Adjuvant letrozole versus tamoxifen according to centrally-assessed ERBB2 status for postmenopausal women with endocrine-responsive early breast cancer: supplementary results from the BIG 1-98 randomised trial

Efficacy and safety of first-line therapy in patients with HER2-positive advanced breast cancer: a network meta-analysis of randomized controlled trials

PURPOSE

The numerous first-line treatment regimens for human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer (ABC) necessitate a comprehensive evaluation to inform clinical decision-making. We conducted a Bayesian network meta-analysis (NMA) to compare the efficacy and safety of different interventions.

METHODS

We systematically searched for relevant randomized controlled trials (RCTs) in Pubmed, Embase, Cochrane Library and online abstracts from inception to June 1, 2023. NMA was performed to calculate and analyze progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and adverse events of grade 3 or higher (≥ 3 AEs).

RESULTS

Out of the 10,313 manuscripts retrieved, we included 28 RCTs involving 11,680 patients. Regarding PFS and ORR, the combination of trastuzumab with tyrosine kinase inhibitors (TKIs) was more favorable than dual-targeted therapy. If only using trastuzumab, combination chemotherapy is superior to monochemotherapy in terms of PFS. It is important to note that the addition of anthracycline did not result in improved PFS. For patients with hormone receptor-positive HER2-positive diseases, dual-targeted combined with endocrine therapy showed better benefit in terms of PFS compared to dual-targeted alone, but it did not reach statistical significance. The comprehensive analysis of PFS and ≥ 3 AEs indicates that monochemotherapy combined with dual-targeted therapy still has the optimal balance between efficacy and safety.

CONCLUSION

Monochemotherapy (Docetaxel) plus dual-target (Trastuzumab and Pertuzumab) therapy remains the optimal choice among all first-line treatment options for ABC. The combination of trastuzumab with TKIs (Pyrotinib) demonstrated a significant improvement in PFS and ORR, but further data are warranted to confirm the survival benefit.

Targeted Approaches to HER2-Low Breast Cancer: Current Practice and Future Directions

Simple Summary

HER2-low breast cancer (BC) accounts for more than half of breast cancer patients. Anti-HER2 therapy has been ineffective in HER2-low BC, for which palliative chemotherapy is the main treatment modality. The definitive efficacy of T-Dxd in HER2-low BC breaks previous treatment strategies, which will redefine HER2-low and thus reshape anti-HER2 therapy. This review summarizes detection technologies and novel agents for HER2-low BC, and explores their possible role in future clinics, to provide ideas for the diagnosis and treatment of HER2-low BC.

Abstract

HER2-low breast cancer (BC) has a poor prognosis, making the development of more suitable treatment an unmet clinical need. While chemotherapy is the main method of treatment for HER2-low BC, not all patients benefit from it. Antineoplastic therapy without chemotherapy has shown promise in clinical trials and is being explored further. As quantitative detection techniques become more advanced, they assist in better defining the expression level of HER2 and in guiding the development of targeted therapies, which include directly targeting HER2 receptors on the cell surface, targeting HER2-related intracellular signaling pathways and targeting the immune microenvironment. A new anti-HER2 antibody-drug conjugate called T-DM1 has been successfully tested and found to be highly effective in clinical trials. With this progress, it could eventually be transformed from a disease without a defined therapeutic target into a disease with a defined therapeutic molecular target. Furthermore, efforts are being made to compare the sequencing and combination of chemotherapy, endocrine therapy, and HER2-targeted therapy to improve prognosis to customize the subtype of HER2 low expression precision treatment regimens. In this review, we summarize the current and upcoming treatment strategies, to achieve accurate management of HER2-low BC.

Human epidermal growth factor receptor-2 and endocrine resistance in hormone-dependent breast cancer

Endocrine therapies are the main treatment strategies for the clinical management of hormone-dependent breast cancer. Despite prolonged time to recurrence in the adjuvant setting and the initial clinical responses in the metastatic setting, many patients eventually encounter tumour relapse due to acquired resistance to these agents. Other patients experience a lack of tumour regression at the beginning of treatment indicating de novo resistance that significantly limits its efficacy in the clinic. There is compelling evidence that human epidermal growth factor receptor-2 (HER2) overexpression contributes to resistance to endocrine therapies in oestrogen receptor-positive (ER+) breast cancer. ER+/HER2+ tumours comprise about 10% of all breast cancer cases and about 60% of the whole set of HER2+ tumours. Most patients with primary ER+/HER2+ disease will receive antibody-based HER2-targeted therapy, but this is generally for no more than one year while endocrine treatment is usually for at least 5 years. A number of HER2-kinase inhibitors are also now in clinical use or in clinical trials, and the interaction of these with endocrine treatment may differ from that of antibody treatment. In this review article, we aim to summarise knowledge on molecular mechanisms of breast cancer resistance to endocrine therapies attributable to the impact of HER2 signalling on endocrine sensitivity, to discuss data from clinical trials addressing the role of HER2 in the development of endocrine resistance in the metastatic, neoadjuvant and adjuvant settings and to explore rational new therapeutic strategies.

The potential markers of endocrine resistance among HR+ /HER2+ breast cancer patients

PURPOSE

Breast cancer with positive hormone receptor (HR) and human epidermal growth factor receptor-2 (HER2) is a special subgroup with different clinical features and survival, especially the endocrine therapy resistance. The main purpose of the study is to find the potential markers to predict the survival and endocrine therapy resistance of patients with HR+ /HER2+ breast cancer.

METHODS

Surveillance, Epidemiology, and End Results (SEER) database was used to collect patients' clinical information and tumor features including age, tumor size, grade, stage and long-term survival; the BioPortal for Cancer Genomics (https://cbioportal.org) was used to download the gene data for specific patient group; cluster analyses of gene expression were conducted through the DAVID Bioinformatics Resources 6.8 software.

RESULTS

All of the included patients were diagnosed as HR positive breast cancer, but the PR positive rates were more common in HER2- group and also the ER+ /PR+ disease. Patients in HR+ /HER2+ group were more likely to present as stage III-IV and grade III disease. Among HR+ /HER2+ patients, 68.6% received chemotherapy, while only 28.9% in HR+ /HER2- group received chemotherapy (P < 0.0001). The survival of HR+ /HER2+ group was poorer. From TCGA database, series genes which were differed between HR+ /HER2+ and HR+ /HER2- were screened out that related to ERBB2 closely: IKZF3, LASP1, CDK12, MLLT6, and RARA. The first three candidate genes were associated with patients' survival, especially in patients who received hormone therapies.

CONCLUSION

This study analyzed the clinical characteristics and survival of patients with HR+/HER2+ breast cancer as a special subgroup. ERBB2, IKZF3, LASP1, and CDK12 were the potential markers of the resistance of endocrine therapy, and they will provide new strategies for clinicians.

Intratumoral Estrogen Receptor Heterogeneity of Expression in Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer as Evaluated by a Brightfield Multiplex Assay

Breast cancer (BC) is a heterogeneous disease with evolving genetic alterations and expressions of receptor proteins. Intratumoral heterogeneity (ITH) is considered to be a resistance factor in response to targeted therapies. The current single-slide, single-marker immunohistochemistry techniques cannot accurately assess ITH at the individual cancer cell level. In this study, we develop a novel brightfield multiplex assay to simultaneously assess estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) protein markers, together with the HER2 gene and the centromere of chromosome 17 (CEP17) copy numbers, using a single tissue section. The data presented herein demonstrate heterogeneous cancer cell subpopulations in 11 HER2-positive/ER-positive (HER2+/ER+) tumors among 33 BCs analyzed immunohistochemically (HER2 score of 2+ or 3+). The predominant cancer cell subpopulation was HER2+/ER- (50.18%), followed by HER2+/ER+ (39.05%), HER2-/ER+ (4.26%), ER- with HER2 microheterogeneity cancer cells (3.58%), and ER+ with HER2 microheterogeneity cancer cells (2.93%). The three other tumor subtypes, namely, HER2-/ER+, HER2+/ER-, and HER2-/ER-, were more homogeneous, representing 82.59%, 99.22%, and 100% of cancer cells, respectively. This novel assay revealed that HER2+ cancer cells were more predominant than ER+ cancer cells in HER2+/ER+ tumors and provided new insights toward our understanding of BC carcinogenesis.

