Overcoming endocrine resistance in hormone receptor-positive breast cancer

Androgen receptor: Structure, signaling, function and potential drug discovery biomarker in different breast cancer subtypes

The Androgen Receptor (AR) is emerging as an important factor in the pathogenesis of breast cancer (BC), which is the most common malignancy worldwide. >70 % of AR expression in primary and metastatic breast tumors has been observed which suggests that AR may be a new marker and a potential therapeutic target among AR-positive BC patients. Biological insight into AR-positive breast cancer reveals that AR may cross-talk with several vital signaling pathways, including key molecules and receptors. Downstream signaling of AR might also affect many clinically important pathways that are emerging as clinical targets in BC. AR exhibits different behaviors depending on the breast cancer molecular subtype. Preliminary clinical research using AR-targeted drugs, which have already been FDA-approved for prostate cancer (PC), has given promising results for AR-positive breast cancer patients. However, since AR positivity's prognostic and predictive value remains uncertain, it is difficult to identify and stratify patients who would benefit from AR-targeted therapies alone. Thus, the need of the hour is to target the androgen receptor as a monotherapy or in combination with other conventional therapies which has proven to be an effective clinical strategy for the treatment of prostate cancer patients, and these therapeutic strategies are increasingly being investigated in breast cancer. Therefore, in this manuscript, we review the role of AR in various cellular processes that promote tumorigenesis and aggressiveness, in different subtypes of breast cancer, as well as discuss ongoing efforts to target AR for the more effective treatment and prevention of breast cancer.

Influence of tumor microenvironment on the different breast cancer subtypes and applied therapies

Despite the significant improvements made in breast cancer therapy during the last decades, this disease still has increasing incidence and mortality rates. Different targets involved in general processes, like cell proliferation and survival, have become alternative therapeutic options for this disease, with some of them already used in clinic, like the CDK4/6 inhibitors for luminal A tumors treatment. Nevertheless, there is a demand for novel therapeutic strategies focused not only on tumor cells, but also on their microenvironment. Tumor microenvironment (TME) is a very complex and dynamic system that, more than surrounding and supporting tumor cells, actively participates in tumor development and progression. During the last decades, it has become clear that the cellular and acellular components of TME differ between the various breast cancer subtypes and shape the differences regarding their severity and prognosis. The pivotal role of the TME in controlling tumor growth and influencing responses to therapy represents a potential source for novel targets and therapeutic strategies. In this review, we present a description of the multiple therapeutic options used for different breast cancer subtypes, as well as the influence that the TME may exert on the development of the disease and on the response to the distinct therapies, which in some cases may explain their failure by the occurrence of relapses and resistance. Furthermore, the ongoing studies focused on the use of TME components for developing potential cancer treatments are described.

Mechanisms of Traditional Chinese medicine/natural medicine in HR-positive Breast Cancer: A comprehensive Literature Review

ETHNOPHARMACOLOGICAL RELEVANCE

With the emergence of endocrine resistance, the survival and good prognosis of HR-positive breast cancer (HR + BC) patients are threatened. As a common complementary and alternative therapy in cancer treatment, traditional Chinese medicine (TCM) has been widely used, and its internal mechanisms have been increasingly explored.

AIM OF THE REVIEW

In this review, the development status and achievements in understanding of the mechanisms related to the anti-invasion and anti-metastasis effects of TCM against HR + BC and the reversal of endocrine drug resistance by TCM in recent years have been summarized to provide ideas for antitumour research on the active components of TCM/natural medicine.

METHODS

We searched the electronic databases PubMed, Web of Science, and China National Knowledge Infrastructure database (CNKI) (from inception to July 2023) with the key words "HR-positive breast cancer" or "HR-positive breast carcinoma", "HR + BC" and "traditional Chinese medicine", "TCM", or "natural plant", "herb", etc., with the aim of elucidating the intrinsic mechanisms of traditional Chinese medicine and natural medicine in the treatment of HR + BC.

RESULTS

TCM/natural medicine monomers and formulas can regulate the expression of related genes and proteins through the PI3K/AKT, JAK2/STAT3, MAPK, Wnt and other signalling pathways, inhibit the proliferation and metastasis of HR + BC tumours, play a synergistic role in combination with endocrine drugs, and reverse endocrine drug resistance.

CONCLUSION

The wide variety of TCM/natural medicine components makes the research and development of new methods of TCM for BC treatments more selective and innovative. Although progress has been made on research on TCM/natural medicine, there are still many problems in clinical and basic experimental designs, and more in-depth scientific explorations and research are still needed.

Prognostic factors for hormone receptor-positive breast cancer with liver metastasis and establishment of novel nomograms for prediction: a SEER-based study

Background

The prognosis of patients with hormone receptor (HR)-positive breast cancer with liver metastasis (BCLM) remains dismal and varies widely from person to person. Thus, we sought to construct nomograms to predict overall survival (OS) and breast cancer-specific survival (BCSS) in patients with HR-positive BCLM using data from the Surveillance, Epidemiology and End Results (SEER) database.

Methods

The data of patients with BCLM, who had received HR-positive diagnoses between 2010 and 2016, were collected from the SEER database. A Cox proportional hazards model was used to evaluate and identify the independent risk factors for OS and BCSS. Subsequently, two new nomograms were developed. Finally, the receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA) results were evaluated.

Results

The data of 1,780 patients diagnosed between 2010 and 2015 were used to build the nomogram models. Using both univariate and multivariate Cox regression analyses, nine variables, including age, marital status, grade, human epidermal growth factor receptor 2 (HER2) status, chemotherapy, surgery, bone metastasis, lung metastasis, and brain metastasis, were found to be significantly associated with OS. Conversely, 10 variables, including age, marital status, T stage, grade, HER2 status, chemotherapy, surgery, bone metastasis, lung metastasis, and brain metastasis, were identified as independent risk factors for BCSS. Using the risk factors listed above, we created 1-, 2-, and 3-year survival nomograms for OS and BCSS, respectively. Subsequently, the data of 312 patients, who had been diagnosed in 2016, were used for the external validation. These results, including the ROC curve, calibration curve, and DCA results, showed that our nomogram had strong predictive power.

Conclusions

Nomograms can effectively and reliably predict a patient's prognosis and could be useful in clinical decision making. The nomograms had strong discrimination, calibration, and clinical values. More aggressive treatment and closer monitoring should be considered when treating high-risk individuals.

Adherence to oral endocrine therapy in racial/ethnic minority patients with low socioeconomic status before and during the COVID-19 pandemic

BACKGROUND

Adherence to oral endocrine therapy (OET) is crucial in ensuring its maximum benefit in the prevention and treatment of hormone receptor-positive (HR +) breast cancer (BC). Medication use behavior is suboptimal especially in racial/ethnic minorities with lower socioeconomic status (SES).

AIM

We aimed to assess the impact of the coronavirus disease 2019 (COVID-19) pandemic on OET adherence and identify demographic and/or clinical characteristics associated with nonadherence in racial/ethnic minorities with lower SES.

METHOD

A retrospective study was conducted at the Harris Health System in Houston, Texas. Data were collected during the 6 months before and 6 months after the start of the pandemic. The adherence was assessed using the prescription refill data using the proportion of days covered. A multivariable logistic regression model was used to identify demographic/clinical characteristics associated with nonadherence. Eighteen years or older patients on appropriate doses of OET for prevention or treatment of BC were included.

RESULTS

In 258 patients, adherence was significantly lower during the pandemic (44%) compared to before the pandemic (57%). The demographic/clinical characteristics associated with OET nonadherence before the pandemic were Black/African American, obesity/extreme obesity, prevention setting, tamoxifen therapy, and 4 or more years on OET. During the pandemic, prevention setting and those not using home delivery were more likely to be nonadherent.

CONCLUSION

OET adherence was significantly reduced during the COVID-19 pandemic in racial/ethnic minority patients with low SES. Patient-centered interventions are necessary to improve OET adherence in these patients.

Coexistent ARID1A-PIK3CA mutations are associated with immune-related pathways in luminal breast cancer

Up to 40% of luminal breast cancer patients carry activating mutations in the PIK3CA gene. PIK3CA mutations commonly co-occur with other mutations, but the implication of this co-occurrence may vary according to the specific genes involved. Here, we characterized a subgroup of luminal breast cancer expressing co-mutations in ARID1A and PIK3CA genes and identified their effect on important signaling pathways. Our study included 2609 primary breast cancer samples from the TCGA and METABRIC datasets that were classified based on tumor subtype and the existence of mutations in PIK3CA and ARID1A genes. Differential expression and WGCNA analyses were performed to detect molecular modules affected by the existence of the mutations. Our results reveal various evidence for the involvement of immune-related pathways in luminal tumors harboring ARID1A and PIK3CA mutations, as well as a unique Tumor-infiltrated immune cells composition. We also identified seven key hub genes in the ARID1A-PIK3CA mutated tumors associated with immune-related pathways: CTLA4, PRF1, LCK, CD3E, CD247, ZAP70, and LCP2. Collectively, these results indicate an immune system function that may contribute to tumor survival. Our data induced a hypothesis that ARID1A and PIK3CA mutations' co-occurrence might predict responses to immunotherapy in luminal BC and, if validated, could guide immunotherapy development.

