Search

Invasive lobular carcinoma (ILC) accounts for approximately 10% to 15% of breast carcinomas, and although it responds poorly to neoadjuvant chemotherapy, it appears to respond well to endocrine therapy. Pre- and on-treatment (after 2 weeks and 3 months) biopsies and surgical samples were obtained from 14 postmenopausal women with estrogen receptor–positive (ER+) histologically confirmed ILC who responded to 3 months of neoadjuvant letrozole and were compared with a cohort of 14 responding invasive ductal carcinomas (IDC) matched on clinicopathologic features. RNA was extracted and processed for whole human genome expression microarray. Dynamic clinical response was assessed using periodic three-dimensional ultrasound measurements performed during treatment and defined as a reduction of >70% in tumor volume by 3 months. Pretreatment profiles of ILC and IDC tumors showed distinctive expression of genes associated with E-cadherin signaling, epithelial adhesion, and stromal rearrangement. The changes in gene expression in response to letrozole were highly similar between responding ILC and IDC tumors; genes involved in proliferation were downregulated and those involved with immune function and extracellular matrix remodeling were upregulated. However, molecular differences between the histologic subtypes were maintained upon treatment. This is the first study of molecular changes in ILC in response to endocrine therapy to date. The genes that change on letrozole are highly consistent between ILC and IDC. Differences in gene expression between ILC and IDC at diagnosis are maintained at each time point on treatment. Cancer Res; 74(19); 5371–6. ©2014 AACR.

555Background: Identifying breast cancer (BC) patients likely to recur on endocrine therapy (ET) is a major challenge. Many multigene classifiers are available for predicting prognosis. These are u...

Background Affymetrix GeneChips and Illumina BeadArrays are the most widely used commercial single channel gene expression microarrays. Public data repositories are an extremely valuable resource, providing array-derived gene expression measurements from many thousands of experiments. Unfortunately many of these studies are underpowered and it is desirable to improve power by combining data from more than one study; we sought to determine whether platform-specific bias precludes direct integration of probe intensity signals for combined reanalysis. Results Using Affymetrix and Illumina data from the microarray quality control project, from our own clinical samples, and from additional publicly available datasets we evaluated several approaches to directly integrate intensity level expression data from the two platforms. After mapping probe sequences to Ensembl genes we demonstrate that, ComBat and cross platform normalisation (XPN), significantly outperform mean-centering and distance-weighted discrimination (DWD) in terms of minimising inter-platform variance. In particular we observed that DWD, a popular method used in a number of previous studies, removed systematic bias at the expense of genuine biological variability, potentially reducing legitimate biological differences from integrated datasets. Conclusion Normalised and batch-corrected intensity-level data from Affymetrix and Illumina microarrays can be directly combined to generate biologically meaningful results with improved statistical power for robust, integrated reanalysis.

International audience; mTOR plays a key role in tumor cell cycle control, proliferation, and survival. RAD001 (everolimus) is a novel macrolide that inhibits mTOR and thus downstream signaling pathways. 31 post-menopausal women with early breast cancer were given 5 mg RAD001 once daily for 14 days prior to surgery. Biopsies were taken at diagnosis and at surgery (post 14 days of treatment) and assessed for immunohistochemical changes in proliferation (Ki67), apoptosis (active caspase-3), p-AKT (s473), p-S6 (s235/236 and s240/244), p-mTOR (s2448), ER, and PR. Five patients did not complete the 2-week treatment period due to adverse events. All adverse events were grade 1 or 2 (NCIC-CTC scale). RAD001 treatment significantly decreased proliferation (geometric mean reduction 74% from baseline ( = 0.019)), particularly in HER-2 positive tumors. High Ki67 pre-treatment correlated with reduction in Ki67, an increase in apoptosis, a reduction in p-AKT (cytoplasmic) and reduction in p-mTOR following treatment. Nuclear expression of p-AKT was significantly reduced with treatment. Tumors that had a reduction in Ki67 with treatment exhibited a significant reduction in cytoplasmic p-AKT. p-S6 staining was significantly reduced independently of Ki67 (

International audience; Previous studies have demonstrated that both anastrozole and letrozole are well tolerated. Letrozole suppresses estrogen to a greater degree than anastrozole in the serum and breast tumor. Concerns have been raised that greater potency may adversely affect patients' quality of life (QOL). One hundred eighty-one postmenopausal women with invasive estrogen receptor-positive breast cancers were randomized to receive either 12 weeks of letrozole followed by 12 weeks of anastrozole or the reverse sequence. One hundred and six received immediate adjuvant aromatase inhibitors (AIs) following surgery, and 75 received extended adjuvant therapy. The Functional Assessment of Cancer Therapy Endocrine Subscale (FACT-B-ES) QOL questionnaires were completed to assess QOL on each drug. Additional side-effect profiles were collected. Each patient completed a patient preference form. Twenty-one patients withdrew before study end, 10/179 (5.6%) while taking letrozole and 4/173 (2.3%) while taking anastrozole ( = 0.12). Tamoxifen-naïve patients had a higher mean ES (endocrine symptoms subscale) score at entry versus those having extended therapy (66.0 vs. 61.9; = 0.001). There was no significant change in FACT-B-ES (overall) scores or ES scores while patients were taking anastrozole or letrozole and no significant differences between drugs. Nearly 80% of patients reported one or more side effects with either agent. No differences in frequency, grade, or range of side effects were seen between drugs. Of 160 patients, 49 (30.6%) preferred letrozole, 57 (35.6%) preferred anastrozole, and 54 (33.8%) had no preference ( = 0.26, Pearson's Chi-squared test). In conclusion, both AIs are equally well tolerated. There were no significant differences in QOL scores between the two drugs.

