Therapeutic implications of estrogen receptor signaling in HER2-positive breast cancers

iGenSig-Rx: an integral genomic signature based white-box tool for modeling cancer therapeutic responses using multi-omics data

Multi-omics sequencing is poised to revolutionize clinical care in the coming decade. However, there is a lack of effective and interpretable genome-wide modeling methods for the rational selection of patients for personalized interventions. To address this, we present iGenSig-Rx, an integral genomic signature-based approach, as a transparent tool for modeling therapeutic response using clinical trial datasets. This method adeptly addresses challenges related to cross-dataset modeling by capitalizing on high-dimensional redundant genomic features, analogous to reinforcing building pillars with redundant steel rods. Moreover, it integrates adaptive penalization of feature redundancy on a per-sample basis to prevent score flattening and mitigate overfitting. We then developed a purpose-built R package to implement this method for modeling clinical trial datasets. When applied to genomic datasets for HER2 targeted therapies, iGenSig-Rx model demonstrates consistent and reliable predictive power across four independent clinical trials. More importantly, the iGenSig-Rx model offers the level of transparency much needed for clinical application, allowing for clear explanations as to how the predictions are produced, how the features contribute to the prediction, and what are the key underlying pathways. We anticipate that iGenSig-Rx, as an interpretable class of multi-omics modeling methods, will find broad applications in big-data based precision oncology. The R package is available: https://github.com/wangxlab/iGenSig-Rx .

Hormone Receptor-Positive/HER2-Positive Breast Cancer: Hormone Therapy and Anti-HER2 Treatment: An Update on Treatment Strategies

Hormone receptor (HR)-positive/HER2-positive breast cancer represents a distinct subtype expressing estrogen and progesterone receptors with an overexpression of HER2. Approximately 14% of female breast cancer cases are HER2-positive, with the majority being HR-positive. These tumors show a cross-talk between the hormonal and HER2 pathways; the interaction has implications for the treatment options for the disease. In this review, we analyze the biology of HR-positive/HER2-positive breast cancer and summarize the evidence concerning the standard of care options both in neoadjuvant/adjuvant settings and in advanced disease. Additionally, we focus on new trials and drugs for HR-positive/HER2-positive breast cancer and the new entity: HER2-low breast cancer.

Endocrine therapy plus HER2-targeted therapy, another favorable option for HR+/HER2+ advanced breast cancer patients

Advanced breast cancer (ABC) that is positive for hormone receptors (HRs) and human epidermal growth factor receptor 2 (HER2) is a cancer subtype with distinctive characteristics. The primary treatment guidelines suggest that a combination therapy comprising anti-HER2 therapy and chemotherapy should be administered as the initial treatment for HR-positive/ HER2-positive (HR+/HER2+) ABC. However, crosstalk between the HR and HER2 pathways can partially account for the resistance of HR+/HER2+ disease to HER2-targeted therapy. This, in turn, provides a rationale for the concomitant administration of HER2-targeted therapy and endocrine therapy (ET). Many clinical studies have confirmed that the combination of HER2-targeted therapy and ET as a first-line treatment is not inferior to the combination of HER2-targeted therapy and chemotherapy, and support its use as a first-line treatment choice for HR+/HER2+ ABC. Other drugs, such as antibody-drug conjugates, cyclin-dependent kinase 4/6 inhibitors, phosphatidylinositol 3-kinase-protein kinase B (AKT)-mammalian target of rapamycin inhibitors, and programmed cell death protein 1 or programmed cell death ligand 1 inhibitors, may also improve the prognosis of patients with breast cancer by blocking signaling pathways associated with tumor proliferation and break new ground for the treatment of HR+/HER2+ ABC.

iGenSig-Rx: an integral genomic signature based white-box tool for modeling cancer therapeutic responses using multi-omics data

Multi-omics sequencing is expected to become clinically routine within the next decade and transform clinical care. However, there is a paucity of viable and interpretable genome-wide modeling methods that can facilitate rational selection of patients for tailored intervention. Here we develop an integral genomic signature-based method called iGenSig-Rx as a white-box tool for modeling therapeutic response based on clinical trial datasets with improved cross-dataset applicability and tolerance to sequencing bias. This method leverages high-dimensional redundant genomic features to address the challenges of cross-dataset modeling, a concept similar to the use of redundant steel rods to reinforce the pillars of a building. Using genomic datasets for HER2 targeted therapies, the iGenSig-Rx model demonstrates stable predictive power across four independent clinical trials. More importantly, the iGenSig-Rx model offers the level of transparency much needed for clinical application, allowing for clear explanations as to how the predictions are produced, how the features contribute to the prediction, and what are the key underlying pathways. We expect that iGenSig-Rx as a class of biologically interpretable multi-omics modeling methods will have broad applications in big-data based precision oncology. The R package is available: https://github.com/wangxlab/iGenSig-Rx. NOTE: the Github website will be released upon publication and the R package is available for review through google drive: https://drive.google.com/drive/folders/1KgecmUoon9-h2Dg1rPCyEGFPOp28Ols3?usp=sharing.

A generalized non-linear model predicting efficacy of neoadjuvant therapy in HER2+ breast cancer

Neoadjuvant therapy (NAT) is currently recommended to patients with human epidermal growth factor receptor 2-positive breast cancer (HER2+ BC) that typically exhibit a poor prognosis. The tumor immune microenvironment profoundly affects the efficacy of NAT. However, the correlation between tumor-infiltrating lymphocytes or their specific subpopulations and the response to NAT in HER2+ BC remains largely unknown. In our study, the immune infiltration status of 295 patients was classified as "immune-rich" or "immune-poor" phenotypes. The "immune-rich" phenotype was significantly positively related to pathological complete response (pCR). Ten genes were correlated with both pCR and the immune phenotype based on the results of spline and logistic regression. We constructed a generalized non-linear model combining linear and non-linear gene effects and successfully validated its predictive power using an internal and external validation set (AUC = 0.819, 0.797; respectively) and a clinical set (accuracy = 0.75).

Treatment strategies for hormone receptor-positive, human epidermal growth factor receptor 2-positive (HR+/HER2+) metastatic breast cancer: A review

Hormone receptor-positive HER2-positive (HR+/HER2+) metastatic breast cancer (MBC) is a unique subtype of breast cancer. Most current guidelines recommend that combination regimens based on anti-HER2 therapy should be used as first-line treatment for HER2+ MBC, irrespective of HR status. Endocrine therapy can be applied as maintenance therapy for patients who are intolerant to chemotherapy or post-chemotherapy. Increasing evidence suggests that complex molecular crosstalk between HR and HER2 pathways may affect the sensitivity to both HER2-targeted and endocrine therapy in patients with HR+/HER2+ breast cancer. Recent research and clinical trials have revealed that a combination of endocrine therapy and anti-HER2 approaches without chemotherapy provides along-term disease control for some patients, but the challenge lies in how to accurately identify the subsets of patients who can benefit from such a de-chemotherapy treatment strategy. In this review, we aim to summarize the results of preclinical and clinical studies in HR+/HER2+ MBC and discuss the possibility of sparing chemotherapy in this subgroup of patients.

Targeting Cell Cycle Progression in HER2+ Breast Cancer: An Emerging Treatment Opportunity

The development of HER2-targeted therapies has dramatically improved patient survival and patient management and increased the quality of life in the HER2+ breast cancer patient population. Due to the activation of compensatory pathways, patients eventually suffer from resistance to HER2-directed therapies and develop a more aggressive disease phenotype. One of these mechanisms is the crosstalk between ER and HER2 signaling, especially the CDK4/6-Cyclin D-Rb signaling axis that is commonly active and has received attention for its potential role in regulating tumor progression. CDK 4/6 inhibitors interfere with the binding of cell-cycle-dependent kinases (CDKs) with their cognate partner cyclins, and forestall the progression of the cell cycle by preventing Rb phosphorylation and E2F release that consequentially leads to cancer cell senescence. CDK 4/6 inhibitors, namely, palbociclib, ribociclib, and abemaciclib, in combination with anti-estrogen therapies, have shown impressive outcomes in hormonal receptor-positive (HR+) disease and have received approval for this disease context. As an extension of this concept, preclinical/clinical studies incorporating CDK 4/6 inhibitors with HER2-targeted drugs have been evaluated and have shown potency in limiting tumor progression, restoring therapeutic sensitivity, and may improving the management of the disease. Currently, several clinical trials are examining the synergistic effects of CDK 4/6 inhibitors with optimized HER2-directed therapies for the (ER+/-) HER2+ population in the metastatic setting. In this review, we aim to interrogate the burden of HER2+ disease in light of recent treatment progress in the field and examine the clinical benefit of CDK 4/6 inhibitors as a replacement for traditional chemotherapy to improve outcomes in HER2+ breast cancer.

