EGFR signaling may be a promising therapeutic strategy.

Conclusions

This study proposes VAV3 as a biomarker and a rationale for its use as a signaling target to prevent and/or overcome resistance to endocrine therapy in breast cancer.

C-X-C ligand 10 and C-X-C receptor 3 status can predict tamoxifen treatment response in breast cancer patients

To investigate the expression levels of CXCL10 and CXCR3 in tumors from breast cancer patients randomized to adjuvant tamoxifen treatment or no endocrine treatment, in order to further study the connection to prognosis and prediction of tamoxifen treatment outcome. Immunohistochemistry on tissue microarrays from 912 breast cancer patients randomized to tamoxifen or no endocrine treatment. CXCR3 status was found to be a prognostic tool in predicting distant recurrence, as well as reduced breast cancer-specific survival. In patients with estrogen receptor (ER)-positive tumors, tumors with strong CXCL10 levels had improved effect of tamoxifen treatment in terms of local recurrence-free survival [risk ratio (RR) 0.46 (95 % CI 0.25–0.85, P = 0.01)] compared with patients with tumors expressing weak CXCL10 expression. Further, patients with ER-positive tumors with strong CXCR3 expression had an improved effect of tamoxifen in terms of breast cancer-specific survival [RR 0.34 (95 % CI 0.19–0.62, P < 0.001)] compared with the group with weak CXCR3 levels [RR 1.33 (95 % CI 0.38–4.79, P = 0.65)]. We show here for the first time that CXCL10 and CXCR3 expression are both predictors of favorable outcome in patients treated with tamoxifen.

Lack of G protein-coupled estrogen receptor (GPER) in the plasma membrane is associated with excellent long-term prognosis in breast cancer

G protein-coupled estrogen receptor (GPER), or GPR30, is a membrane receptor reported to mediate non-genomic estrogen responses. Tamoxifen is a partial agonist at GPER in vitro. Here, we investigated if GPER expression is prognostic in primary breast cancer, if the receptor is treatment-predictive for adjuvant tamoxifen, and if receptor subcellular localization has any impact on the prognostic value. Total and plasma membrane (PM) GPER expression was analyzed by immunohistochemistry in breast tumors from 742 postmenopausal lymph node-negative patients subsequently randomized for tamoxifen treatment for 2-5 years versus no systemic treatment, regardless of estrogen receptor (ER) status, and with a median follow-up of 17 years for patients free of event. PM GPER expression was a strong independent prognostic factor for poor prognosis in breast cancer without treatment-predictive information for tamoxifen. In the tamoxifen-treated ER-positive and progesterone receptor (PgR)-positive patient subgroup, the absence of PM GPER (53 % of all ER-positive tumors) predicted 91 % 20-year distant disease-free survival, compared to 73 % in the presence of GPER (p = 0.001). Total GPER expression showed positive correlations with ER and PgR and negative correlation with histological grade, but the correlations were biphasic. On the other hand, PM GPER expression showed strong negative correlations with ER and PgR, and strong positive correlation with HER2 overexpression and high histological grade. GPER overexpression and PM localization are critical events in breast cancer progression, and lack of GPER in the PM is associated with excellent long-term prognosis in ER-positive and PgR-positive tamoxifen-treated primary breast cancer.

Decreased expression of Yes-associated protein is associated with outcome in the luminal A breast cancer subgroup and with an impaired tamoxifen response

BACKGROUND

Yes-associated protein (YAP1) is frequently reported to function as an oncogene in many types of cancer, but in breast cancer results remain controversial. We set out to clarify the role of YAP1 in breast cancer by examining gene and protein expression in subgroups of patient material and by downregulating YAP1 in vitro and studying its role in response to the widely used anti-estrogen tamoxifen.

METHODS

YAP1 protein intensity was scored as absent, weak, intermediate or strong in two primary breast cancer cohorts (n = 144 and n = 564) and mRNA expression of YAP1 was evaluated in a gene expression dataset (n = 1107). Recurrence-free survival was analysed using the log-rank test and Cox multivariate analysis was used to test for independence. WST-1 assay was employed to measure cell viability and a luciferase ERE (estrogen responsive element) construct was used to study the effect of tamoxifen, following downregulation of YAP1 using siRNAs.

RESULTS

In the ER+ (Estrogen Receptor α positive) subgroup of the randomised cohort, YAP1 expression was inversely correlated to histological grade and proliferation (p = 0.001 and p = 0.016, respectively) whereas in the ER- (Estrogen Receptor α negative) subgroup YAP1 expression correlated positively to proliferation (p = 0.005). Notably, low YAP1 mRNA was independently associated with decreased recurrence-free survival in the gene expression dataset, specifically for the luminal A subgroup (p < 0.001) which includes low proliferating tumours of lower grade, usually associated with a good prognosis. This subgroup specificity led us to hypothesize that YAP1 may be important for response to endocrine therapies, such as tamoxifen, extensively used for luminal A breast cancers. In a tamoxifen randomised patient material, absent YAP1 protein expression was associated with impaired tamoxifen response which was significant upon interaction analysis (p = 0.042). YAP1 downregulation resulted in increased progesterone receptor (PgR) expression and a delayed and weaker tamoxifen in support of the clinical data.