International audience; ALIQUOT (Anastrozole vs. Letrozole, an Investigation of Quality Of Life and Tolerability) was a prospective, open-label, randomized pharmacodynamic study designed to assess the effects of aromatase inhibitors (AIs) on bone turnover in healthy postmenopausal women with estrogen receptor-positive breast cancer. Ninety-four patients were randomized to receive either 12 weeks of letrozole (2.5 mg; = 42) followed by 12 weeks of anastrozole (1 mg), or 12 weeks of anastrozole (1 mg; = 42) followed by 12 weeks of letrozole (2.5 mg). After completion of the study period, patients in the immediate adjuvant group were either switched to tamoxifen ( = 38) or continued on anastrozole or letrozole. In the beginning of the study, 42 patients had taken tamoxifen within 3 months. Patients taking drugs likely to affect bone metabolism, including bisphosphonates, were excluded. Eighty-four patients had complete sample measurements and were included in the analysis. Prior tamoxifen therapy resulted in a significantly lower mean baseline procollagen type 1 N-terminal propeptide (PINP) compared with patients with no prior tamoxifen. There were no significant differences in bone markers between AIs at any time. By 6 months, significant increases were seen in PINP, C-terminal telopeptides (CTX), bone specific alkaline phosphatise (ALP), and urinary N-terminal telopeptides (NTX). Patients with prior tamoxifen had significantly greater increases than patients with no prior tamoxifen. Patients treated with 3 months of tamoxifen following 6 months of an AI showed a significant decrease in markers of bone resorption, serum CTX and urinary NTX. In conclusion, AI-induced bone turnover increases over time. Anastrozole and letrozole produce similar effects on bone metabolism and turnover. Stopping tamoxifen therapy and starting AIs results in a significantly greater increase in bone turnover compared with commencing AIs in tamoxifen-naïve patients. Patients given tamoxifen following AI therapy showed a decrease in markers of bone resorption.

The aim of the study was to identify changes in tumour expression profiling associated with short-term therapy of breast cancer patients with letrozole.Microarray analysis was performed on RNA extracted from paired tumour core biopsies taken before and after 14 days of treatment with letrozole (2.5 mg/daily) in 58 patients. Changes in expression profile were identified by three different approaches on the basis of frequency of changes, magnitude of changes and significance analysis of microarray.No single gene was consistently changed by therapy in all cases. Fifty-two genes, however, were downregulated and 36 upregulated in at least 45 of the 58 cases. In terms of quantitative change, 46 genes showed at least a median 1.5-fold change in expression. Significance analysis of microarray identified 62 genes that were significantly changed by therapy (P0.0001, 56 downregulated and six upregulated). All three approaches showed that greater numbers of genes were downregulated rather than upregulated. Merging data produced a total of 143 genes, which were subject to gene ontology and cluster analysis. The ontology of the 91 downregulated genes showed that they were functionally associated with cell cycle progression, particularly mitosis. In contrast, upregulated genes were associated with organ development, connective tissue extracellular matrix regulation and inflammatory response. Cluster analysis segregated the patients into four groups differing in patterns of gene expression.Genes have been identified which either change markedly or consistently in breast cancer after 14 days treatment with letrozole. These are new important data in understanding letrozole's molecular mechanism of action in breast cancers.

In patients with hormone receptor positive DCIS tamoxifen reduces recurrence rates by almost 50%. Few data are available with aromatase inhibitors from randomised studies. In the ATAC study there were three DCIS lesions in the anastrozole arm and four in the tamoxifen arm in the women with ER positive invasive cancer. In the MA17 study which randomised patients to up to 5 years of letrozole or placebo there was only one DCIS event in the contralateral breast in patients taking letrozole and five on placebo. There were also four patients in this study who had DCIS in the conserved breast on placebo and none in the letrozole treated group. The few clinical data that are available therefore suggest the aromatase inhibitors are likely to be effective in DCIS. A histological review of a study of 206 postmenopausal women with invasive oestrogen receptor positive breast cancer who were randomised as part of a 14 day preoperative study to receive 2.5mg of letrozole or 1mg of anastrozole identified 27 patients with 28 pairs of tumours in whom there was sufficient ER positive DCIS in invasive cancer in the initial core biopsy and in the subsequent surgery specimen, to evaluate for PgR activity and proliferation. Within the DCIS both aromatase inhibitors significantly reduced PgR expression and both drugs also produced a significant fall in proliferation. There was a moderate degree of agreement between the fall in PgR in both the invasive cancer and DCIS (Kappa=0.5; p=0.0013) and between the fall in proliferation and between the invasive and in situ components (correlation coefficient=0.68; p

Fulvestrant (Faslodex) is a pure anti-oestrogen that reduces markers of hormone sensitivity and proliferation in postmenopausal women with oestrogen-receptor (ER)-positive breast cancer. This randomised trial compared the effects on the tumours of a single dose of 750mg fulvestrant to those of daily tamoxifen (20mg) taken 14-16 days prior to surgery in 60 premenopausal women with ER-positive primary breast cancer. There were statistically significant falls in the expression of ER and Ki67 levels compared to the baseline with both drugs. Both drugs caused a decrease in PgR expression from baseline but this was only statistically significant with fulvestrant. No statistically significant differences were seen between the two treatment groups. Fulvestrant caused an increase in circulating levels of oestradiol, irrespective of the stage of the menstrual cycle at which patients commenced treatment. No major changes were seen in LH, FSH and progesterone levels with either drug. The most common adverse events with fulvestrant were headaches, hot flushes, nausea and disturbance of menses. Contrary to previous studies with fulvestrant 250mg, these findings suggest that at a dose of 750mg fulvestrant is effective at reducing the effects of oestrogen on ER-positive breast cancer in premenopausal women.

Background: Axillary management in breast cancer is evolving. Recent ACSO guidelines have suggested that axillary node clearances (ANC) are not necessary in the positive axilla in early breast cancers with small nodal burdens, undergoing breast conserving surgery (BCT). According to ASCO guidelines, G1-2, T1-2 tumours with 1 or 2 SLN macrometastases, undergoing BCT should not undergo ANC. We compare current practice in a screening population against these guidelines. Methods: We retrospectively analysed all patients with invasive breast cancer under the regional screening programme (2011e2014), looking specifically at management of patients who would not be offered ANC under ASCO guidelines. Results: 687 screening patients were diagnosed in the time frame. 516 had normal axillary USS and 143 e abnormal. Of the 516 normal USS, 79 (15.3%) had malignant sentinel lymph nodes (SLNB), (45 (57%) were macrometastases of which, 93% had 1e2 positive nodes. 34 (43%) were micrometastases). 86 abnormal USS had SLNB, 16 of which were malignant, 12 macrometastases (100% 1e2 positive nodes). 36 of the malignantmacrometastatic SLNBmet ASCO guidelines. 24 of those received ANC (67%), 7 (30%) of which were positive, 2 with heavy nodal burdens (10/14 and 5/20). The remainder had 1 positive node. Conclusion: Under updated ASCO guidance on SLNB in early breast cancer, we are over-treating the majority of screening patients. However, had these guidelines been followed, 19% of our patients would have had a missed diagnosis of further axillary disease, and in 5% a significant nodal burden would have remained undetected. As clinicians, there is a responsibility to balance and articulate that trade off when discussing axillary management with patients.