An integral genomic signature approach for tailored cancer therapy using genome-wide sequencing data

Low-cost multi-omics sequencing is expected to become clinical routine and transform precision oncology. Viable computational methods that can facilitate tailored intervention while tolerating sequencing biases are in high demand. Here we propose a class of transparent and interpretable computational methods called integral genomic signature (iGenSig) analyses, that address the challenges of cross-dataset modeling through leveraging information redundancies within high-dimensional genomic features, averaging feature weights to prevent overweighing, and extracting unbiased genomic information from large tumor cohorts. Using genomic dataset of chemical perturbations, we develop a battery of iGenSig models for predicting cancer drug responses, and validate the models using independent cell-line and clinical datasets. The iGenSig models for five drugs demonstrate predictive values in six clinical studies, among which the Erlotinib and 5-FU models significantly predict therapeutic responses in three studies, offering clinically relevant insights into their inverse predictive signature pathways. Together, iGenSig provides a computational framework to facilitate tailored cancer therapy based on multi-omics data.

Modulation of the Estrogen/erbB2 Receptors Cross-talk by CDK4/6 Inhibition Triggers Sustained Senescence in Estrogen Receptor- and ErbB2-positive Breast Cancer

PURPOSE

The interplay between estrogen receptor (ER) and erbB tyrosine-kinase receptors (RTK) impacts growth and progression of ER-positive (ER+)/HER2-positive (HER2+) breast cancer and generates mitogenic signals converging onto the Cyclin-D1/CDK4/6 complex. We probed this cross-talk combining endocrine-therapy (fulvestrant), dual HER2-blockade (trastuzumab and pertuzumab), and CDK4/6-inhibition (palbociclib; PFHPert).

EXPERIMENTAL DESIGN

Cytotoxic drug effects, interactions, and pharmacodynamics were studied after 72 hours of treatment and over 6 more days of culture after drug wash-out in three ER+/HER2+, two HER2low, and two ER-negative (ER-)/HER2+ breast cancer cell lines. We assessed gene-expression dynamic and association with Ki67 downregulation in 28 patients with ER+/HER2+ breast cancer treated with neoadjuvant PFHPert in NA-PHER2 trial (NCT02530424).

RESULTS

In vitro, palbociclib and/or fulvestrant induced a functional activation of RTKs signalling. PFHPert had additive or synergistic antiproliferative activity, interfered with resistance mechanisms linked to the RTKs/Akt/MTORC1 axis and induced sustained senescence. Unexpected synergism was found in HER2low cells. In patients, Ki67 downregulation at week 2 and surgery were significantly associated to upregulation of senescence-related genes (P = 7.7E-4 and P = 1.8E-4, respectively). Activation of MTORC1 pathway was associated with high Ki67 at surgery (P = 0.019).

CONCLUSIONS

Resistance associated with the combination of drugs targeting ER and HER2 can be bypassed by cotargeting Rb, enhancing transition from quiescence to sustained senescence. MTORC1 pathway activation is a potential mechanism of escape and RTKs functional activation may be an alternative pathway for survival also in ER+/HER2low tumor. PFHPert combination is an effective chemotherapy-free regimen for ER+/HER2+ breast cancer, and the mechanistic elucidation of sensitivity/resistance patterns may provide insights for further treatment refinement.

Impact of Immune Cell Heterogeneity on HER2+ Breast Cancer Prognosis and Response to Therapy

Breast cancer is a heterogeneous disease with a high degree of diversity among and within tumors, and in relation to its different tumor microenvironment. Compared to other oncotypes, such as melanoma or lung cancer, breast cancer is considered a "cold" tumor, characterized by low T lymphocyte infiltration and low tumor mutational burden. However, more recent evidence argues against this idea and indicates that, at least for specific molecular breast cancer subtypes, the immune infiltrate may be clinically relevant and heterogeneous, with significant variations in its stromal cell/protein composition across patients and tumor stages. High numbers of tumor-infiltrating T cells are most frequent in HER2-positive and basal-like molecular subtypes and are generally associated with a good prognosis and response to therapies. However, effector immune infiltrates show protective immunity in some cancers but not in others. This could depend on one or more immunosuppressive mechanisms acting alone or in concert. Some of them might include, in addition to immune cells, other tumor microenvironment determinants such as the extracellular matrix composition and stiffness as well as stromal cells, like fibroblasts and adipocytes, that may prevent cytotoxic T cells from infiltrating the tumor microenvironment or may inactivate their antitumor functions. This review will summarize the state of the different immune tumor microenvironment determinants affecting HER2+ breast tumor progression, their response to treatment, and how they are modified by different therapeutic approaches. Potential targets within the immune tumor microenvironment will also be discussed.

Receptor-Mediated Targeted Delivery of Surface-ModifiedNanomedicine in Breast Cancer: Recent Update and Challenges

Breast cancer therapeutic intervention continues to be ambiguous owing to the lack of strategies for targeted transport and receptor-mediated uptake of drugs by cancer cells. In addition to this, sporadic tumor microenvironment, prominent restrictions with conventional chemotherapy, and multidrug-resistant mechanisms of breast cancer cells possess a big challenge to even otherwise optimal and efficacious breast cancer treatment strategies. Surface-modified nanomedicines can expedite the cellular uptake and delivery of drug-loaded nanoparticulate constructs through binding with specific receptors overexpressed aberrantly on the tumor cell. The present review elucidates the interesting yet challenging concept of targeted delivery approaches by exploiting different types of nanoparticulate systems with multiple targeting ligands to target overexpressed receptors of breast cancer cells. The therapeutic efficacy of these novel approaches in preclinical models is also comprehensively discussed in this review. It is concluded from critical analysis of related literature that insight into the translational gap between laboratories and clinical settings would provide the possible future directions to plug the loopholes in the process of development of these receptor-targeted nanomedicines for the treatment of breast cancer.

Resistance to endocrine therapy in HR + and/or HER2 + breast cancer: the most promising predictive biomarkers

Breast cancer is the most common cancer in women. It is a heterogeneous disease, encompassing different biological subtypes that differ in histological features, outcomes, clinical behaviour and different molecular subtypes. Therapy has progressed substantially over the past years with a reduction both for locoregional and systemic therapy. Endocrine therapies have considerably reduced cancer recurrence and mortality. Despite the major diagnostic and therapeutic innovations, resistance to therapy has become a main challenge, especially in metastatic breast cancer, and became a major factor limiting the use of endocrine therapeutic agents in ER positive breast cancers. Approximately 50% of patients with ER positive metastatic disease achieve a complete or partial response with endocrine therapy. However, in the remaining patients, the benefit is limited due to resistance, intrinsic or acquired, resulting in disease progression and poor outcome.Tumour heterogeneity as well as acquired genetic changes and therapeutics pressure have been involved in the endocrine therapy resistance. Nowadays, targeted sequencing of genes involved in cancer has provided insights about genomic tumour evolution throughout treatment and resistance driver mutations. Several studies have described multiple alterations in receptor tyrosine kinases, signalling pathways such as Phosphoinositide-3-kinase-protein kinase B/Akt/mTOR (PI3K/Akt/mTOR) and Mitogen-activated protein kinase (MAPK), cell cycle machinery and their implications in endocrine treatment failure.One of the current concern in cancer is personalized therapy. The focus has been the discovery of new potentially predictive biomarkers capable to identify reliably the most appropriate therapy regimen and which patients will experience disease relapse. The major concern is also to avoid overtreatment/undertreatment and development of resistance.This review focuses on the most promising predictive biomarkers of resistance in estrogen receptor-positive breast cancer and the emerging role of circulating free-DNA as a powerful tool for longitudinal monitoring of tumour molecular profile throughout treatment.

