Enzalutamide for the Treatment of Androgen Receptor-Expressing Triple-Negative Breast Cancer

Metabolic dysfunction-associated steatotic liver disease: A sexually dimorphic disease and breast and gynecological cancer

Metabolic dysfunction-associated steatotic liver disease (MASLD) has become a global public health and economic burden worldwide in the past few decades. Epidemiological studies have shown that MASLD is a multisystem disease that is associated not only with liver-related complications but also with an increased risk of developing extrahepatic cancers. MASLD is a sexually dimorphic disease with sex hormones playing an important role in the development and progression of MASLD, especially by the levels and ratios of circulating estrogens and androgens. MASLD is associated with hormone-sensitive cancers including breast and gynecological cancer. The risk of breast and gynecological cancer is elevated in individuals with MASLD driven by shared metabolic risk factors including obesity and insulin resistance. Multiple potential mechanisms underline these associations including metabolic dysfunction, gut dysbiosis, chronic inflammation and dysregulated release of hepatokines. However, the effect of hormone therapy including hormone replacement therapy and anti-estrogen treatment on MASLD and female-specific cancers remains debatable at this time. This synopsis will review the associations between MASLD and breast and gynecological cancer, their underlying mechanisms, implications of hormonal therapies, and their future directions.

Role of Tumor-Associated Macrophages in Breast Cancer Immunotherapy

Breast cancer (BC) is the second leading cause of death among women worldwide. Immunotherapy has become an effective treatment for BC patients due to the rapid development of medical technology. Considerable breakthroughs have been made in research, marking the beginning of a new era in cancer treatment. Among them, various cancer immunotherapies such as immune checkpoint inhibitors (ICIs), cancer vaccines, and adoptive cell transfer are effective and have good prospects. The tumor microenvironment (TME) plays a crucial role in determining the outcomes of tumor immunotherapy. Tumor-associated macrophages (TAMs) are a key component of the TME, with an immunomodulatory effect closely related to the immune evasion of tumor cells, thereby affecting malignant progression. TAMs also significantly affect the therapeutic effect of ICIs (such as programmed death 1/programmed death ligand 1 (PD-1/PD-L1) inhibitors). TAMs are composed of multiple heterogeneous subpopulations, including M1 phenotypes macrophages (M1) and M2 phenotypes macrophages (M2). Furthermore, they mainly play an M2-like role and moderate a variety of harmful consequences such as angiogenesis, immunosuppression, and metastasis. Therefore, TAMs have become a key area of focus in the development of tumor therapies. However, several tumor immunotherapy studies demonstrated that ICIs are effective only in a small number of solid cancers, and tumor immunotherapy still faces relevant challenges in the treatment of solid tumors. This review explores the role of TAMs in BC immunotherapy, summarizing their involvement in BC development. It also explains the classification and functions of TAMs, outlines current tumor immunotherapy approaches and combination therapies, and discusses the challenges and potential strategies for TAMs in immuno-oncology treatments.

A comprehensive review on targeted therapies for triple negative breast cancer: an evidence-based treatment guideline

Triple-negative breast cancer (TNBC) is an aggressive malignancy characterized by limited therapeutic options and poor prognosis. Despite advancements in precision oncology, conventional chemotherapy remains the cornerstone of TNBC treatment, often accompanied by debilitating side effects and suboptimal outcomes. This review presents a comprehensive analysis of clinical trials on targeted therapies, aiming to establish a novel, evidence-based treatment strategy exclusively leveraging molecularly targeted agents. By integrating patient-specific genetic profiles with therapeutic responses observed across various clinical trial phases, this approach seeks to optimize efficacy while minimizing toxicity. The proposed targeted therapy combinations hold significant potential to revolutionize TNBC treatment, offering a paradigm shift toward precision medicine and improved patient outcomes.

APOBEC-Driven Hypermutation in the Lymphocyte-Predominant Group of Triple-Negative Breast Cancer

This study aimed to evaluate the clinicopathologic and genomic characteristics of triple-negative breast cancer subclassification. Triple-negative breast cancer was classified into the luminal androgen receptor (LAR) subtype and the tumor-infiltrating lymphocytes (TILs) groups of the non-LAR subtype-lymphocyte predominant (LP), lymphocyte intermediate, and lymphocyte depleted-based on androgen receptor immunohistochemistry and TILs. Clinicopathologic and genomic characteristics were evaluated for these triple-negative breast cancer subclasses. The LP group was associated with a histologic type of carcinoma with medullary features, a higher tumor mutation burden, and increased APOBEC activity, indicative of APOBEC-driven hypermutation. The LAR subtype was characterized by a higher prevalence of PIK3CA mutations, lower homologous recombination deficiency scores, and associations with histologic types of invasive lobular carcinoma, and carcinoma with apocrine differentiation. This study demonstrated the distinct clinicopathologic and genomic characteristics of triple-negative breast cancer subclassifications. APOBEC activity-related hypermutation is a defining characteristic of the LP group.

Triple-negative breast cancer molecular subtypes and potential detection targets for biological therapy indications

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer associated with poor prognosis. While chemotherapy remains the conventional treatment approach, its efficacy is limited and often accompanied by significant toxicity. Advances in precision-targeted therapies have expanded treatment options for TNBC, including immunotherapy, poly (ADP-ribose) polymerase inhibitors, androgen receptor inhibitors, cell cycle-dependent kinase inhibitors, and signaling pathway inhibitors. However, the heterogeneous nature of TNBC contributes to variations in treatment outcomes, underscoring the importance of identifying intrinsic molecular subtypes for personalized therapy. Additionally, due to patient-specific variability, the therapeutic response to targeted treatments is inconsistent. This highlights the need to strategize patients based on potential therapeutic targets for targeted drugs to optimize treatment strategies. This review summarizes the classification strategies and immunohistochemical (IHC) biomarkers for TNBC subtypes, along with potential targets for identifying indications for targeted drug therapy. These insights aim to support the development of personalized treatment approaches for TNBC patients.

Association of Androgen Receptor Expression With Tumor Immune Landscape and Treatment Outcomes of Patients With Breast Cancer

PURPOSE

Although estrogen receptor is well studied in breast cancer (BC), the role of androgen receptor (AR) in prognosis and therapy response is less understood. Here, we characterized the clinicopathologic and molecular features of AR gene expression in BC subtypes.

METHODS

Ten thousand seven hundred twenty-eight BC samples were tested by next-generation DNA sequencing, whole-transcriptome sequencing, and immunohistochemistry at Caris Life Sciences (Phoenix, AZ). Tumors with AR-high and AR-low RNA expression were stratified by top and bottom quartiles, respectively. Treatment-associated survival was obtained from insurance claims and calculated from treatment start to last contact using Kaplan-Meier estimates. Statistical significance was determined by chi-square and Mann-Whitney U test with P values adjusted for multiple comparisons (q < .05).

RESULTS

AR-low was associated with basal-like tumors. AR-high tumors were associated with increased mutation rates in several genes-namely PIK3CA and CDH1-across all subtypes, while other associations such as RB1 and MAP3K1 were subtype-dependent. The immune landscape was differentially affected by AR expression in each subtype, but these differences did not correspond to differential responses to immune checkpoint blockade. Patients with AR-high tumors had a longer therapy response for most subtypes, but those with AR-high tumors that were human epidermal growth factor receptor 2-enriched and luminal B trended toward worse chemotherapy or hormone therapy response, respectively.

CONCLUSION

Our data suggest a unique molecular profile of AR-high BC that is subtype-specific and generally associated with improved outcomes. Exploration of specific mutations and immune-oncology markers associated with AR-high may aid in molecularly selected clinical trial design for patients with advanced BC.

The DNA methylation landscape of primary triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a clinically challenging and molecularly heterogenous breast cancer subgroup. Here, we investigate the DNA methylation landscape of TNBC. By analyzing tumor methylome profiles and accounting for the genomic context of CpG methylation, we divide TNBC into two epigenetic subtypes corresponding to a Basal and a non-Basal group, in which characteristic transcriptional patterns are correlated with DNA methylation of distal regulatory elements and epigenetic regulation of key steroid response genes and developmental transcription factors. Further subdivision of the Basal and non-Basal subtypes identifies subgroups transcending genetic and proposed TNBC mRNA subtypes, demonstrating widely differing immunological microenvironments, putative epigenetically-mediated immune evasion strategies, and a specific metabolic gene network in older patients that may be epigenetically regulated. Our study attempts to target the epigenetic backbone of TNBC, an approach that may inform future studies regarding tumor origins and the role of the microenvironment in shaping the cancer epigenome.