Fasting-mimicking diet: a metabolic approach for the treatment of breast cancer

PURPOSE OF REVIEW

Metabolic reprogramming is a new and potentially targetable hallmark of cancer. In recent years, fasting and fasting-mimicking diets (FMDs) have been tested as anticancer strategies both in preclinical experiments and in clinical trials. In this review, we aim at summarizing the available evidence about the antitumour activity of these approaches in preclinical breast cancer models, as well as results from clinical trials investigating fasting/FMD in breast cancer patients.

RECENT FINDINGS

Preclinical evidence demonstrated that nutrient deprivation boosts the antitumor activity of chemotherapy, immunotherapy or targeted therapies in triple-negative breast cancer (TNBC) and HR+/HER2 models through both cell-autonomous antitumour effects in cancer cells and favourable modifications in intratumor immune cells. Several clinical experiences demonstrated that fasting/FMD is feasible and well tolerated in combination with standard treatments in BC patients, and that it could reduce chemotherapy-related toxicities. Finally, despite the absence of randomized trials demonstrating the antitumor activity of fasting/FMD in breast cancer patients, preliminary clinical reports suggest that this experimental nutritional strategy may enhance chemotherapy activity. Randomized clinical trials are ongoing to validate these results at a larger scale.

SUMMARY

Fasting/FMD is a promising therapeutic approach in patients with breast cancer; ongoing and future trials will confirm their role in improving breast cancer care.

The role of the tumor microenvironment in endocrine therapy resistance in hormone receptor-positive breast cancer

Endocrine therapy is the prominent strategy for the treatment of hormone-positive breast cancers. The emergence of resistance to endocrine therapy is a major health concern among hormone-positive breast cancer patients. Resistance to endocrine therapy demands the design of newer therapeutic strategies. The understanding of underlying molecular mechanisms of endocrine resistance, components of the tumor microenvironment (TME), and interaction of resistant breast cancer cells with the cellular/acellular components of the intratumoral environment are essential to formulate new therapeutic strategies for the treatment of endocrine therapy-resistant breast cancers. In the first half of the article, we have discussed the general mechanisms (including mutations in estrogen receptor gene, reregulated activation of signaling pathways, epigenetic changes, and cell cycle alteration) responsible for endocrine therapy resistance in hormone-positive breast cancers. In the latter half, we have emphasized the precise role of cellular (cancer-associated fibroblasts, immune cells, and cancer stem cells) and acellular components (collagen, fibronectin, and laminin) of TME in the development of endocrine resistance in hormone-positive breast cancers. In sum, the article provides an overview of the relationship between endocrine resistance and TME in hormone-positive breast cancers.

Mechanisms of breast cancer progression induced by environment-polluting aryl hydrocarbon receptor agonists

Breast cancer is the most common invasive malignancy among women worldwide and constitutes a complex and heterogeneous disease. Interest has recently grown in the role of the aryl hydrocarbon receptor (AhR) in breast cancer and the contribution of environment-polluting AhR agonists. Here, we present a literature review addressing AhR ligands, including pesticides hexachlorobenzene and chlorpyrifos, polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, parabens, and phthalates. The objectives of this review are a) to summarize recent original experimental, preclinical, and clinical studies on the biological mechanisms of AhR agonists which interfere with the regulation of breast endocrine functions, and b) to examine the biological effects of AhR ligands and their impact on breast cancer development and progression. We discuss biological mechanisms of action in cell viability, cell cycle, proliferation, epigenetic changes, epithelial to mesenchymal transition, and cell migration and invasion. In addition, we examine the effects of AhR ligands on angiogenic processes, metastasis, chemoresistance, and stem cell renewal. We conclude that exposure to AhR agonists stimulates pathways that promote breast cancer development and may contribute to tumor progression. Given the massive use of industrial and agricultural chemicals, ongoing evaluation of their effects in laboratory assays and preclinical studies in breast cancer at environmentally relevant doses is deemed essential. Likewise, awareness should be raised in the population regarding the most harmful toxicants to eradicate or minimize their use.

Modulation of JAK-STAT Signaling by LNK: A Forgotten Oncogenic Pathway in Hormone Receptor-Positive Breast Cancer

Breast cancer remains the most frequently diagnosed cancer in women worldwide. Tumors that express hormone receptors account for 75% of all cases. Understanding alternative signaling cascades is important for finding new therapeutic targets for hormone receptor-positive breast cancer patients. JAK-STAT signaling is commonly activated in hormone receptor-positive breast tumors, inducing inflammation, proliferation, migration, and treatment resistance in cancer cells. In hormone receptor-positive breast cancer, the JAK-STAT cascade is stimulated by hormones and cytokines, such as prolactin and IL-6. In normal cells, JAK-STAT is inhibited by the action of the adaptor protein, LNK. However, the role of LNK in breast tumors is not fully understood. This review compiles published reports on the expression and activation of the JAK-STAT pathway by IL-6 and prolactin and potential inhibition of the cascade by LNK in hormone receptor-positive breast cancer. Additionally, it includes analyses of available datasets to determine the level of expression of LNK and various members of the JAK-STAT family for the purpose of establishing associations between expression and clinical outcomes. Together, experimental evidence and in silico studies provide a better understanding of the potential implications of the JAK-STAT-LNK loop in hormone receptor-positive breast cancer progression.

The impact of poor metabolic health on aggressive breast cancer: adipose tissue and tumor metabolism

Obesity and type 2 diabetes are chronic metabolic diseases that impact tens to hundreds of millions of adults, especially in developed countries. Each condition is associated with an elevated risk of breast cancer and with a poor prognosis after treatment. The mechanisms connecting poor metabolic health to breast cancer are numerous and include hyperinsulinemia, inflammation, excess nutrient availability, and adipose tissue dysfunction. Here, we focus on adipose tissue, highlighting important roles for both adipocytes and fibroblasts in breast cancer progression. One potentially important mediator of adipose tissue effects on breast cancer is the fibroblast growth factor receptor (FGFR) signaling network. Among the many roles of FGFR signaling, we postulate that key mechanisms driving aggressive breast cancer include epithelial-to-mesenchymal transition and cellular metabolic reprogramming. We also pose existing questions that may help better understand breast cancer biology in people with obesity, type 2 diabetes, and poor metabolic health.

Resistance to hormone therapy in breast cancer cells promotes autophagy and EGFR signaling pathway

Breast cancer is the leading cause of cancer deaths for women worldwide. Endocrine therapies represent the cornerstone for hormone-dependent breast cancer treatment. However, in many cases, endocrine resistance is induced with poor prognosis for patients. In the current study, we have developed MCF-7 cell lines resistant to fulvestrant (MCF-7Fulv) and tamoxifen (MCF-7Tam) aiming at investigating mechanisms underlying resistance. Both resistant cell lines exerted lower proliferation capacity in two-dimensional (2-D) cultures but retain estrogen receptor α (ERα) expression and proliferate independent of the presence of estrogens. The established cell lines tend to be more aggressive exhibiting advanced capacity to form colonies, increased expression of epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), and heterodimerization of ERBB family receptors and activation of EGFR downstream pathways like MEK/ERK1/2 and PI3K/AKT. Tyrosine kinase inhibitors tested against resistant MCF-7Fulv and MCF-7Tam cells showed moderate efficacy to inhibit cell proliferation, except for lapatinib, which concomitantly inhibits both EGFR and HER2 receptors and strongly reduced cell proliferation. Furthermore, increased autophagy was observed in resistant MCF-7Fulv and MCF-7Tam cells as shown by the presence of autophagosomes and increased Beclin-1 levels. The increased autophagy in resistant cells is not associated with increased apoptosis, suggesting a cytoprotective role for autophagy that may favor cells' survival and aggressiveness. Thus, by exploiting those underlying mechanisms, new targets could be established to overcome endocrine resistance.NEW & NOTEWORTHY The development of resistance to hormone therapy caused by both fulvestrant and tamoxifen promotes autophagy with concomitant apoptosis evasion, rendering cells capable of surviving and growing. The fact that resistance also triggers ERBB family signaling pathways, which are poorly inhibited by tyrosine kinase inhibitors might attribute to cells' aggressiveness. It is obvious that the development of endocrine therapy resistance involves a complex interplay between deregulated ERBB signaling and autophagy that may be considered in clinical practice.