Recent advances in the treatment of hormone receptor-positive/human epidermal growth factor 2-positive advanced breast cancer

Hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-positive (HR+/HER2+) advanced breast cancer is a special subtype of cancer with unique features. Major guidelines recommend that combination therapy containing anti-HER2 therapy (e.g., trastuzumab and pertuzumab) should be applied as the first-line treatment for HER2+ advanced breast cancer, regardless of HR status. Endocrine therapy could be relegated to patients who cannot tolerate chemotherapy or as a post-chemotherapy empirical maintenance strategy. Previous studies have shown that the HR pathway interacts with the HER2 pathway, and the HR and HER2 pathways of endocrine therapy combined with targeted therapy can effectively avoid tumor resistance. Therefore, the combination of endocrine and targeted therapies is the preferred treatment plan for HR+/HER2+ patients to replace chemotherapy. In this review, we will discuss research progress regarding endocrine therapy combined with anti-HER2 therapy in patients with advanced breast cancer, to provide more evidence for clinical practice and broader perspectives for related research. In the future, we hope there will be more studies on HR+/HER2+ advanced breast cancer to elucidate the optimal and appropriate treatment for these patients.

Current trends in the treatment of HR+/HER2+ breast cancer

Treatment for HR+/HER2+ patients has been debated, as some tumors within this luminal HER2+ subtype behave like luminal A cancers, whereas others behave like non-luminal HER2+ breast cancers. Recent research and clinical trials have revealed that a combination of hormone and targeted anti-HER2 approaches without chemotherapy provides long-term disease control for at least some HR+/HER2+ patients. Novel anti-HER2 therapies, including neratinib and trastuzumab emtansine, and new agents that are effective in HR+ cancers, including the next generation of oral selective estrogen receptor downregulators/degraders and CDK4/6 inhibitors such as palbociclib, are now being evaluated in combination. This review discusses current trials and results from previous studies that will provide the basis for current recommendations on how to treat newly diagnosed patients with HR+/HER2+ disease.

A Network Pharmacology Study on the Molecular Mechanisms of FDY003 for Breast Cancer Treatment

Herbal medicines have drawn considerable attention with regard to their potential applications in breast cancer (BC) treatment, a frequently diagnosed malignant disease, considering their anticancer efficacy with relatively less adverse effects. However, their mechanisms of systemic action have not been understood comprehensively. Based on network pharmacology approaches, we attempted to unveil the mechanisms of FDY003, an herbal drug comprised of Lonicera japonica Thunberg, Artemisia capillaris Thunberg, and Cordyceps militaris, against BC at a systemic level. We found that FDY003 exhibited pharmacological effects on human BC cells. Subsequently, detailed data regarding the biochemical components contained in FDY003 were obtained from comprehensive herbal medicine-related databases, including TCMSP and CancerHSP. By evaluating their pharmacokinetic properties, 18 chemical compounds in FDY003 were shown to be potentially active constituents interacting with 140 BC-associated therapeutic targets to produce the pharmacological activity. Gene ontology enrichment analysis using g:Profiler indicated that the FDY003 targets were involved in the modulation of cellular processes, involving the cell proliferation, cell cycle process, and cell apoptosis. Based on a KEGG pathway enrichment analysis, we further revealed that a variety of oncogenic pathways that play key roles in the pathology of BC were significantly enriched with the therapeutic targets of FDY003; these included PI3K-Akt, MAPK, focal adhesion, FoxO, TNF, and estrogen signaling pathways. Here, we present a network-perspective of the molecular mechanisms via which herbal drugs treat BC.

BioPerine Encapsulated Nanoformulation for Overcoming Drug-Resistant Breast Cancers

The evolving dynamics of drug resistance due to tumor heterogeneity often creates impediments to traditional therapies making it a challenging issue for cancer cure. Breast cancer often faces challenges of current therapeutic interventions owing to its multiple complexities and high drug resistivity， for example against drugs like trastuzumab and tamoxifen. Drug resistance in the majority of breast cancer is often aided by the overtly expressed P-glycoprotein (P-gp) that guides in the rapid drug efflux of chemotherapy drugs. Despite continuous endeavors and ground-breaking achievements in the pursuit of finding better cancer therapeutic avenues, drug resistance is still a menace to hold back. Among newer therapeutic approaches, the application of phytonutrients such as alkaloids to suppress P-gp activity in drug-resistant cancers has found an exciting niche in the arena of alternative cancer therapies. In this work, we would like to present a black pepper alkaloid derivative known as BioPerine-loaded chitosan (CS)-polyethylene glycol (PEG) coated polylactic acid (PLA) hybrid polymeric nanoparticle to improve the bioavailability of BioPerine and its therapeutic efficacy in suppressing P-gp expression in MDA-MB 453 breast cancer cell line. Our findings revealed that the CS-PEG-BioPerine-PLA nanoparticles demonstrated a smooth spherical morphology with an average size of 316 nm, with improved aqueous solubility, and provided sustained BioPerine release. The nanoparticles also enhanced in vitro cytotoxicity and downregulation of P-gp expression in MDA-MB 453 cells compared to the commercial inhibitor verapamil hydrochloride, thus promising a piece of exciting evidence for the development of BioPerine based nano-drug delivery system in combination with traditional therapies as a crucial approach to tackling multi-drug resistance in cancers.

De-escalated therapy for HR+/HER2+ breast cancer patients with Ki67 response after 2-week letrozole: results of the PerELISA neoadjuvant study

BACKGROUND

In human epidermal growth factor receptor 2 (HER2+) breast cancers, neoadjuvant trials of chemotherapy plus anti-HER2 treatment consistently showed lower pathologic complete response (pCR) rates in hormone receptor (HR) positive versus negative tumors. The PerELISA study was aimed to evaluate the efficacy of a de-escalated, chemotherapy-free neoadjuvant regimen in HR+/HER2+ breast cancer patients selected on the basis of Ki67 inhibition after 2-week letrozole.

PATIENTS AND METHODS

PerELISA is a phase II, multicentric study for postmenopausal patients with HR+/HER2+ operable breast cancer. Patients received 2-week letrozole, and then underwent re-biopsy for Ki67 evaluation. Patients classified as molecular responders (Ki67 relative reduction >20% from baseline) continued letrozole and started trastuzumab-pertuzumab for five cycles. Patients classified as molecular non-responders started weekly paclitaxel for 13 weeks combined with trastuzumab-pertuzumab. Primary aim was breast and axillary pCR. According to a two-stage Simon's design, to reject the null hypothesis, at least 8/43 pCR had to be documented.

RESULTS

Sixty-four patients were enrolled, 44 were classified as molecular responders. All these patients completed the assigned treatment with letrozole-trastuzumab-pertuzumab and underwent surgery. A pCR was observed in 9/44 cases (20.5%, 95% confidence interval 11.1% to 34.5%). Among molecular non-responders, 16/17 completed treatment and underwent surgery, with pCR observed in 81.3% of the cases. PAM50 intrinsic subtype was significantly associated with Ki67 response and pCR. Among molecular responders, the pCR rate was significantly higher in HER2-enriched than in other subtypes (45.5% versus 13.8%, P = 0.042).

CONCLUSIONS

The primary end point of the study was met, by reaching the pre-specified pCRs. In patients selected using Ki67 reduction after short-term letrozole exposure, a meaningful pCR rate can be achieved without chemotherapy. PAM50 intrinsic subtyping further refines our ability to identify a subset of patients for whom chemotherapy might be spared.

EUDRACT NUMBER

2013-002662-40.

CLINICALTRIALS.GOV IDENTIFIER

NCT02411344.

Synchronous and Metachronous Metastatic Breast Cancer, with Different Histology and Opposite Immunophenotype, Treated with Combination of Chemotherapy, Anti-Her2, and Endocrine Therapy: A Case Report

In the case of our patient, the synergic action of endocrine therapy and chemotherapy plus dual anti-HER2 combination allowed a complete disease control. Therapy should be scheduled by considering the two cancers as individual entities. The approach to breast cancer is changing from being considered a singular disease to a multiform one, according to current research focused on biological markers such as HER2, ERs, and PRs, with important implications in clinical, prognostic, and therapeutic features.