Prognostic Significance and Molecular Classification of Triple Negative Breast Cancer: A Systematic Review

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer defined by the absence of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 expression. Despite accounting for 15-20% of all breast cancer cases, TNBC is associated with poor prognosis and a high likelihood of recurrence and metastasis. Understanding the molecular subtypes of TNBC is important for developing targeted therapies and improving patient outcomes. This systematic review aimed to assess the prognostic significance of molecular subtypes of TNBC and the implications for therapeutic management. A comprehensive literature search was conducted across multiple databases, including PubMed, Scopus, and Web of Science, to identify studies focusing on the molecular classification of TNBC and its prognostic relevance. Studies were included based on specific inclusion criteria, including original research evaluating clinical outcomes and survival data in molecularly classified TNBC cohorts. Data were extracted, synthesized, and analyzed to determine the prognostic implications of different TNBC subtypes. The review identified several distinct molecular subtypes of TNBC, including basal-like, mesenchymal, immune-modulatory, and luminal androgen receptor (LAR) subtypes. Basal-like TNBC was associated with poor prognosis and high rates of recurrence, while immune-modulatory TNBC exhibited better survival outcomes, particularly in patients with high levels of tumor-infiltrating lymphocytes. Mesenchymal and LAR subtypes exhibited diverse clinical behavior and varying therapeutic responses. Furthermore, key prognostic biomarkers, such as BRCA1/2 mutations and programmed death-ligand 1 expression, were highlighted which have therapeutic implications. Molecular classification of TNBC provides valuable prognostic information and guides therapeutic strategies. Integrating molecular subtyping into clinical decision-making will be essential for the development of personalized treatments and improved outcomes for TNBC patients. However, further research is needed to refine classification systems and address existing therapeutic gaps in TNBC management.

[Apocrine lesions of the breast]

Apocrine breast lesions encompass a spectrum of histopathological abnormalities, ranging from benign apocrine metaplasia to invasive apocrine carcinomas. Their defining feature lies in cells with abundant eosinophilic cytoplasm and round nuclei with prominent nucleoli. These cells strongly express the androgen receptor while lacking estrogen receptor-alpha and progesterone receptor expression. Benign lesions, frequently associated with mammary cysts or papillomas, lack nuclear and architectural atypia. In contrast, atypical apocrine lesions exhibit significant nuclear and structural abnormalities, posing diagnostic challenges when distinguishing them from apocrine ductal or lobular carcinoma in situ. Diagnosis relies on the extent of atypia and the presence of tumor necrosis. Invasive apocrine carcinomas are rare, accounting for less than 1% of all breast cancers, and predominantly occur in postmenopausal women. Histologically, they are often grade 1 or 2 tumors. Approximately 50% exhibit HER2 amplification and overexpression. Immunohistochemically, they are characterized by positivity for FOXA1 and GATA3, and negativity for FOXC1 and SOX10, and variable expression of TRPS1. These carcinomas belong to the molecular apocrine carcinoma family, which includes HER2-enriched tumors driven by HER2 addiction and androgen receptor-positive luminal tumors, a subtype of triple-negative breast cancers. The latter are defined by androgen receptor pathway activation and are frequently associated with PI3K pathway alterations and cell cycle dysregulation, suggesting potential therapeutic targets.

Molecular subtyping and target identification in triple negative breast cancer through immunohistochemistry biomarkers

BACKGROUND

The Triple-Negative Breast Cancer (TNBC) molecular subtyping and target identification based on Immunohistochemistry (IHC) is of considerable worth for routine use. Yet, literature on this topic is limited worldwide and needs to be enriched with data from different populations.

METHODS

We assessed the IHC expression of subtyping biomarkers (Cytokeratins 5, 14 and 17, Epidermal Growth Factor Receptor, Claudins 3 and 7, E-cadherin, Vimentin and Androgen receptor) and predictive biomarkers (Tumor-infiltrating lymphocytes (TILs) density, Breast Cancer Antigen 1 (BRCA1) and P53) in a cohort of TNBC patients. Clinicopathologic parameters and overall survival (OS) were investigated as well.

RESULTS

The patients were aged 50.11 ± 12.13y (more than 40y in 76.56% of patients), and 23.44% had a BC family history. They were in a non-advanced stage: 51.6% T2 stage, 56.2% negative lymph node involvement, 76.6% without metastasis and 64.1% grade II Scarff-Bloom-Richardson classification (SBR). The IHC subtypes were: 53.1% Basal-like1 (BL1), 6.3% Basal-like2 (BL2), 17.2% Mesenchymal (MES), 9.4% Luminal Androgen Receptor (LAR), 4.7% Mixed subtype and 9.4% "Unclassified" type. The LAR subtype involved the youngest patients (40.17 ± 8.68y, p = 0.02). The "Unclassified" subtype expressed the p53 mutated-type pattern more frequently (100%, p = 0.07). The BRCA1 mutated pattern and TILs infiltration were present in (23.44% and 37.5% of patients, respectively). The OS of the subtypes differed significantly (p = 0.007, log-rank test). The subtypes median OS were, respectively, 15.47 mo. (Unclassified), 18.94 mo. (BL2), 27.23 mo. (MES), 27.28 mo. (Mixed), 30.88 mo. (BL1), and 45.07 mo. (LAR). There was no difference in the OS following age, BRCA1 expression, p53 pattern and TILs density. Though, the OS following the TNM stage was different (p = 0.001). A multivariable Cox proportional hazards regression analysis showed that TNM staging and TNBC subtypes, independently influence the OS (p < 0.001 and p = 0.017, respectively). Hence, IHC is useful in TNBC subtyping for prognostic purposes and in the identification of therapeutic biomarkers. Further investigation is required to confirm our results and to implement IHC as a routine tool to improve patient's care.

Tailored therapies for triple-negative breast cancer: current landscape and future perceptions

Triple-negative breast cancer (TNBC) has become one of the most challenging cancers to date due to its great variability in biological features, high growth rate, and rare options for treatment. This review examines several innovative strategies for tailored treatment of TNBC, focusing mainly on the most recent developments and potential directions. The molecular landscape of TNBC is covered in the first section, which keeps the focus on transcriptome and genomic profiling while highlighting key molecular targets like mutations in the BRCA1/2, PIK3CA, androgen receptors (AR), epidermal growth factor receptors (EGFR), and immunological checkpoint molecules. This review also covers novel therapies that aim to block well-defined pathways, including immune checkpoint inhibitors (ICI), EGFR inhibitors, drugs that target AR, poly ADP ribose polymerase (PARP) inhibitors, and drugs that disrupt the PI3K/AKT/mTOR pathway. Additionally, it covers novel strategies focusing on combination therapy, targeting the DNA damage response pathway, and epigenetic modulators. Conclusively, it emphasizes perspectives and directions on topics such as personalized medicine, artificial intelligence (AI), predictive biomarkers, and treatment planning with the inclusion of machine learning (ML).

Darolutamide or capecitabine in triple-negative, androgen receptor-positive, advanced breast cancer (UCBG 3-06 START): a multicentre, non-comparative, randomised, phase 2 trial

BACKGROUND

We proposed in 2005 that androgens replace oestrogens as the driver steroids in a subgroup of triple-negative breast cancer (TNBC) with androgen receptor (AR) expression called molecular apocrine (MA) or luminal androgen receptor (LAR). Here, we report the analysis of a clinical trial evaluating the antitumour activity of the anti-androgen darolutamide in MA breast cancer. Our aim was to assess the clinical benefit in patients with AR-positive TNBCs defined by immunohistochemistry and by RNA profiling.

METHODS

In this multicentre, non-comparative, randomised, phase 2 trial, women aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0-1 and with advanced TNBC that was previously treated with a maximum of one line of chemotherapy were recruited from 45 hospitals in France. After central confirmation of TNBC status and AR positivity (≥10%; SP107 antibody), participants were randomly assigned (2:1) to receive darolutamide 600 mg orally twice daily or capecitabine minimum 1000 mg/m2 twice daily for 2 weeks on and 1 week off, until disease progression, unacceptable toxicity, lost to follow-up, or withdrawal of consent. Randomisation was done centrally using the minimisation procedure and was stratified according to the number of previous lines of chemotherapy. Transcriptomic analysis was used to classify tumours into groups with high and low AR activity (MAhigh and MAlow). The primary clinical endpoint was clinical benefit rate at 16 weeks (confirmed complete response, partial response, or stable disease). The primary translational endpoint was clinical benefit rate in the darolutamide group in MAhigh tumours versus all other tumours. Analyses were done per protocol. This trial is registered with ClinicalTrials.gov (NCT03383679), and is closed to recruitment.

FINDINGS

Between April 9, 2018, and July 20, 2021, 254 women were screened and 94 were randomly assigned to darolutamide (n=61) or capecitabine (n=33), of whom 90 were evaluable for efficacy analyses. Median follow-up at the data cutoff on July 20, 2022, was 22·5 months (IQR 16·5-30·5). The clinical benefit rate was 29% (17 of 58; 90% CI 19-39) with darolutamide and 59% (19 of 32; 90% CI 45-74) with capecitabine. In patients treated with darolutamide, the clinical benefit rate was 57% (12 of 21; 95% CI 36-78) in MAhigh tumours, and 16% (five of 31; 95% CI 3-29; p=0·0020) in other tumours. The most common grade 3 adverse events were palmar-plantar erythrodysaesthesia syndrome (none of 60 in the darolutamide group vs two [6%] of 33 in the capecitabine group), and headache (three [5%] vs none). No grade 4 or 5 adverse events were observed. Drug-related serious adverse events occurred in three (5%) patients in the darolutamide group and three (9%) in the capecitabine group, which were toxicoderma (n=1) and headache (n=2) in the darolutamide group, and diarrhoea, general physical deterioration, and hepatic cytolysis in the capecitabine group (n=1 each).