Long non-coding RNAs as the critical regulators of PI3K/AKT, TGF-β, and MAPK signaling pathways during breast tumor progression

Breast cancer (BC) as one of the most common causes of human deaths among women, is always considered one of the global health challenges. Despite various advances in diagnostic and therapeutic methods, a significant percentage of BC patients have a poor prognosis due to the lack of therapeutic response. Therefore, investigating the molecular mechanisms involved in BC progression can improve the therapeutic and diagnostic strategies in these patients. Cytokine and growth factor-dependent signaling pathways play a key role during BC progression. In addition to cytokines and growth factors, long non-coding RNAs (lncRNAs) have also important roles in regulation of such signaling pathways. Therefore, in the present review we discussed the role of lncRNAs in regulation of PI3K/AKT, MAPK, and TGF-β signaling pathways in breast tumor cells. It has been shown that lncRNAs mainly have an oncogenic role through the promotion of these signaling pathways in BC. This review can be an effective step in introducing the lncRNAs inhibition as a probable therapeutic strategy to reduce tumor growth by suppression of PI3K/AKT, MAPK, and TGF-β signaling pathways in BC patients. In addition, considering the oncogenic role and increased levels of lncRNAs expressions in majority of the breast tumors, lncRNAs can be also considered as the reliable diagnostic markers in BC patients.

Concomitant PIK3CA and TP53 Mutations in Breast Cancer: An Analysis of Clinicopathologic and Mutational Features, Neoadjuvant Therapeutic Response, and Prognosis

PURPOSE

PIK3CA and TP53 are the most prevalently mutated genes in breast cancer (BC). Previous studies have indicated an association between concomitant PIK3CA/TP53 mutations and shorter disease-free survival. As its clinical utility remains largely unknown, we aimed to analyze the prognostic and predictive roles of this co-mutation.

METHODS

We retrospectively analyzed patients who were diagnosed with BC at Guangdong Provincial People's Hospital (GDPH) who underwent next-generation sequencing. The correlation of concomitant PIK3CA/TP53 mutations with clinicopathological and mutational characteristics, and neoadjuvant systemic therapy (NST) responses was analyzed. The Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) dataset was used to verify associations between concurrent mutations and survival outcomes.

RESULTS

In the GDPH cohort, concomitant PIK3CA/TP53 mutations were associated with more aggressive phenotypes, including human epidermal growth factor receptor 2 positive status, hormone receptor negative status, high Ki-67 expression, high histological grade, advanced TNM stage, and additional genetic alterations. Co-mutations also portended a worse response to NST, especially taxane-containing regimens, when compared with the TP53 mutant alone (odds ratio, 3.767; 95% confidence interval, 1.205-13.087; p = 0.028). A significant association was observed between concomitant PIK3CA/TP53 mutations and poor survival outcomes in the METABRIC cohort.

CONCLUSION

Concomitant PIK3CA/TP53 mutations not only suggested unfavorable features and poor prognosis in BC but also conferred less benefit to NST than TP53 mutations alone.

Cell facilitation promotes growth and survival under drug pressure in breast cancer

The interplay of positive and negative interactions between drug-sensitive and resistant cells influences the effectiveness of treatment in heterogeneous cancer cell populations. Here, we study interactions between estrogen receptor-positive breast cancer cell lineages that are sensitive and resistant to ribociclib-induced cyclin-dependent kinase 4 and 6 (CDK4/6) inhibition. In mono- and coculture, we find that sensitive cells grow and compete more effectively in the absence of treatment. During treatment with ribociclib, sensitive cells survive and proliferate better when grown together with resistant cells than when grown in monoculture, termed facilitation in ecology. Molecular, protein, and genomic analyses show that resistant cells increase metabolism and production of estradiol, a highly active estrogen metabolite, and increase estrogen signaling in sensitive cells to promote facilitation in coculture. Adding estradiol in monoculture provides sensitive cells with increased resistance to therapy and cancels facilitation in coculture. Under partial inhibition of estrogen signaling through low-dose endocrine therapy, estradiol supplied by resistant cells facilitates sensitive cell growth. However, a more complete blockade of estrogen signaling, through higher-dose endocrine therapy, diminished the facilitative growth of sensitive cells. Mathematical modeling quantifies the strength of competition and facilitation during CDK4/6 inhibition and predicts that blocking facilitation has the potential to control both resistant and sensitive cancer cell populations and inhibit the emergence of a refractory population during cell cycle therapy.

Pyrotinib in combination with letrozole for hormone receptor-positive, human epidermal growth factor receptor 2-positive metastatic breast cancer (PLEHERM): a multicenter, single-arm, phase II trial

BACKGROUND

Human epidermal growth factor receptor 2 (HER2) targeted therapy combined with endocrine therapy has been recommended as an alternative treatment strategy for patients with hormone receptor (HR)-positive, HER2-positive metastatic breast cancer (MBC). This study aimed to evaluate the role of pyrotinib, an oral pan-HER irreversible tyrosine kinase inhibitor, in combination with letrozole for patients with HR-positive, HER2-positive MBC.

METHODS

In this multi-center, phase II trial, HR-positive and HER2-positive MBC patients who were not previously treated for metastasis disease were enrolled. Patients received daily oral pyrotinib 400 mg and letrozole 2.5 mg until disease progression, unacceptable toxicity, or withdrawal of consent. The primary endpoint was the clinical benefit rate (CBR) assessed by an investigator according to the Response Evaluation Criteria in Solid Tumors version 1.1.

RESULTS

From November 2019 to December 2021, 53 patients were enrolled and received pyrotinib plus letrozole. As of August 2022, the median follow-up duration was 11.6 months (95% confidence interval [CI], 8.7-14.0 months). The CBR was 71.7% (95% CI, 57.7-83.2%), and the objective response rate was 64.2% (95% CI, 49.8-76.9%). The median progression-free survival was 13.7 months (95% CI, 10.7-18.7 months). The most common treatment-related adverse event of grade 3 or higher was diarrhea (18.9%). No treatment-related deaths were reported, and one patient experienced treatment discontinuation due to adverse event.

CONCLUSIONS

Our preliminary results suggested that pyrotinib plus letrozole is feasible for the first-line treatment of patients with HR-positive and HER2-positive MBC, with manageable toxicities.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04407988.

Clinical Management of Potential Toxicity of Abemaciclib and Approaches to Ensure Treatment Continuation

INTRODUCTION

The association between abemaciclib dose reduction and treatment adherence is not clear. In this study, we examined real-world data of Japanese patients with advanced breast cancer (ABC) to determine how abemaciclib dose reduction is related to treatment continuation.

METHODS

This retrospective observational study involved 120 consecutive patients with ABC who received abemaciclib from December 2018 to March 2021. The time to treatment failure (TTF) was estimated using the Kaplan-Meier method. Univariate and multivariate analyses were performed to identify factors associated with a TTF of >365 days (TTF365).

RESULTS

According to the dose reduction during treatment, the patients were classified into 100, 200, and 300 mg/day abemaciclib groups. The 300 mg/day group had a TTF of 7.4 months, whereas the 100 and 200 mg/day groups had significantly longer TTFs (17.9 and 17.3 months, respectively; P = 0.0002). In this study, relative to the 300 mg/day arm, TTF was improved in 200mg/day arm and 100 mg/day arm (hazard ratio [HR], 0.55; 95% confidence interval [CI], 0.33-0.93) and [HR], 0.37; 95% CI, 0.19-0.74). For patients who received 300mg/day of abemaciclib dose arm, 200mg/day, and 100mg/day, the median TTF was 7.4 ,17.9 and 17.3 months. The frequently reported adverse effects (AEs) were anemia, increased blood creatinine levels, diarrhea, and neutropenia (90%, 83%, 83%, and 75% of the patients, respectively). Neutropenia, fatigue, and diarrhea were the top AEs causing dose reduction. A multivariate analysis that examined factors associated with achieving TTF 365 confirmed that dose down was an important factor (odds ratio: 3.95, 95% confidence interval: 1.68-9.36, P = 0.002).

CONCLUSIONS

In this study, the 100 and 200 mg/day groups had a longer TTF than the 300 mg/day group, and dose reduction was identified as an important factor in achieving longer TTF.