Prognostic and predictive value of androgen receptor expression in postmenopausal women with estrogen receptor-positive breast cancer: results from the Breast International Group Trial 1-98

BACKGROUND

The androgen receptor (AR) is an emerging prognostic marker and therapeutic target in breast cancer. AR is expressed in 60-80% of breast cancers, with higher prevalence among estrogen receptor-positive (ER+) tumors. Androgen treatment inhibits ER signaling in ER+/AR+ breast cancer cell lines, and AR expression is associated with improved survival for this subtype in epidemiologic studies. However, whether AR expression modifies the efficacy of selective ER modulators or aromatase inhibitors for ER+ cancers remains unclear.

METHODS

We evaluated the prognostic and predictive value of AR expression among 3021 postmenopausal ER+ breast cancer patients in the Breast International Group (BIG) trial 1-98. The BIG 1-98 study was a four-armed, double-blind, phase III randomized clinical trial that compared 5 years of tamoxifen or letrozole monotherapy, or sequences of 2 years and 3 years treatment with one drug and then the other. AR expression was measured by immunohistochemistry and the percentage of AR-positive nuclei was quantified. The association between AR expression and prognosis was evaluated using Cox proportional hazards models. Continuous AR-by-treatment interactions were assessed using Subpopulation Treatment Effect Pattern Plots (STEPP).

RESULTS

Eighty-two percent of patients had AR+ (≥ 1%) tumors. Patients with AR+ cancers were more likely to have smaller, lower-grade tumors, with higher expression of ER and PR. AR expression was not associated with breast cancer-free interval (BCFI) (415 events) over a median 8.0 years of follow-up (p = 0.12, log-rank test). In multivariable-adjusted models, AR expression was not associated with BCFI (HR = 1.07, 95% CI 0.83-1.36, p = 0.60). The letrozole versus tamoxifen monotherapy treatment effect did not significantly differ for AR+ tumors (HR = 0.63, 95% CI 0.44-0.75, p = 0.003) and AR- tumors (HR = 0.39, 95% CI 0.21-0.72, p = 0.002) (p-heterogeneity = 0.16). STEPP analysis also suggested no heterogeneity of the treatment effect across the continuum of AR expression.

CONCLUSIONS

AR expression was not associated with prognosis, nor was there heterogeneity of the letrozole versus tamoxifen treatment effect by AR expression. These findings suggest that AR expression may not be an informative biomarker for the selection of adjuvant endocrine therapy for postmenopausal women with ER+ breast cancers.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT00004205, Registered 27 January 2003-Retrospectively registered, https://clinicaltrials.gov/ct2/show/study/NCT00004205 .

Forty years of landmark trials undertaken by the Danish Breast Cancer Cooperative Group (DBCG) nationwide or in international collaboration

BACKGROUND

Over the past 40 years the Danish Breast Cancer Cooperative Group (DBCG) has made significant contributions to improve outcome and to make treatment of patients with early breast cancer more tolerable through nationwide and international trials evaluating loco-regional and systemic treatments. These trials have been instrumental to establish standards for the treatment of early breast cancer.

METHODS

The DBCG 82 trials had a global impact by documenting that the significant gain in loco-regional recurrence from postmastectomy radiation added to systemic therapy was associated with a reduction in distant recurrence and mortality in high-risk pre- and postmenopausal patients. The DBCG trials comparing breast conserving surgery and radiotherapy with mastectomy and more recently the trial of internal mammary node irradiation also had a major impact of practice. The trials initiated by the DBCG 40 years ago on tamoxifen and cyclophosphamide based chemotherapy became instrumental for the development of adjuvant systemic therapy not only due to their positive results but by sharing these important data with other members of the Early Breast Cancer Trialist' Collaborative Group (EBCTCG). Trials from the DBCG have also been important for highlighting the relative importance of anthracyclines and taxanes in the adjuvant setting. Furthermore, DBCG has made a major contribution to the development of aromatase inhibitors and targeted adjuvant treatment for human epidermal growth factor receptor 2 positive breast cancers.

RESULTS

The substantial impact of these treatment improvements is illustrated by a 46.7% 10-year overall survival of early breast cancer patients treated in 1978-1987 compared to 71.5% for patients treated 2008-2012.

CONCLUSIONS

The trials conducted and implemented by the DBCG appear to have a major impact on the substantial survival improvements in breast cancer.

Optimal adjuvant endocrine treatment of ER+/HER2+ breast cancer patients by age at diagnosis: A population-based cohort study

BACKGROUND

Prior randomised controlled trials on adjuvant hormonal therapy included HER2_any patients; however, a differential effect of aromatase inhibitors (AIs) versus tamoxifen (TAM) may have been missed in ER+/HER2+ patients that comprise 7-15% of all breast cancer patients. In addition, a woman's hormonal microenvironment may influence sensitivity to TAM and AIs in the adjuvant setting, which changes during menopausal transition, a process that takes years. We studied the efficacy of AIs versus TAM in ER+/HER2+ breast cancer patients grouped by age at diagnosis as a proxy for menopausal status using treatment and outcome data from the nationwide population-based Netherlands Cancer Registry (NCR).

PATIENTS AND METHODS

All women diagnosed between 2005 and 2007 with endocrine-treated, T_anyN_anyM₀, ER+/HER2+ breast cancer were identified through the NCR (n = 1155). Patients were divided by age at diagnosis: premenopausal (≤45 years; n = 326), perimenopausal (45<years≤55; n = 304) and postmenopausal (>55 years; n = 525). A time-dependent variable, indicating whether AI or TAM was received for >50% of endocrine treatment duration, was applied to subdivide groups by predominant treatment received. Recurrence-free survival (RFS) and overall survival (OS) were assessed using Kaplan-Meier survival estimation and Cox regression. Hazard ratios (HRs) were adjusted for chemotherapy, trastuzumab, age at diagnosis, N-status, grade, pT-stage and ovarian ablation.

RESULTS

During follow-up, 237 recurrences and 182 deaths occurred. Perimenopausal women derived significant RFS and OS benefit from AI compared with TAM, HR 0.47 (95% CI 0.25-0.91; P = 0.03) and HR 0.37 (95% CI 0.18-0.79; P = 0.01), respectively, whereas premenopausal women derived no benefit from AI compared with TAM. Treatment effects differed significantly between these age groups (interaction P = 0.03 and P = 0.02, respectively). Among postmenopausal women a small but non-significant AI benefit was observed.

CONCLUSION

AI treatment, preferably without any TAM treatment, was associated with the best RFS and OS outcome in ER+/HER2+ perimenopausal breast cancer patients.

Navigation through inter- and intratumoral heterogeneity of endocrine resistance mechanisms in breast cancer: A potential role for Liquid Biopsies?

The majority of breast cancers are hormone receptor positive due to the expression of the estrogen and/or progesterone receptors. Endocrine therapy is a major treatment option for all disease stages of hormone receptor–positive breast cancer and improves overall survival. However, endocrine therapy is limited by de novo and acquired resistance. Several factors have been proposed for endocrine therapy failures, which include molecular alterations in the estrogen receptor pathway, altered expression of cell-cycle regulators, autophagy, and epithelial-to-mesenchymal transition as a consequence of tumor progression and selection pressure. It is essential to reveal and monitor intra- and intertumoral alterations in breast cancer to allow optimal therapy outcome. Endocrine therapy navigation by molecular profiling of tissue biopsies is the current gold standard but limited in many reasons. “Liquid biopsies” such as circulating-tumor cells and circulating-tumor DNA offer hope to fill that gap in allowing non-invasive serial assessment of biomarkers predicting success of endocrine therapy regimen. In this context, this review will provide an overview on inter- and intratumoral heterogeneity of endocrine resistance mechanisms and discuss the potential role of “liquid biopsies” as navigators to personalize treatment methods and prevent endocrine treatment resistance in breast cancer.

