Prognostic Impact of Discordance in Hormone Receptor Status Between Primary and Recurrent Sites in Patients With Recurrent Breast Cancer

Inactivated cGAS-STING Signaling Facilitates Endocrine Resistance by Forming a Positive Feedback Loop with AKT Kinase in ER+HER2- Breast Cancer

Endocrine-resistant ER+HER2- breast cancer (BC) is particularly aggressive and leads to poor clinical outcomes. Effective therapeutic strategies against endocrine-resistant BC remain elusive. Here, analysis of the RNA-sequencing data from ER+HER2- BC patients receiving neoadjuvant endocrine therapy and spatial transcriptomics analysis both show the downregulation of innate immune signaling sensing cytosolic DNA, which primarily occurs in endocrine-resistant BC cells, not immune cells. Indeed, compared with endocrine-sensitive BC cells, the activity of sensing cytosolic DNA through the cGAS-STING pathway is attenuated in endocrine-resistant BC cells. Screening of kinase inhibitor library show that this effect is mainly mediated by hyperactivation of AKT1 kinase, which binds to kinase domain of TBK1, preventing the formation of a trimeric complex TBK1/STING/IRF3. Notably, inactivation of cGAS-STING signaling forms a positive feedback loop with hyperactivated AKT1 to promote endocrine resistance, which is physiologically important and clinically relevant in patients with ER+HER2- BC. Blocking the positive feedback loop using the combination of an AKT1 inhibitor with a STING agonist results in the engagement of innate and adaptive immune signaling and impairs the growth of endocrine-resistant tumors in humanized mice models, providing a potential strategy for treating patients with endocrine-resistant BC.

Biomarker conversion from primary breast cancer to synchronous axillary lymph node metastasis and neoadjuvant therapy response: a single-center analysis

PURPOSE

The biomarker characteristics of breast cancer plays an important role in predicting treatment sensitivity. The aim of the present study was to compare immunohistochemical profiles (ER, PR, HER2, and Ki67) between the primary tumor and synchronous axillary lymph node metastasis and investigate the subsequent effects on neoadjuvant therapy response.

METHODS

A total of 358 patients with pathologically confirmed synchronous axillary lymph node metastasis at first diagnosis and treated by neoadjuvant therapy at Peking University First Hospital from January 1, 2013 to December 31, 2022 were included in this retrospective study. Clinicopathologic data, especially receptor status in primary and metastatic foci, was collected for each case.

RESULTS

Change of ER, PR, HER2, and Ki67 expression was observed in 5.9%, 8.7%, 12.6%, and 17.3% of patients, respectively. HR discordance was observed more frequently when the ER status (p = 0.023) or PR status (p = 0.010) of primary tumor was negative, while HER2 discordance seemed to be more frequent when the HER2 status of primary tumor was HER2-0 or HER2-low (p < 0.001). Patients with loss of HR-positivity (positive to negative) responded to neoadjuvant chemotherapy better compared to those with stable positive HR expression (50% vs. 11.1%, p = 0.0017). A significantly decrease in pCR rate was observed in patients with unstable HER2 status, but not in the HER2-0/HER2-low subgroup.

CONCLUSION

Receptor discordance between primary tumor and synchronous axillary LNM appears to already exist before any anti-tumor therapy. This instability has limited clinical impact on the choice of neoadjuvant therapy at current stage, but further investigation is warranted with the incremental application of endocrine drugs and ADCs in neoadjuvant therapy.

Early prediction of endocrine responsiveness in ER+/HER2-negative metastatic breast cancer (MBC): pilot study with 18F-fluoroestradiol (18F-FES) CT/PET

BACKGROUND

18F-fluoroestradiol (FES) positron emission tomography (PET)/computed tomography (CT) is considered an accurate diagnostic tool to determine whole-body endocrine responsiveness. In the endocrine therapy (ET)-FES trial, we evaluated 18F-FES PET/CT as a predictive tool in estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC).

PATIENTS AND METHODS

Eligible patients underwent an 18F-FES PET/CT at baseline. Patients with standardized uptake value (SUV) ≥ 2 received single-agent ET until progressive disease; patients with SUV < 2 were randomized to single-agent ET (arm A) or chemotherapy (ChT) (arm B). The primary objective was to compare the activity of first-line ET versus ChT in patients with 18F-FES SUV < 2.

RESULTS

Overall, 147 patients were enrolled; 117 presented with 18F-FES SUV ≥ 2 and received ET; 30 patients with SUV < 2 were randomized to ET or ChT. After a median follow-up of 62.4 months, 104 patients (73.2%) had disease progression and 53 died (37.3%). Median progression-free survival (PFS) was 12.4 months [95% confidence interval (CI) 3.1-59.6 months] in patients with SUV < 2 randomized to arm A versus 23.0 months (95% CI 7.7-30.0 months) in arm B, [hazard (HR) = 0.71, 95% CI 0.3-1.7 months]; median PFS was 18.0 months (95% CI 11.2-23.1 months) in patients with SUV ≥ 2 treated with ET. Median overall survival (OS) was 28.2 months (95% CI 14.2 months-not estimable) in patients with SUV < 2 randomized to ET (arm A) versus 52.8 months (95% CI 16.2 months-not estimable) in arm B (ChT). Median OS was not reached in patients with SUV ≥ 2. 60-month OS rate was 41.6% (95% CI 10.4% to 71.1%) in arm A, 42.0% (95% CI 14.0% to 68.2%) in arm B, and 59.6% (95% CI 48.6% to 69.0%) in patients with SUV ≥ 2. In patients with SUV ≥ 2, 60-month OS rate was 72.6% if treated with aromatase inhibitors (AIs) versus 40.6% in case of fulvestrant or tamoxifen (P < 0.005).

CONCLUSIONS

The ET-FES trial demonstrated that ER+/HER2- MBC patients are a heterogeneous population, with different levels of endocrine responsiveness based on 18F-FES CT/PET SUV.

Novel Endocrine Therapeutic Opportunities for Estrogen Receptor-Positive Ovarian Cancer-What Can We Learn from Breast Cancer?

Low-grade serous ovarian cancer (LGSOC) is a rare ovarian malignancy primarily affecting younger women and is characterized by an indolent growth pattern. It exhibits indolent growth and high estrogen/progesterone receptor expression, suggesting potential responsiveness to endocrine therapy. However, treatment efficacy remains limited due to the development of endocrine resistance. The mechanisms of resistance, whether primary or acquired, are still largely unknown and present a significant hurdle in achieving favorable treatment outcomes with endocrine therapy in these patients. In estrogen receptor-positive breast cancer, mechanisms of endocrine resistance have been largely explored and novel treatment strategies to overcome resistance have emerged. Considering the shared estrogen receptor positivity in LGSOC and breast cancer, we wanted to explore whether there are any parallel mechanisms of resistance and whether we can extend endocrine breast cancer treatments to LGSOC. This review aims to highlight the underlying molecular mechanisms possibly driving endocrine resistance in ovarian cancer, while also exploring the available therapeutic opportunities to overcome this resistance. By unraveling the potential pathways involved and examining emerging strategies, this review explores valuable insights for advancing treatment options and improving patient outcomes in LGSOC, which has limited therapeutic options available.