CONCLUSIONS

Decreased YAP1 expression is an independent prognostic factor for recurrence in the less aggressive luminal A breast cancer subgroup, likely due to the decreased tamoxifen sensitivity conferred by YAP1 downregulation.

The role of microRNA-200 in progression of human colorectal and breast cancer

The role of the epithelial-mesenchymal transition (EMT) in cancer has been studied extensively in vitro, but involvement of the EMT in tumorigenesis in vivo is largely unknown. We investigated the potential of microRNAs as clinical markers and analyzed participation of the EMT-associated microRNA-200–ZEB–E-cadherin pathway in cancer progression. Expression of the microRNA-200 family was quantified by real-time RT-PCR analysis of fresh-frozen and microdissected formalin-fixed paraffin-embedded primary colorectal tumors, normal colon mucosa, and matched liver metastases. MicroRNA expression was validated by in situ hybridization and after in vitro culture of the malignant cells. To assess EMT as a predictive marker, factors considered relevant in colorectal cancer were investigated in 98 primary breast tumors from a treatment-randomized study. Associations between the studied EMT-markers were found in primary breast tumors and in colorectal liver metastases. MicroRNA-200 expression in epithelial cells was lower in malignant mucosa than in normal mucosa, and was also decreased in metastatic compared to non-metastatic colorectal cancer. Low microRNA-200 expression in colorectal liver metastases was associated with bad prognosis. In breast cancer, low levels of microRNA-200 were related to reduced survival and high expression of microRNA-200 was predictive of benefit from radiotheraphy. MicroRNA-200 was associated with ER positive status, and inversely correlated to HER2 and overactivation of the PI3K/AKT pathway, that was associated with high ZEB1 mRNA expression. Our findings suggest that the stability of microRNAs makes them suitable as clinical markers and that the EMT-related microRNA-200 – ZEB – E-cadherin signaling pathway is connected to established clinical characteristics and can give useful prognostic and treatment-predictive information in progressive breast and colorectal cancers.

Abstract P1-08-12: G protein-coupled estrogen receptor in the plasma membrane is prognostic in early breast cancer

Background: G protein-coupled estrogen receptor (GPER), also known as GPR30, is a novel putative estrogen receptor. Although contradictory results have been presented e.g. regarding the subcellular localization and function of the receptor, previous studies have shown a prognostic value in breast cancer and proposed treatment predictive information for tamoxifen (Tam). This study aimed at clarifying the prognostic and treatment predictive value for Tam of GPER, in different subcellular localizations, by using samples from a randomized clinical trial - the ideal population for assessing treatment prediction.

Material and Methods: GPER levels were assessed semi-quantitatively by immunohistochemistry in tissue microarrays from 742 postmenopausal breast cancer patients with no lymph node metastasis and tumor size ≤ 30mm. Patients were originally included in the STO-3 trial 1976-1990. After surgery, they were randomized to Tam treatment (40mg for 2 years or no systemic treatment), regardless of classical estrogen receptor α (ER) status. GPER staining was evaluated in carcinoma both as intensity in 5 levels regardless of subcellular localization, and in the plasma membrane in 3 levels. Due to statistical considerations regarding group size, the final analysis was made with intensity in 3 levels and plasma membrane as positive or negative. The Kaplan-Meier method and logrank test (for trend when applicable) were used for survival analysis and Cox regression analysis for obtaining hazard ratios (HR), interaction testing and multivariate modeling. Distant disease-free survival (DDFS) was used as endpoint.

Results: Analyzing all patients, we found no association between DDFS and GPER intensity. However, positive plasma membrane staining showed a strong correlation with poor prognosis (HR 1.8 p = 0.002). This was only observed in the ER+ subgroup (ER+ patients HR 2.1, p&lt;0.001, ER- patients HR 1.1 p = 0.79). The prognostic value, in untreated patients only, was analyzed with similar results (plasma membrane staining positive vs. negative: all untreated patients HR 1.8 p = 0.008, ER+ patients HR 2.1 p = 0.003, ER- patients HR 1.1 p = 0.83).

No obvious difference in tamoxifen response was observed across plasma membrane or intensity groups, and tests for interaction were not significant.

A multivariate model including GPER in plasma membrane, ER, histological grade, HER2, tamoxifen and tumor size showed that GPER was an independent prognostic factor (HR 1.6 p = 0.01). Finally we created a group with ER+, progesterone receptor (PR) + patients treated with Tam, as this group today is treated with Tam and thought to have a good response. GPER in the plasma membrane significantly separated this group into an excellent prognosis group and a poor prognosis group (HR 3.3, p = 0.01). The excellent prognosis group, which constitutes more than half of ER+ patients, had a 20 year DDFS of 91% (95% CI 84-95).

Conclusion: We found no treatment predictive value of GPER for Tam. However, GPER expressed in the plasma membrane was a strong independent prognostic factor for a poor prognosis in ER+ breast cancer. Used in ER+, PR+, tamoxifen treated patients, it can distinguish patients with an excellent prognosis from patients with a poor outcome that may benefit from additional treatment.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-12.