Prognostic and predictive importance of the estrogen receptor coactivator AIB1 in a randomized trial comparing adjuvant letrozole and tamoxifen therapy in postmenopausal breast cancer: the Danish cohort of BIG 1-98

PURPOSE

To evaluate the estrogen receptor coactivator amplified in breast cancer 1 (AIB1) as a prognostic marker, as well as a predictive marker for response to adjuvant tamoxifen and/or aromatase inhibitors, in early estrogen receptor-positive breast cancer.

METHOD

AIB1 was analyzed with immunohistochemistry in tissue microarrays of the Danish subcohort (N = 1396) of the International Breast Cancer Study Group's trial BIG 1-98 (randomization between adjuvant tamoxifen versus letrozole versus the sequence of the two drugs).

RESULTS

Forty-six percent of the tumors had a high AIB1 expression. In line with previous studies, AIB1 correlated to a more aggressive tumor-phenotype (HER2 amplification and a high malignancy grade). High AIB1 also correlated to higher estrogen receptor expression (80-100 vs. 1-79%), and ductal histological type. High AIB1 expression was associated with a poor disease-free survival (univariable: hazard ratio 1.35, 95% confidence interval 1.12-1.63. Multivariable: hazard ratio 1.29, 95% confidence interval 1.06-1.58) and overall survival (univariable: hazard ratio 1.34, 95% confidence interval 1.07-1.68. Multivariable: hazard ratio 1.25, 95% confidence interval 0.99-1.60). HER2 did not seem to modify the prognostic effect of AIB1. No difference in treatment effect between tamoxifen and letrozole in relation to AIB1 was found.

CONCLUSIONS

In a subset of the large international randomized trial BIG 1-98, we confirm AIB1 to be a strong prognostic factor in early breast cancer. Hence, although tumor AIB1 expression does not seem to be useful for the choice of tamoxifen versus an aromatase inhibitor in postmenopausal endocrine-responsive breast cancer, AIB1 is an interesting target for new anti-cancer therapies and further investigations of this biomarker is warranted.

Treatment with aromatase inhibitors stimulates the expression of epidermal growth factor receptor-1 and neuregulin 1 in ER positive/HER-2/neu non-amplified primary breast cancers

While estrogens have been shown to modulate EGFR/HER-1 and HER-2/neu expression in experimental systems, the effects of estrogen deprivation on expression levels of the HER-receptors and the neuregulin (NRG)1 ligand in breast cancers remain unknown. Here, we measured EGFR/HER-1-4 and NRG1 mRNA in ER positive tumors from 85 postmenopausal breast cancer patients before and after two weeks (n=64) and three months (n=85) of primary treatment with an aromatase inhibitor (AI). In tumors lacking HER-2/neu amplification, quantitative real-time PCR analyses revealed EGFR/HER-1 and NRG1 to vary significantly between the three time points (before therapy, after 2 weeks and after 3 months on treatment; P≤0.001 for both). Pair-wise comparison revealed a significant increase in EGFR/HER-1 already during the first two weeks of treatment (P=0.049) with a further increase for both EGFR/HER-1 and NRG1 after 3 months on treatment (P≤0.001 and P=0.001 for both comparing values at 3 months to values at baseline and 2 weeks respectively). No difference between tumors responding versus non-responders was recorded. Further, no significant change in any parameter was observed among HER-2/neu amplified tumors. Analyzing components of the HER-2/neu PI3K/Akt downstream pathway, the PIK3CA H1047R mutation was associated with treatment response (P=0.035); however no association between either AKT phosphorylation status or PIK3CA gene mutations and EGFR/HER-1 or NRG1 expression levels were observed. Our results indicate primary AI treatment to modulate expression of HER-family members and the growth factor NRG1 in HER-2/neu non-amplified breast cancers in vivo. Potential implications to long term sensitivity warrants further investigations.

Discordance between original and central laboratories in ER and HER2 results in a diverse, population-based sample

PURPOSE

To investigate the discordance between original and central laboratories in estrogen receptor (ER) status, in tumors originally deemed to be ER-negative, and in HER2 status in a diverse population-based sample.

METHODS

In a follow-up study of 1785 women with Stage I-III breast cancer diagnosed between 2005 and 2007 in the Detroit and Los Angeles County SEER registry catchment areas, participants were asked to consent to reassessment of ER (in tumors originally deemed to be ER-negative) and HER2 status on archival tumor samples approximately four years after diagnosis. Blocks were centrally prepared and analyzed for ER and HER2 using standardized methods and the guidelines of the American Society of Clinical Oncology and the College of American Pathologists. Analyses determined the discordance between original and central laboratories.

RESULTS

132 (31%) of those eligible for ER reassessment and 367 (21%) eligible for HER2 reassessment had archival blocks reassessed centrally. ER discordance was only 6%. HER2 discordance by immunohistochemistry (IHC) was 26%, but final HER2 results-employing FISH in tumors that were IHC 2+ at the central laboratory-were discordant in only 6%. Half of the original laboratories did not perform their own assays.

CONCLUSIONS

Discordance between original and central laboratories in two large metropolitan areas was low in this population-based sample compared to previously reported patient samples. Centralization of testing for key pathology variables appears to be occurring in many hospitals. In addition, quality improvement efforts may have preceded the publication and dissemination of specialty society guidelines.

Lower Beclin 1 downregulates HER2 expression to enhance tamoxifen sensitivity and predicts a favorable outcome for ER positive breast cancer

Tamoxifen(TAM) is one of the most effective endocrine treatment for estrogen receptor(ER)-positive breast cancer, however drug resistance greatly limits benefit of it. Our purpose is to uncover the role of Beclin 1 in tamoxifen resistance and prognosis of ER positive breast cancer. We established a tamoxifen resistant ER-positive breast cancer cell subline MCF-7R presenting with higher Beclin 1 and human epidermal growth factor receptor 2(HER2) levels than MCF-7. Silencing Beclin 1 decreased levels of HER2 and significantly promoted TAM sensitivity of MCF-7 and MCF-7R in vitro. Overexpression of HER2 could reverse TAM sensitivity, which was formerly increased in Beclin 1 downregulated cell. Beclin 1 level was not only positively correlated with level of HER2 but also negatively correlated with overall survival of ER-positive breast cancer patients. Using bioinformatic methods, Beclin 1 mRNA was found to be negatively correlated with overall survival in breast cancer patients receiving TAM treatment. This study indicated for the first time that lower HER2 expression by Beclin 1 downregulation contributes to alteration of tamoxifen sensitivity and low Beclin 1 predicts favorable outcome in ER-positive breast cancer.

Cancer Hallmarks, Biomarkers and Breast Cancer Molecular Subtypes

Breast cancer is a complex disease encompassing multiple tumor entities, each characterized by distinct morphology, behavior and clinical implications. Besides estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2, novel biomarkers have shown their prognostic and predictive values, complicating our understanding towards to the heterogeneity of such cancers. Ten cancer hallmarks have been proposed by Weinberg to characterize cancer and its carcinogenesis. By reviewing biomarkers and breast cancer molecular subtypes, we propose that the divergent outcome observed from patients stratified by hormone status are driven by different cancer hallmarks. 'Sustaining proliferative signaling' further differentiates cancers with positive hormone receptors. 'Activating invasion and metastasis' and 'evading immune destruction' drive the differentiation of triple negative breast cancers. 'Resisting cell death', 'genome instability and mutation' and 'deregulating cellular energetics' refine breast cancer classification with their predictive values. 'Evading growth suppressors', 'enabling replicative immortality', 'inducing angiogenesis' and 'tumor-promoting inflammation' have not been involved in breast cancer classification which need more focus in the future biomarker-related research. This review novels in its global view on breast cancer heterogeneity, which clarifies many confusions in this field and contributes to precision medicine.