Epigenetic deregulation in breast cancer microenvironment: Implications for tumor progression and therapeutic strategies

Breast cancer comprises a substantial proportion of cancer diagnoses in women and is a primary cause of cancer-related mortality. While hormone-responsive cases generally have a favorable prognosis, the aggressive nature of triple-negative breast cancer presents challenges, with intrinsic resistance to established treatments being a persistent issue. The complexity intensifies with the emergence of acquired resistance, further complicating the management of breast cancer. Epigenetic changes, encompassing DNA methylation, histone and RNA modifications, and non-coding RNAs, are acknowledged as crucial contributors to the heterogeneity of breast cancer. The unique epigenetic landscape harbored by each cellular component within the tumor microenvironment (TME) adds great diversity to the intricate regulations which influence therapeutic responses. The TME, a sophisticated ecosystem of cellular and non-cellular elements interacting with tumor cells, establishes an immunosuppressive microenvironment and fuels processes such as tumor growth, angiogenesis, and extracellular matrix remodeling. These factors contribute to challenging conditions in cancer treatment by fostering a hypoxic environment, inducing metabolic stress, and creating physical barriers to drug delivery. This article delves into the complex connections between breast cancer treatment response, underlying epigenetic changes, and vital interactions within the TME. To restore sensitivity to treatment, it emphasizes the need for combination therapies considering epigenetic changes specific to individual members of the TME. Recognizing the pivotal role of epigenetics in drug resistance and comprehending the specificities of breast TME is essential for devising more effective therapeutic strategies. The development of reliable biomarkers for patient stratification will facilitate tailored and precise treatment approaches.

MCM2 is involved in subtyping and tamoxifen resistance of ERα-positive breast cancer by acting as the downstream factor of ERα

Tamoxifen (TAM) resistance is finally developed in over 40% of patients with estrogen receptor α-positive breast cancer (ERα+ -BC), documenting that discovering new molecular subtype is needed to confer perception to the heterogeneity of ERα+ -BC. We obtained representative gene sets subtyping ERα+ -BC using gene set variation analysis (GSVA), non-negative matrix factorization (NMF), and COX regression methods on the basis of METABRIC, TCGA, and GEO databases. Furthermore, the risk score of ERα+ -BC subtyping was established using least absolute shrinkage and selection operator (LASSO) regression on the basis of genes in the representative gene sets, thereby generating the two subtypes of ERα+ -BC. We further found that minichromosome maintenance complex component 2 (MCM2) functioned as the hub gene subtyping ERα+ -BC using GO, KEGG, and MCODE. MCM2 expression was capable for specifically predicting 1-year overall survival (OS) of ERα+ -BC and correlated with T stage, AJCC stage, and tamoxifen (TAM) sensitivity of ERα+ -BC. The downregulation of MCM2 expression inhibited proliferation, migration, and invasion of TAM-resistant cells and promoted G0/G1 arrest. Altogether, tamoxifen resistance entails that MCM2 is a hub gene subtyping ERα+ -BC, providing a novel dimension for discovering a potential target of TAM-resistant BC.

Proteomics on malignant pleural effusions reveals ERα loss in metastatic breast cancer associates with SGK1-NDRG1 deregulation

Breast cancer (BCa) is a highly heterogeneous disease, with hormone receptor status being a key factor in patient prognostication and treatment decision-making. The majority of primary tumours are positive for oestrogen receptor alpha (ERα), which plays a key role in tumorigenesis and disease progression, and represents the major target for treatment of BCa. However, around one-third of patients with ERα-positive BCa relapse and progress into the metastatic stage, with 20% of metastatic cases characterised by loss of ERα expression after endocrine treatment, known as ERα-conversion. It remains unclear whether ERα-converted cancers are biologically similar to bona fide ERα-negative disease and which signalling cascades compensate for ERα loss and drive tumour progression. To better understand the biological changes that occur in metastatic BCa upon ERα loss, we performed (phospho)proteomics analysis of 47 malignant pleural effusions derived from 37 BCa patients, comparing ERα-positive, ERα-converted and ERα-negative cases. Our data revealed that the loss of ERα-dependency in this metastatic site leads to only a partial switch to an ERα-negative molecular phenotype, with preservation of a luminal-like proteomic landscape. Furthermore, we found evidence for decreased activity of several key kinases, including serum/glucocorticoid regulated kinase 1 (SGK1), in ERα-converted metastases. Loss of SGK1 substrate phosphorylation may compensate for the loss of ERα-dependency in advanced disease and exposes a potential therapeutic vulnerability that may be exploited in treating these patients.

Estrogen Therapy Induces Receptor-Dependent DNA Damage Enhanced by PARP Inhibition in ER+ Breast Cancer

PURPOSE

Clinical evidence indicates that treatment with estrogens elicits anticancer effects in ∼30% of patients with advanced endocrine-resistant estrogen receptor α (ER)-positive breast cancer. Despite the proven efficacy of estrogen therapy, its mechanism of action is unclear and this treatment remains underused. Mechanistic understanding may offer strategies to enhance therapeutic efficacy.

EXPERIMENTAL DESIGN

We performed genome-wide CRISPR/Cas9 screening and transcriptomic profiling in long-term estrogen-deprived ER+ breast cancer cells to identify pathways required for therapeutic response to the estrogen 17β-estradiol (E2). We validated findings in cell lines, patient-derived xenografts (PDX), and patient samples, and developed a novel combination treatment through testing in cell lines and PDX models.

RESULTS

Cells treated with E2 exhibited replication-dependent markers of DNA damage and the DNA damage response prior to apoptosis. Such DNA damage was partially driven by the formation of DNA:RNA hybrids (R-loops). Pharmacologic suppression of the DNA damage response via PARP inhibition with olaparib enhanced E2-induced DNA damage. PARP inhibition synergized with E2 to suppress growth and prevent tumor recurrence in BRCA1/2-mutant and BRCA1/2-wild-type cell line and PDX models.

CONCLUSIONS

E2-induced ER activity drives DNA damage and growth inhibition in endocrine-resistant breast cancer cells. Inhibition of the DNA damage response using drugs such as PARP inhibitors can enhance therapeutic response to E2. These findings warrant clinical exploration of the combination of E2 with DNA damage response inhibitors in advanced ER+ breast cancer, and suggest that PARP inhibitors may synergize with therapeutics that exacerbate transcriptional stress.