PurposeTo investigate the impact of human epidermal growth factor receptor (HER) 1 and HER2 gene amplification on endocrine therapy responsiveness, a fluorescence in situ hybridization (FISH) study was conducted on tumor samples from 305 postmenopausal patients with stage II and III estrogen receptor (ER) –positive (ER ≥ 10%) breast cancers treated on two independent neoadjuvant endocrine therapy trials.Patients and MethodsFISH analysis focused on HER1 and/or HER2 immunohistochemistry (IHC) -positive patients and a random selection of HER1/2 IHC-negative patients. HER2 FISH status was correlated with response and changes in the proliferation marker Ki67.ResultsHER1 was rarely amplified (< 1%), and HER2 amplification was observed in 9.2% of patients. Letrozole response by clinical measurement (71% HER2 FISH positive v 71% HER2 FISH negative), mammogram (44% HER2 FISH positive v 47% HER2 FISH negative), or ultrasound (47% HER2 FISH positive v 54% HER2 FISH negative) was not impaired by HER2 FISH-positive status. In contrast, HER2 FISH-positive tumors showed higher histologic grade (P = .009), higher pretreatment Ki67 (P = .005), and less Ki67 suppression after letrozole when compared with HER2 FISH-negative tumors (P = .0001). Similar observations regarding Ki67 were made in a smaller cohort of tamoxifen-treated tumors.ConclusionNeoadjuvant letrozole is clinically effective in ER-positive HER2 FISH-positive tumors, indicating sensitivity to short-term estrogen deprivation. However, continued proliferation despite ongoing letrozole or tamoxifen treatment in the majority of ER-positive HER2 FISH-positive samples (88%) could imply therapeutic resistance that may manifest later in the clinical course of the disease. Discordance between clinical and biomarker findings in this study serves to emphasize the need for surrogate end point validation in neoadjuvant endocrine trials through correlation with information on long-term outcomes.

There are important surgical issues related to the use of the third generation aromatase inhibitors in both the neoadjuvant and adjuvant settings. Neoadjuvant hormone therapy is effective at downstaging tumours, particularly large tumours initially thought to be inoperable or requiring mastectomy. Randomised trials have shown that the newer aromatase inhibitors letrozole and anastrozole increase the numbers of women who are suitable for breast-conservation compared with tamoxifen, and that letrozole is superior to tamoxifen in terms of clinical response. Aromatase inhibitors are most effective in ER-rich tumours and are clinically and biologically effective in both HER2 positive and negative tumours, whereas HER2 positive tumours show a level of resistance to tamoxifen. In neoadjuvant studies comparing aromatase inhibitors with tamoxifen, the duration of use has been 3-4 months, by which time any response is usually evident but longer treatment periods produce continued shrinkage and response. The re-excision rate following breast conservation surgery after neoadjuvant hormone therapy is favourable compared with the rates following immediate wide local excision. Local recurrence rates are acceptable in patients undergoing neoadjuvant therapy and breast-conserving surgery providing post-operative radiotherapy is given. Adjuvant aromatase inhibitors, as well as having an effect on metastatic disease and survival, reduce local and regional recurrence.

Postmenopausal patients with oestrogen receptor-positive locally advanced T4b, N0-1, M0 and large operable breast cancers T2>3 cm, T3, T4, N0-1 and M0 have been treated with 2.5 mg letrozole (12 patients), 10 mg letrozole (12 patients), 1 or 10 mg anastrozole (24 patients) and 20 mg tamoxifen (65 patients). There was no apparent difference in response rate between 2.5 and 10 mg letrozole. Only 17 patients with anastrozole have so far completed the 3-month treatment period. Median clinical, mammographic and ultrasound reductions in tumour volumes for patients treated with letrozole were 81% (95% confidence interval (CI) 66-88), 77% (95% CI 64-82) and 81% (95% CI 69-86) respectively and for anastrozole, values were 87% (95% CI 59-97), 73% (95% CI 58-82) and 64% (95% CI 52-76) respectively. This compares with a median reduction in tumour volume for tamoxifen-treated patients as assessed by ultrasound of 48% (95% CI 27-48). There were seven complete clinical responses (CR), sixteen patients who achieved 50% or greater reduction in tumour volume (PR) and one no change (NC) for letrozole and four CRs, twelve PRs and one progressive disease for anastrozole. Best radiological responses were one CR, twenty PRs and three NCs for letrozole and one CR, fifteen PRs and one NC for anastrozole. This study has shown that the new aromatase inhibitors, letrozole and anastrozole, are highly effective agents in the neoadjuvant setting and they should now be compared with tamoxifen as first-line treatment in a randomised study.

Background: Aromatase inhibitors (AIs) have an established role in the treatment of estrogen receptor alpha positive (ER+) post-menopausal breast cancer. Response rates are 50-70% in the neoadjuvant setting and lower in advanced disease. There is a need to identify biomarkers to predict response that outperform those currently available, to be able to offer more stratified treatments and improved patient care. Methods: Pre- and on-treatment (at 14 days and 3-months) biopsies were obtained from 89 post-menopausal women with ER+ breast cancer receiving 3 months of neoadjuvant Letrozole. Illumina Beadarray gene expression data (n = 34) were combined with Affymetrix GeneChip data (n = 55) and cross-platform integration approaches developed as part of this study were implemented to combine data. Dynamic clinical response was assessed for each patient using periodic 3D ultrasound measurements performed during treatment. A gene classifier was developed from pre and 14 day gene array expression data to predict response. An independent series from the Royal Marsden was used to validate the classifier. Results: Response to endocrine therapy in the neoadjuvant setting based on the expression of 4 genes has been developed. The classifier comprises baseline expression of an immune signalling gene and an apoptosis related gene, together with 14 day expression of two proliferation genes. Early on-treatment gene changes in combination with pre-treatment gene expression significantly improve predictive power compared to pre-treatment gene expression alone. The classifier had a 96% accuracy in a training dataset (n = 73) and 91% accuracy in an independent validation dataset (n = 44) dataset. Table 1 AccuracySensitivitySpecificityPPVNPVAUC (ROC)Training0.960.890.980.890.960.96Validation0.910.80.970.920.9NASensitivity and specificity of model in training and validation datasets Expression of the pre-treatment immune signalling gene alone predicted for response with 85% and 82% accuracy in training and validation datasets respectively. Higher pre-treatment levels of this gene were associated with a significantly better 1 year progression free survival (PFS) (P = 0.0001). In a larger series of patients treated with neoadjuvant Letrozole (n = 129) higher expression of this gene alone was associated with a significantly improved 10 year RFS (p = 0.0359). In a separate tamoxifen treated cohort (n = 212) higher expression of this gene at diagnosis was associated with a significantly improved 5 year (p = 0.0015) and 10 year (p = 0.04) recurrence free survival (RFS). Conclusion: • A 4 gene classifier has been developed and validated to predict response to neoadjuvant Letrozole. • One of the genes identified is a significant predictor in independent data sets of long term RFS in endocrine treated patients. • This new classifier has the potential to predict accurately the benefit of endocrine therapy and has huge potential clinical value. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD3-2.