Hormone Receptor/Human Epidermal Growth Factor Receptor 2-positive breast cancer: Where we are now and where we are going

Near 75% of all breast cancers (BC) express estrogen receptors (ER) and/or progesterone receptors (PgR), while up to 20% of BC show an overexpression/amplification of Human Epidermal Growth Factor Receptor 2 (HER2). Around 50% of all HER2-overexpressing BC show the coexistence of both HER2 overexpression/amplification and ER and/or PgR overexpression. Numerous in vitro and in vivo studies suggest the existence of a cross-talk between their downstream pathways, which seem to affect the natural history, response to therapy and outcome of patients affected by this subset of BC. Meta-analyses or subgroup analysis of numerous neo-/adjuvant trials demonstrated significant clinical implications deriving from ER/HER2 co-existence, consisting in a different pattern of relapse and dissimilar outcome in response to anti-HER2 therapy. However, only two randomized trials in early disease and three in advanced disease specifically addressed the issue whether a combined approach with both hormonal and anti-HER2 therapy would have a better therapeutic impact in this subset of BC compared to the lone anti-HER2 or hormonal therapies (HT). None of these trials demonstrated improvements in overall survival, even though several efficacy end-points such as progression free survival, in advanced setting, or pCR rates in neoadjuvant setting, often favored the combined hormonal and anti-HER2 therapeutic approach. In the next few years, a certain number of ongoing randomized trials, both in neoadjuvant and advanced setting, will evaluate the efficacy of new anti-HER2 drugs, T-DM1 and pertuzumab, in combination with HT, helping to improve the therapeutic strategy for this specific subtype of breast tumors.

Prognostic and Predictive Biomarkers of Endocrine Responsiveness for Estrogen Receptor Positive Breast Cancer

The estrogen-dependent nature of breast cancer is the fundamental basis for endocrine therapy. The presence of estrogen receptor (ER), the therapeutic target of endocrine therapy, is a prerequisite for this therapeutic approach. However, estrogen-independent growth often exists de novo at diagnosis or develops during the course of endocrine therapy. Therefore ER alone is insufficient in predicting endocrine therapy efficacy. Several RNA-based multigene assays are now available in clinical practice to assess distant recurrence risk, with majority of these assays evaluated in patients treated with 5 years of adjuvant endocrine therapy. While MammaPrint and Oncotype Dx are most predictive of recurrence risk within the first 5 years of diagnosis, Prosigna, Breast Cancer Index (BCI), and EndoPredict Clin have also demonstrated utility in predicting late recurrence. In addition, PAM50, or Prosigna, provides further biological insights by classifying breast cancers into intrinsic molecular subtypes. Additional strategies are under investigation in prospective clinical trials to differentiate endocrine sensitive and resistant tumors and include on-treatment Ki-67 and Preoperative Endocrine Prognostic Index (PEPI) score in the setting of neoadjuvant endocrine therapy. These biomarkers have become important tools in clinical practice for the identification of low risk patients for whom chemotherapy could be avoided. However, there is much work ahead toward the development of a molecular classification that informs the biology and novel therapeutic targets in high-risk disease as chemotherapy has only modest benefit in this population. The recognition of somatic mutations and their relationship to endocrine therapy responsiveness opens important opportunities toward this goal.

Relative Effectiveness of Letrozole Compared With Tamoxifen for Patients With Lobular Carcinoma in the BIG 1-98 Trial

PURPOSE

To evaluate the relative effectiveness of letrozole compared with tamoxifen for patients with invasive ductal or lobular carcinoma.

PATIENTS AND METHODS

Patients diagnosed with early-stage invasive ductal carcinoma (IDC) or classic invasive lobular carcinoma (ILC) who were randomly assigned onto the Breast International Group (BIG) 1-98 trial and who had centrally reviewed pathology data were included (N = 2,923). HER2-negative IDC and ILC were additionally classified as hormone receptor-positive with high (luminal B [LB] -like) or low (luminal A [LA] -like) proliferative activity by Ki-67 labeling index. Survival analyses were performed with weighted Cox models that used inverse probability of censoring weighted modeling.

RESULTS

The median follow-up time was 8.1 years. In multivariable models for disease-free survival (DFS), significant interactions between treatment and histology (ILC or IDC; P = .006) and treatment and subgroup (LB like or LA like; P = .01) were observed. In the ILC subset, there was a 66% reduction in the hazard of a DFS event with letrozole for LB (hazard ratio [HR], 0.34; 95% CI, 0.21 to 0.55) and a 50% reduction for LA subtypes (HR, 0.50; 95% CI, 0.32 to 0.78). In the IDC subset, there was a significant 35% reduction in the hazard of a DFS event with letrozole for the LB subtype (HR, 0.65; 95% CI, 0.53 to 0.79), but no difference between treatments was noted for IDC and the LA subtype (HR, 0.95; 95% CI, 0.76 to 1.20).

CONCLUSION

The magnitude of benefit of adjuvant letrozole is greater for patients diagnosed with lobular carcinoma versus ductal carcinoma.

Predicting benefit of endocrine therapy for early breast cancer

Adjuvant endocrine therapy is a mainstay of treatment for patients with endocrine-responsive early breast cancer. Questions remain concerning which patients should receive what type of endocrine therapy and for how long. Several factors have been considered as potential indicators to predict benefit of endocrine therapy, including patient factors, clinico-pathological factors and multigene assays. To date, factors associated with risk of recurrence have been the most widely adopted to influence treatment selection. The International Breast Cancer Study Group (IBCSG)-led adjuvant endocrine therapy trials BIG 1-98, for postmenopausal women, and SOFT and TEXT, for premenopausal women, can shed light on the role for risk of recurrence in identifying who should receive which type of adjuvant endocrine therapy and for how long.

Status of adjuvant endocrine therapy for breast cancer

Adjuvant endocrine therapy reduces the risk of recurrence and death from breast cancer in women with hormone receptor-positive early breast cancer. Tamoxifen has been the standard therapy for decades, and this is still the case for pre-menopausal women. Ovarian suppression is of similar efficacy but currently there is no strong evidence for adding this to tamoxifen and the additional morbidity can be considerable. Results from two important trials addressing this issue are imminent. In post-menopausal women, aromatase inhibitors (AIs) (letrozole, anastrozole, or exemestane) are superior to tamoxifen in preventing recurrence but only letrozole has been shown to improve survival. The main gain is against high-risk cancers, and tamoxifen gives very similar benefit for low-risk disease. Traditionally, treatment has been given for around 5 years, but many women remain at risk of relapse for 10 years or more. The AIs, and more recently tamoxifen, have been shown to reduce further the risk of late recurrence in women still in remission after 5 years of tamoxifen if given for a further 5 years. The comparative benefits of these two options and the selection of patients most likely to benefit from long-term adjuvant endocrine therapy are important topics for further research, as is the optimum duration of AI therapy started upfront.

Trefoil factor 3 promotes metastatic seeding and predicts poor survival outcome of patients with mammary carcinoma

Introduction

Recurrence or early metastasis remains the predominant cause of mortality in patients with estrogen receptor positive (ER+) mammary carcinoma (MC). However, the molecular mechanisms underlying the initial progression of ER+ MC to metastasis remains poorly understood. Trefoil factor 3 (TFF3) is an estrogen-responsive oncogene in MC. Herein, we provide evidence for a functional role of TFF3 in metastatic progression of ER+ MC.