Dependency of Tamoxifen Sensitive and Resistant ER+ Breast Cancer Cells on Semaphorin 3C (SEMA3C) for Growth

Estrogen receptor positive (ER+) breast cancer (BCa) accounts for the highest proportion of breast cancer-related deaths. While endocrine therapy is highly effective for this subpopulation, endocrine resistance remains a major challenge and the identification of novel targets is urgently needed. Previously, we have shown that Semaphorin 3C (SEMA3C) is an autocrine growth factor that drives the growth and treatment resistance of various cancers, but its role in breast cancer progression and endocrine resistance is poorly understood. Here, we report that SEMA3C plays a role in maintaining the growth of ER+ BCa cells and is a novel, tractable therapeutic target for the treatment of ER+ BCa patients. Analyses of publicly available clinical datasets indicate that ER+ BCa patients express significantly higher levels of SEMA3C mRNA than other subtypes. Furthermore, SEMA3C mRNA expression was positively correlated with ESR1 mRNA expression. ER+ BCa cell lines (MCF7 and T47D) expressed higher levels of SEMA3C mRNA and protein than a normal mammary epithelial MCF10A cell line. ER siRNA knockdown was suppressed, while dose-dependent beta-estradiol treatment induced SEMA3C expression in both MCF7 and T47D cells, suggesting that SEMA3C is an ER-regulated gene. The stimulation of ER+ BCa cells with recombinant SEMA3C activated MAPK and AKT signaling in a dose-dependent manner. Conversely, SEMA3C silencing inhibited Estrogen Receptor (ER) expression, MAPK and AKT signaling pathways while simultaneously inducing apoptosis, as monitored by flow cytometry and Western blot analyses. SEMA3C silencing significantly inhibited the growth of ER+ BCa cells, implicating a growth dependency of ER+ BCa cells on SEMA3C. Moreover, the analysis of tamoxifen resistant (TamR) cell models (TamC3 and TamR3) showed that SEMA3C levels remain high despite treatment with tamoxifen. Tamoxifen-resistant cells remained dependent on SEMA3C for growth and survival. Treatment with B1SP Fc fusion protein, a SEMA3C pathway inhibitor, attenuated SEMA3C-induced signaling and growth across a panel of tamoxifen sensitive and resistant ER+ breast cancer cells. Furthermore, SEMA3C silencing and B1SP treatment were associated with decreased EGFR signaling in TamR cells. Here, our study implicates SEMA3C in a functional role in ER+ breast cancer signaling and growth that suggests ER+ BCa patients may benefit from SEMA3C-targeted therapy.

Stratification of Tamoxifen Synergistic Combinations for the Treatment of ER+ Breast Cancer

Breast cancer alone accounts for the majority of cancer deaths among women, with the most commonly diagnosed subtype being estrogen receptor positive (ER+). Survival has greatly improved for patients with ER+ breast cancer, due in part to the development of antiestrogen compounds, such as tamoxifen. While treatment of the primary disease is often successful, as many as 30% of patients will experience recurrence and metastasis, mainly due to developed endocrine therapy resistance. In this study, we discovered two tamoxifen combination therapies, with simeprevir and VX-680, that reduce the tumor burden in animal models of ER+ breast cancer more than either compound or tamoxifen alone. Additionally, these tamoxifen combinations reduced the expression of HER2, a hallmark of tamoxifen treatment, which can facilitate acquisition of a treatment-resistant phenotype. These combinations could provide clinical benefit by potentiating tamoxifen treatment in ER+ breast cancer.

Oral selective estrogen receptor degraders (SERDs): The new emperors in breast cancer clinical practice?

Endocrine therapy (ET) targeting estrogen receptor (ER) signaling is still the mainstay treatment option for early or advanced ER-positive breast cancer (BC) and may involve suppressing estrogen production by means of aromatase inhibitors or directly blocking the ER pathway through selective estrogen receptor modulators such as tamoxifen or selective estrogen receptor degraders such as fulvestrant. However, despite the availability of this armamentarium in clinical practice, de novo or acquired resistance to ET is the main cause of endocrine-based treatment failure leading to the progression of the BC. Recent advances in targeting, modulating, and degrading ERs have led to the development of new drugs capable of overcoming intrinsic or acquired ET resistance related to alterations in the ESR1 gene. The new oral selective estrogen receptor degraders, which are capable of reducing ER protein expression and blocking estrogen-dependent and -independent ER signaling, have a broader spectrum of activity against ESR1 mutations and seem to be a promising means of overcoming the failure of standard ET. The aim of this review is to summarize the development of oral selective estrogen receptor degraders, their current status, and their future perspectives.

Estrogen therapy induces receptor-dependent DNA damage enhanced by PARP inhibition in ER+ breast cancer

Purpose

Clinical evidence indicates that treatment with estrogens elicits anti-cancer effects in ∼30% of patients with advanced endocrine-resistant estrogen receptor alpha (ER)-positive breast cancer. Despite the proven efficacy of estrogen therapy, its mechanism of action is unclear and this treatment remains under-utilized. Mechanistic understanding may offer strategies to enhance therapeutic efficacy.

Experimental Design

We performed genome-wide CRISPR/Cas9 screening and transcriptomic profiling in long-term estrogen-deprived (LTED) ER+ breast cancer cells to identify pathways required for therapeutic response to the estrogen 17β-estradiol (E2). We validated findings in cell lines, patient-derived xenografts (PDXs), and patient samples, and developed a novel combination treatment through testing in cell lines and PDX models.

Results

Cells treated with E2 exhibited replication-dependent markers of DNA damage and the DNA damage response prior to apoptosis. Such DNA damage was partially driven by the formation of DNA:RNA hybrids (R-loops). Pharmacological suppression of the DNA damage response via poly(ADP-ribose) polymerase (PARP) inhibition with olaparib enhanced E2-induced DNA damage. PARP inhibition synergized with E2 to suppress growth and prevent tumor recurrence in BRCA1/2 -mutant and BRCA1 /2-wild-type cell line and PDX models.

Conclusions

E2-induced ER activity drives DNA damage and growth inhibition in endocrine-resistant breast cancer cells. Inhibition of the DNA damage response using drugs such as PARP inhibitors can enhance therapeutic response to E2. These findings warrant clinical exploration of the combination of E2 with DNA damage response inhibitors in advanced ER+ breast cancer, and suggest that PARP inhibitors may synergize with therapeutics that exacerbate transcriptional stress.

Network-informed discovery of multidrug combinations for ERα+/HER2-/PI3Kα-mutant breast cancer

Breast cancer is a persistent threat to women worldwide. A large proportion of breast cancers are dependent on the estrogen receptor α (ERα) for tumor progression. Therefore, targeting ERα with antagonists, such as tamoxifen, or estrogen deprivation by aromatase inhibitors remain standard therapies for ERα + breast cancer. The clinical benefits of monotherapy are often counterbalanced by off-target toxicity and development of resistance. Combinations of more than two drugs might be of great therapeutic value to prevent resistance, and to reduce doses, and hence, decrease toxicity. We mined data from the literature and public repositories to construct a network of potential drug targets for synergistic multidrug combinations. With 9 drugs, we performed a phenotypic combinatorial screen with ERα + breast cancer cell lines. We identified two optimized low-dose combinations of 3 and 4 drugs of high therapeutic relevance to the frequent ERα + /HER2-/PI3Kα-mutant subtype of breast cancer. The 3-drug combination targets ERα in combination with PI3Kα and cyclin-dependent kinase inhibitor 1 (p21). In addition, the 4-drug combination contains an inhibitor for poly (ADP-ribose) polymerase 1 (PARP1), which showed benefits in long-term treatments. Moreover, we validated the efficacy of the combinations in tamoxifen-resistant cell lines, patient-derived organoids, and xenograft experiments. Thus, we propose multidrug combinations that have the potential to overcome the standard issues of current monotherapies.