Therapeutic significance of hormone receptor positivity in patients with HER-2 positive breast cancer

Breast cancer with high expression of human epidermal growth factor receptor (HER)-2 represents a biologically and clinically heterogeneous group of neoplastic disorders. Importantly, hormone receptor expression has an effect on biological properties and affects the selection of therapies. On the basis of molecular genetics, four principal subtypes, including luminal A, luminal B, HER2-enriched (HER-2-E), and basal-like can be distinguished. Breast tumors characterized by HER-2 positivity and simultaneous expression of hormone receptors, triple positive breast cancers (TPBC) are of increasing interest owing to the unique biological characteristics associated with complex interactions between HER-2 and hormone receptor signaling pathways. Interactions between hormone receptors and HER-2 explain the decreased efficacy of hormonal therapy in comparison with HER-2-negative patients. The expression of estrogen receptors in HER-2 positive tumors may also be associated with resistance to anti-HER-2 treatment. Multiple available therapeutic options, including hormonal therapy, anti-HER-2 agents and cytotoxic drugs explain favorable prognosis of TPBC. Escalation and de-escalation therapeutic strategies that could result in lower toxicities are being investigated as well as combinations of anti-HER-2 agents with hormonal therapy, immunotherapy, cyclin dependent kinase 4/6 and phosphatidyl inositol-3-kinase inhibitors. Distinction between subtypes of HER-2-positive breast cancer and treatment diversification may result in improved outcomes in TPBC. A response to neoadjuvant therapy may serve in the tailoring of therapy management.

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.

Involvement of miR-770-5p in trastuzumab response in HER2 positive breast cancer cells

miRNAs may play effective roles in breast cancer so modulating their expression levels could have therapeutic benefits. Recent studies have found the combination of miRNA-based therapeutics with conventional drugs as promising. This study aimed to find drug-responsive miRNAs, and explore their anticancer activities in HER2+ breast cancer cells and regulatory role in the trastuzumab response. qRT-PCR-array analysis was performed with effective concentrations of tamoxifen and trastuzumab treated BT-474, SK-BR-3 and MCF-7 cells. Motility and invasion analyses were performed with wound healing and xCELLigence impedance-based assays respectively. Viability of cells following mimic transfection and drug treatment was assessed by WST-1 assay. Western blot analysis was used to assess miR-770-5p regulation of proteins and their phosphorylated forms. The clinical relevance of miR-770-5p was examined by TCGA data analysis. The qRT-PCR-array results indicated that miR-770-5p was responsive in a drug and cell line independent manner. Overexpression of miR-770-5p inhibited the motility and cell invasion through regulation of AKT and ERK proteins. Additionally, miR-770-5p potentiated the effectiveness of trastuzumab. Thus, regulating the expression level of miR-770-5p in combination with trastuzumab treatment may simultaneously inhibit the downstream elements of PI3K and MAPK signalling, thereby blocking the proliferation, motility and invasion capacities of HER2+ breast cancer cells.

Clinical Differences in Triple-Positive Operable Breast Cancer Subtypes in Korean Patients: An Analysis of Korean Breast Cancer Registry Data

Purpose

Triple-positive breast cancer is defined by estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) positivity. Several systemic breast cancer therapies target hormonal and HER2 responsiveness. We compared clinical outcomes of triple-positive disease with those of HER2-enriched and luminal HER2-negative disease and investigated the clinical efficacy of anti-HER2 therapy for triple-positive disease.

Methods

We retrospectively compared overall and recurrence-free survival among cases included in the Korean Breast Cancer Society (KBCS) and Seoul St. Mary's Hospital breast cancer registries and the therapeutic efficacy of trastuzumab for triple-positive and HER2-enriched cases.

Results

KBCS registry data (2006–2010; median follow-up, 76 months) indicated that patients with triple-positive breast cancer had intermediate survival between those with luminal A and HER2-enriched subtypes (p<0.001). Trastuzumab did not improve overall survival among patients with triple-positive breast cancer (p=0.899) in contrast to the HER2-enriched subtype (p=0.018). Seoul St. Mary's Hospital registry data indicated similar recurrence-free survival outcomes (p<0.001) and a lack of improvement with trastuzumab among patients with triple-positive breast cancer (median follow-up, 33 months; p=0.800). Multivariate analysis revealed that patients with triple-positive breast cancer had better overall survival than those with HER2-enriched disease and similar survival as those with the luminal A subtype (triple-positive: hazard ratio, 1.258, p=0.118; HER2-enriched: hazard ratio, 2.377, p<0.001).

Conclusion

Our findings showed that anti-HER2 therapy was less beneficial for treatment of triple-positive breast cancer than for HER2-enriched subtypes of breast cancer, and the triple-positive subtype had a distinct prognosis.

Combined Blockade of Activating ERBB2 Mutations and ER Results in Synthetic Lethality of ER+/HER2 Mutant Breast Cancer

PURPOSE

We examined the role of ERBB2-activating mutations in endocrine therapy resistance in estrogen receptor positive (ER+) breast cancer.

EXPERIMENTAL DESIGN

ERBB2 mutation frequency was determined from large genomic databases. Isogenic knock-in ERBB2 mutations in ER+ MCF7 cells and xenografts were used to investigate estrogen-independent growth. Structural analysis was used to determine the molecular interaction of HER ^L755S with HER3. Small molecules and siRNAs were used to inhibit PI3Kα, TORC1, and HER3.

RESULTS

Genomic data revealed a higher rate of ERBB2 mutations in metastatic versus primary ER+ tumors. MCF7 cells with isogenically incorporated ERBB2 kinase domain mutations exhibited resistance to estrogen deprivation and to fulvestrant both in vitro and in vivo, despite maintaining inhibition of ERα transcriptional activity. Addition of the irreversible HER2 tyrosine kinase inhibitor neratinib restored sensitivity to fulvestrant. HER2-mutant MCF7 cells expressed higher levels of p-HER3, p-AKT, and p-S6 than cells with wild-type HER2. Structural analysis of the HER2 ^L755S variant implicated a more flexible active state, potentially allowing for enhanced dimerization with HER3. Treatment with a PI3Kα inhibitor, a TORC1 inhibitor or HER3 siRNA, but not a MEK inhibitor, restored sensitivity to fulvestrant and to estrogen deprivation. Inhibition of mutant HER2 or TORC1, when combined with fulvestrant, equipotently inhibited growth of MCF7/ERBB2 ^V777L xenografts, suggesting a role for TORC1 in antiestrogen resistance induced by ERBB2 mutations.

CONCLUSIONS

ERBB2 mutations hyperactivate the HER3/PI3K/AKT/mTOR axis, leading to antiestrogen resistance in ER+ breast cancer. Dual blockade of the HER2 and ER pathways is required for the treatment of ER+/HER2 mutant breast cancers.

Effects of trastuzumab on locoregional recurrence in human epidermal growth factor receptor 2-overexpressing breast cancer patients treated with chemotherapy and radiotherapy

PURPOSE

In the present study, the ability of adjuvant trastuzumab to reduce locoregional recurrence in patients with human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer receiving adjuvant chemotherapy and radiotherapy (RT) was investigated.

MATERIALS AND METHODS

We retrospectively included 520 patients with HER2-overexpressing breast cancer who received surgery followed by adjuvant RT and cytotoxic chemotherapy from 2003 to 2011. Adjuvant trastuzumab was administered to 286 patients. Propensity score matching was conducted to compare trastuzumab-treated and non-treated cohorts.

RESULTS

Median follow-up duration was 7.1 years (range 1.1-14.1 years). Propensity score matching yielded 171 matched pairs of patients with no significantly different clinical factors. An improved 7-year locoregional control (LRC) rate was observed in the trastuzumab-treated cohort compared with the non-treated cohort (95.6% vs. 89.9%, p = 0.014). Based on multivariate analysis, hormone receptor negativity (hazard ratio [HR] = 5.348, p = 0.007), positive lymph node ratio > 0.25 (HR = 2.549, p = 0.040), and lack of adjuvant trastuzumab (HR = 3.401, p = 0.017) were identified as significant risk factors for poor LRC. Adjuvant trastuzumab significantly reduced the locoregional recurrence rate in patients with one or two risk factors (7-year LRC = 95.0% vs. 84.2%, p = 0.007); however, the benefit of adjuvant trastuzumab was non-significant in patients with no risk factors (7-year LRC = 95.8% vs. 97.9%, p = 0.75).

CONCLUSIONS

Adjuvant trastuzumab improved LRC in patients with HER2-overexpressing breast cancer receiving adjuvant RT and cytotoxic chemotherapy, especially in hormone receptor-negative, HER2-enriched subtype, and high positive lymph node ratio breast cancer.

C-Cbl reverses HER2-mediated tamoxifen resistance in human breast cancer cells

Background

Tamoxifen is a frontline therapy for estrogen receptor (ER)-positive breast cancer in premenopausal women. However, many patients develop resistance to tamoxifen, and the mechanism underlying tamoxifen resistance is not well understood. Here we examined whether ER-c-Src-HER2 complex formation is involved in tamoxifen resistance.