Methods

The association of TFF3 expression with clinicopathological parameters and survival outcome in a cohort of MC patients was assessed by immunohistochemistry. The expression of TFF3 in MCF7 and T47D cells was modulated by forced expression or siRNA-mediated depletion of TFF3. mRNA and protein levels were determined using qPCR and western blot. The functional effect of modulation of TFF3 expression in MC cells was determined in vitro and in vivo. Mechanistic analyses were performed using reporter constructs, modulation of signal transducer and activator of transcription 3 (STAT3) expression, and pharmacological inhibitors against c-SRC and STAT3 activity.

Results

TFF3 protein expression was positively associated with larger tumour size, lymph node metastasis, higher stage, and poor survival outcome. Forced expression of TFF3 in ER+ MC cells stimulated colony scattering, cell adhesion to a Collagen I-coated matrix, colony formation on a Collagen I- or Matrigel-coated matrix, endothelial cell adhesion, and transmigration through an endothelial cell barrier. In vivo, forced expression of TFF3 in MCF7 cells stimulated the formation of metastatic nodules in animal lungs. TFF3 regulation of the mRNA levels of epithelial, mesenchymal, and metastatic-related genes in ER+ MC cells were consistent with the altered cell behaviour. Forced expression of TFF3 in ER+ MC cells stimulated phosphorylation of c-SRC that subsequently increased STAT3 activity, which lead to the downregulation of E-cadherin. siRNA-mediated depletion of TFF3 reduced the invasiveness of ER+ MC cells.

Conclusions

TFF3 expression predicts metastasis and poor survival outcome of patients with MC and functionally stimulates cellular invasion and metastasis of ER+ MC cells. Adjuvant functional inhibition of TFF3 may therefore be considered to ameliorate outcome of ER+ MC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0429-3) contains supplementary material, which is available to authorized users.

Lapatinib for the treatment of breast cancer in the People's Republic of China

Lapatinib is an oral, small-molecule, reversible inhibitor of both epidermal growth factor receptor and human epidermal growth factor receptor-2 (HER2) tyrosine kinases. In March 2007, the US Food and Drug Administration approved lapatinib for use in combination with capecitabine for the treatment of women with HER2-overexpressing, advanced or metastatic breast cancer. This review discusses the available information of lapatinib in Chinese breast cancer patients, focusing on its effectiveness and clinical application against advanced or metastatic breast cancer. In pivotal phase III trials, a combination of lapatinib and capecitabine significantly decreased the risk of disease progression compared to capecitabine alone in women with HER2-positive advanced or metastatic breast cancer. Other trials were used to evaluate lapatinib in combination with hormone therapy, in combination with trastuzumab, and as an adjunct to adjuvant therapy for early-stage disease. Preclinical data have revealed that lapatinib is active in trastuzumab-resistant cell lines as well as synergistic with trastuzumab. In clinical trials, lapatinib has not been associated with serious or symptomatic cardiotoxicity. Further, it can cross the blood-brain barrier and may therefore have a role in preventing cancer progression in the central nervous system. Thus, lapatinib warrants further evaluation in HER2-positive metastatic and early-stage breast cancer patients.

Gene expression profiling identifies FYN as an important molecule in tamoxifen resistance and a predictor of early recurrence in patients treated with endocrine therapy

To elucidate the molecular mechanisms of tamoxifen resistance in breast cancer, we performed gene array analyses and identified 366 genes with altered expression in four unique tamoxifen-resistant (TamR) cell lines vs the parental tamoxifen-sensitive MCF-7/S0.5 cell line. Most of these genes were functionally linked to cell proliferation, death and control of gene expression, and include FYN, PRKCA, ITPR1, DPYD, DACH1, LYN, GBP1 and PRLR. Treatment with FYN-specific small interfering RNA or a SRC family kinase inhibitor reduced cell growth of TamR cell lines while exerting no significant effect on MCF-7/S0.5 cells. Moreover, overexpression of FYN in parental tamoxifen-sensitive MCF-7/S0.5 cells resulted in reduced sensitivity to tamoxifen treatment, whereas knockdown of FYN in the FYN-overexpressing MCF-7/S0.5 cells restored sensitivity to tamoxifen, demonstrating growth- and survival-promoting function of FYN in MCF-7 cells. FYN knockdown in TamR cells led to reduced phosphorylation of 14-3-3 and Cdc25A, suggesting that FYN, by activation of important cell cycle-associated proteins, may overcome the anti-proliferative effects of tamoxifen. Evaluation of the subcellular localization of FYN in primary breast tumors from two cohorts of endocrine-treated ER+ breast cancer patients, one with advanced disease (N=47) and the other with early disease (N=76), showed that in the former, plasma membrane-associated FYN expression strongly correlated with longer progression-free survival (P<0.0002). Similarly, in early breast cancer patients, membrane-associated expression of FYN in the primary breast tumor was significantly associated with increased metastasis-free (P<0.04) and overall (P<0.004) survival independent of tumor size, grade or lymph node status. Our results indicate that FYN has an important role in tamoxifen resistance, and its subcellular localization in breast tumor cells may be an important novel biomarker of response to endocrine therapy in breast cancer.

The broad-spectrum metalloproteinase inhibitor BB-94 inhibits growth, HER3 and Erk activation in fulvestrant-resistant breast cancer cell lines

Breast cancer cells can switch from estrogen receptor α (ER)- to human epidermal growth factor receptor (HER)-driven cell growth upon acquiring antiestrogen resistance. HER ligands are cleaved by metalloproteinases leading to release of active HER ligands, activation of HER receptors and consequently increased cell growth. In this study, we investigated the importance of HER receptors, in particular HER3, and HER ligand shedding for growth and signaling in human MCF-7 breast cancer cells and MCF-7-derived sublines resistant to the antiestrogen fulvestrant. The HER3/HER4 ligand heregulin 1β induced phosphorylation of HER3, Akt and Erk, and partly rescued fulvestrant-inhibited growth of MCF-7 cells. HER3 ligands were found to be produced and shed from the fulvestrant-resistant cells as conditioned medium from fulvestrant-resistant MCF-7 cells induced phosphorylation of HER3 and Akt in MCF-7 cells. This was prevented by treatment of resistant cells with the metalloproteinase inhibitor TAPI-2. Only the broad-spectrum metalloproteinase inhibitor BB-94, and not the more selective inhibitors GM6001 or TAPI-2, which inhibited shedding of the HER ligands produced by the fulvestrant-resistant cells, was able to inhibit growth and activation of HER3 and Erk in resistant cells. Compared to MCF-7, fulvestrant-resistant cells have increased HER3 phosphorylation, but knockdown of HER3 had no inhibitory effect on resistant cell growth. The EGFR inhibitor gefitinib exhibited only a minor growth inhibition, whereas the pan-HER inhibitor CI-1033 exerted growth arrest. Thus, neither HER3 nor EGFR alone are the main driver of fulvestrant-resistant cell growth and treatment should target both receptors. Ligand shedding is not a treatment target, as receptor activation occurred, independent of release of ligands. Only the broad-spectrum metalloproteinase inhibitor BB-94 could abrogate HER3 and Erk activation in the resistant cells, which stresses the complexity of the resistance mechanisms and the requirement of targeting signaling from HER receptors by multiple strategies.