INTERPRETATION

This study did not reach its prespecified endpoint for darolutamide activity in patients with triple-negative breast cancer selected on the basis of immunohistochemistry for AR. Further studies selecting patients based on RNA profiling might allow better identification of tumours sensitive to anti-androgens.

FUNDING

Bayer and Fondation Bergonié.

Clinicopathological significance of androgen receptor expression and tumor infiltrating lymphocytes in triple-negative breast cancer: a retrospective cohort study

BACKGROUND

Triple-negative breast cancer (TNBC) is a serious disease with limited treatment options. We explored the significance of androgen receptor (AR) expression and tumor-infiltrating lymphocytes (TILs) in predicting neoadjuvant chemotherapy (NAC) resistance in TNBC, hypothesizing that AR/TIL classification using pretreatment biopsies can identify NAC-resistant subgroups and improve the understanding of apocrine differentiation.

METHODS

This retrospective study included 156 consecutive patients with TNBC treated with NAC. AR immunostaining was defined positive if ≥ 1% of the tumor cell nuclei were stained. Stromal TIL levels were assessed, with high levels defined as ≥ 50%. Apocrine differentiation was detected using an anti-15-PGDH antibody. The pathological response to NAC was evaluated.

RESULTS

Overall, 36% (n = 56) of the patients achieved a pathological complete response (pCR). AR+/TILlow tumors had a high non-pCR rate (76%, 42/55) and were resistant to NAC. Kaplan-Meier plots showed significant differences in overall survival (OS) and distant metastasis-free survival (DMFS) among the four AR/TIL subgroups (OS: p = 0.013; DMFS: p = 0.0016). All 11 cases with some degree of apocrine differentiation were AR+/TILlow, 15-PGDH-positive, and NAC-resistant. AR+/TILlow status was significantly associated with a high likelihood of non-pCR (OR = 0.26, p = 0.009). Multivariate analysis confirmed pCR as an independent predictor of better prognosis (OS, HR = 0.13, p = 0.006; DMFS, HR = 0.15, p = 0.002), whereas AR+/TILlow status was not significantly associated with OS or DMFS.

CONCLUSIONS

AR/TIL classification using pretreatment biopsies identified TNBC subgroups with distinct NAC responses and prognoses. AR+/TILlow TNBC, including apocrine differentiation cases, were NAC-resistant, highlighting the need for alternative therapies.

Breast cancer: pathogenesis and treatments

Breast cancer, characterized by unique epidemiological patterns and significant heterogeneity, remains one of the leading causes of malignancy-related deaths in women. The increasingly nuanced molecular subtypes of breast cancer have enhanced the comprehension and precision treatment of this disease. The mechanisms of tumorigenesis and progression of breast cancer have been central to scientific research, with investigations spanning various perspectives such as tumor stemness, intra-tumoral microbiota, and circadian rhythms. Technological advancements, particularly those integrated with artificial intelligence, have significantly improved the accuracy of breast cancer detection and diagnosis. The emergence of novel therapeutic concepts and drugs represents a paradigm shift towards personalized medicine. Evidence suggests that optimal diagnosis and treatment models tailored to individual patient risk and expected subtypes are crucial, supporting the era of precision oncology for breast cancer. Despite the rapid advancements in oncology and the increasing emphasis on the clinical precision treatment of breast cancer, a comprehensive update and summary of the panoramic knowledge related to this disease are needed. In this review, we provide a thorough overview of the global status of breast cancer, including its epidemiology, risk factors, pathophysiology, and molecular subtyping. Additionally, we elaborate on the latest research into mechanisms contributing to breast cancer progression, emerging treatment strategies, and long-term patient management. This review offers valuable insights into the latest advancements in Breast Cancer Research, thereby facilitating future progress in both basic research and clinical application.

A Multimodal Framework to Uncover Drug-Responsive Subpopulations in Triple-Negative Breast Cancer

Understanding how individual cancer cells adapt to drug treatment is a fundamental challenge limiting precision medicine cancer therapy strategies. While single-cell technologies have advanced our understanding of cellular heterogeneity, efforts to connect the behavior of individual cells to broader tumor drug responses and uncover global trends across diverse systems remain limited. There is a growing availability of single-cell and bulk omics data, but a lack of centralized tools and repositories makes it difficult to study drug response globally, especially at the level of single-cell adaptation. To address this, we present a multimodal framework that integrates bulk and single-cell treated and untreated transcriptomics data to identify drug responsive cell populations in triple-negative breast cancer (TNBC). Our framework leverages population-scale bulk transcriptomics data from TNBC samples to define seven main "identities", each representing unique combinations of biologically relevant genes. These identities are dynamic and trackable, allowing us to map them onto single cells and uncover global patterns of how cell populations respond to drug treatment. Unlike static classifications, this approach captures the evolving nature of cellular states, revealing that a select few identities dominate and drive population-level responses during treatment. Crucially, our ability to decode these trends through the inherent noise of single-cell data provides a clearer picture of how heterogeneous cell populations adapt to therapy. By identifying the dominant identities and their dynamics, we can better predict how entire tumors respond to treatment. This insight is essential for designing precise combination therapies tailored to the unique heterogeneity of patient tumors, addressing the single-cell variations that ultimately determine therapeutic outcomes.

Androgen receptor expression and clinical significance in breast cancer

PURPOSE

This study aimed to investigate the expression and clinical relevance of the androgen receptor (AR) in breast cancer.

METHODS

This retrospective study examined the expression of AR in breast cancer and its correlation with patients' clinicopathological and immunohistochemical characteristics. A total of 521 patient records were gathered and assessed. Patients were categorized as either positive or negative for AR expression, and statistical analyses were conducted using the chi-square test, logistic regression in SPSS 26.0, and Kaplan-Meier analysis.

RESULTS

AR was detected in 83.7% of the 521 patients studied. There was a statistically significant difference in the prevalence of AR positivity among different molecular subtypes, estrogen receptor (ER) status, progesterone receptor (PR) status, human epidermal growth factor receptor 2 (HER2) status, and epidermal growth factor receptor (EGFR) (P < 0.05). Logistic regression analysis further revealed that ER and PR positivity were identified as risk factors for AR expression, and Kaplan-Meier curve analysis demonstrated the potential of AR as a prognostic indicator for breast cancer outcomes. Additionally, AR positivity was associated with a favorable prognosis.

CONCLUSIONS

The results suggest a strong correlation between AR expression and ER and PR co-expression in breast cancer. Additionally, AR positivity in the absence of ER and PR expression is associated with a favorable prognosis, indicating potential therapeutic value as a novel target in breast cancer treatment. Particularly in endocrine resistance or triple-negative breast cancer (TNBC), AR may serve as a significant prognostic indicator, warranting further investigation.

Divide and Conquer-Targeted Therapy for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive and malignant type of breast cancer with limited treatment options and poor prognosis. One of the most significant impediments in TNBC treatment is the high heterogeneity of this disease, as highlighted by the detection of several molecular subtypes of TNBC. Each subtype is driven by distinct mutations and pathway aberrations, giving rise to specific molecular characteristics closely connected to clinical behavior, outcomes, and drug sensitivity. This review summarizes the knowledge regarding TNBC molecular subtypes and how it can be harnessed to devise tailored treatment strategies instead of blindly using targeted drugs. We provide an overview of novel targeted agents and key insights about new treatment modalities with an emphasis on the androgen receptor signaling pathway, cancer stem cell-associated pathways, phosphatidylinositol 3-kinase (PI3K)/AKT pathway, growth factor signaling, and immunotherapy.

Classifications of triple-negative breast cancer: insights and current therapeutic approaches

Triple-negative breast cancer (TNBC) is an aggressive and challenging type of cancer, characterized by the absence of specific receptors targeted by current therapies, which limits effective targeted treatment options. TNBC has a high risk of recurrence and distant metastasis, resulting in lower survival rates. Additionally, TNBC exhibits significant heterogeneity at histopathological, proteomic, transcriptomic, and genomic levels, further complicating the development of effective treatments. While some TNBC subtypes may initially respond to chemotherapy, resistance frequently develops, increasing the risk of aggressive recurrence. Therefore, precisely classifying and characterizing the distinct features of TNBC subtypes is crucial for identifying the most suitable molecular-based therapies for individual patients. In this review, we provide a comprehensive overview of these subtypes, highlighting their unique profiles as defined by various classification systems. We also address the limitations of conventional therapeutic approaches and explore innovative biological strategies, all aimed at advancing the development of targeted and effective therapeutic strategies for TNBC.