Case report: Response to endocrine therapy in triple-negative breast cancer metastases with altered hormone receptors

Triple-negative breast cancer refers to breast cancer patients with negative estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor (HER2). Metastatic triple-negative breast cancer is predominantly treated with chemotherapy, but later-line treatment remains challenging. Breast cancer is highly heterogeneous, and the expression of hormone receptors is often inconsistent between primary and metastatic lesions. Here, we report a case of triple-negative breast cancer 17 years after surgery with lung metastases for 5 years that progressed to pleural metastases after multiple lines of chemotherapy. The pleural pathology suggested ER (+) and PR (+) and transformation to luminal A breast cancer. This patient received fifth-line letrozole endocrine therapy and achieved partial response (PR). The patient's cough and chest tightness improved after treatment, associated tumor markers decreased, and progression-free survival (PFS) exceeded 10 months. Our results may be of clinical relevance for patients with hormone receptor alterations in advanced triple-negative breast cancer and suggest that individualized regimens should be developed for breast cancer based on the molecular expression of tumor tissue at the primary and metastatic sites.

[Therapeutic strategies for the treatment of endocrine resistant hormone receptor positive advanced breast cancer]

HR+ breast cancers are defined by the prominence of signaling pathways dependent on the estrogen receptor. Endocrine therapy is the standard treatment for these advanced diseases. Resistance to these treatments, called hormone resistance, appears invariably with biological mechanisms that have led to the development of therapeutic opportunities. An exhaustive literature review was carried out concerning the biology of the hormone resistance pathways, the therapeutic options before the era of CDK4/6 inhibitors, the rise of CDK4/6 inhibitors and the therapeutic prospects in a situation of hormone resistance. Various biological abnormalities have been identified in the mechanisms of hormone resistance such as changes in the estrogen receptor, mutations in the ESR1 gene, aberrant activation of the PI3K pathway or cell cycle deregulations. Historical strategies for circumventing this hormone resistance have been based on hormonal manipulation, on the development of new endocrine therapy such as fulvestrant (selective estrogen receptor inhibitor, SERD), on combinations of treatments such as everolimus, a mTOR inhibitor. This strategy combining endocrine therapy and targeted therapy has led to the development of combinations with CDK4/6 inhibitors which have now become a standard treatment in the hormone resistance phase. The future of this therapeutic era remains to be written with new combinations of hormone therapy and targeted therapy such as PI3K inhibitors or even with the positioning of new SERDs in clinical development.

Hypoxia and ERα Transcriptional Crosstalk Is Associated with Endocrine Resistance in Breast Cancer

Simple Summary

Hormone receptor positive breast cancer patients are treated with anti-hormone molecules as a standard of care. However, resistance frequently occurs, leading to hormone resistant metastatic relapses in foreign organs. Understanding the molecular mechanisms through which breast cancer cells evade therapeutic pressure is of paramount interest. Hypoxia, which refers to oxygen deprivation and is characterized by the activation of hypoxia inducible factors, is a common feature of the solid tumor microenvironment, yet its influence on estrogen receptor alpha activity remains elusive. Here, we investigate the consequence of hypoxia and the signaling of hypoxia inducible factors on hormone responsiveness in breast cancer cells and its clinical implications.

Abstract

Estrogen receptor-alpha (ERα) is the driving transcription factor in 70% of breast cancers and its activity is associated with hormone dependent tumor cell proliferation and survival. Given the recurrence of hormone resistant relapses, understanding the etiological factors fueling resistance is of major clinical interest. Hypoxia, a frequent feature of the solid tumor microenvironment, has been described to promote endocrine resistance by triggering ERα down-regulation in both in vitro and in vivo models. Yet, the consequences of hypoxia on ERα genomic activity remain largely elusive. In the present study, transcriptomic analysis shows that hypoxia regulates a fraction of ERα target genes, underlying an important regulatory overlap between hypoxic and estrogenic signaling. This gene expression reprogramming is associated with a massive reorganization of ERα cistrome, highlighted by a massive loss of ERα binding sites. Profiling of enhancer acetylation revealed a hormone independent enhancer activation at the vicinity of genes harboring hypoxia inducible factor (HIFα) binding sites, the major transcription factors governing hypoxic adaptation. This activation counterbalances the loss of ERα and sustains hormone-independent gene expression. We describe hypoxia in luminal ERα (+) breast cancer as a key factor interfering with endocrine therapies, associated with poor clinical prognosis in breast cancer patients.

Epigenetic factors in breast cancer therapy

Epigenetic modifications are inherited differences in cellular phenotypes, such as cell gene expression alterations, that occur during somatic cell divisions (also, in rare circumstances, in germ line transmission), but no alterations to the DNA sequence are involved. Histone alterations, polycomb/trithorax associated proteins, short non-coding or short RNAs, long non—coding RNAs (lncRNAs), & DNA methylation are just a few biological processes involved in epigenetic events. These various modifications are intricately linked. The transcriptional potential of genes is closely conditioned by epigenetic control, which is crucial in normal growth and development. Epigenetic mechanisms transmit genomic adaptation to an environment, resulting in a specific phenotype. The purpose of this systematic review is to glance at the roles of Estrogen signalling, polycomb/trithorax associated proteins, DNA methylation in breast cancer progression, as well as epigenetic mechanisms in breast cancer therapy, with an emphasis on functionality, regulatory factors, therapeutic value, and future challenges.

Comprehensive Transcriptomic and Proteomic Analyses Identify a Candidate Gene Set in Cross-Resistance for Endocrine Therapy in Breast Cancer

Endocrine therapy (ET) of selective estrogen receptor modulators (SERMs), selective estrogen receptor downregulators (SERDs), and aromatase inhibitors (AIs) has been used as the gold standard treatment for hormone-receptor-positive (HR+) breast cancer. Despite its clinical benefits, approximately 30% of patients develop ET resistance, which remains a major clinical challenge in patients with HR+ breast cancer. The mechanisms of ET resistance mainly focus on mutations in the ER and related pathways; however, other targets still exist from ligand-independent ER reactivation. Moreover, mutations in the ER that confer resistance to SERMs or AIs seldom appear in SERDs. To date, little research has been conducted to identify a critical target that appears in both SERMs/SERDs and AIs. In this study, we conducted comprehensive transcriptomic and proteomic analyses from two cohorts of The Cancer Genome Atlas Breast Invasive Carcinoma (TCGA-BRCA) to identify the critical targets for both SERMs/SERDs and AIs of ET resistance. From a treatment response cohort with treatment response for the initial ET regimen and an endocrine therapy cohort with survival outcomes, we identified candidate gene sets that appeared in both SERMs/SERDs and AIs of ET resistance. The candidate gene sets successfully differentiated progress/resistant groups (PD) from complete response groups (CR) and were significantly correlated with survival outcomes in both cohorts. In summary, this study provides valuable clinical implications for the critical roles played by candidate gene sets in the diagnosis, mechanism, and therapeutic strategy for both SERMs/SERDs and AIs of ET resistance for the future.

The role of epigenetic modifications in drug resistance and treatment of breast cancer

Background

Breast cancer is defined as a biological and molecular heterogeneous disorder that originates from breast cells. Genetic predisposition is the most important factor giving rise to this malignancy. The most notable mutations in breast cancer occur in the BRCA1 and BRCA2 genes. Owing to disease heterogeneity, lack of therapeutic target, anti-cancer drug resistance, residual disease, and recurrence, researchers are faced with challenges in developing strategies to treat patients with breast cancer.