2-Hydroxypropyl-β-cyclodextrin (HPβCD) as a Potential Therapeutic Agent for Breast Cancer

Cholesterol accumulation is documented in various malignancies including breast cancer. Consequently, depleting cholesterol in cancer cells can serve as a viable treatment strategy. We identified the potency of 2-hydroxypropyl-β-cyclodextrin (HPβCD), a cholesterol-depletor in vitro against two breast cancer cell lines: MCF-7 (Oestrogen-receptor positive, ER+) and MDA-MB-231 (Triple negative breast cancer (TNBC)). The results were then compared against two non-cancerous cell lines using cytotoxic-, apoptosis-, and cholesterol-based assays. Treatment with HPβCD showed preferential and significant cytotoxic potential in cancer cells, inducing apoptosis in both cancer cell lines (p < 0.001). This was mediated due to significant depletion of cholesterol (p < 0.001). We further tested HPβCD in a MF-1 mice (n = 14) xenograft model and obtained 73.9%, 94% and 100% reduction in tumour size for late-, intermediate-, and early-stage TNBC, respectively. We also detected molecular-level perturbations in the expression patterns of several genes linked to breast cancer and cholesterol signalling pathways using RT²-PCR arrays and have identified SFRP1 as a direct binding partner to HPβCD through SPR drug interaction analysis. This work unravels mechanistic insights into HPβCD-induced cholesterol depletion, which leads to intrinsic apoptosis induction. Results from this study potentiate employing cholesterol depletion as a promising unconventional anticancer therapeutic strategy, which warrants future clinical investigations.

Extracellular Vesicles in Breast Cancer: From Biology and Function to Clinical Diagnosis and Therapeutic Management

Breast cancer (BC) is the first worldwide most frequent cancer in both sexes and the most commonly diagnosed in females. Although BC mortality has been thoroughly declining over the past decades, there are still considerable differences between women diagnosed with early BC and when metastatic BC is diagnosed. BC treatment choice is widely dependent on precise histological and molecular characterization. However, recurrence or distant metastasis still occurs even with the most recent efficient therapies. Thus, a better understanding of the different factors underlying tumor escape is mainly mandatory. Among the leading candidates is the continuous interplay between tumor cells and their microenvironment, where extracellular vesicles play a significant role. Among extracellular vesicles, smaller ones, also called exosomes, can carry biomolecules, such as lipids, proteins, and nucleic acids, and generate signal transmission through an intercellular transfer of their content. This mechanism allows tumor cells to recruit and modify the adjacent and systemic microenvironment to support further invasion and dissemination. By reciprocity, stromal cells can also use exosomes to profoundly modify tumor cell behavior. This review intends to cover the most recent literature on the role of extracellular vesicle production in normal and cancerous breast tissues. Specific attention is paid to the use of extracellular vesicles for early BC diagnosis, follow-up, and prognosis because exosomes are actually under the spotlight of researchers as a high-potential source of liquid biopsies. Extracellular vesicles in BC treatment as new targets for therapy or efficient nanovectors to drive drug delivery are also summarized.

A Tumor Microenvironment-Driven Network Regulated by STAT3 and p65 Negatively Controls the Enrichment of Cancer Stem Cells in Human HR+/HER2- Breast Cancer

Hormone receptor-positive and HER2-negative (HR+/HER2-; luminal A) tumors are prevalent in breast cancer. Our past studies demonstrated that "TME Stimulation" (estrogen + TNFα + EGF, representing three arms of the tumor microenvironment, TME) has enriched metastasis-forming cancer stem cells (CSCs) in HR+/HER2- human breast cancer cells. Here, following information obtained by RNAseq analyses of TME-stimulated CSCs and Non-CSCs, we found that TME Stimulation has induced the activation of S727-STAT3, Y705-STAT3, STAT1 and p65. Upon TME Stimulation, stattic (STAT3 inhibitor) usage demonstrated that Y705-STAT3 activation negatively controlled CSC enrichment and epithelial-to-mesenchymal transition (EMT) traits, while inducing CXCL8 (IL-8) and PD-L1 expression. However, STAT3 knock-down (siSTAT3) had no effect on these functions; in terms of CSC enrichment, p65 had down-regulatory roles that compensated for the loss of an entire STAT3 protein. Y705-STAT3 and p65 acted additively in reducing CSC enrichment, and Y705A-STAT3 variant + sip65 has enriched chemo-resistant CSCs. Clinical data analyses revealed an inverse correlation between Y705-STAT3 + p65 phosphorylation and CSC signature in luminal A patients, and connection to improved disease course. Overall, we find regulatory roles for Y705-STAT3 and p65 in TME-stimulated HR+/HER2- tumors, with the ability to limit CSC enrichment. These findings raise concerns about using inhibitors of STAT3 and p65 as therapeutic strategies in the clinic.

Structure-guided identification of novel dual-targeting estrogen receptor α degraders with aromatase inhibitory activity for the treatment of endocrine-resistant breast cancer

Drug resistance is a major challenge in conventional endocrine therapy for estrogen receptor (ER) positive breast cancer (BC). BC is a multifactorial disease, in which simultaneous aromatase (ARO) inhibition and ERα degradation may effectively inhibit the signal transduction of both proteins, thus potentially overcoming drug resistance caused by overexpression or mutation of target proteins. In this study, guided by the X-ray structure of a hit compound 30a in complex with ER-Y537S, a structure-based optimization was performed to get a series of multiacting inhibitors targeting both ERα and ARO, and finally a novel class of potent selective estrogen receptor degraders (SERDs) based on a three-dimensional oxabicycloheptene sulfonamide (OBHSA) scaffold equipped with aromatase inhibitor (AI) activity were identified. Of these dual-targeting SERD-AI hybrids, compound 31q incorporating a 1H-1,2,4-triazole moiety showed excellent ERα degradation activity, ARO inhibitory activity and remarkable antiproliferative activity against BC resistant cells. Furthermore, 31q manifested efficient tumor suppression in MCF-7 tumor xenograft models. Taken together, our study reported for the first time the highly efficient dual-targeting SERD-AI hybrid compounds, which may lay the foundation of translational research for improved treatment of endocrine-resistant BC.

LPCAT1 is transcriptionally regulated by FOXA1 to promote breast cancer progression and paclitaxel resistance

Bioinformatics analysis indicates that lysophosphatidylcholine acyltransferase 1 (LPCAT1) and forkhead box A1 (FOXA1) are highly expressed in breast cancer tissues and their expression levels are correlated. Therefore, the aim of the present study was to investigate their involvement in the malignant progression and drug resistance of breast cancer. The clinical significance of LPCAT1 was analyzed using The Cancer Genome Atlas data. The enrichment of LPCAT1 in breast cancer cells was determined and the effects of LPCAT1 knockdown on cell proliferation, colony formation, migration, invasion and paclitaxel (PTX) resistance were evaluated. The association between LPCAT1 and FOXA1 was verified using luciferase reporter and chromatin immunoprecipitation assays. Thereafter, the ability of FOXA1 overexpression to regulate LPCAT1 regulation was evaluated. The results revealed that a high LPCAT1 level was associated with poor overall survival in patients with breast cancer. Furthermore, LPCAT1 was found to be highly expressed in breast cancer cells, and its knockdown resulted in suppressed proliferation, colony formation, migration and invasion, and weakened PTX resistance. Furthermore, FOXA1 overexpression attenuated the effects of LPCAT1 knockdown on cells, indicating that FOXA1 transcriptionally regulates LPCAT1. In summary, the present study reveals that LPCAT1 is transcriptionally regulated by FOXA1, which influences breast cancer cell proliferation, metastatic potential and PTX resistance.

E3 Ubiquitin Ligase NEDD4 Affects Estrogen Receptor α Expression and the Prognosis of Patients with Hormone Receptor-Positive Breast Cancer

Neural precursor cell-expressed developmentally downregulated 4-1 (NEDD4) is an E3 ligase that leads to the degradation of proteins, including estrogen receptor α. We evaluated whether the expression level of NEDD4 affected the outcome of breast cancer patients. We performed a retrospective cohort study enrolling 143 patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer. Of the 66 patients with high NEDD4 mRNA levels (high NEDD4 group) and 77 patients with low NEDD4 mRNA levels (low NEDD4 group), 98.4% and 96.1%, respectively, of the patients had received neoadjuvant/adjuvant hormone therapy. Disease-free survival and overall survival were significantly longer in the low NEDD4 group than in the high NEDD4 group (p = 0.048 and p = 0.022, respectively). Western blotting revealed a high expression of estrogen receptor α in the NEDD4-knockdown culture cells. The proliferation of NEDD4-knockdown cells treated with tamoxifen or estradiol deprivation was suppressed, compared with that of NEDD4-expressing cells. Knockdown of NEDD4 in breast cancer cells induced the accumulation of estrogen receptor α and increased sensitivity to hormone therapy. In summary, this mechanism may lead to a better prognosis in hormone receptor-positive breast cancer patients with a low expression of NEDD4.

Scoring Systems for Immunohistochemistry in Urothelial Carcinoma

Immunohistochemistry is widely used in diagnostic and scientific analysis of urothelial carcinoma. Objective interpretation of staining results is mandatory for accuracy and comparability in diagnostic and therapeutic patient care as well as research.Herein we summarize and explain standardized microscopic evaluation and scoring approaches for immunohistochemical stainings. We focus on commonly used and generally feasible approaches for different cellular compartments and comment on their utility in diagnostics and research practice.