Subtype-specific role for Jagged1 in promoting or inhibiting breast tumor formation

Notch signaling is altered in breast cancer. Recent studies highlighted both tumor-suppressive and oncogenic roles for Notch in this tissue. The function of Jagged1, the most highly expressed Notch ligand in the mammary gland, is not well defined. Here we report that deletion of Jagged1 in the mammary epithelium of virgin mice led to expansion of the mammary stem cell (MaSC) compartment and defective luminal differentiation associated with decreased expression of the progesterone receptor (PR). In contrast, deletion of Jagged1 in alveolar cells of pregnant mice had no effect on alveolar and lactogenic differentiation or post-lactational involution. Interestingly, deletion of Jagged1 promoted mouse mammary tumor formation from luminal cells but suppressed them from basal cells, associated with downregulation of Notch target genes Hey1 and Hey2, respectively. In agreement with mouse experiments, high expression of JAG1 and HEY1 are associated with better overall survival among patients with luminal tumors, whereas high expression of JAG1 and HEY2 are both associated with worse overall survival in basal subtype of human breast cancer. These results identified Jagged1 as an important regulator of mammary epithelial hierarchy and revealed differential roles of Jagged1-mediated Notch signaling in different subtypes of breast cancer arising from distinct cell types.

Looking beyond the ER, PR, and HER2: what's new in the ARsenal for combating breast cancer?

Breast cancer (BrCa) is a complex and heterogeneous disease with diverse molecular subtypes, leading to varied clinical outcomes and posing significant treatment challenges. The increasing global burden of BrCa, particularly in low- and middle-income countries, underscores the urgent need for more effective therapeutic strategies. The androgen receptor (AR), expressed in a substantial proportion of breast cancer cases, has emerged as a potential biomarker and therapeutic target. In breast cancer, AR exhibits diverse functions across subtypes, often interacting with other hormone receptors, thereby influencing tumor progression and treatment responses. This intricate interplay is further complicated by the presence of constitutively expressed AR splice variants (AR-Vs) that drive resistance to AR-targeting therapies through structural rearrangements in the domains and activation of aberrant signaling pathways. Although AR-targeting drugs, initially developed for prostate cancer (PCa), have shown promise in AR-positive breast cancer, significant gaps remain in understanding AR's precise functions and therapeutic potential. The systemic management of breast cancer is guided primarily by theranostic biomarkers; ER, PR, HER2, and Ki67 which also dictate the breast cancer classification. The ubiquitous expression of AR in BrCa and the emergence of AR-Vs can assist the management of disease complementing the standard of care. This article provides a comprehensive overview of AR and its splice variants in the context of breast cancer, highlighting their prognostic and predictive value across different subtypes looking beyond the conventional ER, PR, and HER2 status. This review also raises the possibility of using AR splice variants in predicting tumor aggressiveness. From the settings of developing nations, this may provide useful insight by integrating recent advances in AR-targeted therapies and exploring their translational potential, emphasizing the critical need for further research to optimize AR-based therapeutic strategies for breast cancer management.

Design and optimization strategies of PROTACs and its Application, Comparisons to other targeted protein degradation for multiple oncology therapies

Recent years have witnessed notable breakthroughs in the field of biotherapeutics. Proteolysis Targeting Chimeras (PROTACs) are novel molecules which used to degrade particular proteins despite the blockage by small drug molecules, which leads to a predicted therapeutic activity. This is a unique finding, especially at the cellular level targets degradations. Clinical trials and studies on PROTACs are in progress for oncology indications for demonstration of high potency and activity. PROTAC molecules are having excellent tissue distribution properties and their capacity to mutate the proteins and target overexpressed. This concept has attained wide attention from modern researchers in oncological drug discovery with particular physical qualities not offered by other therapeutic approaches. The modular nature of the PROTACs enables their methodical optimization and logical design. A thorough review was conducted in order to delve deeper into the subject and gain a better understanding of its development, computational supports, important factors for the optimization of developed PROTAC candidates, pharmacokinetic and pharmacodynamic (PK-PD) aspects, safety risks such as the degradation of undesired proteins, and other PROTAC-related issues and their target immunotherapeutic response. Furthermore discussed about the benefits, possible challenges, viewpoints, comparison with other targeted protein degraders (LYTACs, AUTOTACs) and the most current research results of PROTACs technology in multiple oncology therapies. Abbreviations: PROTACs, Proteolysis Targeting Chimeras; PK, Pharmacokinetic; PD, Pharmacodynamic; MetAP-2, (methionine aminopeptidase 2); BCL6, B-cell lymphoma 6; GCN5, General Control Nonderepressible 5; BKT, Bruton's tyrosine kinase; BET, Bromodomain and extra-terminal; AR, Androgen or Androgen receptor; ER, Estrogen or Estrogen receptor; FDA, Food and Drug Administration; mCRPC, Metastatic castration-resistant prostate cancer; STAT3, Signal Transducer and Activator of Transcription 3; FAK, Focal adhesion kinase; POI, Protein of interest; PEG, Polyethylene glycol; UPS, Ubiquitin-Proteasome System; VHL, Von Hippel-Lindau; CRBN, Cereblon; MDM2, Mouse Double Minute 2 homologue; cIAP, Cellular Inhibitor of Apoptosis; RNF, Ring Finger Protein; BRD, Bromodomain; CDK, Cyclin-dependent kinase; PAMPA, Parallel Artificial Membrane Permeability studies; BRET, Bioluminescence Resonance Energy Transfer; MCL, Mantle cell lymphoma; MCL-1, Myeloid Cell Leukemia 1; BCL-XL, B-cell lymphoma extra-large; TRK, Tropomyosin Receptor Kinase; RTKs, Transmembrane Receptor Tyrosine Kinase; NTRK, Neurotrophic Tyrosine Receptor Kinase; DHT, Dihydrotestosterone; EGFR, Epidermal Growth Factor Receptor; EGFR-TKIs, EGFR tyrosine kinase inhibitors; NSCLC, non-small cell lung cancer; BCR, B-cell receptor; CML, Chronic myelogenous leukemia; TKI, Tyrosine kinase inhibitors; MoA, Mechanism of action; TPD, Targetted protein degraders; LYTACs, Lysosome targeting chimeras; ASGPR, Asialoglycoprotein receptor; AUTOTACs, Autophagy-Targeting Chimeras; ATTECs, Autophagy-tethering compounds; CRISPR-Cas9, Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-associated protein 9; TALEN, Transcription Activator-Like Effector Nuclease; ZFN, Zinc Finger Nuclease.

Classification of Breast Cancer Through the Perspective of Cell Identity Models

The mammary epithelium has an inner luminal layer that contains estrogen receptor (ER)-positive hormone-sensing cells and ER-negative alveolar/secretory cells, and an outer basal layer that contains myoepithelial/stem cells. Most human tumours resemble either hormone-sensing cells or alveolar/secretory cells. The most widely used molecular classification, the Intrinsic classification, assigns hormone-sensing tumours to Luminal A/B and human epidermal growth factor 2-enriched (HER2E)/molecular apocrine (MA)/luminal androgen receptor (LAR)-positive classes, and alveolar/secretory tumours to the Basal-like class. Molecular classification is most useful when tumours have classic invasive carcinoma of no special type (NST) histology. It is less useful for special histological types of breast cancer, such as metaplastic breast cancer and adenoid cystic cancer, which are better described with standard pathology terms. Compared to mice, humans show a strong bias towards making tumours that resemble mammary hormone-sensing cells. This could be caused by the formation in adolescence of der(1;16), a translocation through the centromeres of chromosomes 1 and 16, which only occurs in humans and could trap the cells in the hormone-sensing state.

Latest Therapeutical Approaches for Triple-Negative Breast Cancer: From Preclinical to Clinical Research

Triple-negative breast cancer (TNBC) represents roughly one-sixth of all breast cancer patients, but accounts for 30-40% of breast cancer deaths. Due to the lack of typical biomarkers exploited clinically for breast cancer, it remains very difficult to treat. Moreover, its intrinsic high heterogeneity and proneness to become resistant to the drugs administered makes the treatment management very challenging for oncologists. Herein, we outline the different therapies used currently for TNBC and list the ongoing clinical trials to provide an overview of the most recent TNBC therapeutic landscape. In addition, we highlight the emerging therapies in the preclinical stage that hold the most promise, such as epigenetic modulators, CRISPR, miniproteins, radioconjugates, cancer vaccines, and PROTACs. Moreover, we navigate through the existing limitations and challenges which hamper the development of new and more effective treatments for TNBC. Lastly, we point to emerging new directions that may revolutionize future therapy for TNBC.