INTRODUCTION Activation of the Phosphatidylinositide 3-kinase/mammalian target of rapamycin (PI3K)/mTOR pathway is thought to play a role in the development of resistance to endocrine therapy. The aim was to investigate PIK3CA mutation and PTEN status in a series of patients with estrogen receptor positive alpha (ER+) breast cancer at diagnosis and on progression, recurrence or development of a new breast cancer during or following adjuvant endocrine treatment. METHODS Formalin fixed paraffin embedded tissue was available from a series of 120 patients at diagnosis and from; local recurrences (in breast tumour recurrence, or recurrence in mastectomy scars), metastatic recurrences (nodal, or distant metastatic disease), local progression (patients treated with neoadjuvant endocrine therapy who initially responded well and then progressed), and from second breast cancers (ipsilateral second breast cancers, or contralateral new primaries). Samples were profiled with a comprehensive qPCR based mutation assay covering 17 mutational hotspots in PIK3CA, as well as having immunohistochemistry for PTEN assessment. RESULTS PIK3CA mutation status was available from 88 paired-matched samples at both diagnosis and recurrence. 38 (43%) had at least one PIK3CA mutation at diagnosis, and 37 (42%) had a mutation present in tissue taken at the time of recurrence. The most common mutations in the 176 tissues analysed in order were: H1047R (35 samples), H1047L (11 samples), E545K (19 samples), E542K (6 samples), H1047R (3 samples), C420R (4 samples), 542K (1 sample). Three cancers had 2 mutations. PTEN protein status by immunohistochemistry at diagnosis was: null = 1, 1-100 = 7, 101-200 = 24, >200 = 14. At recurrence the PTEN status was null = 6, 1-100 = 5, 101-200 = 13, >200 = 32. The change in PIK3CA mutation status in different groups is outlined in Table 1. Table 1.EventNumberPIK3CA gainPIK3CA lossChange in PIK3CA mutation status%Local progression28011 (3.6%)Metastatic recurrences19112 (10.5%)Local recurrence30303 (10%)Contralateral new primary6235 (83%)Ipsilateral 2nd tumour5213 (60%)Total8814814 Few patients changed their PIK3CA mutation status on development of local recurrence, metastatic disease or progression on hormone treatment. Frequent changes in PIK3CA mutation status were seen in patients who developed a new cancer in the treated or in the contralateral breast. There was an increase in PTEN null cases (from 2.2% to 10.7%) and PTEN over-expression >200 (from 30.4% to 57%) from the first to the second samples. CONCLUSION • The acquisition of mutations in PIK3CA does not appear to be responsible for the development of endocrine resistance. • PIK3CA mutation status does not change in the majority of patients on progression or development of recurrence on or after endocrine therapy. PIK3CA mutation status at diagnosis can thus be used to determine whether a PI3-Kinase inhibitor might be suitable for treatment in patients with metastatic disease. • Patients who develop new breast cancers frequently develop cancers with a different PIK3CA mutation status. • These are the most comprehensive currently available data correlating PIK3CA status and endocrine resistance. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD1-1.

Background: Estrogen is a key hormone involved in cancer cell development. It forms a complex with estrogen receptor alpha (ER) which binds to estrogen response elements (EREs) in the promoter regions of genes under its transcriptional control. Letrozole inhibits local production of estrogen. Despite the prevalent use of such drugs little is known about their effect at molecular and transcriptomic level. A better understanding of the molecular mechanisms underlying why approximately 75% of ER rich cancers respond might help to elucidate the mechanisms characterising a lack of response in some patients. Methods: A new gene expression dataset was generated from sequential core biopsy/theatre samples (before treatment, 10–14 days on treatment and at surgery) taken from ER+ patients undergoing neo-adjuvant letrozole treatment. Clinical response to treatment was assessed by changes in tumour volume based on 3D ultrasound (performed by a single operator). Results: On letrozole the majority of ER+ tumours respond with dramatic early transcriptomic changes. A significant reduction in proliferation is seen through down-regulation of key cell cycle control genes such as CyclinD1, CyclinA, CyclinB1, CyclinB2 and CDK2, and genes involved with the initiation phase of DNA replication such as the MCM complex. Several of these (including CyclinD1, CyclinB2 and MCM2) have been shown to contain candidate ERE sequences in their promoter region and therefore down-regulation of these would be concordant with deprivation of estrogen. There is also a significant up-regulation of genes including collagens, lamanins, integrins and others involved with intra-cellular adhesion and extra-cellular matrix (ECM) remodelling. Preliminary analysis suggests the involvement of a local immune response as a potential mechanism for tumour cell death, as genes involved with antigen presentation, leukocyte trans-endothelial mediation, natural killer cell mediated cytotoxicity and T-cell mediated cell death are significantly up-regulated within the clinically responding group. Two distinct subsets were seen in non-responders. The first subgroup shows a ‘classical non-response profile’ with very little change in expression of genes involved with cell cycle, ECM remodelling, cellular adhesion and antigen presentation between baseline and 14-days of treatment. The second subgroup have a gene expression profile similar to the responding group with a down-regulation of cell cycle and up-regulation of genes involved with ECM remodelling, cellular adhesion and antigen presentation. Whether these are true non-responders is not clear. Conclusion: Approximately half of clinically non-responding patients have molecular profiles similar to responding patients whilst the other half have a distinct pattern of expression with significantly less change in genes associated with cell cycle control, ECM remodelling, intra-cellular adhesion and antigen presentation. On-going work will elucidate long term outcomes in these two groups. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-04-09.