Methods

MTT and colony formation assays were used to measure cell viability and proliferation. Western blot was used to detect protein expression and protein complex formations were detected by immunoprecipitation and immunofluorescence. SiRNA was used to examine the function of HER2 in of BT474 cells. An in vivo xenograft animal model was established to examine the role of c-Cbl in tumor growth.

Results

MTT and colony formation assay showed that BT474 cells are resistant to tamoxifen and T47D cells are sensitive to tamoxifen. Immunoprecipitation experiments revealed ER-c-Src-HER2 complex formation in BT474 cells but not in T47D cells. However, ER-c-Src-HER2 complex formation was detected after overexpressing HER2 in T47D cells and these cells were more resistant to tamoxifen. HER2 knockdown by siRNA in BT474 cells reduced ER-c-Src-HER2 complex formation and reversed tamoxifen resistance. ER-c-Src-HER2 complex formation was also disrupted and tamoxifen resistance was reversed in BT474 cells by the c-Src inhibitor PP2 and HER2 antibody trastuzumab. Nystatin, a lipid raft inhibitor, reduced ER-c-Src-HER2 complex formation and partially reversed tamoxifen resistance. ER-c-Src-HER2 complex formation was disrupted by overexpression of c-Cbl but not by the c-Cbl ubiquitin ligase mutant. In addition, c-Cbl could reverse tamoxifen resistance in BT474 cells, but the ubiquitin ligase mutant had no effect. The effect of c-Cbl was validated in BT474 tumor-bearing nude mice in vivo. Immunofluorescence also revealed ER-c-Src-HER2 complex formation was reduced in tumor tissues of nude mice with c-Cbl overexpression.

Conclusions

Our results suggested that c-Cbl can reverse tamoxifen resistance in HER2-overexpressing breast cancer cells by inhibiting the formation of the ER-c-Src-HER2 complex.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4387-5) contains supplementary material, which is available to authorized users.

Survival Analysis After Neoadjuvant Chemotherapy With Trastuzumab or Lapatinib in Patients With Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer in the GeparQuinto (G5) Study (GBG 44)

Purpose

The GeparQuinto phase III trial demonstrated a lower pathologic complete response (pCR; pT0 ypN0) rate when lapatinib was added to standard anthracycline–taxane chemotherapy compared with trastuzumab in patients with human epidermal growth factor receptor 2 (HER2) –positive breast cancer. Here, we report the long-term outcomes.

Methods

Patients with HER2-positive tumors (n = 615) received neoadjuvant treatment with epirubicin (E) plus cyclophosphamide (C), followed by docetaxel (T) in combination with either lapatinib (L) or trastuzumab (H; ECH-TH arm: n = 307; ECL-TL arm: n = 308). All patients received adjuvant trastuzumab for a total of 12 months and 18 months in the ECH-TH and ECL-TL arms, respectively. Median follow-up was 55 months.

Results

Three-year disease-free survival (DFS), distant DFS (DDFS), and overall survival (OS) were not significantly different between the two treatment arms. Long-term outcomes correlated with pCR (DFS: hazard ratio [HR], 0.63; P = .042; DDFS: HR, 0.55; P = .021; and OS: HR, 0.31; P = .004). A benefit only for OS was observed in patients who were treated with trastuzumab and achieved pCR versus no pCR (HR, 0.15; P = .010), whereas no difference was found in patients with pCR versus without pCR in the lapatinib arm. DFS and DDFS remained unchanged in both treatment arms according to hormone receptor status, whereas OS was significantly better in hormone receptor–positive patients who were treated with neoadjuvant lapatinib (HR, 0.32; P = .019), followed by adjuvant trastuzumab. No difference was observed in hormone receptor–negative patients; however, the small number of events limits this interpretation. Within the hormone receptor–negative cohort, pCR was significantly associated with DFS, DDFS, and OS ( P = .002, .005, and .002, respectively).

Conclusion

pCR correlated with long-term outcome. In patients with hormone receptor–positive tumors, prolonged anti-HER2 treatment—neoadjuvant lapatinib for 6 months, followed by adjuvant trastuzumab for 12 months—significantly improved survival compared with anti-HER2 treatment with trastuzumab alone.

Release of HER2 repression of trefoil factor 3 (TFF3) expression mediates trastuzumab resistance in HER2+/ER+ mammary carcinoma

HER2+/ER+ breast cancer, a subset of the luminal B subtype, makes up approximately 10% of all breast cancers. The bidirectional crosstalk between HER2 and estrogen receptor (ER) in HER2+/ER+ breast cancer contributes to resistance towards both anti-estrogens and HER2-targeted therapies. TFF3 promotes breast cancer progression and has been implicated in anti-estrogen resistance in breast cancer. Herein, we investigated the cross-regulation between HER2 and estrogen-responsive TFF3, and the role of TFF3 in mediating trastuzumab resistance in HER2+/ER+ breast cancer. TFF3 expression was decreased by HER2 activation, and increased by inhibition of HER2 with trastuzumab in HER2+/ER+ breast cancer cells, partially in an ERα-independent manner. In contrast, the forced expression of TFF3 activated the entire HER family of receptor tyrosine kinases (HER1-4). Hence, HER2 negatively regulates its own signalling through the transcriptional repression of TFF3, while trastuzumab inhibition of HER2 results in increased TFF3 expression to compensate for the loss of HER2 signalling. In HER2+/ER+ breast cancer cells with acquired trastuzumab resistance, TFF3 expression was markedly upregulated and associated with a corresponding decrease in HER signalling. siRNA mediated depletion or small molecule inhibition of TFF3 decreased the survival and growth advantage of the trastuzumab resistant cells without re-sensitization to trastuzumab. Furthermore, TFF3 inhibition abrogated the enhanced cancer stem cell-like behaviour in trastuzumab resistant HER2+/ER+ breast cancer cells. Collectively, TFF3 may function as a potential biomarker and therapeutic target in trastuzumab resistant HER2+/ER+ breast cancer.

Dual inhibition of IGF1R and ER enhances response to trastuzumab in HER2 positive breast cancer cells

Although HER2 targeted therapies have improved prognosis for HER2 positive breast cancer, HER2 positive cancers which co-express ER have poorer response rates to standard HER2 targeted therapies, combined with chemotherapy, than HER2 positive/ER negative breast cancer. Administration of hormone therapy concurrently with chemotherapy and HER2 targeted therapy is generally not recommended. Using publically available gene expression datasets we found that high expression of IGF1R is associated with shorter disease-free survival in patients whose tumors are ER positive and HER2 positive. IGF1R is frequently expressed in HER2 positive breast cancer and there is significant evidence for crosstalk between IGF1R and both HER2 and ER. Therefore, we evaluated the therapeutic potential of targeting ER and IGF1R in cell line models of HER2/ER/IGF1R positive breast cancer, using tamoxifen and two IGF1R targeted tyrosine kinase inhibitors (NVP-AEW541 and BMS-536924). Dual inhibition of ER and IGF1R enhanced growth inhibition in the four HER2 positive cell lines tested and caused an increase in cell cycle arrest in G1 in BT474 cells. In addition, combined treatment with trastuzumab, tamoxifen and either of the IGF1R TKIs enhanced response compared to dual targeting strategies in three of the four HER2 positive breast cancer cell lines tested. Furthermore, in a cell line model of trastuzumab-resistant HER2 positive breast cancer (BT474/Tr), tamoxifen combined with an IGF1R TKI produced a similar enhanced response as observed in the parental BT474 cells suggesting that this combination may overcome acquired trastuzumab resistance in this model. Combining ER and IGF1R targeting with HER2 targeted therapies may be an alternative to HER2 targeted therapy and chemotherapy for patients with HER2/ER/IGF1R positive breast cancer.

Inhibition of Akt phosphorylation attenuates resistance to TNF-α cytotoxic effects in MCF-7 cells, but not in their doxorubicin resistant derivatives

Objective(s):

Acquisition of TNF-α resistance plays role in the onset and growth of malignant tumors. Previous studies have demonstrated that MCF-7 cell line and its doxorubicin resistant variant MCF-7/Adr are resistant against the cytotoxic effects of TNF-α. In this study, we investigated the role of Akt activation in resistance of MCF-7 and MCF-7/Adr against TNF-α cytotoxicity.

Materials and Methods:

The role of Akt activation in TNF-α cytotoxicity was investigated by MTT cell viability assay following treatment of the cells with the chemical inhibitor of Akt activation with or without TNF-α treatment. Phosphorylation of Akt at Ser473 before and after 72 hr TNF-α treatment was also determined by western blot.