Analyzing Androgen Receptor Expression in Breast Cancer: Insights into Histopathological Parameters and Hormone Receptor Status Among Indian Women

Breast cancer, an exceptionally hormone-dependent tumor, exhibits a diverse clinical profile. Its therapeutic categorization relies on the expression of key receptors, namely, estrogen receptor (ER), progesterone receptor (PR), and Her2neu. The androgen receptor (AR), a member of the nuclear receptor superfamily, is a biomarker gaining attention in breast cancer research, particularly for triple-negative breast cancers. We conducted an analysis of AR expression in 113 primary breast cancer cases, using a cutoff criterion of ≥ 10% tumor cell positivity. ER, PR, and Her2neu statuses were determined based on the 2023 ASCO-CAP criteria. AR expression was then correlated with various clinicopathological factors, including age, menopausal status, centricity, histological type, grade, tumor size, nodal status, lymphovascular and perineural invasion, and ER, PR, and HER2neu statuses. Among the 113 cases, 57 (50.4%) showed positive AR expression. No statistically significant associations were found between AR expression and age, menopausal status, histological type, histological grade, nodal status, or ER and PR expression. Notably, all multicentric tumors (n = 7, 100%) were AR negative. AR expression was linked to smaller tumor sizes. Positive AR cases exhibited an association with Her2neu overexpression, particularly in ER and PR-negative tumors. Of note, 35% of triple-negative tumors displayed AR positivity. AR emerges as a promising marker in breast cancers, particularly in triple-negative cases. Larger-scale studies are warranted to comprehensively assess the relationship between AR expression and histopathological parameters, as well as other immunohistochemical markers.

Machine learning-guided differential gene expression analysis identifies a highly-connected seven-gene cluster in triple-negative breast cancer

Background

One of the most challenging cancers is triple-negative breast cancer, which is subdivided into many molecular subtypes. Due to the high degree of heterogeneity, the role of precision medicine remains challenging. With the use of machine learning (ML)-guided gene selection, the differential gene expression analysis can be optimized, and eventually, the process of precision medicine can see great advancement through biomarker discovery.

Purpose

Enhancing precision medicine in the oncology field by identification of the most representative differentially-expressed genes to be used as biomarkers or as novel drug targets.

Methods

By utilizing data from the Gene Expression Omnibus (GEO) repository and The Cancer Genome Atlas (TCGA), we identified the differentially expressed genes using the linear model for microarray analysis (LIMMA) and edgeR algorithms, and applied ML-based feature selection using several algorithms.

Results

A total of 27 genes were selected by merging features identified with both LIMMA and ML-based feature selection methods. The models with the highest area under the curve (AUC) are CatBoost, Extreme Gradient Boosting (XGBoost), Random Forest, and Multi-Layer Perceptron classifiers. ESR1, FOXA1, GATA3, XBP1, GREB1, AR, and AGR2 were identified as hub genes in a highly interconnected cluster.

Conclusion

ML-based gene selection shows a great impact on the identification of hub genes. The ML models built can improve precision oncology in diagnosis and prognosis. The identified hub genes can serve as biomarkers and warrant further research for potential drug target development.

Expression of nuclear receptors and glucose metabolic pathway proteins in sebaceous carcinoma: Androgen receptor and monocarboxylate transporter 1 have a key role in disease progression

Standard systemic treatments are not consistently effective for treating unresectable or advanced sebaceous carcinoma (SC). The present study investigated the pathogenic roles of nuclear receptors (NRs), glucose metabolic dysregulation and immune checkpoint proteins in SC as prognostic markers or therapeutic targets. Patients with pathologically confirmed SC between January 2002 and December 2019 at three university hospitals in South Korea were included in the present study. Immunohistochemistry was performed on paraffin-embedded tumor tissues for glucocorticoid receptors (GR), androgen receptors (AR), estrogen receptors (ER), progesterone receptors (PR), glucose transporter 1 (GLUT1), monocarboxylate transporters (MCT1 and MCT4), CD147, phosphorylated adenosine monophosphate-activated protein kinase (pAMPK) and the immune checkpoint protein, programmed cell death-ligand 1 (PD-L1). The results were semi-quantitatively assessed and the associations of these proteins with various clinicopathological parameters were determined. A total of 39 cases of SC comprising 19 periocular and 20 extraocular tumors were enrolled. NRs were frequently detected in the tumor nuclei, with GR having the highest frequency (89.7%), followed by AR, ER (both 51.3%) and PR (41.0%). Regarding glucose metabolism, CD147, GLUT1 and MCT1 were highly expressed at 100, 89.7 and 87.2%, respectively, whereas MCT4 and pAMPK expression levels were relatively low at 38.5 and 35.9%, respectively. Membranous expression of PD-L1 was detected in five cases (12.8%), four of which were extraocular. In the multivariate analysis, advanced stage, low AR positivity and high MCT1 expression were independent poor prognostic factors for metastasis-free survival (all P<0.05). The present results suggested that hormonal and metabolic dysregulation may be associated with the pathogenesis of SC, and that AR and MCT1 in particular may serve as prognostic indicators and potential therapeutic targets. Additionally, ~10% of SC cases exhibited PD-L1 expression within the druggable range, and these patients are expected to benefit from treatment with immune checkpoint inhibitors.

Targeting CDK7 enhances the antitumor efficacy of enzalutamide in androgen receptor-positive triple-negative breast cancer by inhibiting c-MYC-mediated tumorigenesis

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer. Among TNBC subtypes, the luminal androgen receptor (LAR) subtype expresses high levels of androgen receptor (AR) and generally responds poorly to neoadjuvant chemotherapy. AR has been reported as a promising therapeutic target for the LAR TNBC subtype. Here, we evaluated the preclinical antitumor efficacy of enzalutamide, an AR inhibitor, in TNBC. Enzalutamide had moderate anti-proliferation activity against AR-positive (AR+) TNBC cells (IC50 > 15 µM). To enhance its antitumor efficacy, we performed high-throughput kinome siRNA screening and identified the cell cycle pathway as a potential target. Inhibition of cell cycle progression using the CDK7 inhibitor KRLS-017 showed a synergistic anti-proliferation effect with enzalutamide in AR+ LAR MDA-MB-453 and SUM185 TNBC cells. Downstream target analysis revealed that enzalutamide and KRLS-017 combination dramatically reduced c-MYC expression at both mRNA and protein levels. c-MYC knockdown significantly suppressed growth of MDA-MB-453 and SUM185 cells to a degree comparable to that of enzalutamide and KRLS-017 combination treatment, whereas c-MYC overexpression reversed the synergistic effect. An enhancement in inhibition of tumor growth and suppression of c-MYC expression was further confirmed when enzalutamide combined with KRLS-017 in an MDA-MB-453 mouse model. Our study suggests that KRLS-017 enhances the antitumor efficacy of enzalutamide by inhibiting c-MYC-mediated tumorigenesis and presents a potential new approach for treating AR+ LAR TNBC.

Combined inhibition of CDK4/6 and AKT is highly effective against the luminal androgen receptor (LAR) subtype of triple negative breast cancer

Luminal Androgen Receptor (LAR) triple-negative breast cancers (TNBC) express androgen receptors (AR), exhibit high frequency of PIK3CA mutations and intact RB. Herein, we investigated combined blockade of the CDK4/6 and PI3K signaling with palbociclib, alpelisib, and capivasertib, which inhibit CDK4/6, PI3Kα, and AKT1-3, respectively. The combination of palbociclib/capivasertib, but not palbociclib/alpelisib, synergistically inhibited proliferation of MDA-MB-453 and MFM-223 LAR cells [synergy score 7.34 (p = 5.81x10-11) and 4.78 (p = 0.012), respectively]. The AR antagonist enzalutamide was inactive against MDA-MB-453, MFM-223, and CAL148 cells and did not enhance the efficacy of either combination. Palbociclib/capivasertib inhibited growth of LAR patient-derived xenografts more potently than palbociclib/alpelisib. Treatment of LAR cells with palbociclib suppressed phosphorylated-RB and resulted in adaptive phosphorylation/activation of S473 pAKT and AKT substrates GSK3β, PRAS40, and FoxO3a. Capivasertib blocked palbociclib-induced phosphorylation of AKT substrates more potently than alpelisib. Treatment with PI3Kβ inhibitors did not block phosphorylation of AKT substrates, suggesting that PI3Kβ did not mediate the adaptive response to CDK4/6 inhibition. Phosphokinase arrays of MDA-MB-453 cells treated with palbociclib showed time-dependent upregulation of PDGFRβ, GSK3β, STAT3, and STAT6. RNA silencing of PDGFRβ in palbociclib-treated MDA-MB-453 and MFM-223 cells blocked the upregulation of S473 pAKT, suggesting that the adaptive response to CDK4/6 blockade involves PDGFRβ signaling. Finally, treatment with palbociclib and the PDGFR inhibitor CP637451 arrested growth of MDA-MB-453 and MFM-223 cells to the same degree as palbociclib/capivasertib. These findings support testing the combination of CDK4/6 and AKT inhibitors in patients with LAR TNBC, and further investigation of PDGFR antagonists in this breast cancer subtype.

Triple-Negative Breast Cancer: Tumor Immunogenicity and Beyond

Triple-negative breast cancer (TNBC) is a breast malignancy with a poor prognosis and limited therapeutic options. Many studies show that TNBC exhibits heterogeneity across clinical, histopathological, and molecular levels. In this review, we discuss the immunogenic features of TNBC with a focus on immunotherapy and the current standard of care in the neoadjuvant, adjuvant, and metastatic setting. In addition, we address the ongoing research on immunotherapy, antibody-drug conjugates (ADCs), poly ADP-ribose polymerase (PARP) inhibitors, and future challenges in the treatment of this entity.