Background: Older postmenopausal patients with large operable or locally advanced oestrogen receptor positive, invasive breast cancers are candidates for treatment with neoadjuvant letrozole. HER2 positivity is a potential marker for early endocrine therapy resistance. In this study we have evaluated the effects of HER2 amplification, gene and protein expression at diagnosis and following 14 and 90 days of treatment with neoadjuvant Letrozole. Methods: 70 postmenopausal women with large operable and locally advanced oestrogen receptor (ER) positive invasive breast cancers were treated with neoadjuvant letrozole. Response was assessed by 3D ultrasound. Sequential core biopsies were taken at 0, 14 days and 3 months of treatment. 12 patients were HER2 positive (either 3+ or 2+ FISH positive), 20 were HER2 2+ FISH negative and 38 were HER2 negative (0 or +). Results: 43 patients were responders to letrozole and 17 were non-responders. 7 of the 17 non-responders were HER2 positive. Analysing response in two groups (HER2 2+ and 3+ together versus 0 or +) there was a greater difference in response rate between these two groups than when splitting into conventional HER2 positive and negative groups (P < 0.0001). In non-responding patients HER2 gene expression levels from the microarrays taken at baseline were significantly higher than the HER2 expression in responding patients (p = 0.01). There was also an increase in HER2 gene expression seen during the first 14 days of treatment in non-responding but not responding patients (p = 0.08). Rank product analysis of gene expression identified 34 down-regulated genes and 7 up-regulated genes which were shared between the HER2 2+ FISH negative samples and samples which were HER2 3+ or HER2 2+ FISH positive. Conclusion: This large cohort of patients treated with neoadjuvant letrozole shows that: HER2 expression correlates with response to letrozole. A better cut off for prediction of response to letrozole is the split between 0 and + versus 2+ and 3+ rather than the traditional 3+. Patients with increased MRNA expression at diagnosis for HER2 have a significantly lower response rate to neoadjuvant letrozole. Endocrine therapy together with anti-HER2 therapies should be considered for patients having neoadjuvant endocrine therapy for cancers which over express HER2. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-04-10.

Background:Aromatase inhibitors (AIs) reduce circulating oestrogen which may have a detrimental effect on lipid metabolism and subsequently ↑ cardiovascular risk. This study compares the effects of adjuvant A, L and E on lipid metabolism.Patients and Methods:This was an open, randomised pharmacodynamic study. Plasma lipids were measured in 120 postmenopausal women with invasive ER +ve breast cancer. As part of their adjuvant hormone therapy, patients were randomized to receive either:• 4 months of A or• 4 months of L or• 4 months of EFasting blood and urine samples were collected at the same time of day on each of (a) the day of entry, (b) after 3 months and (c) after 4 months. Patients were then switched to tamoxifen (T) and further samples collected after 12 months.• Triglycerides, cholesterol, ApoB and cLDL were measured.↑ levels are associated with ↑ cardiovascular risk.• ApoA-1 and HDL were also measured.↑ levels are associated with ↓ cardiovascular risk.Analyses were performed using repeated measures or analysis of covariance.ResultsDifferences between A vs L vs ETriglycerides E significantly ↓ triglycerides. There was a borderline significant difference between the drugs (p=0.055).Cholesterol E significantly ↓ cholesterol (p=0.03).ApoB No significant changes were detected.cLDL No significant changes were detected.ApoA-1 There were no significant differences detected between A or L although the fall with E was less but not significantly different to A or L (p=0.08).HDL E significantly ↓ HDL (p=0.008).Differences between steroidal vs non-steroidal AIsTriglyceride and ApoA-1 levels fell significantly more with E compared to the non-steroidal A+L (p=0.02, p=0.045 respectively).Effects of tamoxifenChanges from baseline after treatment on AIs and subsequent treatment with TFollowing T there was no evidence to suggest that the changes from baseline were influenced by the type of AI that patients received.Changes from end of treatment on AIs and subsequent treatment with TT increased HDL by a statistically significant greater amount following E than it did after A or L (p=0.009). From the end of treatment with AIs, T produced significant rises in triglyceride (p=0.0001), HDL (p=0.006) and ApoA1 (p=0.0003), and significant falls in cholesterol (p=0.03) and cLDL (p Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4086.

Background:Invasive lobular cancers are poorly responsive to neoadjuvant chemotherapy. They are commonly hormone sensitive. This study set out to investigate the efficacy of neoadjuvant letrozole in post-menopausal women with large operable or locally advanced breast cancers.Patients and Methods:48 consecutive patients with large operable or locally advanced invasive lobular ER positive (Allred score 8 = 38, 7 =8, 6=1, 5=1) were treated in a single Breast Unit by neoadjuvant letrozole for 3 months or longer. The mean age was 76.7 years with a range of 55 to 91 years. 6 tumours measured >2-4 cm (T2), 26 tumours measured >4 cm (T2, T3) and 16 were locally advanced (T4). Response was assessed by a single observer at 3 months.Results:Response to TreatmentThe mean reduction in clinical volume at 3 months was 60% (95% CI 50-79%) with a median of 67% (95% CI 60-79%). Responses were classified as 1 Complete Response (CR), 25 Partial Response (PR), 16 Minimal Response (MR), 4 Stable Disease (SD) and 2 Progression.The mean USS in volume was 69% (60-78%), with a median of median 80% (66-84%). Response was classified as CR= 12, PR = 25, MR = 7, SD = 3 and Progression = 1.Surgery and Outcome32 have come to surgery and 16 have continued on letrozole.24 patients were considered suitable for breast conserving surgery (WLE) of whom 16 successful had WLE (67% with Clear Margins), 4 had a WLE and then a successful re- excision of margins and 4 had a WLE followed by mastectomy. The final rate of successful breast conservation was thus 20/24 (83%).8 patients with locally advanced breast cancer became operable and were treated by mastectomy.SummaryThis is the largest series of invasive lobular carcinomas treated by neoadjuvant letrozole ever reported.Invasive lobular carcinomas are often large at diagnosis.They are mainly ER rich.In post-menopausal women they respond well to endocrine therapy with letrozole.Neoadjuvant therapy with letrozole allows many women with large invasive lobular carcinomas to be treated successfully with breast conservation.This contrasts with the poor results obtained with neoadjuvant chemotherapy.ConclusionNeoadjuvant letrozole therapy is an effective treatment for shrinking invasive lobular ER positive breast cancers in post-menopausal women. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1085.