The potential role of nanomedicine in the treatment of breast cancer to overcome the obstacles of current therapies

Breast cancer (BC) is the most frequently diagnosed malignant tumor among women in the world. BC is the heterogeneous tumor with different subtypes including luminal A-like, luminal B-like (HER2-/HER2+), HER2 enriched, and triple-negative BC. The therapeutic strategies including surgery, chemotherapy, radiotherapy, targeted therapy, and endocrine therapy are well developed and commonly used in the treatment of BC. However, some adverse effects of these conventional treatments limited their wide application in clinical. Therefore, it is necessary to develop more safe and more efficient individualized treatment strategies of the BC. Nanomedicine, as the most promising strategy for controlled and targeted drug delivery, is widely used in multiple aspects of cancer therapy. Importantly, accumulative evidences show that nanomedicine has achieved good outcomes in the treatment of BC and a huge amount of BC patients benefited from the nanomedicine related treatments. In this review, we summarized and discussed the major problems occurred during the administration of conventional treatment strategies for BC and the potential roles of nanomedicine in promoting the treatment efficacy of BC by overcoming obstacles of current treatment of BC.

Identifying the predictors of adherence to oral endocrine therapy in racial/ethnic minority patients with low socioeconomic status

Background Adherence to oral endocrine therapy (OET) is crucial in ensuring its maximum benefit in prevention and treatment of hormone receptor-positive (HR+) breast cancer (BC) in patients. Medication use behavior is suboptimal especially in racial/ethnic minorities of lower socioeconomic status (SES). We aimed to assess the OET adherence and its predictors in racial/ethnic minority patients of lower SES. Aim We aimed to assess the OET adherence and determine the predictors of OET nonadherence in racial/ethnic minority patients of lower SES. Method A retrospective study was conducted at the Harris Health System in Houston, Texas. Since the study period included the COVID-19 pandemic, data was collected during the 6 months prior and 6 months after the start of the pandemic. The adherence was assessed using the prescription refill data using the proportion of days covered. Multivariable logistic regression model was used to identify predictors of nonadherence. Eighteen years or older patients on appropriate doses of OET for prevention or treatment of BC were included. Result In 258 patients, the adherence was significantly lower during the pandemic (44%) compared to before the pandemic (57%). The predictors of OET nonadherence before the pandemic were Black/African American, obesity/extreme obesity, prevention setting, tamoxifen therapy, and 4 or more years on OET. During the pandemic, prevention setting and those not using home delivery were more likely to be nonadherent. Conclusion Racial/ethnic minority patients of lower SES, especially African Americans and those using OET for prevention of BC, require individualized interventions to improve adherence.

Clinicopathological characteristics and prognostic analysis of PIK3CA mutation in breast cancer patients in Northwest China

PURPOSE

Multiple studies on PIK3CA mutations in breast cancer (BC) had been performed, which showed the controversial results among different countries and races even those from the same country. The present study aimed to explore the PIK3CA gene mutation status in BC patients in Northwest China and reveal the relationship between PIK3CA mutations and clinicopathological features along with prognosis.

MATERIALS AND METHODS

1002 BC patients from Northwest China were recruited in this study, genomic DNA was extracted from formalin-fixed paraffin-embedded (FFPE) tumor tissues, and hotspot mutations in the exon 9 and 20 of PIK3CA gene were detected by ARMS-PCR.

RESULTS

PIK3CA mutations were found in 31.2% (313/1002) of BC patients, among them 66.1% were mutations in exon 20% and 32.6% were mutations in exon 9. H1047R was the most common mutation type, accounting for 56.5% of the total mutated samples. Significant correlations were observed between PIK3CA mutation status and age (P = 0.035), histopathologic types (P = 0.004), pathological grade (P = 0.013), ER positivity (P < 0.001), PR positivity (P < 0.001), molecular subtypes (P = 0.004) and family history (P = 0.007). Cox multivariate analysis showed that patients with mutations in exon 9 or 20 had shorter DFS and OS than wild-type patients. Those with exon 9 mutations subgroup had the worst prognosis. Interestingly, patients with H1047L mutation had the best prognosis than others.

CONCLUSION

PIK3CA mutations could be used as an indicator of clinical outcome or targeted therapy for multiple breast cancer subgroups in Northwest China.

Combinatorial treatments of tamoxifen and SM6Met, an extract from Cyclopia subternata Vogel, are superior to either treatment alone in MCF-7 cells

Synergistic drug combinations are not only popular in antibiotic, anti-microbial, immune disease (i.e., AIDS) and viral infection studies, but has also gained traction in the field of cancer research as a multi-targeted approach. It has the potential to lower the doses needed of standard of care (SOC) therapeutic agents, whilst maintaining an effective therapeutic level. Lower dosages could ameliorate the fundamental problems such as drug resistance and metastasis associated with current SOC therapies. In the current study, we show that the combination of SM6Met with (2)-4-hydroxytamoxifen (4-OH-Tam, the active metabolite of tamoxifen) produces a strong synergistic effect in terms of inhibiting MCF7 ER-positive (ER⁺) breast cancer cell proliferation and that a 20 times lower dose of 4-OH-Tam in combination with SM6Met is required to produce the same inhibitory effect on cell proliferation as 4-OH-Tam on its own. Cell cycle analyses of the best combination ratios of SM6Met and 4-OH-Tam also suggests that the combination results in increased accumulation of cells in the S-phase and in the apoptotic phase. Moreover, the best combination ratio (20:1) of SM6Met with 4-OH-Tam displayed greater anti-metastatic potential in terms of inhibiting ER⁺ breast cancer cell migration, invasion, and colony formation than the SOC therapy alone, suggesting that SM6Met together with 4-OH-Tam could be a viable drug combination for not only delaying resistance and ameliorating the negative side-effects associated with current SOC therapies, like tamoxifen, but could also provide a novel, more affordable therapeutic alternative for treating or preventing ER⁺ breast cancer metastasis.

Comparative biomarker analysis of PALOMA-2/3 trials for palbociclib

While cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, including palbociclib, combined with endocrine therapy (ET), are becoming the standard-of-care for hormone receptor-positive/human epidermal growth factor receptor 2‒negative metastatic breast cancer, further mechanistic insights are needed to maximize benefit from the treatment regimen. Herein, we conducted a systematic comparative analysis of gene expression/progression-free survival relationship from two phase 3 trials (PALOMA-2 [first-line] and PALOMA-3 [≥second-line]). In the ET-only arm, there was no inter-therapy line correlation. However, adding palbociclib resulted in concordant biomarkers independent of initial ET responsiveness, with shared sensitivity genes enriched in estrogen response and resistance genes over-represented by mTORC1 signaling and G2/M checkpoint. Biomarker patterns from the combination arm resembled patterns observed in ET in advanced treatment-naive patients, especially patients likely to be endocrine-responsive. Our findings suggest palbociclib may recondition endocrine-resistant tumors to ET, and may guide optimal therapeutic sequencing by partnering CDK4/6 inhibitors with different ETs. Pfizer (NCT01740427; NCT01942135).

Diagnostic and Prognostic Role of 18F-Fluoroestradiol PET in Metastatic Breast Cancer: The Second Youth of an Older Theranostic Concept

Since the discovery of the role of female hormones in breast cancer (BC) pathophysiology, in vivo detection of oestrogen receptor (ER) distribution has been one of the major goals of nuclear medicine and molecular imaging [...]

Exploring new pathways in endocrine-resistant breast cancer

The most common breast cancer (BC) subtypes are hormone-dependent, being either estrogen receptor-positive (ER⁺), progesterone receptor-positive (PR⁺), or both, and altogether comprise the luminal subtype. The mainstay of treatment for luminal BC is endocrine therapy (ET), which includes several agents that act either directly targeting ER action or suppressing estrogen production. Over the years, ET has proven efficacy in reducing mortality and improving clinical outcomes in metastatic and nonmetastatic BC. However, the development of ET resistance promotes cancer survival and progression and hinders the use of endocrine agents. Several mechanisms implicated in endocrine resistance have now been extensively studied. Based on the current clinical and pre-clinical data, the present article briefly reviews the well-established pathways of ET resistance and continues by focusing on the three most recently uncovered pathways, which may mediate resistance to ET, namely receptor activator of nuclear factor kappa B ligand (RANKL)/receptor activator of nuclear factor kappa B (RANK), nuclear factor kappa B (NFκB), and Notch. It additionally overviews the evidence underlying the approval of combined therapies to overcome ET resistance in BC, while highlighting the relevance of future studies focusing on putative mediators of ET resistance to uncover new therapeutic options for the disease.