Results

It has recently been reported that epigenetic processes such as DNA methylation and histone modification, as well as microRNAs (miRNAs), have potently contributed to the pathophysiology, diagnosis, and treatment of breast cancer. These observations have persuaded researchers to move their therapeutic approaches beyond the genetic framework toward the epigenetic concept.

Conclusion

Herein we discuss the molecular and epigenetic mechanisms underlying breast cancer progression and resistance as well as various aspects of epigenetic-based therapies as monotherapy and combined with immunotherapy.

In vitro breast cancer models for studying mechanisms of resistance to endocrine therapy

The development of endocrine resistance is a common reason for the failure of endocrine therapies in hormone receptor-positive breast cancer. This review provides an overview of the different types of in vitro models that have been developed as tools for studying endocrine resistance. In vitro models include cell lines that have been rendered endocrine-resistant by ex vivo treatment; cell lines with de novo resistance mechanisms, including genetic alterations; three-dimensional (3D) spheroid, co-culture, and mammosphere techniques; and patient-derived organoid models. In each case, the key discoveries, different analysis strategies that are suitable, and strengths and weaknesses are discussed. Certain recently developed methodologies that can be used to further characterize the biological changes involved in endocrine resistance are then emphasized, along with a commentary on the types of research outcomes that using these techniques can support. Finally, a discussion anticipates how these recent developments will shape future trends in the field. We hope this overview will serve as a useful resource for investigators that are interested in understanding and testing hypotheses related to mechanisms of endocrine therapy resistance.

The initial hormone receptor/HER2 subtype is the main determinator of subtype discordance in advanced breast cancer: a study of the SONABRE registry

Purpose

The hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) are the main parameters in guiding systemic treatment choices in breast cancer, but can change during the disease course. This study aims to evaluate the biopsy rate and receptor subtype discordance rate in patients diagnosed with advanced breast cancer (ABC).

Methods

Patients diagnosed with ABC in seven hospitals in 2007–2018 were selected from the SOutheast Netherlands Advanced BREast cancer (SONABRE) registry. Multivariable logistic regression analyses were performed to identify factors influencing biopsy and discordance rates.

Results

Overall, 60% of 2854 patients had a biopsy of a metastatic site at diagnosis. One of the factors associated with a reduced biopsy rate was the HR + /HER2 + primary tumor subtype (versus HR + /HER2- subtype: OR = 0.68; 95% CI: 0.51–0.90). Among the 748 patients with a biopsy of the primary tumor and a metastatic site, the overall receptor discordance rate was 18%. This was the highest for the HR + /HER2 + primary tumor subtype, with 55%. In 624 patients with metachronous metastases, the HR + /HER2 + subtype remained the only predictor significantly related to a higher discordance rate, irrespective of prior (neo-)adjuvant therapies (OR = 7.49; 95% CI: 3.69–15.20).

Conclusion

The HR + /HER2 + subtype has the highest discordance rate, but the lowest biopsy rate of all four receptor subtypes. Prior systemic therapy was not independently related to subtype discordance. This study highlights the importance of obtaining a biopsy of metastatic disease, especially in the HR + /HER2 + subtype to determine the most optimal treatment strategy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10549-021-06472-5.

Next-generation selective estrogen receptor degraders and other novel endocrine therapies for management of metastatic hormone receptor-positive breast cancer: current and emerging role

Endocrine therapy (ET) is a pivotal strategy to manage early- and advanced-stage estrogen receptor-positive (ER+) breast cancer. In patients with metastatic breast cancer (MBC), progression of disease inevitably occurs due to the presence of acquired or intrinsic resistance mechanisms. ET resistance can be driven by ligand-independent, ER-mediated signaling that promotes tumor proliferation in the absence of hormone, or ER-independent oncogenic signaling that circumvents endocrine regulated transcription pathways. Estrogen receptor 1 (ESR1) mutations induce constitutive ER activity and upregulate ER-dependent gene transcription, provoking resistance to estrogen deprivation and aromatase inhibitor therapy. The role ESR1 mutations play in regulating response to other therapies, such as the selective estrogen receptor degrader (SERD) fulvestrant and the available CDK4/6 inhibitors, is less clear. Novel oral SERDs and other next-generation ETs are in clinical development for ER+ breast cancer as single agents and in combination with established targeted therapies. Recent results from the phase III EMERALD trial demonstrated improved outcomes with the oral SERD elacestrant compared to standard anti-estrogen therapies in ER+ MBC after prior progression on ET, and other agents have shown promise in both the laboratory and early-phase clinical trials. In this review, we will discuss the emerging data related to oral SERDs and other novel ET in managing ER+ breast cancer. As clinical data continue to mature on these next-generation ETs, important questions will emerge related to the optimal sequence of therapeutic options and the genomic and molecular landscape of resistance to these agents.

A systematic literature review of prognostic factors in patients with HR+/HER2- advanced breast cancer in Japan

BACKGROUND

Breast cancer is the most prevalent cancer in women in Japan and the fifth in mortality. This systematic review summarized the evidence for prognostic factors for patients with HR+/HER2- advanced and metastatic breast cancer in Japan.

METHODS

MEDLINE and EMBASE were searched with keywords 'breast neoplasms' AND 'Japan' AND 'advanced' or equivalent, and Japan Medical Abstract Society database with 'breast cancer' AND 'advanced/metastatic' for publications from January 2010 to October 2019. ASCO, ESMO, ABC4 abstracts and WHO website were hand searched. The endpoints of interest were overall survival, progression-free survival, tumour response and post-progression survival. Factors were evaluated based on the consistency in direction and the strength (hazard ratios) of association.

RESULTS

Searches identified 4530 publications, of which 27 were eligible. All were observational studies. Among the endpoints, overall survival was the most commonly assessed (n = 22) and evaluated further. Ki-67 expression, progesterone receptor expression status, tumour grade and lymph node metastases were consistently associated with poor overall survival in univariate analysis but not in multivariate analysis. Short disease-free interval, the number of metastatic organs and liver metastasis were consistently associated with poor overall survival in both of univariate and multivariate analysis. The association was strong for liver metastasis (hazard ratio ≥2.8 in the majority of studies) and moderate for disease-free interval and the number of metastatic organs (hazard ratio 1.3-2.8 in the majority of studies).

CONCLUSIONS

Disease-free interval, the number of metastatic organs and liver metastasis were identified as independent prognostic factors for overall survival. These findings may help clinical decision-making to improve outcomes in patients with HR+/HER2- advanced and metastatic breast cancer.