Therapeutic potential of the dual EGFR/HER2 inhibitor AZD8931 in circumventing endocrine resistance

Modest up-regulation of either HER-ligands or receptors has been implicated in acquired endocrine resistance. AZD8931, a dual tyrosine kinase inhibitor (TKI) of epithelial growth factor receptor (EGFR)/HER2, has been shown to more effectively block ligand-dependent HER signaling than the HER TKIs lapatinib or gefitinib. We therefore examined the effect of AZD8931 in ER-positive/HER2-negative breast cancer cells with acquired resistance to tamoxifen, where there is ligand up-regulation associated with HER pathway activation. RNA-seq ligand profiling and levels of HER receptors and signaling by western blotting were conducted in ER+ MCF7 and T47D parental cells and their Tam-resistant derivatives (TamRes). In vitro cell growth and apoptosis and HER ligand-stimulated signaling were measured in response to endocrine and HER TKIs. For studies in vivo, transplantable MCF7/TamRes xenografts were treated with tamoxifen or fulvestrant, either alone or in combination with AZD8931. AZD8931 only minimally enhanced endocrine sensitivity in MCF7 parental cells, but showed a greater effect in the T47D parental model. AZD8931 combined with either tamoxifen or fulvestrant inhibited cell growth more than lapatinib in T47D TamRes cells, and was also significantly, though modestly, more potent in MCF7 TamRes cells. In both TamRes models, AZD8931 significantly inhibited cell proliferation and induced apoptosis. Under ligand-stimulated conditions, AZD8931 more potently inhibited HER signaling than lapatinib or gefitinib. AZD8931 also significantly delayed the growth of MCF7 TamRes xenografts in the presence of tamoxifen or fulvestrant. The strongest inhibition was achieved with a fulvestrant and AZD8931 combination, though no tumor regression was observed. This study provides evidence that AZD8931 has greater inhibitory efficacy in tamoxifen-resistant settings than in an endocrine therapy naïve setting. The absence of tumor regression, however, suggests that additional escape pathways contribute to resistant growth and will need to be targeted to fully circumvent tamoxifen resistance.

Long-term outcome of neoadjuvant endocrine therapy with aromatase inhibitors in elderly women with hormone receptor-positive breast cancer

Background

Aromatase inhibitors (AIs) are more effective than tamoxifen as neoadjuvant endocrine therapy (NET) for hormone receptor (HR)-positive breast cancer. Here we report the surgical and long-term outcome of elderly postmenopausal patients with locally advanced, HR-positive breast cancer treated with preoperative AIs.

Methods

Between January 2003 and December 2012, 144 postmenopausal patients inoperable with breast conservative surgery (BCS) received letrozole, anastrozole, or exemestane as NET. Patients underwent breast surgery and received adjuvant AIs. Adjuvant systemic therapy, chemotherapy and/or trastuzumab, and adjuvant radiotherapy were administered as appropriate, but limited to high-risk patients with few or no comorbidities.

Results

After a median follow-up of 49 months, 4 (3.0 %) patients had local relapse, 18 (12.5 %) had distant metastases, and 24 (17.0 %) died. BCS was performed in 121 (84.0 %) patients. A tumor size <3 cm and human epidermal growth factor receptor 2 (HER2) negativity were predictors of BCS. The achievement of BCS and grade G1 were significantly associated with longer disease-free survival (DFS) (p = 0.009 and p = 0.01, respectively) and overall survival (p = 0.002 and p = 0.005, respectively). Residual tumor ≤2 cm (yT0–yT1) in the longest diameter after NET was also statistically associated with longer DFS (p = 0.005).

Conclusions

The results of this retrospective study indicate that elderly breast cancer patients with a tumor size <3 cm at diagnosis and HER2 negativity have a higher probability of achieving BCS after NET. Moreover, patients treated with BCS and with grade G1 tumor have a reduced risk of recurrence and death in the long-term follow-up.

HER2 overexpression a major risk factor for recurrence in pT1a-bN0M0 breast cancer: results from a French regional cohort

The management of pT1a-bN0M0 breast cancer remains an area of controversy. Data from 714 patients classified as having pT1a-bN0M0 breast cancer and treated, from 1999 to 2004 in the Languedoc-Roussillon France, were analyzed. The human epidermal growth factor receptor 2 (HER2) status analyses were centralized. The objective of this study was to describe the prognosis of pT1a-bN0M0 breast cancer according to HER2 distribution and hormonal status. The median follow-up was 6.4 years. Ten-year overall survival was 94%. HER2 overexpression was observed in 6.1% of the patients. The 10-year prognosis of patients with HER2-positive tumors was worse than that of those with HER2-negative (disease-free survival 73% vs. 89%, P < 0.0001). Tumor size (T1a/T1b) was not a relevant prognostic factor. The co-expression of HER2 with hormonal receptors (HR) was associated with high recurrence at 10 years. In both univariate and multivariate analyses, the most relevant prognostic factor for this population was HER2 amplification. In multivariate analysis, patients with HER2-positive tumors had higher risk of mortality (HR, 3.89; 95% CI, 1.58–9.56). In pT1a-bN0M0 breast cancers, HER2 amplification or overexpression is a risk factor for recurrence. In HER2-positive breast cancers, HR expression is associated with a poor prognosis despite the hormone therapy. For this population, a personalized management may be required.

Integrative analyses of gene expression and DNA methylation profiles in breast cancer cell line models of tamoxifen-resistance indicate a potential role of cells with stem-like properties

Introduction

Development of resistance to tamoxifen is an important clinical issue in the treatment of breast cancer. Tamoxifen resistance may be the result of acquisition of epigenetic regulation within breast cancer cells, such as DNA methylation, resulting in changed mRNA expression of genes pivotal for estrogen-dependent growth. Alternatively, tamoxifen resistance may be due to selection of pre-existing resistant cells, or a combination of the two mechanisms.

Methods

To evaluate the contribution of these possible tamoxifen resistance mechanisms, we applied modified DNA methylation-specific digital karyotyping (MMSDK) and digital gene expression (DGE) in combination with massive parallel sequencing to analyze a well-established tamoxifen-resistant cell line model (TAM^R), consisting of 4 resistant and one parental cell line. Another tamoxifen-resistant cell line model system (LCC1/LCC2) was used to validate the DNA methylation and gene expression results.

Results

Significant differences were observed in global gene expression and DNA methylation profiles between the parental tamoxifen-sensitive cell line and the 4 tamoxifen-resistant TAM^R sublines. The 4 TAM^R cell lines exhibited higher methylation levels as well as an inverse relationship between gene expression and DNA methylation in the promoter regions. A panel of genes, including NRIP1, HECA and FIS1, exhibited lower gene expression in resistant vs. parental cells and concurrent increased promoter CGI methylation in resistant vs. parental cell lines. A major part of the methylation, gene expression, and pathway alterations observed in the TAM^R model were also present in the LCC1/LCC2 cell line model. More importantly, high expression of SOX2 and alterations of other SOX and E2F gene family members, as well as RB-related pocket protein genes in TAM^R highlighted stem cell-associated pathways as being central in the resistant cells and imply that cancer-initiating cells/cancer stem-like cells may be involved in tamoxifen resistance in this model.

Conclusion

Our data highlight the likelihood that resistant cells emerge from cancer-initiating cells/cancer stem-like cells and imply that these cells may gain further advantage in growth via epigenetic mechanisms. Illuminating the expression and DNA methylation features of putative cancer-initiating cells/cancer stem cells may suggest novel strategies to overcome tamoxifen resistance.

Lapatinib plus chemotherapy or endocrine therapy (CET) versus CET alone in the treatment of HER-2-overexpressing locally advanced or metastatic breast cancer: systematic review and meta-analysis

BACKGROUND

This paper reports a systematic review and meta-analysis of all randomized controlled trials comparing the efficacy of lapatinib plus chemotherapy or endocrine therapy (CET) versus CET alone in human epidermal growth factor receptor 2-overexpressing (HER-2+) locally advanced or metastatic breast cancer.

METHODS

Several databases were searched, including MEDLINE, EMBASE, LILACS, and CENTRAL. The primary endpoints were progression-free survival and overall survival. The side effects of each treatment were analyzed. The data extracted from the studies were combined by using the hazard ratio or risk ratio with their corresponding 95% confidence interval (CI).