To determine whether the addition of Zoledronic Acid to endocrine therapy increases apoptosis or decreases proliferation in early invasive breast cancer, a placebo controlled randomised trial comparing 14 days treatment with Letrozole or Letrozole and Zoledronic Acid pre-operatively was performed.PatientsIn total 109 postmenopausal women with early invasive hormone receptor positive breast cancer were randomised (1:1:1) to either placebo, Letrozole 2.5mg/day or Letrozole with Zoledronic Acid 4mg single dose intravenously 2-4 days before definitive surgical excision. Epithelial proliferation and apoptosis were measured on paired baseline and surgical biopsy specimens (after 14 days of treatment) using Ki67 and Activated Caspase 3 immunohistochemistry. Alterations in angiogenic markers (VCAM/VEGF and CD31) were also studied. The primary endpoint was fall in Ki67 between diagnosis and surgical excision.ResultsOverall 109 women were enrolled but paired biopsies were only available for 101 patients. PlaceboLetrozoleLet + Zoln323435Absolute Ki67 change (median,range)-0.8 (-12,12)8.6 (-14,37)12.9 (-12,29) Caspase 3 change (median,range)0.1 (-3.8, 9.3)0.4 (-2.7, -4.1)0.2 (-10.9, -14.4) Absolute change (Cell turnover index)-0.3 (-142, -59)18.9 (-201, 192)17.7 (-14, 379) Statistically significant reductions in Ki67 and Cell Turnover Index were seen with Letrozole and Let & Zol (p ≤ 0.001) but there was no significant different between Letrozole and Letrozole plus Zoledronic Acid groups (p = 0.26). Apoptosis did not change between the three groups.ConclusionLetrozole reduces proliferation by 70% when used for 14 days prior to surgery. Zoledronic Acid administration prior to surgery is safe but when administered as a single dose at a median of 3 days before surgery did not significantly increase apoptosis or decrease proliferation compared to Letrozole alone. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2009.

e11625 Background: Aromatase inhibitors (AIs) reduce tumor cell proliferation and improve breast cancer survival. Recent evidence from in vivo models and the ABCSG-12 Trial suggests that bisphosphonates such as zoledronic acid add to the inhibitory effect of AIs but the mechanism is unclear. We assessed the effect of letrozole alone and in combination with zoledronic acid in a 14 day pre-surgical study in women with primary breast cancer. Methods: Postmenopausal women (n=109) aged 50–75 years with untreated estrogen receptor positive invasive breast cancer (no prior hormonal therapy) gave written informed consent to the study and were randomized to letrozole (2.5mg) or placebo tablets (2:1). Letrozole treated patients were randomized further to zoledronic acid 4mg intravenously or no treatment 2–4 days prior to surgery. Epithelial proliferation and apoptosis was measured pre and post treatment by immunohistochemistry for Ki67 and activated caspase 3 respectively counting at least 1,000 cells. Smooth Muscle Actin immunohistochemistry was also assessed pre and post treatment to determine fibroblast activation. Results: The study is powered to detect a 10% difference in epithelial proliferation with the combination arm (80% chance) compared to the letrozole alone arm. Conclusions: This preoperative biological study should provide important insight into the cellular mechanism or action of zoledronic acid in addition to AIs on primary breast cancer. [Table: see text]

Abstract #2032 Background: RAD001 (everolimus) is a rapamycin derivative that inhibits mTOR and its downstream substrates and has shown promising results in Phase I trials. The aim of this study was to assess the feasibility of predicting patient response to RAD001 treatment from pre-treatment biopsies. Materials & Methods: 32 post-menopausal, ER-positive early breast cancer patients received 5mg RAD001 pre-operative treatment daily for 14 days prior to primary surgery. 25 patients completed the regimen, 6 patients withdrew and 1 did not start treatment. Biopsies were taken at diagnosis and at surgery from the RAD001 treated patients. Pre-treatment samples were flash frozen prior to RNA isolation. Patient response status was classified based on the % of Ki-67 positive cells determined by immunohistochemistry in the post-treatment biopsy (Macaskill et al., 2006: Breast Cancer Research & Treatment: 100: S1: S286). RNA from the pre-treatment group was analysed using the Almac Diagnostics Breast Cancer DSATM Research Tool, which represents ∼60,000 normal breast and breast cancer transcripts and Illumina Human Ref.8 chip v2 containing ∼24,500 transcripts representing well-categorised and most commonly known genes, irrespective of disease or tissue. For each array platform, modulated genes were identified using statistically robust gene selection methods. In addition, the sequence content of the two platforms was compared by probe-level analysis using BLAST. Results & Discussion: Preliminary assessment of the expression differences between the non-responder and responder groups using the DSA™ Research Tool demonstrated 169 up-regulated and 93 down-regulated genes. This list is comprised of genes involved in chemokine activity, cell adhesion and transport. Cross-platform content comparison demonstrated that the Illumina bead arrays represented 41% of transcripts on the DSA™ Research Tool whilst 82% of the Illumina beadarray transcripts were represented on the DSA™ Research Tool. Genes of interest identified will be validated by quantitative real time PCR and the key pathways reported. These datasets have enabled us to begin the identification of tumours most suited to RAD001 treatment and may be used as a guide for the generation of a gene expression classifier for predicting patient response to RAD001. Acknowledgements: This work was supported by a grant from Breast Cancer Research Treatment, UK. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2032.

Abstract #1065 Introduction: Changes in proliferation as measured by Ki67 occur within 14 days of starting treatment with an aromatase inhibitor and have been shown to be predictors of long term outcome. The biological effect of different aromatase inhibitors on low ER expressing cancers has not been studied. This study compared changes in proliferation in breast cancers expressing low levels of ER (Allred score 2-5) following 14 days of treatment with anastrozole or letrozole. Materials and methods: Thirty six postmenopausal women with invasive breast cancer, classified as estrogen receptor (ER) poor by an Allred score of 2-5 on initial core biopsy, were enrolled into a randomised pre-operative trial of 14 days treatment with either 2.5 mg of letrozole or 1 mg of anastrozole. Paired biopsy tissue was available for all patients: [15 who received anastrozole and 21 letrozole] with sufficient invasive cancer present for analysis. Assessment included ER (Allred score) and proliferation (% tumor cells Ki67 positive) by immunohistochemistry. Results are presented as means (SEM) and medians (range). Due to the non-normality of the data, pre- and post-treatment Ki67 values were transformed on the log scale. Change between pre- and post- treatment scores was calculated as the difference in the logged scores; analysis is by t-test and Fisher's Exact Test. All tests are two-sided. Results were back-transformed in order to preserve the original scale. Results: Proliferation measured by Ki67: Anastrozole reduced tumour cell proliferation from baseline in 10/15 cancers from a mean of 31.0% (7.1) to 20.8% (6.1). The median and mean reductions in Ki67 were 37% (range -94.0% to 92.6%) and 38% (13.9) from baseline. This equates to an average fall of 2.6 times from baseline, p=0.006, by analysis of the transformed data. Letrozole reduced proliferation from baseline in 17/21 cancers from a mean of 39.0% (7.3) to 25.3% (6.4). The median and mean reductions were 67% (range -115.6% to 99.6%) and 46% (10.6) from baseline. This equates to an average fall of 3.13 times from baseline, p=0.0002, by analysis of the transformed data. There was no evidence of a significant difference between drugs in reduction of proliferation, the number of cases showing a fall in proliferation, or the absolute Ki67 index at 14 days. Only 3/15 (anastrozole) and 2/21 (letrozole) tumours had post-treatment absolute Ki67 indices of ≤1%. There were no significant differences in changes in proliferation between tumours with ER score 2-3 vs score 4-5. Conclusions: 1. Both anastrozole and letrozole significantly reduced proliferation in invasive cancers with low ER expression. 2. There were no evident significant differences between drugs. 3. These data suggest that aromatase inhibitors are of value even in low-ER expressing cancers, either on their own or perhaps as part of combined therapy. 4. Analysis of more patients and of biological response according to molecular phenotype is underway. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1065.

