Emerging Therapeutics for Patients with Triple-Negative Breast Cancer

Machine learning and single-cell analysis uncover distinctive characteristics of CD300LG within the TNBC immune microenvironment: experimental validation

Investigating the essential function of CD300LG within the tumor microenvironment in triple-negative breast cancer (TNBC). Transcriptomic and single-cell data from TNBC were systematically collected and integrated. Four machine learning algorithms were employed to identify distinct target genes in TNBC patients. Specifically, CIBERSORT and ssGSEA algorithms were utilized to elucidate immune infiltration patterns, whereas TIDE and TCGA algorithms predicted immune-related outcomes. Moreover, single-cell sequencing data were analyzed to investigate the function of CD300LG-positive cells within the tumor microenvironment. Finally, immunofluorescence staining confirmed the significance of CD300LG in tumor phenotyping. After machine learning screening and independent dataset validation, CD300LG was identified as a unique prognostic biomarker for triple-negative breast cancer. Enrichment analysis revealed that CD300LG expression is strongly linked to immune infiltration and inflammation-related pathways, especially those associated with the cell cycle. The presence of CD8+ T cells and M1-type macrophages was elevated in the CD300LG higher group, whereas the abundance of M2-type macrophage infiltration showed a significant decrease. Immunotherapy prediction models indicated that individuals with low CD300LG expression exhibited better responses to PD-1 therapy. Additionally, single-cell RNA sequencing and immunofluorescence analyses uncovered a robust association between CD300LG and genes involved in tumor invasion. CD300LG plays a pivotal role in the tumor microenvironment of TNBC and represents a promising therapeutic target.

Recent Advances in Immunotherapy and Targeted Therapy of Triple Negative Breast Cancer

The truancy of representation of the estrogen, progesterone, and human epidermal growth factor receptors occurs during TNBC. TNBC is recognized for the upper reappearance and has a poorer diagnosis compared with rest breast cancer (BC) types. Presently, as such, no targeted therapy is approved for TNBC and treatment options are subjected to chemotherapy and surgery, which have high mortality rates. Hence, the current article focuses on the scenario of TNBC vital pathways and discusses the latest advances in TNBC treatment, including immune checkpoint inhibitors (ICIs), PARP suppressors, and cancer vaccines. Immunotherapy and ICIs, like PD 1 and PD L1 suppressors, displayed potential in clinical trials (CTs). These suppressors obstruct the mechanisms which allow tumor cells to evade the system thereby boosting the body's defense against TNBC. Immunotherapy, either alone or combined with chemotherapy has demonstrated patient outcomes such as increased survival rates and reduced treatment-related side effects. Additionally, targeted therapy approaches include BRCA/2 mutation poly ribose polymerase inhibitors, Vascular Endothelial Growth Factor Receptor (VEGFR) inhibitors, Epidermal growth factor receptor inhibitors, Fibroblast growth factor inhibitors, Androgen Receptor inhibitors, PIK3/AKT/mTOR pathway inhibitors, Cyclin-dependent kinase (CDK) inhibitors, Notch signaling pathway inhibitors, Signal transducer and activator of transcription 3 (STAT3) signaling pathway inhibitors, Chimeric antigen receptor T (CAR-T) cell therapy, Transforming growth factor (TGF) -β inhibitors, Epigenetic modifications (EPM), Aurora Kinase inhibitors and antibody-drug conjugates. We also highlight ongoing clinical trials and potential future directions for TNBC therapy. Despite the challenges in treating TNBC, recent developments in understanding the molecular and immune characteristics of TNBC have opened up new opportunities for targeted therapies, which hold promise for improving outcomes in this aggressive disease.

Developing an Arene Binuclear Ruthenium(II) Complex to Induce Ferroptosis and Activate the cGAS-STING Pathway: Targeted Inhibiting Growth and Metastasis of Triple Negative Breast Cancer

To effectively inhibit the growth and metastasis of triple-negative breast cancer (TNBC), we developed a high-efficiency and low-toxicity arene ruthenium (Ru) complex based on apoferritin (AFt). To achieve this, we optimized a series of Ru(II) 1,10-phenanthroline-2,9-diformaldehyde thiosemicarbazone complexes by studying their structure-activity relationships to obtain an arene binuclear Ru(II) complex (C5) with significant cytotoxicity and high accumulation in the mitochondria of tumor cells. Subsequently, a C5-AFt nanoparticle (NPs) delivery system was constructed. We found that the C5/C5-AFt NPs effectively inhibited TNBC growth and metastasis with few side effects. The C5-AFt NPs improved the anticancer and targeting abilities of C5 in vivo. Moreover, we confirmed the mechanism by which C5/C5-AFt NPs inhibit tumor growth and metastasis via mitochondrial damage-mediated ferroptosis and activation of the cGAS-STING pathway.