RESULTS

A total of 113 references were identified and screened. The final analysis included four trials comprising 1,073 patients with HER-2+. The overall response rate was higher in patients who received the combination of CET plus lapatinib (risk ratio 0.78; 95% CI 0.71-0.85; P < 0.00001) but with significant heterogeneity (χ(2) = 15.61, df = 3; P = 0.001; I(2) = 81%). This result remained favorable to the use of lapatinib when a random-effects model analysis was performed (risk ratio 0.76; 95% CI 0.62-0.94; P = 0.01). Progression-free survival was also higher in patients who received CET plus lapatinib (hazard ratio 0.57; 95% CI 0.49-0.66; P < 0.00001) with no heterogeneity detected on this analysis (χ(2) = 3.05; df = 3; P = 0.38; I(2) = 1%). Overall survival was significantly longer in patients who received CET plus lapatinib (hazard ratio 0.80; 95% CI 0.69-0.92; P = 0.002) without heterogeneity on this analysis (χ(2) = 1.26; df = 3; P = 0.74; I(2) = 0%). Regarding adverse events and severe toxicities (grade ≥3), the group receiving CET plus lapatinib had higher rates of neutropenia (risk ratio 2.08; 95% CI 1.64-2.62; P < 0.00001), diarrhea (risk ratio 4.82; 95% CI 3.14-7.41; P < 0.00001), and rash (risk ratio 8.03; 95% CI 2.46-26.23; P = 0.0006).

CONCLUSION

The combination of CET plus lapatinib increased the overall response rate, progression-free survival, and overall survival in patients with HER-2+ locally advanced or metastatic breast cancer.

Aromatase inhibition 2013: clinical state of the art and questions that remain to be solved

Following their successful implementation for the treatment of metastatic breast cancer, the 'third-generation' aromatase inhibitors (anastrozole, letrozole, and exemestane) have now become standard adjuvant endocrine treatment for postmenopausal estrogen receptor-positive breast cancers. These drugs are characterized by potent aromatase inhibition, causing >98% inhibition of estrogen synthesis in vivo. A recent meta-analysis found no difference in anti-tumor efficacy between these three compounds. As of today, aromatase inhibitor monotherapy and sequential treatment using tamoxifen followed by an aromatase inhibitor for a total of 5 years are considered equipotent treatment options. However, current trials are addressing the potential benefit of extending treatment duration beyond 5 years. Regarding side effects, aromatase inhibitors are not found associated with enhanced risk of cardiovascular disease, and enhanced bone loss is prevented by adding bisphosphonates in concert for those at danger of developing osteoporosis. However, arthralgia and carpal tunnel syndrome preclude drug administration among a few patients. While recent findings have questioned the use of aromatase inhibitors among overweight and, in particular, obese patients, this problem seems to focus on premenopausal patients treated with an aromatase inhibitor and an LH-RH analog in concert, questioning the efficacy of LH-RH analogs rather than aromatase inhibitors among overweight patients. Finally, recent findings revealing a benefit from adding the mTOR inhibitor everolimus to endocrine treatment indicate targeted therapy against defined growth factor pathways to be a way forward, by reversing acquired resistance to endocrine therapy.

Estrogen receptor α is the major driving factor for growth in tamoxifen-resistant breast cancer and supported by HER/ERK signaling

Resistance to tamoxifen is a major clinical challenge in the treatment of breast cancer; however, it is still unclear which signaling pathways are the major drivers of tamoxifen-resistant growth. To characterize resistance mechanisms, we have generated different tamoxifen-resistant breast cancer cell lines from MCF-7. In this model, we investigated whether signaling from human epidermal growth factor receptors (HERs), their downstream kinases, or from the estrogen receptor α (ERα) was driving tamoxifen-resistant cell growth. Increased expression of EGFR and increased phosphorylation of HER3 were observed upon acquisition of tamoxifen resistance, and the extracellular activated kinase (ERK) signaling pathway was highly activated in the resistant cells. The EGFR inhibitor gefitinib and the ERK pathway inhibitor U0126 resulted in partial and preferential growth inhibition of tamoxifen-resistant cells. All the tamoxifen-resistant cell lines retained ERα expression but at a lower level compared to that in MCF-7. Importantly, we showed via ERα knockdown that the tamoxifen-resistant cells were dependent on functional ERα for growth and we observed a clear growth stimulation of resistant cell lines with clinically relevant concentrations of tamoxifen and 4-OH-tamoxifen, indicating that tamoxifen-resistant cells utilize agonistic ERα stimulation by tamoxifen for growth. The tamoxifen-resistant cells displayed high phosphorylation of ERα at Ser118 in the presence of tamoxifen; however, treatment with U0126 neither affected the level of Ser118 phosphorylation nor expression of the ERα target Bcl-2, suggesting that ERK contributes to cell growth independently of ERα in our cell model. In support of this, combined treatment against ERα and ERK signaling in resistant cells was superior to single-agent treatment and as effective as fulvestrant treatment of MCF-7 cells. Together, these findings demonstrate that ERα is a major driver of growth in tamoxifen-resistant cells supported by HER/ERK growth signaling, implying that combined targeting of these pathways may have a clinical potential for overcoming tamoxifen resistance.

Low expression of Beclin 1 and elevated expression of HIF-1α refine distant metastasis risk and predict poor prognosis of ER-positive, HER2-negative breast cancer

Even though ER-positive, HER2-negative breast tumors represent a subset of breast cancers with a better clinical outcome, approximately 12.7 % of patients in this subgroup ultimately develop cancer-related mortality. Recent studies had confirmed that hypoxia-induced autophagy-related gene Beclin 1 expression might be important for disease progression and be correlated with patient outcome in several tumors. Here, we examined the autophagic Beclin 1 and hypoxic HIF-1α levels in 378 ER-positive, HER2-negative breast cancer patients by immunohistochemistry using tissue microarray. We found that Beclin 1 was highly expressed in normal mammary gland epithelia. In contrast, it was either not expressed or only moderately expressed in 78.0 % of breast adenocarcinoma tissue. Compared to the subset overexpressing Beclin 1, the subset in which Beclin 1 levels were reduced had a poor 5-year overall survival rate (OS, 85.1 % vs. 94.1 %, P = 0.005) and a poor distant metastasis-free survival (DMFS, 79.1 % vs. 89.3 %, P = 0.037). Cox multivariate analysis confirmed that Beclin 1 was indeed an independent prognostic factor for OS and DMFS. Additionally, Beclin 1 positively correlated with HIF-1α expression (r = 0.206, P < 0.001). Importantly, among patients with HIF-1α overexpression, low levels of Beclin 1 predicted a worse OS. Our study confirmed that deficiency of Beclin 1 was a negative prognostic factor for OS and DMFS in ER-positive, HER2-negative breast cancer. The combination of Beclin 1 and HIF-1α refined the risk definition of the patient subset and provided a novel way to identify those with a high risk of relapse.