Oral Selective Estrogen Receptor Degraders (SERDs) as a Novel Breast Cancer Therapy: Present and Future from a Clinical Perspective

Estrogen receptor-positive (ER+) is the most common subtype of breast cancer. Endocrine therapy is the fundamental treatment against this entity, by directly or indirectly modifying estrogen production. Recent advances in novel compounds, such as cyclin-dependent kinase 4/6 inhibitors (CDK4/6i), or phosphoinositide 3-kinase (PI3K) inhibitors have improved progression-free survival and overall survival in these patients. However, some patients still develop endocrine resistance after or during endocrine treatment. Different underlying mechanisms have been identified as responsible for endocrine treatment resistance, where ESR1 gene mutations are one of the most studied, outstanding from others such as somatic alterations, microenvironment involvement and epigenetic changes. In this scenario, selective estrogen receptor degraders/downregulators (SERD) are one of the weapons currently in research and development against aromatase inhibitor- or tamoxifen-resistance. The first SERD to be developed and approved for ER+ breast cancer was fulvestrant, demonstrating also interesting activity in ESR1 mutated patients in the second line treatment setting. Recent investigational advances have allowed the development of new oral bioavailable SERDs. This review describes the evolution and ongoing studies in SERDs and new molecules against ER, with the hope that these novel drugs may improve our patients’ future landscape.

Association of Biomarker Discrepancy and Treatment Decision, Disease Outcome in Recurrent/Metastatic Breast Cancer Patients

Background

Biomarker discrepancy between primary and recurrent/metastatic breast cancer is well known, however its impact on prognosis and treatment after relapse is still unclear. Current study aims to evaluate biomarkers discrepancy between primary and recurrent/metastatic lesions as well as to investigate its association with following treatment pattern and disease outcome.

Patients and methods

We retrospectively included consecutive breast cancer patients undergoing surgery in our center from Jan. 2009 to Dec. 2016 and reported disease recurrence. Patients with re-biopsy and paired biomarkers statuses on primary and recurrent/metastatic lesions were further analyzed. Kappa test was used to analyze the concordance rate of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2) status. Post-recurrence survival (PRS) was compared between subgroups by Kaplan-Meier curve. Cox regression model was applied to identify impact factors for PRS.

Results

A total of 156 patients were finally included, of whom 70 and 86 had loco-regional and distant recurrence, respectively. Concordance rates of ER, PR and HER2 were 83.3%, 66.7%, and 97.1%, respectively, which was similarly distributed among different recurrent sites (all P > 0.05). Primary ER-positivity (vs ER-negativity, P = 0.014) and loco-regional recurrence (vs distant metastasis, P = 0.001) were independently associated with superior PRS, while patients with visceral metastasis (P < 0.001) had the worst disease outcome. Hormone receptor/HER2 status discrepancy was observed in 28 patients. Fifteen of them changed systemic treatment based on biomarker statuses of recurrent lesion, however, their PRS was not improved compared to those 13 patients who continued the same treatment according to primary biomarkers statuses (P = 0.298).

Conclusion

Biomarker discrepancy was observed between primary and recurrent/metastatic breast cancer lesions and had certain influence on treatment strategies after relapse. However, its impact on disease outcome wasn’t established in the current study, which deserves further evaluation.

Epigenetic mechanisms in breast cancer therapy and resistance

The majority of breast cancers express the estrogen receptor (ERα) and agents targeting this pathway represent the main treatment modality. Endocrine therapy has proven successful in the treatment of hormone-responsive breast cancer since its early adoption in the 1940s as an ablative therapy. Unfortunately, therapeutic resistance arises, leading to disease recurrence and relapse. Recent studies increased our understanding in how changes to the chromatin landscape and deregulation of epigenetic factors orchestrate the resistant phenotype. Here, we will discuss how the epigenome is an integral determinant in hormone therapy response and why epigenetic factors are promising targets for overcoming clinical resistance.

Endocrine therapy has been the mainstay for hormone responsive breast cancer treatment. Here, Garcia-Martinez and colleagues discuss epigenetic mechanisms regulating ER + breast cancer and endocrine therapy resistance, and highlight approaches to rewire the cancer epigenome to improve targeted therapies for this cancer.

The lingering mysteries of metastatic recurrence in breast cancer

Despite being the hallmark of cancer that is responsible for the highest number of deaths, very little is known about the biology of metastasis. Metastatic disease typically manifests after a protracted period of undetectable disease following surgery or systemic therapy, owing to relapse or recurrence. In the case of breast cancer, metastatic relapse can occur months to decades after initial diagnosis and treatment. In this review, we provide an overview of the known key factors that influence metastatic recurrence, with the goal of highlighting the critical unanswered questions that still need to be addressed to make a difference in the mortality of breast cancer patients.

Significance of the Genomic Landscape of a De Novo Endocrine-Resistant Metastatic Hormone Receptor-Positive Breast Cancer

Endocrine therapy with or without CDK4/6 inhibitors is the most commonly used frontline treatment option for metastatic hormone receptor-positive breast cancer. Approximately, 25% to 30% of women may have resistance to endocrine therapy, especially in the setting of certain genomic mutations in the tumor. This prompts the need to identify those patients who may benefit from frontline chemotherapy over endocrine therapy. Here, we present a case of a patient who presented with a de novo metastatic hormone receptor-positive breast cancer with visceral involvement (including bone marrow) as well as multiple somatic genomic alterations. The patient was treated with upfront chemotherapy, resulting in clinical and radiographic response, but rapidly progressed when she was transitioned to hormonal therapy. This report focuses on the role of upfront chemotherapy in the setting of visceral crisis including bone marrow involvement, the role of genomic alterations in contributing to endocrine resistance, and the need for biomarker-driven treatment options for hormone receptor-positive breast cancer.

Characterization of Stromal Tumor-infiltrating Lymphocytes and Genomic Alterations in Metastatic Lobular Breast Cancer

PURPOSE

Invasive lobular carcinoma (ILC) represents the second most common histologic breast cancer subtype after invasive ductal carcinoma (IDC). While primary ILC has been extensively studied, metastatic ILC has been poorly characterized at the genomic and immune level.

EXPERIMENTAL DESIGN

We retrospectively assembled the multicentric EuroILC series of matched primary and metastatic samples from 94 patients with estrogen receptor (ER)-positive ILC. Stromal tumor-infiltrating lymphocytes (sTILs) were assessed by experienced pathologists. Targeted sequencing and low pass whole-genome sequencing were conducted to detect mutations and copy-number aberrations (CNAs). We compared the frequencies of the alterations in EuroILC with those from patients with ER-positive metastatic ILC (n = 135) and IDC (n = 563) from MSK-IMPACT.

RESULTS

Low sTIL levels were observed in ILC metastases, with higher levels in the mixed nonclassic histology. Considering ILC metastases from EuroILC and MSK-IMPACT, we observed that >50% of tumors harbor genomic alterations that have previously been associated with endocrine resistance. A matched primary/metastasis comparison in EuroILC revealed mutations (AKT1, ARID1A, ESR1, ERBB2, or NF1) and CNAs (PTEN or NF1 deletion, CYP19A1 amplification) associated with endocrine resistance that were private to the metastasis in 22% (7/32) and 19% (4/21) of patients, respectively. An increase in CDH1, ERBB2, FOXA1, and TBX3 mutations, in CDH1 deletions and a decrease in TP53 mutations was observed in ILC as compared with IDC metastases.

CONCLUSIONS

ILC metastases harbor genomic alterations that may potentially explain endocrine resistance in a large proportion of patients, and present genomic differences as compared with IDC metastases.