Ribociclib plus letrozole in patients with hormone receptor-positive, HER2-negative advanced breast cancer with no prior endocrine therapy: subgroup safety analysis from the phase 3b CompLEEment-1 trial

BACKGROUND

The CDK4/6 inhibitor, ribociclib in combination with endocrine therapy significantly improved progression-free survival in the first line setting in post-menopausal patients with HR+/HER2- advanced breast cancer (ABC) in a pivotal phase 3, placebo-controlled trial (MONALEESA-2) and demonstrated superior overall survival in premenopausal patients with HR+/HER2- ABC (MONALEESA-7). The multinational, phase 3b, CompLEEment-1 trial, which assessed the safety and efficacy of ribociclib plus letrozole in a broader population of patients who have not received prior endocrine therapy for advanced disease, is the largest phase 3 clinical trial to date to evaluate the safety and efficacy of a CDK4/6 inhibitor. We report a subanalysis of data from patients (N = 339) enrolled in the central and south European countries of the SERCE (Southern Europe, RUC, Central Europe) cluster of CompLEEment-1.

PATIENTS AND METHODS

Men and women of any menopausal status with HR+/HER2- ABC received once-daily oral ribociclib 600 mg (3-weeks on/1-week-off), plus letrozole 2.5 mg continuously. Men/premenopausal women also received a GnRH-agonist. The primary outcome was the number of patients with adverse events (AEs) over a timeframe of approximately 36 months. Time-to-progression, overall response rate, and clinical benefit rate were also measured.

RESULTS

Safety results in the SERCE subgroup were consistent with those in the pivotal clinical trials of ribociclib in combination with endocrine therapy. Treatment-related AEs leading to dose adjustments/interruption occurred in 63.1% of patients but led to treatment discontinuation in only 10.6%. The most common treatment-related AEs of grade ≥ 3 were neutropenia and transaminase elevations. There were no fatal treatment-related events.

CONCLUSIONS

These findings from the SERCE subgroup support the safety and manageable tolerability of ribociclib in a broad range of patients with HR+/HER2- ABC more representative of patients in real-world clinical practice.

Ultrasonic Omics Based on Intelligent Classification Algorithm in Hormone Receptor Expression and Efficacy Evaluation of Breast Cancer

The changes of hormone expression and efficacy of breast cancer (BC) were investigated under the VGG19FCN algorithm and ultrasound omics. 120 patients with BC were selected, of which 90 were positive for hormone receptor and 30 were negative. The VGG19FCN model algorithm and classifier were selected to classify the features of ultrasound breast map, and reliable ultrasound feature data were obtained. The evaluation and analysis of BC hormone receptor expression and clinical efficacy in patients with BC were realized by using ultrasonic omics. The evaluation of the results of the VGG19FCN algorithm was $\text{DSC}\left(\text{Dice}\text{similarity}\text{coefficient}\right)=0.9626$ , $\text{MPA}\left(\text{mean}\text{pixel}\text{accuracy}\right)=0.9676$ , and $\text{IOU}\left(\text{intersection}\text{over}\text{union}\right)=0.9155$ . When the classifier was used to classify the lesion features of BC image, the sensitivity of classification was improved to a certain extent. Compared with the classification of radiologists, when classifying whether patients had BC lesions, the sensitivity increased by 22.7%, the accuracy increased from 71.9% to 79.7%, and the specific evaluation index increased by 0.8%. No substantial difference was indicated between RT (arrive time), WIS (wash in slope), and TTP (time to peak) before and after chemotherapy, $P>0.05$ . After chemotherapy, the AUC (area under curve) and PI (peak intensity) of ultrasonographic examination were substantially lower than those before chemotherapy, and there were substantial differences in statistics ( $P<0.05$ ). In summary, the VGG19FCN algorithm effectively reduces the subjectivity of traditional ultrasound images and can effectively improve the value of ultrasound image features in the accurate diagnosis of BC. It provides a theoretical basis for the subsequent treatment of BC and the prediction of biological behavior. The VGG19FCN algorithm had a good performance in ultrasound image processing of BC patients, and hormone receptor expression changed substantially after chemotherapy treatment.

Trastuzumab Plus Endocrine Therapy or Chemotherapy as First-line Treatment for Patients with Hormone Receptor-Positive and HER2-Positive Metastatic Breast Cancer (SYSUCC-002)

PURPOSE

There is no research evidence demonstrate which is the better partner strategy, endocrine therapy or chemotherapy, to combine with anti-HER2 therapy as the first-line management of hormone receptor (HR)-positive (HR+) and HER2-positive (HER2+) metastatic breast cancer (MBC). We wished to ascertain if trastuzumab plus endocrine therapy is noninferior to trastuzumab plus chemotherapy.

PATIENTS AND METHODS

We conducted an open-label, noninferiority, phase III, randomized, controlled trial (NCT01950182) at nine hospitals in China. Participants, stratified by previous adjuvant endocrine therapy and disease status (recurrent disease vs. de novo metastasis), were assigned randomly (1:1) to receive trastuzumab plus endocrine therapy (per investigator's choice of oestrogen-receptor modulators or aromatase inhibitor, with/without concurrent ovarian suppression) or chemotherapy (per investigator's choice of taxanes, capecitabine, or vinorelbine). The primary endpoint was progression-free survival (PFS) with a noninferiority upper margin of 1.35 for the HR. The intention-to-treat population was used in primary and safety analyses.

RESULTS

A total of 392 patients were enrolled and assigned randomly to receive trastuzumab plus endocrine therapy (ET group, n = 196) or trastuzumab plus chemotherapy (CT group, n = 196). After a median follow-up of 30.2 months [interquartile range (IQR) 15.0-44.7], the median PFS was 19.2 months [95% confidence interval (CI), 16.7-21.7)] in the ET group and 14.8 months (12.8-16.8) in the CT group (hazard ratio, 0.88; 95% CI, 0.71-1.09; Pnoninferiority < 0.0001). A significantly higher prevalence of toxicity was observed in the CT group compared with the ET group.

CONCLUSIONS

Trastuzumab plus endocrine therapy was noninferior to trastuzumab plus chemotherapy in patients with HR+HER2+ MBC.

Comprehensive immunohistochemical analysis of RET, BCAR1, and BCAR3 expression in patients with Luminal A and B breast cancer subtypes

PURPOSE

Breast cancer (BC) is considered a heterogeneous disease composed of distinct subtypes with diverse clinical outcomes. Luminal subtype tumors have the best prognosis, and patients benefit from endocrine therapy. However, resistance to endocrine therapies in BC is an obstacle to successful treatment, and novel biomarkers are needed to understand and overcome this mechanism. The RET, BCAR1, and BCAR3 genes may be associated with BC progression and endocrine resistance.

METHODS

Aiming to evaluate the expression profile and prognostic value of RET, BCAR1, and BCAR3, we performed immunohistochemistry on tissue microarrays (TMAs) containing a cohort of 361 Luminal subtype BC.

RESULTS

Low expression levels of these three proteins were predominantly observed. BCAR1 expression was correlated with nuclear grade (p = 0.057), and BCAR3 expression was correlated with lymph node status (p = 0.011) and response to hormonal therapy (p = 0.021). Further, low expression of either BCAR1 or BCAR3 was significantly associated with poor prognosis (p = 0.005; p = 0.042). Pairwise analysis showed that patients with tumors with low BCAR1/low BCAR3 expression had a poorer overall survival (p = 0.013), and the low BCAR3 expression had the worst prognosis with RET high expression stratifying these patients into two different groups. Regarding the response to hormonal therapy, non-responder patients presented lower expression of RET in comparison to the responder group (p = 0.035). Additionally, the low BCAR1 expression patients had poorer outcomes than BCAR1 high (p = 0.015).

CONCLUSION

Our findings suggest RET, BCAR1, and BCAR3 as potential candidate markers for endocrine therapy resistance in Luminal BC.

miR-641 Inhibited Cell Proliferation and Induced Apoptosis by Targeting NUCKS1/PI3K/AKT Signaling Pathway in Breast Cancer

Objective

Studies revealed an important role of microRNAs (miRNAs) in multiple cancers, including breast cancer. In the present study, we evaluated the role and function of miR-641 in breast cancer.

Methods

The expression level of miR-641 in breast cancer cell lines (Hs-578T, MCF7, HCC1937, and MAD-MB-231) was determined by real-time PCR. Functional analyses, including CCK-8 assay, transwell assay, wound-healing assay, and apoptosis detection, were carried out to explore the roles of miRNA-641 in malignant behaviors of breast cancer. Luciferase report assay was used to investigate the regulatory association of miRNA-641 with its potential targets.

Results

The expression levels of miR-641 were downregulated, while the expression levels of nuclear casein kinase and cyclin-dependent kinase substrate 1 (NUCKS1) were increased in breast cancer cell lines. The in vitro results showed that miR-641 repressed proliferation and migration/invasion and promoted apoptosis of breast cancer cells. NUCKS1, a positive regulator of phosphatidylinositol-3-kinases (PI3K)/protein-serine-threonine kinase (AKT) pathway, was confirmed as a direct target of miR-641. The of treatment of the PI3K agonist, 740Y-P, could abrogate the antioncogenic potentials of miR-641 in breast cancer cells.