Molecular Changes in Breast Cancer Induced by Radiation Therapy

PURPOSE

Breast cancer treatments are based on prognostic clinicopathologic features that form the basis for therapeutic guidelines. Although the utilization of these guidelines has decreased breast cancer-associated mortality rates over the past three decades, they are not adequate for individualized therapy. Radiation therapy (RT) is the backbone of breast cancer treatment. Although a highly successful therapeutic modality clinically, from a biological perspective, preclinical studies have shown RT to have the potential to alter tumor cell phenotype, immunogenicity, and the surrounding microenvironment, potentially changing the behavior of cancer cells and resulting in a significant variation in RT response. This review presents the recent advances in revealing the complex molecular changes induced by RT in the treatment of breast cancer and highlights the complexities of translating this information into clinically relevant tools for improved prognostic insights and the revelation of novel approaches for optimizing RT.

METHODS AND MATERIALS

Current literature was reviewed with a focus on recent advances made in the elucidation of tumor-associated radiation-induced molecular changes across molecular, genetic, and proteomic bases. This review was structured with the aim of providing an up-to-date overview over the very broad and complex subject matter of radiation-induced molecular changes and radioresistance, familiarizing the reader with the broader issue at hand.

RESULTS

The subject of radiation-induced molecular changes in breast cancer has been broached from various physiological focal points including that of the immune system, immunogenicity and the abscopal effect, tumor hypoxia, breast cancer classification and subtyping, molecular heterogeneity, and molecular plasticity. It is becoming increasingly apparent that breast cancer clinical subtyping alone does not adequately account for variation in RT response or radioresistance. Multiple components of the tumor microenvironment and immune system, delivered RT dose and fractionation schedules, radiation-induced bystander effects, and intrinsic tumor physiology and heterogeneity all contribute to the resultant RT outcome.

CONCLUSIONS

Despite recent advances and improvements in anticancer therapies, tumor resistance remains a significant challenge. As new analytical techniques and technologies continue to provide crucial insight into the complex molecular mechanisms of breast cancer and its treatment responses, it is becoming more evident that personalized anticancer treatment regimens may be vital in overcoming radioresistance.

Advances in the understanding of androgen receptor structure and function and in the development of next-generation AR-targeted therapeutics

Androgen receptor (AR) and its ligand androgens are important for development and physiology of various tissues. AR and its ligands also play critical role in the development of various diseases, making it a valuable therapeutic target. AR ligands, both agonists and antagonists, are being widely used to treat pathological conditions, including prostate cancer and hypogonadism. Despite AR being studied widely over the last five decades, the last decade has seen striking advances in the knowledge on AR and discoveries that have the potential to translate to the clinic. This review provides an overview of the advances in AR biology, AR molecular mechanisms of action, and next generation molecules that are currently in development. Several of the areas described in the review are just unraveling and the next decade will bring more clarity on these developments that will put AR at the forefront of both basic biology and drug development.

Molecular Targets of Minor Cannabinoids in Breast Cancer: In Silico and In Vitro Studies

BACKGROUND

Breast cancer therapy has been facing remarkable changes. Classic treatments are now combined with other therapies to improve efficacy and surpass resistance. Indeed, the emergence of resistance demands the development of novel therapeutic approaches. Due to key estrogen signaling, estrogen receptor-positive (ER+) breast cancer treatment has always been focused on aromatase inhibition and ER modulation. Lately, the effects of phytocannabinoids, mainly Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), have been evaluated in different cancers, including breast. However, Cannabis sativa contains more than 120 phytocannabinoids less researched and understood.

METHODS

Here, we evaluated, both in silico and in vitro, the ability of 129 phytocannabinoids to modulate important molecular targets in ER+ breast cancer: aromatase, ER, and androgen receptor (AR).

RESULTS

In silico results suggested that some cannabinoids may inhibit aromatase and act as ERα antagonists. Nine selected cannabinoids showed, in vitro, potential to act either as ER antagonists with inverse agonist properties, or as ER agonists. Moreover, these cannabinoids were considered as weak aromatase inhibitors and AR antagonists with inverse agonist action.

CONCLUSIONS

Overall, we present, for the first time, a comprehensive analysis of the actions of the phytocannabinoids in targets of ER+ breast tumors, pointing out their therapeutic potential in cancer and in other diseases.

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.

Androgen receptor and estrogen receptor variants in prostate and breast cancers

The androgen receptor (AR) and estrogen receptor alpha (ERα) are steroid receptor transcription factors with critical roles in the development and progression of prostate and breast cancers. Advances in the understanding of mechanisms underlying the ligand-dependent activation of these transcription factors have contributed to the development of small molecule inhibitors that block AR and ERα actions. These inhibitors include competitive antagonists and degraders that directly bind the ligand binding domains of these receptors, luteinizing hormone releasing hormone (LHRH) analogs that suppress gonadal synthesis of testosterone or estrogen, and drugs that block specific enzymes required for biosynthesis of testosterone or estrogen. However, resistance to these therapies is frequent, and is often driven by selection for tumor cells with alterations in the AR or ESR1 genes and/or alternatively spliced AR or ESR1 mRNAs that encode variant forms AR or ERα. While most investigations involving AR have been within the context of prostate cancer, and the majority of investigations involving ERα have been within the context of breast cancer, important roles for AR have been elucidated in breast cancer, and important roles for ERα have been elucidated in prostate cancer. Here, we will discuss the roles of AR and ERα in breast and prostate cancers, outline the effects of gene- and mRNA-level alterations in AR and ESR1 on progression of these diseases, and identify strategies that are being developed to target these alterations therapeutically.

Stem cell-like circulating tumor cells identified by Pep@MNP and their clinical significance in pancreatic cancer metastasis

Objective

The circulating tumor cells (CTCs) could be captured by the peptide functionalized magnetic nanoparticles (Pep@MNP) detection system in pancreatic ductal adenocarcinoma (PDAC). CTCs and the CXCR4 expression were detected to explore their clinical significance. The CXCR4+ CTCs, this is highly metastatic-prone stem cell-like subsets of CTCs (HM-CTCs), were found to be associated with the early recurrence and metastasis of PDAC.

Methods

CTCs were captured by Pep@MNP. CTCs were identified via immunofluorescence with CD45, cytokeratin antibodies, and the CXCR4 positive CTCs were assigned to be HM-CTCs.

Results

The over-expression of CXCR4 could promote the migration of pancreatic cancer cell in vitro and in vivo. In peripheral blood (PB), CTCs were detected positive in 79.0% of all patients (49/62, 9 (0-71)/2mL), among which 63.3% patients (31/49, 3 (0-23)/2mL) were HM-CTCs positive. In portal vein blood (PVB), CTCs were positive in 77.5% of patients (31/40, 10 (0-40)/2mL), and 67.7% of which (21/31, 4 (0-15)/2mL) were HM-CTCs positive CTCs enumeration could be used as diagnostic biomarker of pancreatic cancer (AUC = 0.862), and the combination of CTCs positive and CA19-9 increase shows improved diagnostic accuracy (AUC = 0.963). in addition, PVB HM-CTCs were more accurate to predict the early recurrence and liver metastasis than PB HM-CTCs (AUC 0.825 vs. 0.787 and 0.827 vs. 0.809, respectively).

Conclusions

The CTCs identified by Pep@MNP detection system could be used as diagnostic and prognostic biomarkers of PDAC patients. We identified and defined the CXCR4 over-expressed CTC subpopulation as highly metastatic-prone CTCs, which was proved to identify patients who were prone to suffering from early recurrence and metastasis.

Clinical Advances in Triple Negative Breast Cancer Treatment: Focus on Poly (L-lactide-coglycolide) Nanoparticles

Triple negative breast cancer (TNBC) is the most aggressive type of breast cancer and is associated with high probability of metastasis and poor prognosis. Chemotherapeutics and surgery remain the most common options for TNBC patients; however, chemotherapeutic resistance and relapse of tumors limit the progression free survival and patient life span. This review provides an overview of recent chemotherapeutics that are in clinical trial, and the combination of drugs that are being investigated to overcome the drug resistance and to improve patient survival in different molecular subtypes of TNBCs. Nanotherapeutics have emerged as a promising platform for TNBC treatment and aim to improve the selectivity and solubility of drugs, reduce systemic side effects, and overcome multi-drug resistance. The study explores the role of nanoparticles for TNBC treatment and summarizes the types of nanoparticles that are in clinical trials. Poly(L-lactide-co-glycolide) (PLGA) is the most studied polymeric carrier for drug delivery and for TNBC treatment in research and in clinics. This review is about providing recent advancements in PLGA nanotherapeutic formulations and their application to help treat TNBC. Some background on current chemotherapies and pathway inhibitors is provided so that the readers are aware of what is currently considered for TNBC. Some of the pathway inhibitors may also be of importance for nanotherapeutics development. SIGNIFICANCE STATEMENT: This minireview summarizes the progress on chemotherapeutics and nanoparticle delivery for treatment of TNBC and specifically highlights the lead compounds that are in clinical trials.