Abstract #1145 Background: Aromatase inhibitors (AIs) reduce circulating oestrogen which increases bone turnover. L decreases circulating oestrogen levels to a greater degree than A. This study compares the effects of the non-steroidal aromatase inhibitors, A and L and the steroidal inactivator, E on bone turnover. Patients and Methods: This was an open, randomized pharmacodynamic study. Bone turnover markers were measured in 162 postmenopausal women with invasive ER +ve breast cancer. As part of their adjuvant hormone therapy, patients were randomized to receive either: 16 weeks of A, 16 weeks of L or 16 weeks of E Fasting blood and urine samples were collected at entry and after 12 and 16 weeks of each drug. Bone remodelling releases breakdown products of type 1 collagen including the terminal peptide fragments N-terminal telopeptides (NTx) and C-terminal telopeptides (CTx). An increase in these indicates bone resorption. Increases in type 1 pro-collagen peptides (N-terminal – PINP) and bone specific alkaline phosphatase (ALP) indicate bone formation. These were measured as was parathyroid hormone (PTH) which is an indirect measure of overall bone turnover. Results: A vs E vs L A, E and L significantly increased the bone turnover markers - PINP, CTX and bone ALP. E showed a greater change in bone turnover but there were no significant differences between the drugs. E resulted in a greater increase in PINP and uNTX compared to the non-steroidal AIs however these were of borderline significance. PINP, CTX and bone ALP all have significantly higher than zero percentage changes, regardless of drug or drug type. Conclusions: AIs cause a significant increase in both bone breakdown and bone formation. There is no evidence to suggest E has less effects on bone turnover than A or L. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1145.

Abstract #1132 Background: Aromatase inhibitors (AIs) reduce circulating oestrogens and so should have either no or a positive effect on coagulation . This study compares the effects of the non-steroidal aromatase inhibitors, A and L and the steroidal inactivator, E on coagulation. Patients and Methods: This was an open, randomized pharmacodynamic study. Plasma coagulation factors were measured in 120 postmenopausal women with invasive ER +ve breast cancer. As part of their adjuvant hormone therapy, patients were randomized to receive upfront therapy with either: 16 weeks of A, 16 weeks of L or 16 weeks of E. Fasting blood samples were collected at entry and after 12 and 16 weeks of each drug. AI patients were then switched to T and further samples measured after 8 months on T. Plasminogen activator inhibitor (PAI) antigen, von Willebrand's Factor (vWF) antigen, antithrombin III (AT111), protein C, protein S total, protein S free, activated protein C, resistance (APCR), factor VIII and fibrinogen were measured. Results: Results expressed as % change from baseline. E vs A vs L Protein C. E caused a significant fall compared to A and L (-15.75 (-21.48, -10.02) vs -3.80 (-10.77, 3.16) vs -3.63 (-10.50, 3.25)) respectively. p = 0.008. ATIII. E caused a significant fall from baseline (-8.55 (-13.33, -3.79)) Protein S Free. E + A caused a significant increase from baseline (E 6.90 (1.98, 11.82), A 7.36 (1.37, 13.34). Steroidal vs non-steroidal: Protein C. A significantly greater fall was seen with E than A+L (-15.75 (-21.45, -10.05) vs -3.71 (-8.58, 1.15)) p = 0.002. vWF A+L caused a significant increase from baseline (6.52 (0.66, 12.38) but this was not statistically different to E 5.02 (-1.88, 11.91)). ATIII A significant decrease from baseline was seen with A + L, -4.54 (-8.64, -0.43) but no difference from E 8.55 (13.31, -3.70) p=0.21. Protein S Free There was a significant increase from baseline in both groups (A+L: 5.70 (1.47, 9.92), E: 6.90 (1.98, 11.81), but no difference between the groups p=0.72. T effect: AT111 and protein C levels fell significantly on T whereas protein S free increased on T. Prior A, E or L had no significant impact on post-tamoxifen results. Conclusions: No significant differences in any coagulation factors were seen between A and L E caused a significant fall in protein C and ATIII. The non-steroidal AIs caused a significant increase in vWF. T caused a significant fall in protein C and ATIII and a significant increase in protein S free. No AI significantly influenced post-tamoxifen results. These drugs have significant effects on coagulation which helps to explain their clinical effects on thrombotic and thromboembolic disease. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1132.

Abstract #2035 Background: RAD001 (everolimus) is a rapamycin derivative that inhibits mTOR and its downstream substrates and has shown promising results in Phase I clinical trials. This is the first clinical study of RAD001 administered alone in breast cancer. The aim of this study was to characterise the effects of RAD001 treatment on tumour gene expression and to assess whether we can predict which patients will respond to RAD001. Materials & Methods: 32 post-menopausal women with operable estrogen receptor positive early breast cancer received 5mg RAD001 pre-operative treatment daily for 14 days prior to primary surgery. 25 patients completed treatment, 6 withdrew and 1 did not start medication. Paired biopsies were taken at diagnosis and at surgery from each of the 31 patients who received RAD001. Half of the biopsy was immediately flash frozen in liquid nitrogen and RNA extracted, amplified in duplicate and analysed using Illumina Human Ref.8 chip v2, the other half of the biopsy was embedded in paraffin for the analysis of biological response markers, including changes in proliferation (Ki67) by immunohistochemistry (Macaskill et al., 2006: Breast Cancer Research & Treatment: 100: S1: S286). 15 patients were classified as responders to RAD001 and 10 patients non-responders (responders were defined by a fall in % Ki-67 positive cells). Gene expression changes were compared before and after treatment with RAD001 and between the responders and non-responders using Bioconductor programs implemented in the R statistical programming language. Results & Discussion: All pre- and post-treatment biopsies were available for microarray processing and assessment of biological response markers for patients completing RAD001 treatment. Analysing data from duplicate samples enabled us to vigorously evaluate the reproducibility of the Illumina beadarray platform and revealed some slight batch-to-batch variation which can be accounted for in the analysis. This dataset has enabled us to begin to identify genes and pathways associated with RAD001 treatment and to generate a gene expression classifier for predicting which patients will benefit from RAD001 treatment. Genes of interest will be validated by quantitative real time PCR and key pathways reported. Acknowledgements: This work was supported by a grant from Breast Cancer Research & Treatment, UK. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2035.