Results:

TNF-α treatment led to enhancement of Akt Ser473 phosphorylation. Treatment of MCF-7 cells with TNF-α along with Akt-inhibitor agent, tricribine, attenuated Akt Ser473 phosphorylation and sensitized these cells to the cytotoxic effects of TNF-α in a dose and time dependent manner while tricribine treatment did not cause any significant cytotoxicity in MCF-7/Adr cells alone or in combination with TNF-α.

Conclusion:

These results demonstrate that Akt phosphorylation plays pivotal role in the resistance of MCF-7 cells against TNF-α-induced cytotoxicity while it might play no significant role in the resistance of MCF-7/Adr cells against TNF-α.

Predicting and Overcoming Chemotherapeutic Resistance in Breast Cancer

Our understanding of breast cancer and its therapeutic approach has improved greatly due to the advancement of molecular biology in recent years. Clinically, breast cancers are characterized into three basic types based on their immunohistochemical properties. They are triple-negative breast cancer, estrogen receptor (ER) and progesterone receptor (PR)-positive-HR positive breast cancer, and human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Even though these subtypes have been characterized, assessment of a breast cancer's receptor status is still widely used to determine whether or not a targeted therapy could be applied. Moreover, drug resistance is common in all breast cancer types despite the different treatment modalities applied. The development of resistance to different therapeutics is not mutually exclusive. It seems that tumor could be resistant to multiple treatment strategies, such as being both chemoresistant and monoclonal antibody resistant. However, the underlying mechanisms are complicated and need further investigation. In this chapter, we aim to provide a brief review of the different types of breast cancer and their respective treatment strategies. We also review the possible mechanisms of potential drug resistance associated with each treatment type. We believe that a better understanding of the drug resistance mechanisms can lead to a more effective and efficient therapeutic success.

Targeted therapy for breast cancer and molecular mechanisms of resistance to treatment

In recent years, clinical trials investigating new drugs and therapeutic combinations have led to promising advances in breast cancer therapy. Subtyping breast cancers into hormone receptor (HR) positive, epidermal growth factor receptor (HER2) positive, and triple negative breast cancer (TNBC) is currently the basis of diagnosing and treating this disease. In addition to endocrine and HER2-targeted therapies in their respective subtypes, evidence from recent preclinical studies have shown several targetable pathways that overcome resistance in the clinical setting. The mTOR inhibitor everolimus and the CDK4/6 inhibitor palbociclib have been approved in HR-positive metastatic breast cancer (MBC) due to improved disease-free survival (DFS). Adding pertuzumab to trastuzumab in combination with taxanes further improves DFS in HER2-positive breast cancer. Targeted therapy to the heterogeneous group of TNBC is needed in combination with chemotherapy. However, patient selection and predictive biomarker development remains a big challenge for targeted therapy development in TNBC.

Resistance to therapy in estrogen receptor positive and human epidermal growth factor 2 positive breast cancers: progress with latest therapeutic strategies

In this article, we focus on the subtype of estrogen receptor (ER)-positive, human epidermal growth factor 2 (HER2)-positive breast cancer (BC). Preclinical and clinical data indicate a complex molecular bidirectional crosstalk between the ER and HER2 pathways. This crosstalk probably constitutes one of the key mechanisms of drug resistance in this subclass of BC. Delaying or even reversing drug resistance seems possible by targeting pathways implicated in this crosstalk. High-risk patients currently receive anti-HER2 therapy, chemotherapy and endocrine therapy in the adjuvant setting. In metastatic cases, most patients receive a combination of anti-HER2 therapy and chemotherapy. Only selected patients presenting more indolent disease are candidates for combinations of anti-HER2 therapy and endocrine therapy. However, relative improvements in progression-free survival by chemotherapy-based regimens are usually lower in ER-positive patients than the ER-negative and HER2-positive subgroup. Consequently, new approaches aiming to overcome endocrine therapy resistance by adding targeted therapies to endocrine therapy based regimens are currently explored. In addition, dual blockade of HER2 or the combination of trastuzumab and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOP) inhibitors targeting the downstream pathway are strategies to overcome resistance to trastuzumab. This may lead in the near future to the less frequent use of chemotherapy-based treatment options in ER-positive, HER2-positive BC.

Tamoxifen Resistance: Emerging Molecular Targets

17β-Estradiol (E2) plays a pivotal role in the development and progression of breast cancer. As a result, blockade of the E2 signal through either tamoxifen (TAM) or aromatase inhibitors is an important therapeutic strategy to treat or prevent estrogen receptor (ER) positive breast cancer. However, resistance to TAM is the major obstacle in endocrine therapy. This resistance occurs either de novo or is acquired after an initial beneficial response. The underlying mechanisms for TAM resistance are probably multifactorial and remain largely unknown. Considering that breast cancer is a very heterogeneous disease and patients respond differently to treatment, the molecular analysis of TAM’s biological activity could provide the necessary framework to understand the complex effects of this drug in target cells. Moreover, this could explain, at least in part, the development of resistance and indicate an optimal therapeutic option. This review highlights the implications of TAM in breast cancer as well as the role of receptors/signal pathways recently suggested to be involved in the development of TAM resistance. G protein—coupled estrogen receptor, Androgen Receptor and Hedgehog signaling pathways are emerging as novel therapeutic targets and prognostic indicators for breast cancer, based on their ability to mediate estrogenic signaling in ERα-positive or -negative breast cancer.

Whole-transcriptome analysis links trastuzumab sensitivity of breast tumors to both HER2 dependence and immune cell infiltration

While results thus far demonstrate the clinical benefit of trastuzumab, some patients do not respond to this therapy. To identify a molecular predictor of trastuzumab benefit, we conducted whole-transcriptome analysis of primary HER2+ breast carcinomas obtained from patients treated with trastuzumab-containing therapies and correlated the molecular portrait with treatment benefit.

The estimated association between gene expression and relapse-free survival allowed development of a trastuzumab risk model (TRAR), with ERBB2 and ESR1 expression as core elements, able to identify patients with high and low risk of relapse. Application of the TRAR model to 24 HER2+ core biopsies from patients treated with neo-adjuvant trastuzumab indicated that it is predictive of trastuzumab response. Examination of TRAR in available whole-transcriptome datasets indicated that this model stratifies patients according to response to trastuzumab-based neo-adjuvant treatment but not to chemotherapy alone. Pathway analysis revealed that TRAR-low tumors expressed genes of the immune response, with higher numbers of CD8-positive cells detected immunohistochemically compared to TRAR-high tumors.

The TRAR model identifies tumors that benefit from trastuzumab-based treatment as those most enriched in CD8-positive immune infiltrating cells and with high ERBB2 and low ESR1 mRNA levels, indicating the requirement for both features in achieving trastuzumab response.

Identification of stromal ColXα1 and tumor-infiltrating lymphocytes as putative predictive markers of neoadjuvant therapy in estrogen receptor-positive/HER2-positive breast cancer

Background

The influence of the tumor microenvironment and tumor-stromal interactions on the heterogeneity of response within breast cancer subtypes have just begun to be explored. This study focuses on patients with estrogen receptor-positive/human epidermal growth factor receptor 2-positive (ER+/HER2+) breast cancer receiving neoadjuvant chemotherapy and HER2-targeted therapy (NAC+H), and was designed to identify novel predictive biomarkers by combining gene expression analysis and immunohistochemistry with pathologic response.

Methods

We performed gene expression profiling on pre-NAC+H tumor samples from responding (no or minimal residual disease at surgery) and non-responding patients. Gene set enrichment analysis identified potentially relevant pathways, and immunohistochemical staining of pre-treatment biopsies was used to measure protein levels of those pathways, which were correlated with pathologic response in both univariate and multivariate analysis.

Results

Increased expression of genes encoding for stromal collagens, including Col10A1, and reduced expression of immune-associated genes, reflecting lower levels of total tumor-infiltrating lymphocytes (TILs), were strongly associated with poor pathologic response. Lower TILs in tumor biopsies correlated with reduced likelihood of achieving an optimal pathologic response, but increased expression of the Col10A1 gene product, colXα1, had greater predictive value than stromal abundance for poor response (OR = 18.9, p = 0.003), and the combination of increased colXα1 expression and low TILs was significantly associated with poor response in multivariate analysis. ROC analysis suggests strong specificity and sensitivity for this combination in predicting treatment response.