Phase 2 study of neoadjuvant enzalutamide and paclitaxel for luminal androgen receptor-enriched TNBC: Trial results and insights into "ARness"

Luminal androgen receptor (LAR)-enriched triple-negative breast cancer (TNBC) is a distinct subtype. The efficacy of AR inhibitors and the relevant biomarkers in neoadjuvant therapy (NAT) are yet to be determined. We tested the combination of the AR inhibitor enzalutamide (120 mg daily by mouth) and paclitaxel (80 mg/m2 weekly intravenously) (ZT) for 12 weeks as NAT for LAR-enriched TNBC. Eligibility criteria included a percentage of cells expressing nuclear AR by immunohistochemistry (iAR) of at least 10% and a reduction in sonographic volume of less than 70% after four cycles of doxorubicin and cyclophosphamide. Twenty-four patients were enrolled. Ten achieved a pathologic complete response or residual cancer burden-I. ZT was safe, with no unexpected side effects. An iAR of at least 70% had a positive predictive value of 0.92 and a negative predictive value of 0.97 in predicting LAR-enriched TNBC according to RNA-based assays. Our data support future trials of AR blockade in early-stage LAR-enriched TNBC.

Incidence and Prognostic Significance of Androgen Receptors (AR) in Indian Triple-Negative Breast Cancer (TNBC)

Molecular sub-characterization of triple-negative breast cancer (TNBC) has great therapeutic and possibly prognostic implications. The primary aim of this study was to investigate the incidence of luminal androgen receptor (LAR) subtype of TNBC and secondary aims were sub-categorization and clinico-pathologic correlation of LAR breast cancers. Retrospective study (January 2008 and 31st of December 2018) consisting of 157 TNBC patients. Androgen receptor (AR) expression was measured by immunohistochemical analysis. One percent cutoff was set as a positive expression. Sub-categorization was done on the basis of EGFR (> 15% of tumor cells) and Ki-67 expression (low- < 11%, intermediate- 11-20%, and high- > 21%). AR expression was correlated with various clinico-pathologic features and outcomes of the patients. The incidence of AR expression in TNBC was 24.8%. Considering different thresholds of > 5%, > 10%, and > 20% immunostaining, the incidence of AR positivity was 18.4, 15.2, and 11.5% respectively. The incidence of Ki-67 (p = 0.89) and EGFR (p = 0.643) expression did not differ significantly in AR-positive and -negative TNBC. Based on EGFR expression 19, 67 and 14% patients were categorized as low, intermediate, and high risk respectively. Low-risk (p ≤ 0.001) and low-grade (p = 0.014) tumors were more likely to have > 10% AR expression. Clinico-pathological profile, response to neoadjuvant chemotherapy, disease-free survival (p = 0.458), and overall survival (p = 0.806) did not significantly differ between AR expressing and negative TNBC. On multivariate analysis, only tumor staging was a significant predictor of survival (p = 0.012) and AR expression of > 10% revealed a trend towards improved survival (p = 0.07). When considering only AR-positive TNBC, AR expression of > 10% (p = 0.038), distant metastases (p = 0.003), and EGFR status (p = 0.024) were significantly associated with survival. AR expression does not seem to very strongly correlate with prognosis in TNBC and further studies could focus more on its predictive role in deciding anti-androgen therapy.

Precise nano-system-based drug delivery and synergistic therapy against androgen receptor-positive triple-negative breast cancer

Targeting androgen receptor (AR) has shown great therapeutic potential in triple-negative breast cancer (TNBC), yet its efficacy remains unsatisfactory. Here, we aimed to identify promising targeted agents that synergize with enzalutamide, a second-generation AR inhibitor, in TNBC. By using a strategy for screening drug combinations based on the Sensitivity Index (SI), we found that MK-8776, a selective checkpoint kinase1 (CHK1) inhibitor, showed favorable synergism with enzalutamide in AR-positive TNBC. The combination of enzalutamide and MK-8776 was found to exert more significant anti-tumor effects in TNBC than the single application of enzalutamide or MK-8776, respectively. Furthermore, a nanoparticle-based on hyaluronic acid (HA)-modified hollow-manganese dioxide (HMnO2), named HMnE&M@H, was established to encapsulate and deliver enzalutamide and MK-8776. This HA-modified nanosystem managed targeted activation via pH/glutathione responsiveness. HMnE&M@H repressed tumor growth more obviously than the simple addition of enzalutamide and MK-8776 without a carrier. Collectively, our study elucidated the synergy of enzalutamide and MK-8776 in TNBC and developed a novel tumor-targeted nano drug delivery system HMnE&M@H, providing a potential therapeutic approach for the treatment of TNBC.

Guidelines for diagnosis and treatment of advanced breast cancer in China (2022 edition)

Breast cancer is the most common cancer among women worldwide. It has been estimated that about 416 000 new cases and over 117 000 deaths of breast cancer occurred in China in 2020. Among the new cases of breast cancer diagnosed each year, 3-10% have distant metastasis at the time of initial diagnosis. In addition, approximately 30% of patients with early-stage breast cancer may eventually experience recurrence or metastases. The 5-year survival rate of patients with advanced breast cancer is only 20% with a median overall survival of 2-3 years. Although advanced breast cancer remains incurable at present, new therapeutic options and multidisciplinary treatment could be utilized to alleviate symptoms, improve quality of life, and prolong patients' survival. The choice of treatment regimens for patients with advanced breast cancer is very important, and the optimal treatment strategy beyond the first- and second-line therapy is often lacking. Herein, the China Advanced Breast Cancer Guideline Panel discussed and summarized recent clinical evidence, updated the guidelines for the diagnosis and treatment of advanced breast cancer based on the 2020 edition, and formulated the "Guidelines for diagnosis and treatment of advanced breast cancer in China (2022 edition)" for clinicians' reference.

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.

Frequency of Androgen Receptor Positivity in Tumors: A Study Evaluating More Than 18,000 Tumors

Androgen receptor (AR) is a transcription factor expressed in various normal tissues and is a therapeutic target for prostate and possibly other cancers. A TMA containing 18,234 samples from 141 different tumor types/subtypes and 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. AR positivity was found in 116 tumor types including 66 tumor types (46.8%) with ≥1 strongly positive tumor. Moderate/strong AR positivity was detected in testicular sex cord-stromal tumors (93.3-100%) and neoplasms of the prostate (79.3-98.7%), breast (25.0-75.5%), other gynecological tumors (0.9-100%), kidney (5.0-44.1%), and urinary bladder (5.4-24.2%). Low AR staining was associated with advanced tumor stage (pTa versus pT2-4; p < 0.0001) in urothelial carcinoma; advanced pT (p < 0.0001), high tumor grade (p < 0.0001), nodal metastasis (p < 0.0001), and reduced survival (p = 0.0024) in invasive breast carcinoma; high pT (p < 0.0001) and grade (p < 0.0001) in clear cell renal cell carcinoma (RCC); and high pT (p = 0.0055) as well as high grade (p < 0.05) in papillary RCC. AR staining was unrelated to histopathological/clinical features in 157 endometrial carcinomas and in 221 ovarian carcinomas. Our data suggest a limited role of AR immunohistochemistry for tumor distinction and a prognostic role in breast and clear cell RCC and highlight tumor entities that might benefit from AR-targeted therapy.

Everolimus decreases [U-13C]glucose utilization by pyruvate carboxylase in breast cancer cells in vitro and in vivo

Reprogrammed metabolism is a hallmark of cancer, but notoriously difficult to target due to metabolic plasticity, especially in response to single metabolic interventions. Combining mTOR inhibitor everolimus and mitochondrial complex 1 inhibitor metformin results in metabolic synergy in in vitro models of triple-negative breast cancer. Here, we investigated whether the effect of this drug combination on tumor size is reflected in changes in tumor metabolism using [U-13C]glucose labeling in an MDA-MB-231 triple negative breast cancer xenograft model. The in vitro effects of everolimus and metformin treatment on oxidative phosphorylation and glycolysis reflected changes in 13C-labeling of metabolites in MDA-MB-231 cells. Treatment of MDA-MB-231 xenografts in SCID/Beige mice with everolimus resulted in slower tumor growth and reduced tumor size and tumor viability by 35%. Metformin treatment moderately inhibited tumor growth but did not enhance everolimus-induced effects. High serum levels of everolimus were reached, whereas levels of metformin were relatively low. Everolimus decreased TCA cycle metabolite labeling and inhibited pyruvate carboxylase activity. Metformin only caused a mild reduction in glycolytic metabolite labeling and did not affect pyruvate carboxylase activity or TCA cycle metabolite labeling. In conclusion, treatment with everolimus, but not metformin, decreased tumor size and viability. Furthermore, the efficacy of everolimus was reflected in reduced 13C-labeling of TCA cycle intermediates and reduced pyruvate carboxylase activity. By using in-depth analysis of drug-induced changes in glucose metabolism in combination with measurement of drug levels in tumor and plasma, effects of metabolically targeted drugs can be explained, and novel targets can be identified.