The prevalence of immunohistochemically determined oestrogen receptor positivity in primary breast cancer is dependent on the choice of antibody and method of heat-induced epitope retrieval - prognostic implications?

BACKGROUND

Oestrogen receptor (ER) status is important for the choice of systemic treatment of breast cancer patients. However, most data from randomised trials on the effect of adjuvant endocrine therapy according to ER status are based on the cytosol methods. Comparisons with immunohistochemical methods have given similar results. The aim of the present study was to examine whether different ER antibodies and heat-induced epitope retrieval (HIER) methods influence the prevalence of ER-positivity in primary breast cancer.

MATERIAL AND METHODS

This study is based on patients included in a clinical trial designed to compare the effect of two years of adjuvant tamoxifen versus no adjuvant systemic treatment in premenopausal women. From 1986 to 1991, 564 patients from two study centres in Sweden were enrolled and randomised. Patients were randomised independently of ER status. In the present study, ER status was assessed on tissue microarrays with the three different ER antibody/HIER combinations: 1D5 in citrate pH 6 (n = 390), SP1 in Tris pH 9 (n = 390) and PharmDx in citrate pH 6 (n = 361).

RESULTS

At cut-offs of 1% and 10%, respectively, the prevalence of ER-positivity was higher with SP1 (75% and 72%) compared with 1D5 (68% and 66%) and PharmDx (66% and 62%). At these cut-offs, patients in the discordant groups (SP1-positive and 1D5-negative) seem to have a prognosis intermediate between those of the double-positive and double-negative groups. Comparison with the ER status determined by the cytosol-based methods in the discordant group also showed an intermediate pattern. The repeatability was good for all antibodies and cut-offs, with overall agreement ≥ 93%.

CONCLUSION

The present study shows that the choice of antibody and HIER method influences the prevalence of ER-positivity. We suggest that this be taken into consideration when choosing a cut-off for clinical decision making.

Breast cancer index identifies early-stage estrogen receptor-positive breast cancer patients at risk for early- and late-distant recurrence

PURPOSE

Residual risk of relapse remains a substantial concern for patients with hormone receptor-positive breast cancer, with approximately half of all disease recurrences occurring after five years of adjuvant antiestrogen therapy.

EXPERIMENTAL DESIGN

The objective of this study was to examine the prognostic performance of an optimized model of Breast Cancer Index (BCI), an algorithmic gene expression-based signature, for prediction of early (0-5 years) and late (>5 years) risk of distant recurrence in patients with estrogen receptor-positive (ER(+)), lymph node-negative (LN(-)) tumors. The BCI model was validated by retrospective analyses of tumor samples from tamoxifen-treated patients from a randomized prospective trial (Stockholm TAM, n = 317) and a multi-institutional cohort (n = 358).

RESULTS

Within the Stockholm TAM cohort, BCI risk groups stratified the majority (∼65%) of patients as low risk with less than 3% distant recurrence rate for 0 to 5 years and 5 to 10 years. In the multi-institutional cohort, which had larger tumors, 55% of patients were classified as BCI low risk with less than 5% distant recurrence rate for 0 to 5 years and 5 to 10 years. For both cohorts, continuous BCI was the most significant prognostic factor beyond standard clinicopathologic factors for 0 to 5 years and more than five years.

CONCLUSIONS

The prognostic sustainability of BCI to assess early- and late-distant recurrence risk at diagnosis has clinical use for decisions of chemotherapy at diagnosis and for decisions for extended adjuvant endocrine therapy beyond five years.

Oestrogen receptor co-activator AIB1 is a marker of tamoxifen benefit in postmenopausal breast cancer

Background

The oestrogen receptor (ER) co-activator amplified in breast cancer 1 (AIB1) has been suggested as a treatment predictive and prognostic marker in breast cancer. Studies have however not been unanimous.

Patients and methods

AIB1 protein expression was analysed by immunohistochemistry on tissue micro-arrays with tumour samples from 910 postmenopausal women randomised to tamoxifen treatment or no adjuvant treatment. Associations between AIB1 expression, clinical outcome in the two arms and other clinicopathological variables were examined.

Results

In patients with ER-positive breast cancer expressing low tumour levels of AIB1 (<75%), we found no significant difference in recurrence-free survival (RFS) or breast cancer-specific survival (BCS) between tamoxifen treated and untreated patients. In patients with high AIB1 expression (>75%), there was a significant decrease in recurrence rate (HR 0.40, 95% CI 0.26–0.61, P < 0.001) and breast cancer mortality rate (HR 0.38, 95% CI 0.21–0.69, P = 0.0015) with tamoxifen treatment. In the untreated arm, we found high expression of AIB1 to be significantly associated with lower RFS (HR 1.74, 95% CI 1.20–2.53, P = 0.0038).

Conclusion

Our results suggest that high AIB1 is a predictive marker of good response to tamoxifen treatment in postmenopausal women and a prognostic marker of decreased RFS in systemically untreated patients.