Neoadjuvant Pembrolizumab Plus Chemotherapy in Early-Stage Triple-Negative Breast Cancer: A Nationwide Retrospective Turkish Oncology Group Study

Background/Objectives: Following the results of the phase 3 KEYNOTE-522 trial, the U.S. Food and Drug Administration approved pembrolizumab, a humanized IgG4 kappa monoclonal antibody, in combination with neoadjuvant chemotherapy as a new standard of care for high-risk early-stage triple-negative breast cancer (TNBC). This retrospective, multicenter study in Türkiye assessed the real-world efficacy and safety of neoadjuvant pembrolizumab combined with chemotherapy in early-stage TNBC. Methods: The study included 108 patients treated between 2021 and 2023 across 14 oncology centers. Three distinct neoadjuvant regimens incorporating pembrolizumab were administered at the discretion of the treating physicians. The primary outcomes were the pathological complete response (pCR) rate after neoadjuvant therapy and the 2-year event-free survival (EFS) and overall survival (OS) rates. Results: The observed pCR rate was 63.9%, closely mirroring the 64.8% reported in the KEYNOTE-522 trial. At the two-year mark, the EFS rate was 87.2% and the OS rate was 92.3%. Multivariable analysis identified pCR as the sole independent predictor of both EFS and OS. The safety profile was consistent with previous clinical trial data, with most adverse events being of grade 1-2 in severity. Conclusions: These findings provide valuable real-world confirmation of the efficacy and safety of neoadjuvant pembrolizumab-chemotherapy in early-stage TNBC, complementing evidence from randomized trials.

Advances in immunotherapy for breast cancer and feline mammary carcinoma: From molecular basis to novel therapeutic targets

The role of inflammation in cancer is a topic that has been investigated for many years. As established, inflammation emerges as a defining characteristic of cancer, presenting itself as a compelling target for therapeutic interventions in the realm of oncology. Controlling the tumor microenvironment (TME) has gained paramount significance, modifying not only the effectiveness of immunotherapy but also modulating the outcomes and prognoses of standard chemotherapy and other anticancer treatments. Immunotherapy has surfaced as a central focus within the domain of tumor treatments, using immune checkpoint inhibitors as cancer therapy. Immune checkpoints and their influence on the tumor microenvironment dynamic are presently under investigation, aiming to ascertain their viability as therapeutic interventions across several cancer types. Cancer presents a significant challenge in humans and cats, where female breast cancer ranks as the most prevalent malignancy and feline mammary carcinoma stands as the third most frequent. This review seeks to summarize the data about the immune checkpoints cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), lymphocyte activation gene-3 (LAG-3), programmed cell death protein-1 (PD-1), V-domain Ig suppressor of T cell activation (VISTA), and T-cell immunoglobulin and mucin domain 3 (TIM-3) respective ongoing investigations as prospective targets for therapy for human breast cancer, while also outlining findings from studies reported on feline mammary carcinoma (FMC), strengthening the rationale for employing FMC as a representative model in the exploration of human breast cancer.

Ibulocydine Inhibits Migration and Invasion of TNBC Cells via MMP-9 Regulation

Triple-negative breast cancer (TNBC) accounts for approximately 15-20% of all breast cancer types, indicating a poor survival prognosis with a more aggressive biology of metastasis to the lung and a short response duration to available therapies. Ibulocydine (IB) is a novel (cyclin-dependent kinase) CDK7/9 inhibitor prodrug displaying potent anti-cancer effects against various cancer cell types. We performed in vitro and in vivo experiments to determine whether IB inhibits metastasis and eventually overcomes the poor drug response in TNBC. The result showed that IB inhibited the growth of TNBC cells by inducing caspase-mediated apoptosis and blocking metastasis by reducing MMP-9 expression in vitro. Concurrently, in vivo experiments using the metastasis model showed that IB inhibited metastasis of MDA-MB-231-Luc cells to the lung. Collectively, these results demonstrate that IB inhibited the growth of TNBC cells and blocked metastasis by regulating MMP-9 expression, suggesting a novel therapeutic agent for metastatic TNBC.