Conclusions

Increased expression of stromal colXα1 and low TILs correlate with poor pathologic response in ER+/HER2+ breast tumors. Further studies are needed to confirm their predictive value and impact on long-term outcomes, and to determine whether this collagen exerts a protective effect on the cancer cells or simply reflects other factors within the tumor microenvironment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2302-5) contains supplementary material, which is available to authorized users.

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.

Neratinib after trastuzumab-based adjuvant therapy in patients with HER2-positive breast cancer (ExteNET): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Neratinib, an irreversible tyrosine-kinase inhibitor of HER1, HER2, and HER4, has clinical activity in patients with HER2-positive metastatic breast cancer. We aimed to investigate the efficacy and safety of 12 months of neratinib after trastuzumab-based adjuvant therapy in patients with early-stage HER2-positive breast cancer.

METHODS

We did this multicentre, randomised, double-blind, placebo-controlled, phase 3 trial at 495 centres in Europe, Asia, Australia, New Zealand, and North and South America. Eligible women (aged ≥18 years, or ≥20 years in Japan) had stage 1-3 HER2-positive breast cancer and had completed neoadjuvant and adjuvant trastuzumab therapy up to 2 years before randomisation. Inclusion criteria were amended on Feb 25, 2010, to include patients with stage 2-3 HER2-positive breast cancer who had completed trastuzumab therapy up to 1 year previously. Patients were randomly assigned (1:1) to receive oral neratinib 240 mg per day or matching placebo. The randomisation sequence was generated with permuted blocks stratified by hormone receptor status (hormone receptor-positive [oestrogen or progesterone receptor-positive or both] vs hormone receptor-negative [oestrogen and progesterone receptor-negative]), nodal status (0, 1-3, or ≥4), and trastuzumab adjuvant regimen (sequentially vs concurrently with chemotherapy), then implemented centrally via an interactive voice and web-response system. Patients, investigators, and trial sponsors were masked to treatment allocation. The primary outcome was invasive disease-free survival, as defined in the original protocol, at 2 years after randomisation. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00878709.

FINDINGS

Between July 9, 2009, and Oct 24, 2011, we randomly assigned 2840 women to receive neratinib (n=1420) or placebo (n=1420). Median follow-up time was 24 months (IQR 20-25) in the neratinib group and 24 months (22-25) in the placebo group. At 2 year follow-up, 70 invasive disease-free survival events had occurred in patients in the neratinib group versus 109 events in those in the placebo group (stratified hazard ratio 0·67, 95% CI 0·50-0·91; p=0·0091). The 2-year invasive disease-free survival rate was 93·9% (95% CI 92·4-95·2) in the neratinib group and 91·6% (90·0-93·0) in the placebo group. The most common grade 3-4 adverse events in patients in the neratinib group were diarrhoea (grade 3, n=561 [40%] and grade 4, n=1 [<1%] vs grade 3, n=23 [2%] in the placebo group), vomiting (grade 3, n=47 [3%] vs n=5 [<1%]), and nausea (grade 3, n=26 [2%] vs n=2 [<1%]). QT prolongation occurred in 49 (3%) patients given neratinib and 93 (7%) patients given placebo, and decreases in left ventricular ejection fraction (≥grade 2) in 19 (1%) and 15 (1%) patients, respectively. We recorded serious adverse events in 103 (7%) patients in the neratinib group and 85 (6%) patients in the placebo group. Seven (<1%) deaths (four patients in the neratinib group and three patients in the placebo group) unrelated to disease progression occurred after study drug discontinuation. The causes of death in the neratinib group were unknown (n=2), a second primary brain tumour (n=1), and acute myeloid leukaemia (n=1), and in the placebo group were a brain haemorrhage (n=1), myocardial infarction (n=1), and gastric cancer (n=1). None of the deaths were attributed to study treatment in either group.

INTERPRETATION

Neratinib for 12 months significantly improved 2-year invasive disease-free survival when given after chemotherapy and trastuzumab-based adjuvant therapy to women with HER2-positive breast cancer. Longer follow-up is needed to ensure that the improvement in breast cancer outcome is maintained.

FUNDING

Wyeth, Pfizer, Puma Biotechnology.

Centrosome amplification induces high grade features and is prognostic of worse outcomes in breast cancer

Background

Centrosome amplification (CA) has been reported in nearly all types of human cancer and is associated with deleterious clinical factors such as higher grade and stage. However, previous reports have not shown how CA affects cellular differentiation and clinical outcomes in breast cancer.

Methods

We analyzed centrosomes by immunofluorescence and compared to ploidy and chromosomal instability (CIN) as assessed by 6-chromosome FISH in a cohort of 362 breast cancers with median clinical follow-up of 8.4 years. Centrosomes were recognized by immunofluorescence using antibodies for pericentriolar material (PCM; pericentrin) and centrioles (polyglutamylated tubulin). CA was experimentally induced in cell culture by overexpression of polo-like kinase 4 (PLK4).

Results

CA is associated with reduced all-cause and breast cancer-specific overall survival and recurrence-free survival. CA correlates strongly with high-risk subtypes (e.g. triple negative) and higher stage and grade, and the prognostic nature of CA can be explained largely by these factors. A strong correlation between CA and high tumor ploidy demonstrates that chromosome and centrosome doubling often occur in concert. CA is proposed to be a method of inducing CIN via aberrant mitotic cell divisions; consonant with this, we observed a strong correlation between CA and CIN in breast cancers. However, some CA tumors had low levels of CIN, indicating that protective mechanisms are at play, such as centrosome clustering during mitosis. Intriguingly, some high-risk tumors have more acentriolar centrosomes, suggesting PCM fragmentation as another mechanism of CA. In vitro induction of CA in two non-transformed human cell lines (MCF10A and RPE) demonstrated that CA induces a de-differentiated cellular state and features of high-grade malignancy, supporting the idea that CA intrinsically causes high-grade tumors.

Conclusions

CA is associated with deleterious clinical factors and outcomes in breast cancer. Cell doubling events are the most prevalent causes of CA in cancer, although PCM fragmentation may be a secondary cause. CA promotes high-risk breast cancer in part by inducing high-grade features. These findings highlight the importance of centrosome aberrations in the biology of human breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2083-x) contains supplementary material, which is available to authorized users.

Targeting HER2 for the treatment of breast cancer

HER2 (ErbB2), a member of the HER family of tyrosine kinase receptors (HER1-4), is a major driver of tumor growth in 20% of breast cancers. Treatment with the anti-HER2 monoclonal antibody trastuzumab has revolutionized the outcome of patients with this aggressive breast cancer subtype, but intrinsic and acquired resistance is common. Growing understanding of the biology and complexity of the HER2 signaling network and of potential resistance mechanisms has guided the development of new HER2-targeted agents. Combinations of these drugs to more completely inhibit the HER receptor layer, or combining HER2-targeted agents with agents that target downstream signaling, alternative pathways, or components of the host immune system, are being vigorously investigated in the preclinical and clinical settings. As a result, the list of more effective and well tolerated FDA-approved new regimens for patients with HER2+ tumors is constantly growing.

Upregulation of ER Signaling as an Adaptive Mechanism of Cell Survival in HER2-Positive Breast Tumors Treated with Anti-HER2 Therapy

PURPOSE

To investigate the direct effect and therapeutic consequences of epidermal growth factor receptor 2 (HER2)-targeting therapy on expression of estrogen receptor (ER) and Bcl2 in preclinical models and clinical tumor samples.

EXPERIMENTAL DESIGN

Archived xenograft tumors from two preclinical models (UACC812 and MCF7/HER2-18) treated with ER and HER2-targeting therapies and also HER2+ clinical breast cancer specimens collected in a lapatinib neoadjuvant trial (baseline and week 2 posttreatment) were used. Expression levels of ER and Bcl2 were evaluated by immunohistochemistry and Western blot analysis. The effects of Bcl2 and ER inhibition, by ABT-737 and fulvestrant, respectively, were tested in parental versus lapatinib-resistant UACC812 cells in vitro.