Toxicoproteomics Disclose Pesticides as Downregulators of TNF-α, IL-1β and Estrogen Receptor Pathways in Breast Cancer Women Chronically Exposed

Deleterious effects have been widely associated with chronic pesticide exposure, including cancer development. In spite of several known consequences that pesticides can trigger in the human body, few is known regarding its impact on breast cancer women that are chronically exposed to such substances during agricultural work lifelong. In this context, the present study performed a high-throughput toxicoproteomic study in association with a bioinformatics-based design to explore new putative processes and pathways deregulated by chronic pesticide exposure in breast cancer patients. To reach this goal, we analyzed comparatively non-depleted plasma samples from exposed (n = 130) and non-occupationally exposed (n = 112) women diagnosed with breast cancer by using a label-free proteomic tool. The list of proteins differentially expressed was explored by bioinformatics and the main pathways and processes further investigated. The toxicoproteomic study revealed that women exposed to pesticides exhibited mainly downregulated events, linked to immune response, coagulation and estrogen-mediated events in relation to the unexposed ones. Further investigation shown that the identified deregulated processes and pathways correlated with significant distinct levels tumor necrosis factor alpha and interleukin 1 beta in the blood, and specific clinicopathological characteristics pointed out by bioinformatics analysis as adipose-trophic levels, menopause and intratumoral clots formation. Altogether, these findings reinforce pesticides as downregulators of several biological process and highlight that these compounds can be linked to poor prognosis in breast cancer.

Receptor discordance and phenotype change in metastatic breast cancer

BACKGROUND

changes may occur in tumor phenotype and receptor status during the progression of breast cancer. Discordance between primary and metastases has implications for further treatment and prognosis.

METHODS

185 patients confirmed breast cancer metastasis were retrospectively analyzed during 1999-2019. All the pathological assessments of receptors and phenotypes of both primaries and metastases were recorded.

RESULTS

rates of receptor discordance were 18.65%, 30.57%, and 16.06% for ER, PR, and HER2, respectively and 31.62% for phenotype change. Patients with ER discordance experienced a worse OS and PMS, and those with ER loss had worse PMS compared with ER positive concordance. Patients with PR discordance experienced poorer OS and loss of PR positivity also had decreased OS and PMS when comparing with PR positive concordance. There was also significantly poorer PMS of hormon receptor (HR) discordance than HR positive concordance. In phenotype change, the luminal A type concordance group showed better PMS result.

CONCLUSIONS

this study demonstrated that discordance in subtype and receptor status between primary and metastatic lesions ultimately affects the survival and has a potential impact on treatment options.

Neoadjuvant Endocrine Therapy in Breast Cancer: Current Knowledge and Future Perspectives

In locally advanced (LA) breast cancer (BC), neoadjuvant treatments have led to major achievements, which hold particular relevance in HER2-positive and triple-negative BC. Conversely, their role in hormone receptor positive (HR+), hormone epidermal growth factor 2 negative (HER2-) BC is still under debate, mainly due to the generally low rates of pathological complete response (pCR) and lower accuracy of pCR as predictors of long-term outcomes in this patient subset. While administration of neoadjuvant chemotherapy (NCT) in LA, HR+, HER2- BC patients is widely used in clinical practice, neoadjuvant endocrine therapy (NET) still retains an unfulfilled potential in the management of these subgroups, particularly in elderly and unfit patients. In addition, NET has gained a central role as a platform to test new drugs and predictive biomarkers in previously untreated patients. We herein present historical data regarding Tamoxifen and/or Aromatase Inhibitors and a debate on recent evidence regarding agents such as CDK4/6 and PI3K/mTOR inhibitors in the neoadjuvant setting. We also discuss key issues concerning the optimal treatment length, appropriate comparisons with NCT efficacy and use of NET in premenopausal patients.

Overcoming Endocrine Resistance in Breast Cancer

Estrogen receptor-positive (ER+) breast cancer is the most common breast cancer subtype. Treatment of ER+ breast cancer comprises interventions that suppress estrogen production and/or target the ER directly (overall labeled as endocrine therapy). While endocrine therapy has considerably reduced recurrence and mortality from breast cancer, de novo and acquired resistance to this treatment remains a major challenge. An increasing number of mechanisms of endocrine resistance have been reported, including somatic alterations, epigenetic changes, and changes in the tumor microenvironment. Here, we review recent advances in delineating mechanisms of resistance to endocrine therapies and potential strategies to overcome such resistance.

The Prognostic Impact of Hormonal Receptor and HER-2 Expression Discordance in Metastatic Breast Cancer Patients

Background

Hormone receptor (HR) and human epidermal growth factor receptor (HER2) discordance between primary and metastatic breast cancer lesions is common. However, its impact on long-term survival remains unclear. We aimed to determine the prognostic value of this discordance in patients with metastaticf breast cancer (MBC).

Methods

A total of 270 patients with MBC who were underwent re-biopsy of progressive metastases at Zhejiang Cancer Hospital from January 1, 2012 to December 31, 2015 with patients consent and then review their primary tumors pathological findings. The HR and HER2 status in both primary and progressive metastatic lesions was determined by immunohistochemistry and/or fluorescence in situ hybridization. The discordance rates were correlated with the clinicopathologic characteristics, metastatic lesions, salvage treatment, and survival analysis in this population.

Results

A total of 142 (52.6%) MBC patients were diagnosed with discordant HR and HER2 status. Alterations in estrogen receptor (ER), progesterone receptor (PR), and HER2 status were observed in 20.70%, 37.78%, and 11.48% cases, respectively. Chemotherapy (P=0.0192) and endocrine therapy (P=0.048) significantly affected the conversion of HR status. Endocrine therapy was positively correlated with PR discordance (P=0.002), while ER discordance was associated with adjuvant chemotherapy (P=0.031). Survival analysis showed that ER status alterations between primary and metastatic lesions were associated with overall survival (P=0.002). The clinical prognosis was significantly worse with HR losses than with persistent HR positivity (P=0.023). In Cox multivariate analysis, the loss of HR expression and conversion to triple negative were independent prognostic indicators.

Conclusion

Discordance in HR status between primary and metastatic lesions may impact the prognosis of MBC, and HR conversion has independent prognostic value.

Case report: recurrent metastatic breast cancer in internal mammary dissection bed discovered at the time of coronary bypass

Introduction

Many patients who undergo coronary artery bypass surgery have a prior history of cancer and potentially chest radiation which is a known risk factor for coronary atherosclerosis. Prior radiation increases fibrosis and can make the dissection of the left internal mammary artery (LIMA) more challenging.

Case report

A 72-year-old woman with a history of stage IIA pT2N0M0 left breast intraductal carcinoma treated with lumpectomy, adjuvant chemotherapy and radiation therapy 11 years prior presented to the emergency room with a non-ST elevation myocardial infarction and was taken for cardiac catheterization followed by three-vessel coronary artery bypass grafting. The LIMA was found to be encased in scar tissue and was deemed unsuitable as a conduit, and a saphenous vein graft was bypassed to the left anterior descending artery in its place. Pathologic review of the LIMA showed nests of tumor cells infiltrating within dense fibrous tissue with areas of necrosis and calcifications consistent with recurrent breast cancer. Interestingly the patients original breast cancer was positive for estrogen receptors (ER) and progesterone receptors (PR) ER and PR and negative for HER2 and she had therefore been treated with 5 years of hormonal therapy. The recurrent cancer found in the LIMA dissection bed at the time of bypass surgery was ER, PR, and HER2 negative, suggesting hormonal therapy driven clonal selection of these metastatic tumor cells.