Abstract #4063 Background: The activation of the PI3K-AKT pathway produces abnormalities in cell growth, proliferation and survival in a number of tumour types. PIK3CA (phosphoinositide-3-kinase, catalytic, alpha polypeptide) mutations have been described in a significant proportion of breast cancers and may predict response to treatment with inhibitors of this pathway. RAD001 (everolimus) is a rapamycin derivative that inhibits mTOR and its downstream substrates and has shown promising results in Phase I studies. The aim of this study was to assess the PI3KCA mutational status in post-menopausal women with breast cancer and to relate this to response following RAD001 treatment using a multiplex real-time PCR assay by DxS Ltd. Materials & Methods: 32 post-menopausal women with early breast cancer were treated with 5mg RAD001 pre-operative treatment daily for 14 days prior to primary surgery. 25 patients completed treatment, 6 withdrew and 1 did not start medication. Biopsies were taken at diagnosis and at surgery from the 31 patients who received RAD001 and embedded in paraffin. Pre- and post-treatment biopsies were available for the analysis of biological response markers, including changes in proliferation (Ki67) and phospho-AKT (s473) by immunohistochemistry (Macaskill et al., 2006: Breast Cancer Research & Treatment: 100: S1: S286). 15 patients were classified as responders to RAD001 and 10 patients non-responders (responders were defined by a fall in % Ki-67 positive cells). Post-treatment biopsies were available for evaluation of PI3KCA mutational status. DNA was extracted from post-treatment paraffin-embedded tissues and analysed for the 3 most commonly occurring PIK3CA mutations (H1047R, E542K, E545K) using a multiplex real-time PCR assay (DxS Ltd; Board et al., 2008: Clinical Chemistry: 54:4: 757-760). Results: 8/31 (25.8%) DNA samples were found to contain PI3KCA mutations: 5 - E545K; 2 - H1047R; 1 – E542K. Although cytoplasmic phospho-AKT expression was higher in pre-treatment tumours containing PI3KCA mutations than in those without detected mutations (median histoscore - 113.8 and 70, respectively; interquartile range – 94.4 and 88, respectively), the difference was not statistically significant. 5 mutations were found in tumours from 25 patients who completed treatment. 2/15 (13%) responders and 3/10 (30%) non-responders exhibited PI3KCA mutations. However, no significant association between PI3KCA mutations and response was observed. Discussion: PI3KCA mutations were detected in 8/31 patients treated with RAD001. 5 mutations were found in tumours from the 25 patients who completed treatment. Although no significant associations with cytoplasmic phospho-AKT expression in pre-treatment tumours and “response” were observed, the association between PI3KCA mutations and increased levels of phospho-AKT or altered response to RAD001 warrants further investigation. Acknowledgements: This work was supported by a grant from Breast Cancer Research & Treatment, UK. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4063.

Abstract #1152 Background: Aromatase inhibitors (AIs) reduce circulating oestrogen which may have a detrimental effect on lipid metabolism. Letrozole (L) decreases circulating oestrogen levels to a greater degree than anastrozole (A). This study compares the effects of adjuvant anastrozole and letrozole on lipid metabolism. Patients and Methods: This was an open, randomised pharmacodynamic study. Plasma lipids were measured in a subset of 57 out of 182 postmenopausal women with invasive ER positive breast cancer. As part of their adjuvant hormone therapy, patients were randomized to receive either · 12 weeks of L followed by 12 weeks of A (L→A) or · 12 weeks of A followed by 12 weeks of L (A→L). Fasting blood and urine samples were collected at the same time of day and the same day at entry and after 12 weeks of each drug. · 29 had no prior tamoxifen and · 27 had received tamoxifen. The following lipoproteins were measured: - Triglyceride - HDL - Cholesterol - ApoA1 - ApoB - Cholesterol - cLDL HDL and ApoA1 are cardioprotective whereas ↑ levels of the others are associated with an ↑ risk of coronary artery disease. Results: (Expressed as absolute changes +/- 95% CI) Patients who stopped tamoxifen >12 weeks prior to trial entry were considered tamoxifen free. Patients who had stopped tamoxifen Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1152.

552 Background: Letrozole (L) is a more potent aromatase inhibitor in vitro than anastrozole (A). One study in 12 patients showed that in patients L provides more complete inhibition of whole body aromatase and suppression of estrone sulphate levels than A but L did not significantly suppress E2 levels more than A possibly because of the small size of the study and the difficulty of measuring E2 in postmenopausal women (Geisler et al, JCO, 20, 751, 2002). The current aim was to conduct a much larger study to determine whether 2.5mg L suppresses E2 significantly more than 1mg A and if so in what proportion of patients this is the case. Methods: 54 postmenopausal women with invasive estrogen receptor positive breast cancer were randomised as part of their adjuvant hormone therapy to receive either: 12 weeks of L followed by 12 weeks of A (L→A) or 12 weeks of A followed by 12 weeks of L (A→L). Blood for hormones were taken at the same time of the day before and after 12 weeks of each drug. E2 was measured by a highly sensitive radioimmunoassay (Dowsett et al, Cancer Res 1987;47:1957–61) with a formal detection limit of 3pmol/l. In this study we also quantified values by extrapolation below this limit. Results: 27 patients had L→A and 27 A→L. Baseline E2 levels varied from 3 to 91 pmol/l with a median of 26 pmol/l. Only 1of 54 (2%) patients had an E2 value ≥ 3pmol/l after L compared with 20 of 54 (37%) after A(p [Table: see text]

9538 Background: Relationships between HER2 status and the efficacy of aromatase inhibitor (AI) therapy for early stage breast cancer require further study. The LET 024 neoadjuvant trial reported t...