Molecular pathways and therapeutic targets linked to triple-negative breast cancer (TNBC)

Cancer is a group of diseases characterized by uncontrolled cellular growth, abnormal morphology, and altered proliferation. Cancerous cells lose their ability to act as anchors, allowing them to spread throughout the body and infiltrate nearby cells, tissues, and organs. If these cells are not identified and treated promptly, they will likely spread. Around 70% of female breast cancers are caused by a mutation in the BRCA gene, specifically BRCA1. The absence of progesterone, oestrogen and HER2 receptors (human epidermal growth factor) distinguishes the TNBC subtype of breast cancer. There were approximately 6,85,000 deaths worldwide and 2.3 million new breast cancer cases in women in 2020. Breast cancer is the most common cancer globally, affecting 7.8 million people at the end of 2020. Compared to other cancer types, breast cancer causes more women to lose disability-adjusted life years (DALYs). Worldwide, women can develop breast cancer at any age after puberty, but rates increase with age. The maintenance of mammary stem cell stemness is disrupted in TNBC, governed by signalling cascades controlling healthy mammary gland growth and development. Interpreting these essential cascades may facilitate an in-depth understanding of TNBC cancer and the search for an appropriate therapeutic target. Its treatment remains challenging because it lacks specific receptors, which renders hormone therapy and medications ineffective. In addition to radiotherapy, numerous recognized chemotherapeutic medicines are available as inhibitors of signalling pathways, while others are currently undergoing clinical trials. This article summarizes the vital druggable targets, therapeutic approaches, and strategies associated with TNBC.

Analysis of the responsiveness to antiandrogens in multiple breast cancer cell lines

Antiandrogens were originally developed as therapeutic agents for prostate cancer but are also expected to be effective for breast cancer. However, the role of androgen signaling in breast cancer has long been controversial due to the limited number of experimental models. Our study aimed to comprehensively investigate the efficacy of antiandrogens on breast cancer. In the present study, a total of 18 breast cancer cell lines were treated with the agonist or antagonists of the androgen receptor (AR). Among the 18 cell lines tested, only T-47D cells proliferated in an androgen-dependent manner, while the other cell lines were almost irresponsive to AR stimulation. On the other hand, treatment with AR antagonists at relatively high doses suppressed the proliferation of not only T-47D cells but also some other cell lines including AR-low/negative cells. In addition, expression of the full-length AR and constitutively active AR splice variants, AR-V7 and ARV567es, was not correlated with sensitivity to AR antagonists. These data suggest that the antiproliferative effect of AR antagonists is AR-independent in some cases. Consistently, proliferation of AR-knockout BT-549 cells was inhibited by AR antagonists. Identification of biomarkers would be necessary to determine which breast cancer patients will benefit from these drugs.

The molecular subtyping and precision medicine in triple-negative breast cancer---based on Fudan TNBC classification

Triple-negative breast cancer (TNBC) is widely recognized as the most aggressive form of breast cancer, occurring more frequently in younger patients and characterized by high heterogeneity, early distant metastases and poor prognosis. Multiple treatment options have failed to achieve the expected therapeutic effects due to the lack of clear molecular targets. Based on genomics, transcriptomics and metabolomics, the multi-omics analysis further clarifies TNBC subtyping, which provides a greater understanding of tumour heterogeneity and targeted therapy sensitivity. For instance, the luminal androgen receptor subtype (LAR) exhibits responsiveness to anti-AR therapy, and the basal-like immune-suppressed subtype (BLIS) tends to benefit from poly (ADP-ribose) polymerase inhibitors (PARPis) and anti-angiogenic therapy. The efficacy of multi-dimensional combination therapy holds immense importance in guiding personalized and precision medicine for TNBC. This review offers a systematic overview of recent FuDan TNBC molecular subtyping and its role in the instruction of clinical precision therapy.

Exploring the potential of Ziziphus nummularia and luteolin-7-O-glucoside as tubulin inhibitors in cancer therapy and survival

Cancer is responsible for approximately 10 million deaths worldwide, with 70% of the deaths occurring in low- and middle-income countries; as such safer and more effective anti-cancer drugs are required. Therefore, the potential benefits of Ziziphus nummularia and Ziziphus spina-christi as sources of anti-cancer agents were investigated. Z. nummularia and Z. spina-christi extracts were prepared using chloroform, ethanol, ethyl acetate, and water. The extracts' anti-cancer properties were determined using the MTT Cell Viability Assay in four cancer cell lines: breast (KAIMRC2 and MDA-MB-231), colorectal (HCT8), and liver (HepG2). The ApoTox-Glo Triplex Assay and high-content imaging (HCI)-Apoptosis Assay were used to assess KAIMRC2 and HCT8 cells further. In addition, KAIMRC2 cells were tested for microtubule staining, and AKT/mTOR protein expression was determined by western blot analysis. Liquid chromatography-mass spectrometry (LC-MS) was performed to identify the secondary metabolites in the ethanol and ethyl acetate extracts, followed by in silico techniques to predict molecular targets and interactions, safety, and pharmacokinetic profile for identified metabolites. Out of the eight extracts, the ethanolic extract of Z. nummularia, exhibited the most potent activity against KAIMRC2 cells with an IC50 value of 29.2 μg/ml. Cancer cell treatment with the ethanolic extract of Z. nummularia resulted in a dose-dependent decrease in cell viability with increased apoptosis and cytotoxic effects. Microtubule staining showed a disrupted microtubular network. The ethanolic extract treatment of KAIMRC2 cells led to upregulated expression of pAKT and pmTOR. In silico studies predicted luteolin-7-O-glucoside to be a ligand for tubulin with the highest docking score (- 7.686) and similar binding interactions relative to the native ligand. Further computational analysis of the metabolites showed acceptable pharmacokinetic and safety profiles, although ethanolic extract metabolites were predicted to have cardiotoxic effects. Ethanolic extraction is optimal for solubilizing active anticancer metabolites from Z. nummularia, which may act by causing M-phase arrest via inhibition of tubulin polymerization. Luteolin-7-O-glucoside is the lead candidate for further research and development as an anti-cancer agent. In addition, this study suggests that herbal treatment could switch on mechanisms of adaptation and survival in cancer cells.

Immunohistochemical detection of cancer genetic abnormalities

New applications of immunohistochemistry (IHC) expand rapidly due to the development of molecular analyses and an increased understanding of molecular biology. IHC becomes much more important as a screening or even a confirmatory test for molecular changes in cancer. The past decades have witnessed the release of many immunohistochemical markers of the new generation. The novel markers have extensively high specificity and sensitivity for the detection of genetic abnormalities. In addition to diagnostic utility, IHC has been validated to be a practical tool in terms of treatments, especially molecular targeted therapy. In this review, we first describe the common alterations of protein IHC staining in human cancer: overexpression, underexpression, or loss of expression and altered staining pattern. Next, we examine the relationship between staining patterns and genetic aberrations regarding both conventional and novel IHC markers. We also mention current mutant-specific and fusion-specific antibodies and their concordance with molecular techniques. We then describe the basic molecular mechanisms from genetic events to corresponding protein expression patterns (membranous, cytoplasmic, or nuclear patterns). Finally, we shortly discuss the applications of immunohistochemistry in molecular targeted therapy. IHC markers can serve as a complementary or companion diagnostic test to provide valuable information for targeted therapy. Moreover, immunohistochemistry is also crucial as a companion diagnostic test in immunotherapy. The increased number of IHC novel antibodies is broadening its application in anti-cancer therapies.

Subcellular expression pattern and clinical significance of CBX2 and CBX7 in breast cancer subtypes

Chromobox (CBX)2 and CBX7, members of CBX family protein, show diverse expression patterns and contrasting roles in certain cancers. We aimed to investigate the subcellular expression patterns and clinical significances of CBXs in breast cancer (BC) subtypes, which have heterogeneous clinical course and therapeutic responses. Among the subtypes, the triple-negative BC (TNBC) is a heterogeneous group that lacks specific markers. We categorized TNBC into quadruple-negative BC (QNBC) and TNBC, based on androgen receptor (AR) status, to make the groups more homogeneous. Immunohistochemistry for CBX proteins was performed on 323 primary invasive BC tissues and their clinical significances were analyzed. Cytoplasmic CBX2 (CBX2-c) was linked to adverse clinicopathological factors and TNBC and QNBC subtypes. In contrast, nuclear CBX7 (CBX7-n) was associated with favorable parameters and luminal A subtype. CBX2-c expression increased progressively from that in benign lesions to that in in situ carcinomas and invasive cancers, whereas CBX7-n and AR expressions showed sequential downregulation. AR was lower in metastatic tissues compared to matched primary cancer tissues. We speculate that the upregulation of CBX2-c and downregulation of CBX7-n could play a role in breast oncogenesis and an adverse clinical course, suggesting them as potential prognostic markers and therapeutic targets in invasive BCs.