Conclusion

miR-641 functioned as a tumor suppressor through the PI3K/AKT signaling pathway via targeting NUCKS1 in breast cancer.

Proteolysis-targeting chimeras and their implications in breast cancer

Breast cancer (BC) is a highly heterogeneous neoplasm of the mammary tissue, causing the deaths of a large number of women worldwide. Nearly 70% and 20% of BC cases are estrogen receptor alpha positive (ERα+) and human epidermal growth factor receptor 2-positive (HER2+), respectively; therefore, ER and HER2 targeted therapies have been employed in BC treatment. However, resistance to these therapies has been reported, indicating a need for developing novel therapeutic strategies. Proteolysis-targeting chimeras (PROTACs) are new, promising therapeutic tools designed with a bimodular structure: one module allows specific binding to target proteins, and the other module allows efficient degradation of these target proteins. In this paper, PROTACs and their potential in controlling the progression of ERα and HER2+ BC are discussed.

Evaluation of Therapeutic Targets in Histological Subtypes of Bladder Cancer

Histologically, bladder cancer is a heterogeneous group comprising urothelial carcinoma (UC), squamous cell carcinoma, adenocarcinomas (ACs), urachal carcinomas (UrCs), and small cell neuroendocrine carcinomas (SCCs). However, all bladder cancers have been treated so far uniformly, and targeted therapy options are still limited. Thus, we aimed to determine the protein expression/molecular status of commonly used cancer targets (programmed cell death 1 ligand 1 (PD-L1), mismatch repair (MMR), androgen and estrogen receptors (AR/ER), Nectin-4, tumor-associated calcium signal transducer 2 (Tacstd2, Trop-2), epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), and fibroblast growth factor receptor 3 (FGFR3)) to give first insights into whether patients with SCC, AC/UrCs, and squamous-differentiated carcinomas (Sq-BLCA) of the bladder could be eligible for targeted therapies. In addition, for MMR-deficient tumors, microsatellite instability was analyzed. We completed our own data with molecular data from The Cancer Genome Atlas (TCGA). We present ratios for each drug and cumulative ratios for multiple therapeutic options for each nonurothelial subtype. For example, 58.9% of SCC patients, 33.5% of AC/UrCs patients, and 79.3% of Sq-BLCA patients would be eligible for at least one of the analyzed targets. In conclusion, our findings hold promise for targeted therapeutic approaches in selected patients in the future, as various drugs could be applied according to the biomarker status.

The Place of Chemotherapy in The Evolving Treatment Landscape for Patients With HR-positive/HER2-negative MBC

Endocrine therapy (ET) for the treatment of patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR-positive/HER2-negative) metastatic breast cancer (MBC) has changed markedly over recent years with the emergence of new ETs and the use of molecularly targeted agents. Cytotoxic chemotherapy continues, however, to have an important role in these patients and it is important to maximize its efficacy while minimizing toxicity to optimize outcomes. This review examines current HR-positive/HER2-negative MBC clinical guidelines and addresses key questions around the use of chemotherapy in the face of emerging therapeutic options. Specifically, the indications for chemotherapy in patients with HR-positive/HER2-negative MBC and the choice of optimal chemotherapy are discussed.

HNRNPA2B1 regulates tamoxifen- and fulvestrant-sensitivity and hallmarks of endocrine resistance in breast cancer cells

Despite new combination therapies improving survival of breast cancer patients with estrogen receptor α (ER+) tumors, the molecular mechanisms for endocrine-resistant disease remain unresolved. Previously we demonstrated that expression of the RNA binding protein and N6-methyladenosine (m6A) reader HNRNPA2B1 (A2B1) is higher in LCC9 and LY2 tamoxifen (TAM)-resistant ERα breast cancer cells relative to parental TAM-sensitive MCF-7 cells. Here we report that A2B1 protein expression is higher in breast tumors than paired normal breast tissue. Modest stable overexpression of A2B1 in MCF-7 cells (MCF-7-A2B1 cells) resulted in TAM- and fulvestrant- resistance whereas knockdown of A2B1 in LCC9 and LY2 cells restored TAM and fulvestrant, endocrine-sensitivity. MCF-7-A2B1 cells gained hallmarks of TAM-resistant metastatic behavior: increased migration and invasion, clonogenicity, and soft agar colony size, which were attenuated by A2B1 knockdown in MCF-7-A2B1 and the TAM-resistant LCC9 and LY2 cells. MCF-7-A2B1, LCC9, and LY2 cells have a higher proportion of CD44+/CD24-/low cancer stem cells (CSC) compared to MCF-7 cells. MCF-7-A2B1 cells have increased ERα and reduced miR-222-3p that targets ERα. Like LCC9 cells, MCF-7-A2B1 have activated AKT and MAPK that depend on A2B1 expression and are growth inhibited by inhibitors of these pathways. These data support that targeting A2B1 could provide a complimentary therapeutic approach to reduce acquired endocrine resistance.

Nuclear Mechanisms Involved in Endocrine Resistance

Endocrine therapy is a standard treatment offered to patients with ERα (estrogen receptor α)-positive breast cancer. In endocrine therapy, ERα is either directly targeted by anti-estrogens or indirectly by aromatase inhibitors which cause estrogen deficiency. Resistance to these drugs (endocrine resistance) compromises the efficiency of this treatment and requires additional measures. Endocrine resistance is often caused by deregulation of the PI3K/AKT/mTOR pathway and/or cyclin-dependent kinase 4 and 6 activities allowing inhibitors of these factors to be used clinically to counteract endocrine resistance. The nuclear mechanisms involved in endocrine resistance are beginning to emerge. Exploring these mechanisms may reveal additional druggable targets, which could help to further improve patients' outcome in an endocrine resistance setting. This review intends to summarize our current knowledge on the nuclear mechanisms linked to endocrine resistance.

Relationship between endocrine resistance and the periods of adjuvant endocrine treatment for hormone receptor-positive, HER2-negative breast cancer

BACKGROUND

Current guidelines define primary and secondary endocrine resistance according to the periods of adjuvant endocrine therapy (adj-ET); however, the relationship between adj-ET period and endocrine resistance remains unclear.

OBJECTIVE

We examined progression-free survival (PFS) after primary ET for recurrent hormone receptor-positive/HER2-negative breast cancer, and evaluated the relationship between endocrine resistance and the periods of adj-ET.

METHODS

We assessed PFS among 183 patients who received ET as primary treatment for the first recurrence, according to the period of adj-ET (adj-ET < 1 year, 1-2 years, ≥2 years, and completion).

RESULTS

Patients who relapsed during the first year of adj-ET had the significantly shortest PFS. PFS did not significantly differ between patients who relapsed at 1-2 years of adj-ET and patients who relapsed while on adj-ET but after the first 2 years.

CONCLUSIONS

Relapse at 1-2 years after adj-ET initiation might be better classified as secondary endocrine resistance rather than primary endocrine resistance.

Cytocidal Antitumor Effects against Human Ovarian Cancer Cells Induced by B-Lactam Steroid Alkylators with Targeted Activity against Poly (ADP-Ribose) Polymerase (PARP) Enzymes in a Cell-Free Assay

We evaluated three newly synthesized B-lactam hybrid homo-aza-steroidal alkylators (ASA-A, ASA-B and ASA-C) for their PARP1/2 inhibition activity and their DNA damaging effect against human ovarian carcinoma cells. These agents are conjugated with an alkylating component (POPA), which also served as a reference molecule (positive control), and were tested against four human ovarian cell lines in vitro (UWB1.289 + BRCA1, UWB1.289, SKOV-3 and OVCAR-3). The studied compounds were thereafter compared to 3-AB, a known PARP inhibitor, as well as to Olaparib, a standard third-generation PARP inhibitor, on a PARP assay investigating their inhibitory potential. Finally, a PARP1 and PARP2 mRNA expression analysis by qRT-PCR was produced in order to measure the absolute and the relative gene expression (in mRNA transcripts) between treated and untreated cells. All the investigated hybrid steroid alkylators and POPA decreased in vitro cell growth differentially, according to the sensitivity and different gene characteristics of each cell line, while ASA-A and ASA-B presented the most significant anticancer activity. Both these compounds induced PARP1/2 enzyme inhibition, DNA damage (alkylation) and upregulation of PARP mRNA expression, for all tested cell lines. However, ASA-C underperformed on average in the above tasks, while the compound ASA-B induced synthetic lethality effects on the ovarian cancer cells. Nevertheless, the overall outcome, leading to a drug-like potential, provides strong evidence toward further evaluation.