High concordance between HercepTest immunohistochemistry and ERBB2 fluorescence in situ hybridization before and after implementation of American Society of Clinical Oncology/College of American Pathology 2007 guidelines

Human epidermal growth factor receptor 2 (HER2, ERBB2) is an important critical predictive marker in patients with invasive breast cancer. It is thus imperative to ensure accuracy and precision in HER2 and ERBB2 testing. In 2007, the American Society of Clinical Oncology and College of American Pathologists (ASCO/CAP) proposed new guidelines for immunohistochemistry and fluorescence in-situ hybridization scoring in an effort to improve accuracy and utility of these companion diagnostic tests. The goal of the 2007 guidelines was to improve concordance rates between the diagnostic tests and decrease the number of inconclusive cases. This study examines the impact in concordance rates and number of inconclusive cases based on the recent change in guidelines in a large study cohort. HER2 immunohistochemistry and ERBB2 fluorescence in-situ hybridization were performed on all specimens from our facility from years 2003 through 2010 (n=1437). Cases from 2003-2007 (n=1016) were scored using Food and Drug Administration guidelines, with immunohistochemical 3+ cases staining >10% of tumor cells and fluorescence in-situ hybridization amplification cutoff value of 2.0. The 2007 guidelines were implemented and scored accordingly for cases from 2008-2010 (n=421), with immunohistochemical 3+ cases staining >30% of tumor cells and fluorescence in-situ hybridization amplification cutoff value of 2.2. We compared concordance rates before and after 2007 guidelines. For the 2003-2007 study population, the concordance rate between the assays was 97.6% with a corresponding kappa coefficient (k) of 0.90. For the 2008-2010 study population, concordance rate was 97.6% with a corresponding k of 0.89. There was no significant difference in number of inconclusive rates before and after 2007 guidelines. In our study, implementation of the new ASCO/CAP 2007 HER2 guidelines did not show a significant difference in concordance rates and did not decrease the number of inconclusive cases.

Presurgical (neoadjuvant) endocrine therapy is a useful model to predict response and outcome to endocrine treatment in breast cancer patients

Endocrine therapy of breast cancer has been improved continuously during the last decades. Currently, aromatase inhibitors are dominating treatment algorithms for postmenopausal women with hormone-receptor positive breast cancer while tamoxifen still is the most widely used drug for premenopausal women. Several research tools and study designs have been used to challenge established drugs and develop the field of antihormonal therapy. One pivotal study option has been the observation of clinical responses during presurgical/neoadjuvant endocrine therapy (PSET/NET). This strategy has several major advantages. First, the breast tumor, still present in the patient's breast during therapy, can be followed by clinical observations and radiological measurements and any treatment effect will be immediately registered. Second, tumor biopsies may be obtained before initiation and following therapy allowing intra-patient comparisons. These tumor-biopsies may be used for the evaluation of intra-tumor changes associated with drug treatment. As examples, presurgical breast cancer trials have been used to evaluate intra-tumor estrogen levels during therapy with aromatase inhibitors and also to study mechanisms involved in the adaptation processes to estrogen suppression. Biomarker studies have provided information that may be used for patient selection in the future. Finally, recently published results from presurgical trials testing combinations of classical endocrine drugs and novel targeted therapies have produced promising results.

Poor-prognosis estrogen receptor- positive disease: present and future clinical solutions

Use of chemotherapy for patients with estrogen receptor (ER)-positive breast cancer has been a conflicting issue. Recent studies have identified predictive markers allowing identification of poor-prognosis ER-positive breast cancers in need of more aggressive therapy. In general, tumours belonging to the so-called luminal B class, tumours expressing a high Ki67, human epidermal growth factor receptor 2 (HER-2) overexpression or a high score on the Oncotype DX gene expression profile reveal a poor prognosis compared with ER-rich tumours of the luminal A class. In contrast, recent studies have shown these tumours, contrasting tumours of the luminal A class, to benefit from more aggressive anthracycline-containing chemotherapy including a taxane. In the case of metastatic disease, patients with HER-2-positive, ER-positive tumours may benefit from having endocrine therapy and an anti-HER-2 agent administered in combination.

Activated HER-receptors in predicting outcome of ER-positive breast cancer patients treated with adjuvant endocrine therapy

The four human epidermal growth factor receptors (HER1-4) are involved in growth stimulation and may play a role in endocrine resistance. The receptors form dimers, leading to activation by mutual phosphorylation. Our purpose was to explore the role of the activated receptors (pHER1, pHER2, pHER3) in endocrine treated breast cancer in terms of co-expression and association with disease-free survival (DFS) in 1062 patients with ER-positive tumors. Furthermore, HER2 amplification was evaluated. We found positive associations between the phosphorylated receptors. pHER1 and pHER3 were co-expressed with one or two of the other activated receptors in 85% and 89% of tumors, respectively, whereas pHER2 was co-expressed with the other activated receptors in 54% of tumors. Except for HER2, which was associated with poor prognosis, none of the remaining markers were associated with DFS. However, frequent co-expression indicates a role of the other HER-family members in activation of HER2.

Prognostic and predictive role of ESR1 status for postmenopausal patients with endocrine-responsive early breast cancer in the Danish cohort of the BIG 1-98 trial

BACKGROUND

Estrogen Receptor 1 (ESR1) aberrations may be associated with expression of estrogen receptor (ER) or progesterone receptor (PgR), human epidermal growth factor receptor-2 (HER2) or Ki-67 labeling index and prognosis.

PATIENTS AND METHODS

ESR1 was assessed in 1129 (81%) of 1396 postmenopausal Danish women with early breast cancer randomly assigned to receive 5 years of letrozole, tamoxifen or a sequence of these agents in the Breast International Group 1-98 trial and who had ER ≥ 1% after central review.

RESULTS

By FISH, 13.6% of patients had an ESR1-to-Centromere-6 (CEN-6) ratio ≥ 2 (amplified), and 4.2% had ESR1-to-CEN-6 ratio <0.8 (deleted). Deletion of ESR1 was associated with significantly lower levels of ER (P < 0.0001) and PgR (P = 0.02) and more frequent HER2 amplification. ESR1 deletion or amplification was associated with higher-Ki-67 than ESR1-normal tumors. Overall, there was no evidence of heterogeneity of disease-free survival (DFS) or in treatment effect according to ESR1 status. However, significant differences in DFS were observed for subsets based on a combination of ESR1 and HER2 status (P = 0.02).

CONCLUSIONS

ESR1 aberrations were associated with HER2 status, Ki-67 labeling index and ER and PgR levels. When combined with HER2, ESR1 may be prognostic but should not be used for endocrine treatment selection in postmenopausal women with endocrine-responsive early breast cancer.

Trastuzumab for small HER-2+ breast cancer: small tumor, big decision

A 53-year-old postmenopausal woman was found to have a new area of microcalcification at the 10 o'clock position of her right breast during a routine screening mammogram. Ultrasound-guided core biopsy revealed a grade 2 invasive ductal carcinoma, estrogen receptor (ER)+ (90%), progesterone receptor positive (20%), and human epidermal growth factor receptor (HER)-2+ (3+ by immunohistochemistry). A right breast lumpectomy and sentinel node biopsy were performed. The invasive tumor measured 0.7 cm, no lymphovascular space invasion was identified, surgical margins were uninvolved, and the sentinel lymph nodes were negative for tumor. She was evaluated postoperatively in the medical oncology clinic to discuss an adjuvant treatment strategy. The question for our colleagues is: should she be offered adjuvant chemotherapy and trastuzumab prior to adjuvant radiation and 5 years of hormonal therapy?

Understanding the mechanisms of aromatase inhibitor resistance

Aromatase inhibitors (AIs) have a central role in the treatment of breast cancer; however, resistance is a major obstacle to optimal management. Evidence from endocrine, molecular and pathological measurements in clinical material taken before and after therapy with AIs and data from clinical trials in which AIs have been given as treatment either alone or in combination with other targeted agents suggest diverse causes for resistance. These include inherent tumour insensitivity to oestrogen, ineffective inhibition of aromatase, sources of oestrogenic hormones independent of aromatase, activation of signalling by non-endocrine pathways, enhanced cell survival and selection of hormone-insensitive cellular clones during treatment.

Target therapy in elderly breast cancer patients

Substantial progress has been made in the management of breast cancer by targeting HER2 and VEGF pathways. Although the efficacy and safety of target therapy in breast cancer have been established, no specific phase III trial has addressed these issues in the elderly population and the only data available derive from subanalyses or retrospective series. The aim of this review is to summarize the available evidence in this special population and to encourage further well designed studies in elderly breast cancer patients.