RESULTS

Expression of ER and Bcl2 was significantly increased in xenograft tumors with acquired resistance to anti-HER2 therapy compared with untreated tumors in both preclinical models (UACC812: ER P = 0.0014; Bcl2 P < 0.001 and MCF7/HER2-18: ER P = 0.0007; Bcl2 P = 0.0306). In the neoadjuvant clinical study, lapatinib treatment for 2 weeks was associated with parallel upregulation of ER and Bcl2 (Spearman coefficient: 0.70; P = 0.0002). Importantly, 18% of tumors originally ER-negative (ER(-)) converted to ER(+) upon anti-HER2 therapy. In ER(-)/HER2(+) MCF7/HER2-18 xenografts, ER reexpression was primarily observed in tumors responding to potent combination of anti-HER2 drugs. Estrogen deprivation added to this anti-HER2 regimen significantly delayed tumor progression (P = 0.018). In the UACC812 cells, fulvestrant, but not ABT-737, was able to completely inhibit anti-HER2-resistant growth (P < 0.0001).

CONCLUSIONS

HER2 inhibition can enhance or restore ER expression with parallel Bcl2 upregulation, representing an ER-dependent survival mechanism potentially leading to anti-HER2 resistance.

Combination of everolimus with trastuzumab plus paclitaxel as first-line treatment for patients with HER2-positive advanced breast cancer (BOLERO-1): a phase 3, randomised, double-blind, multicentre trial

BACKGROUND

mTOR inhibition reverses trastuzumab resistance via the hyperactivated PIK/AKT/mTOR pathway due to PTEN loss, by sensitising PTEN-deficient tumours to trastuzumab. The BOLERO-1 study assessed the efficacy and safety of adding everolimus to trastuzumab and paclitaxel as first-line treatment for patients with HER2-positive advanced breast cancer.

METHODS

In this phase 3, randomised, double-blind trial, patients were enrolled across 141 sites in 28 countries. Eligible patients were aged 18 years or older, with locally assessed HER2-positive advanced breast cancer, with Eastern Cooperative Oncology Group (ECOG) performance status of 0-1, who had not received previous trastuzumab or chemotherapy for advanced breast cancer within 12 months of randomisation, had measurable disease as per Response Evaluation Criteria in Solid Tumors (RECIST) or bone lesions in the absence of measurable disease, without previous systemic treatment for advanced disease except endocrine therapy. Patients were randomly assigned (2:1) with an interactive voice and web response system to receive either 10 mg everolimus once a day orally or placebo plus weekly trastuzumab intravenously at 4 mg/kg loading dose on day 1 with subsequent weekly doses of 2 mg/kg of each 4 week cycle plus paclitaxel intravenously at a dose of 80 mg/m(2) on days 1, 8, and 15 of each 4 week cycle. Randomisation was stratified according to previous use of trastuzumab and visceral metastasis. Patients and investigators were masked to the assigned treatments. Identity of experimental treatments was concealed by use of everolimus and placebo that were identical in packaging, labelling, appearance, and administration schedule. The two primary objectives were investigator-assessed progression-free survival in the full study population and in the subset of patients with hormone receptor-negative breast cancer at baseline; the latter was added during the course of the study, before unmasking based on new clinical and biological findings from other studies. All efficacy analyses were based on the intention-to-treat population. Enrolment for this trial is closed and results of the final progression-free survival analyses are presented here. This trial is registered with ClinicalTrials.gov, number NCT00876395.

FINDINGS

Between Sept 10, 2009, and Dec 16, 2012, 719 patients were randomly assigned to receive everolimus (n=480) or placebo (n=239). Median follow-up was 41·3 months (IQR 35·4-46·6). In the full population, median progression-free survival was 14·95 months (95% CI 14·55-17·91) with everolimus versus 14·49 months (12·29-17·08) with placebo (hazard ratio 0·89, 95% CI 0·73-1·08; p=0·1166). In the HR-negative subpopulation (n=311), median progression-free survival with everolimus was 20·27 months (95% CI 14·95-24·08) versus 13·08 months (10·05-16·56) with placebo (hazard ratio 0·66, 95% CI 0·48-0·91; p=0·0049); however, the protocol-specified significance threshold (p=0·0044) was not crossed. The most common adverse events with everolimus were stomatitis (314 [67%] of 472 patients in the everolimus group vs 77 [32%] of 238 patients in the placebo group), diarrhoea (267 [57%] vs 111 [47%] patients), and alopecia (221 [47%] vs 125 [53%]). The most frequently reported grade 3 or 4 adverse events in the everolimus group versus the placebo group were neutropenia (117 [25%] vs 35 [15%]), stomatitis (59 [13%] vs three [1%]), anaemia (46 [10%] vs six [3%]) and diarrhoea (43 [9%] vs 10 [4%]) On-treatment adverse event-related deaths were reported in 17 (4%) patients in the everolimus group and none in the placebo group.

INTERPRETATION

Although progression-free survival was not significantly different between groups in the full analysis population, the 7·2 months prolongation we noted with the addition of everolimus in the HR-negative, HER2-positive population warrants further investigation, even if it did not meet prespecified criteria for significance. The safety profile was generally consistent with what was previously reported in BOLERO-3. Proactive monitoring and early management of adverse events in patients given everolimus and chemotherapy is crucial.

FUNDING

Novartis Pharmaceuticals.

Triple positive breast cancer: a distinct subtype?

Breast cancer is a heterogeneous disease, and within the HER-2 positive subtype this is highly exemplified by the presence of substantial phenotypical and clinical heterogeneity, mostly related to hormonal receptor (HR) expression. It is well known how HER-2 positivity is commonly associated with a more aggressive tumor phenotype and decreased overall survival and, moreover, with a reduced benefit from endocrine treatment. Preclinical studies corroborate the role played by functional crosstalks between HER-2 and estrogen receptor (ER) signaling in endocrine resistance and, more recently, the activation of ER signaling is emerging as a possible mechanism of resistance to HER-2 blocking agents. Indeed, HER-2 positive breast cancer heterogeneity has been suggested to underlie the variability of response not only to endocrine treatments, but also to HER-2 blocking agents. Among HER-2 positive tumors, HR status probably defines two distinct subtypes, with dissimilar clinical behavior and different sensitivity to anticancer agents. The triple positive subtype, namely, ER/PgR/Her-2 positive tumors, could be considered the subset which most closely resembles the HER-2 negative/HR positive tumors, with substantial differences in biology and clinical outcome. We argue on whether in this subgroup the "standard" treatment may be considered, in selected cases, i.e., small tumors, low tumor burden, high expression of both hormonal receptors, an overtreatment. This article review the existing literature on biologic and clinical data concerning the HER-2/ER/PgR positive tumors, in an attempt to better define the HER-2 subtypes and to optimize the use of HER-2 targeted agents, chemotherapy and endocrine treatments in the various subsets.

Effectiveness of adjuvant trastuzumab in daily clinical practice

Background

Human epidermal growth factor receptor 2 (HER2) positive breast cancer is an entity with aggressive behaviour. One year of adjuvant trastuzumab significantly improves the disease free survival in the range of 40–50% and reduces the risk of dying from HER2 positive breast cancer by one third. Adjuvant treatment with trastuzumab became available in Slovenia in 2005 and the aim of this study is to explore, if the exceptional results reported in adjuvant clinical trials are achieved also in daily clinical practice.

Patients and methods.

An analysis of tumour and patient characteristics, type of treatment and outcome (relapse free and overall survival) of 313 patients (median age 52 years) treated at the Institute of Oncology Ljubljana in years 2005–2009 was performed.

Results

Median follow-up was 4.4 years. Sixty-one patients relapsed and 24 died. Three and four years relapse free survival was 84.2% and 80.8% and the overall survival was 94.4% and 92.5%, respectively. Independent prognostic factors for relapse were tumour grade (HR 2.10; 95% CI 1.07–4.14; p = 0.031) and nodal stage (HR 1.35; 1.16–1.56; p < 0.0001) and for the overall survival nodal stage only (HR 1.36; 1.05–1.78; p = 0.021).

Conclusions

The outcome in patients with adjuvant trastuzumab in daily clinical practice, treated by medical oncologists, is comparable to results obtained in international adjuvant studies.

Systemic therapy for early-stage HER2-positive breast cancers: time for a less-is-more approach?

Trastuzumab-based chemotherapy has dramatically improved outcomes for patients with all stages of human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Additional HER2-directed agents that have recently been approved are also expected to improve outcomes. Patients with small, lymph node-negative, HER2-positive breast cancers who are treated with trastuzumab-based chemotherapy demonstrate especially favorable responses, with 5-year recurrence rates of <5%. In this review, recent data regarding response rates among patients with early-stage HER2-positive breast cancer treated with trastuzumab-based chemotherapy are discussed. This review supports future studies of the possible omission of chemotherapy in a subset of patients with HER2-positive cancers, specifically those that coexpress hormone receptors.