Discussion and conclusions

Scarring in the LIMA dissection bed in patients with a history of cancer and prior chest radiation should be carefully evaluated for the possibility of recurrent cancer. The gross appearance of tissue can be misleading and sending a biopsy for a formal frozen section histologic evaluation should be considered if there is any question of recurrent malignancy.

Biomarker discordance between primary breast cancer and bone or bone marrow metastases

BACKGROUND

Discordance in biomarker expression between primary and metastatic tumor sites has been reported in several studies; yet, few have examined this feature in bone lesions.

METHODS

We retrospectively enrolled patients with breast cancer metastasis to the bone or bone marrow, excluding cases where samples from both the primary and metastatic lesions were not available. Expression patterns of the estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2) and Ki67 were compared in primary tumors and bone or bone marrow lesions.

RESULTS

Forty-six patients with a median age of 52 years (range, 34-72 years) were included in the study. Discordant rates of ER, PgR and HER2 were 20%, 46% and 0%, respectively. Physicians usually determined treatment options considering the results of biomarker re-evaluation. It is unlikely that biomarker discordance was related to prior treatment.

CONCLUSIONS

Biomarker discordance in bone or bone marrow lesions is common in patients with breast cancer. An accurate and thorough analysis of biomarkers and metastatic tumor properties is important for clinical decision-making.

Reliability of Estrogen Receptor and Human Epidermal Growth Factor Receptor 2 Expression on Breast Cancer Cells Stored in Cellprep® Vials

OBJECTIVE

The aim of this study was to evaluate the reliability of estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) expression levels in Cellprep® (CP).

STUDY DESIGN

We evaluated the stability of immunocytochemistry (ICC) of ER and HER2 for primary or recurrent breast cancer samples rinsed in CP vials. Samples were prepared from CP vials stored for 1-30 or 160-240 days. ER and HER2 statuses were determined after 1-30 days (26 and 25 tests, respectively) or 160-240 days (15 and 18 tests, respectively) with the same protocols as immunohistochemistry (IHC), and were compared with the corresponding surgically resected specimens.

RESULTS

ER statuses according to CP samples showed perfect agreement (1-30 days: kappa, κ = 1; 160-240 days: κ = 1). HER2 statuses also showed good agreement (1-30 days: κ = 0.79; 160-240 days: κ = 0.64), although there were more equivocal HER2 cases in CP than in the surgically resected specimens.

CONCLUSION

ER ICC in CP vials is reliable regardless of the preservation period. HER2 ICC in CP has more equivocal cases than HER2 IHC in surgically resected specimens. Both improvement of the immunostaining protocol and further validation study of in situ hybridization are indispensable for the practical application of ICC in CP.

Breast cancer subtype discordance: impact on post-recurrence survival and potential treatment options

Background

Recent studies have shown that breast cancer subtype can change from the primary tumour to the recurrence. Discordance between primary and recurrent breast cancer has implications for further treatment and ultimately prognosis. The aim of the study was to determine the rate of change between primary and recurrence of breast cancer and to assess the impact of these changes on survival and potential treatment options.

Methods

Patient demographics were collected on those who underwent surgery for breast cancer between 2001 and 2014 and had a recurrence with biopsy results and pathology scoring of both the primary and recurrence.

Results

One hundred thirty two consecutive patients were included. There were 31 (23.5%) changes in subtype. Discordance occurred most frequently in luminal A breast cancer (n = 20), followed by triple negative (n = 4), luminal B (n = 3) and HER2 (n = 3). Patients who changed from luminal A to triple negative (n = 18) had a significantly worse post-recurrence survival (p < 0.05) with overall survival approaching significance (p = 0.064) compared to concordant luminal A cases (n = 46). Overall receptor discordance rates were: estrogen receptor 20.4% (n = 27), progesterone receptor 37.7% (n = 50) and HER2 3% (n = 4). Loss of estrogen receptor and progesterone receptor was more common than gain (21 vs. 6 (p = 0.04) and 44 vs. 6 (p = 0.01) respectively). Nine patients (6.8%) gained receptor status potentially impacting treatment options.

Conclusion

Discordance in subtype and receptor status occurs between primary and recurrent breast cancer, ultimately affecting survival and potentially impacting treatment options.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4101-7) contains supplementary material, which is available to authorized users.

Multifunctional superparamagnetic nanoparticles conjugated with fluorescein-labeled designed ankyrin repeat protein as an efficient HER2-targeted probe in breast cancer

Based on the discordance of human epidermal growth factor receptor-2 (HER2) expression between primary and metastatic/recurrent breast cancer, HER2 molecular imaging, which had potential to systemically assess and dynamically monitor HER2 expression, might improve the selection of patients for anti-HER2 therapy. In this study, designed ankyrin repeat protein (DARPin) G3, a novel binding protein with picomolar affinity for HER2, was used and multifunctional superparamagnetic nanoparticles modified with fluorescein-5-maleimide-labeled DARPin G3 (SPIO-G3-5MF) were developed for HER2 imaging. Our results showed that SPIO-G3-5MF nanoparticles, which possessed uniform size of about 100 nm, favorable dispersity and low cytotoxicity, could selectively bind to HER2-positive breast cancer cells even in the presence of trastuzumab. Biodistribution assay demonstrated that abundant accumulation and long retention of SPIO-G3-5MF were observed in HER2-positive transplantation breast tumors although a portion of SPIO-G3-5MF nanoparticles were unavoidably captured by liver and spleen. Further MR imaging revealed that SPIO-G3-5MF could selectively image HER2-positive transplantation breast tumors, yielding remarkable T₂ signal reduction (50.33 ± 2.90% at 6 h and 47.29 ± 9.36% at 24 h). Our study suggested that SPIO-G3-5MF might be a promising MR molecular probe for diagnosing and monitoring HER2 expression state of breast cancer in the future.

New Strategies in Metastatic Hormone Receptor-Positive Breast Cancer: Searching for Biomarkers to Tailor Endocrine and Other Targeted Therapies

Although major advances in our understanding of the molecular underpinnings of hormone receptor-positive (HR+) breast cancer have led to new therapies that have substantially improved patient outcomes, endocrine-resistant disease still remains a leading cause of breast cancer mortality. Comprehensive molecular profiling of breast cancers has highlighted tremendous tumor heterogeneity, and analysis of paired primary and metastatic tumors has shown the evolution that can occur during acquired resistance to systemic therapies. Novel techniques for monitoring tumor load under treatment pressure, including "liquid biopsy" techniques, such as circulating free tumor DNA (cfDNA) and circulating tumor cells, have shown promise as biomarkers to direct treatment without invasive tumor biopsies. However, more research is needed to deepen our understanding of breast cancer alterations under treatment pressure to reveal mechanisms of drug resistance and apply precision medicine in biomarker-driven clinical trials. Clin Cancer Res; 23(5); 1126-31. ©2016 AACR.