Efficacy and safety of CDK4/6 and PI3K/AKT/mTOR inhibitors as second-line treatment in postmenopausal patients with hormone receptor-positive, HER-2-negative metastatic breast cancer: a network meta-analysis

BACKGROUND

We compared the efficacy and safety of combinations of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors and PI3K/AKT/mTOR inhibitors as second-line treatment in postmenopausal women with HR⁺, HER2^- metastatic breast cancer.

METHODS

We searched the Medline, Embase, and Cochrane Library electronic databases for phase II/III randomized trials evaluating CDK4/6 and PI3K/AKT/mTOR inhibitors plus fulvestrant. We compared the results with a network meta-analysis. Study quality was assessed following the GRADE approach. Outcomes of interest were progression-free survival, overall response rate, overall survival and G3-4 adverse drug events (ADEs).

RESULTS

Eight RCTs were identified in the network meta-analysis. PFS was significantly improved by treatment with abemaciclib plus fulvestrant and ribociclib plus fulvestrant compared to pictilisib plus fulvestrant. The ORR following treatment with abemaciclib plus fulvestrant, ribociclib plus fulvestrant, palbociclib plus fulvestrant, buparlisib plus fulvestrant, and alpelisib plus fulvestrant significantly differed from that observed following treatment with placebo plus fulvestrant. In terms of OS, compared with placebo plus fulvestrant, abemaciclib plus fulvestrant, ribociclib plus fulvestrant, and buparlisib plus fulvestrant had a significant difference. The risks of ADEs were similar among three CDK4/6 inhibitors.

CONCLUSION

As second-line treatment, three CDK4/6 inhibitors showed superior clinical efficacy compared to other PI3K/AKT/mTOR inhibitors with comparable safety profiles.

PI3K/AKT and MAPK1 molecular changes preceding matrix metallopeptidases overexpression during tamoxifen-resistance development are correlated to poor prognosis in breast cancer patients

BACKGROUND

Metastasis and drug resistance remain a persistent key clinical obstacle to the success of breast cancer treatments. Recent years have seen an increased focus on understanding the factors that influence metastasis and drug resistance.

METHODS

In this study, the changes in MMPs gene expression were investigated together with their regulatory pathways-PI3K, MAPK and NFKβ pathways-during the process of developing tamoxifen resistance in MCF7 cell line. Gene correlation maps and Kaplan-Meier survival plots among all breast cancer patients and patients treated with tamoxifen were evaluated.

RESULTS

MMPs gene expression was found to be up regulated in MCF7 cell line treated with tamoxifen during the development of tamoxifen resistance using two approaches. Up-regulation of gene expression of AKT1 and MAPK1 started in cells treated with 10 μM tamoxifen that was followed with up-regulation of other genes in these pathways and MMPs in cells treated with 35 μM tamoxifen. MMPs and genes from PI3K, MAPK and NFKβ pathways showed highly significant increase of expression at 50 μM or when cells were treated sequentially six times with 35 μM. Furthermore, increased genes expression was associated with aggressive pattern, clear morphological changes, higher growth rate, increased migration and adhesion potential and tamoxifen insensitivity. Breast cancer distant metastasis-free survival, and survival among tamoxifen treated patients had high expression levels of MAPK1, AKT1, TIMP2, MMP1, and MMP9 showed poor prognosis.

CONCLUSION

Early changes of MAPK1, AKT1 gene expression upon tamoxifen treatment could possibly be used as an early marker of resistance and future poor prognosis.

Suppression of Tumorigenicity 5 Ameliorates Tumor Characteristics of Invasive Breast Cancer Cells via ERK/JNK Pathway

BACKGROUND

Suppression of tumorigenicity 5 (ST5) has been considered as a tumor suppressor gene in HeLa tumor cells. However, its role in the progression of breast cancer remains vague.

METHODS

Online database analysis was determined by Oncomine and Breast Cancer Gene-Expression Miner v4.4 (bc-GenExMiner v4.4). Tumor biology behaviors were measured by MTT assay, wound healing model, Transwell and Flow cytometry assays. Methylation-specific PCR (MSP) was employed to detect promoter methylation.

RESULTS

Low level of ST5 was observed in breast cancer specimens, particularly in recurrent, invasive breast cancer cases compared to para-carcinoma tissue or non-invasive breast cancer. The downregulation of ST5 was also proved in MDA-MB-231 and SKBR3 cell lines with a high invasive capability as compared to MCF-7 cell with a low invasive capability. ST5 was negatively associated with pathological stages of breast cancer. ST5-downregulation promoted, while ST5-upregulation inhibited the progression of cell proliferation, cell cycle and migration of MDA-MB-231 cells. Additionally, ST5 knockdown inhibited, whereas ST5 overexpression promoted apoptosis of MDA-MB-231 cells. However, ST5 modification, either upregulation or downregulation, had no significant impact on tumor behaviors of MCF-7 cells. Mechanistically, ST5 protein ablation activated, while ST5-upregulation repressed the activities of phosphorylated ERK1/2 and JNK, and subsequently the expression of c-Myc. PD98059-mediated ERK1/2 inhibition abolished the stimulatory effects of ST5-depletion on ERK1/2/JNK/c-Myc signaling axis, and ST5 depletion-mediated cell over-proliferation and migration. Of note, ST5 reduction in invasive breast cancer cells should implicate in the hypermethylation of ST5 promoter region.

CONCLUSION

Our findings suggest that ST5 potentially acts as a tumor suppressor gene in invasive breast cancer through regulating ERK/JNK signaling pathway and provide a novel insight for breast cancer treatment.

Preoperative Serum Hypersensitive-c-Reactive-Protein (Hs-CRP) to Albumin Ratio Predicts Survival in Patients with Luminal B Subtype Breast Cancer

Objective

To evaluate the clinical prognostic significance of preoperative serum hypersensitive-c-reactive-protein (Hs-CRP) to albumin ratio (CAR) in patients with luminal B subtype breast cancer.

Methods

A total of 199 patients with luminal B subtype breast cancer enrolled in this study were analyzed retrospectively. The optimal cutoff value of CAR was performed by the receiver operating characteristic curve (ROC). The associations between luminal B subtype breast cancer and clinicopathological variables by CAR were performed by chi-square test. Kaplan–Meier and log rank method were used for survival analysis. The independent prognostic factors were determined by univariate and multivariate Cox’s proportional hazards regression model.

Results

The patients were divided into low CAR group (CAR<0.044) and high CAR group (CAR≥0.044) by ROC. CAR was the independent factor by univariate and multivariate analysis, and the mean DFS and OS in the low CAR group survived longer than those in the high CAR group (p<0.05). According to the endocrine therapy with aromatase inhibitors, the mean survival time of DFS and OS in the low CAR group was significantly higher than that in the high CAR group (p<0.05). Moreover, patients with pathological I+II stage survived longer than those with pathological III stage, and the mean survival time of DFS and OS in the low CAR group was significantly higher than that in the high CAR group (p<0.05). Patients without lymph vessel invasion survived longer than those with lymph vessel invasion (p<0.05), and the mean survival time of DFS and OS in low the CAR group was significantly higher than that in the high CAR group (p<0.05).

Conclusion

Preoperative CAR was significantly associated with survival and prognosis of breast cancer, and it can be used as a routine prognostic indicator to predict the prognosis of luminal B subtype breast cancer.

Landmark trials in the medical oncology management of metastatic breast cancer

Significant advances in the management of metastatic breast cancer (MBC) have guided more personalized treatment according to disease biology and led to improved survival outcomes and quality of life for patients. In this review, we discuss landmark clinical trials in medical oncology that have shaped the current standard of care for MBC. Combinations of endocrine therapy with cyclin-dependent kinase 4/6 inhibitors have led to substantial improvements in overall survival, thus becoming standard first-line treatment for patients with HR-positive MBC. Inhibition of the PI3K and mTOR pathway is another promising strategy to overcome resistance to endocrine therapy. HER2-targeted therapies have also evolved with the addition of pertuzumab to trastuzumab plus a taxane demonstrating remarkable overall survival advantage in patient with HER2-positive MBC. In second or later line therapies, novel anti-HER2 antibody-drug conjugates and TKIs have durable antitumor activity, survival benefit, and encouraging efficacy in the subgroup of patients with brain metastases. Triple negative breast cancer remains the most challenging subtype due to lack of druggable targets. Immunotherapy for patients with PDL-1 expression on tumor infiltrating immune cells and poly (ADP-ribose) polymerase inhibitors for those with germline BRCA1/2 mutations are the latest approved targeted strategies in this population. Numerous obstacles still exist in treating MBC, especially for patients whose disease develops resistance to available agents. Future research is eagerly awaited to address the optimal sequence or combination of therapies and to identify better biomarkers to guide precision medicine.