Cyclin-dependent kinase 2 (CDK2) inhibitors and others novel CDK inhibitors (CDKi) in breast cancer: clinical trials, current impact, and future directions

Aberrant cyclin-dependent kinase 2 (CDK2) activation has been identified as a main resistance mechanism to CDK4/6 inhibition in hormone-receptor positive (HR+) breast cancer. Additionally, consistent preclinical evidence states its crucial role in MYC and CCNE1 overexpressed cancer survival, such as triple-negative breast cancers (TNBC), thus representing an appealing and relatively unexplored target treatment opportunity. Despite emerging initial results of novel CDK2 inhibitors (CDK2i) activity, a comprehensive outcomes collection is currently absent from the scientific literature. We aim to provide an overview of ongoing clinical trials involving CDK2i in the context of metastatic breast cancer (mBC), either as monotherapy or in combination with other agents. The review extends beyond CDK2i to encompass novel emerging CDK4 inhibitors, combined CDK2/4/6 inhibitors, and the well-known pan-CDK inhibitors including those specifically directed at CDK2. Delving into the results, we critically appraise the observed clinical efficacy and offer valuable insights into their potential impact and future applications.

The emerging role of noncoding RNAs in the PI3K/AKT/mTOR signalling pathway in breast cancer

Breast cancer persists as a major problem for the world's healthcare, thus it is essential to fully understand the complex molecular processes that cause its growth and development. ncRNAs had been discovered to serve critical roles in a variety of cellular functions, including the regulation of signalling pathways. Within different pathways, the AKT/PI3K/mTOR signalling cascade has received a lot of interest because of its role in cancer. A complex interaction between ncRNAs, notably miRNAs, lncRNAs, and circRNAs, and the AKT/PI3K/mTOR signalling pathway exerts both oncogenic and tumor-suppressive activities by targeting critical components of the pathway directly or indirectly. Through miRNA-mediated post-transcriptional regulation, lncRNA-guided chromatin remodelling, and circRNA sequestration, ncRNAs modulate the activity of PI3K, AKT, and mTOR, influencing cell proliferation, survival, and metastasis. Furthermore, ncRNAs can serve as promising biomarkers for breast cancer prognosis, diagnosis, and treatment response, as their dysregulation is commonly observed in breast cancer patients. Harnessing the potential of ncRNAs as therapeutic targets or tools for restoring pathway homeostasis holds promise for innovative treatment strategies in breast cancer. Understanding the intricate regulatory networks orchestrated by ncRNAs in this context may pave the way for novel diagnostic approaches, therapeutic interventions, and a deeper comprehension of breast cancer's molecular landscape, ultimately improving patient outcomes. This abstract underscores the emerging significance of ncRNAs in the AKT/PI3K/mTOR signaling pathway in breast cancer.

Cuproptosis-related genes predict prognosis and trastuzumab therapeutic response in HER2-positive breast cancer

Breast cancer is the most common diagnosed cancer, the HER2-positive subtype account for 15% of all breast cancer. HER2-targeted therapy is the mainstay treatment for HER2-positive breast cancer. Cuproptosis is a novel form of programmed cell death, and is caused by mitochondrial lipoylation and destabilization of iron-sulfur proteins triggered by copper, which was considered as a key player in various biological processes. However, the roles of cuproptosis-related genes in HER2-positive breast cancer remain largely unknown. In the present study, we constructed a prognostic prediction model of HER2-positive breast cancer patients using TCGA database. Dysregulated genes for cells resistant to HER2-targeted therapy were analyzed in the GEO dataset. KEGG pathway, GO enrichment and GSEA was performed respectively. The immune landscape of DLAT was analyzed by CIBERSORT algorithm and TIDE algorithm. HER2-positive breast cancer patients with high CRGs risk score showed shorter OS. DLAT was downregulated and correlated with better survival of HER2-positive breast cancer patients (HR = 3.30, p = 0.022). High expressed DLAT was associated with resistant to HER2-targeted therapy. Knocking down DLAT with siRNA increased sensitivity of breast cancer to trastuzumab. KEGG pathway and GO enrichment of DEGs indicated that DLAT participates in various pathways correlated with organelle fission, chromosome segregation, nuclear division, hormone-mediated signaling pathway, regulation of intracellular estrogen receptor signaling pathway, condensed chromosome and PPAR signaling pathway. There was a negative correlation between TIDE and DLAT expression (r = - 0.292, p < 0.001), which means high DLAT expression is an indicator of sensitivity to immunotherapy. In conclusion, our study constructed a four CRGs signature prognostic prediction model and identified DLAT as an independent prognostic factor and associated with resistant to HER2-targeted therapy for HER2-positive breast cancer patients.

Gankyrin inhibits ferroptosis through the p53/SLC7A11/GPX4 axis in triple-negative breast cancer cells

Gankyrin is found in high levels in triple-negative breast cancer (TNBC) and has been established to form a complex with the E3 ubiquitin ligase MDM2 and p53, resulting in the degradation of p53 in hepatocarcinoma cells. Therefore, this study sought to determine whether gankyrin could inhibit ferroptosis through this mechanism in TNBC cells. The expression of gankyrin was investigated in relation to the prognosis of TNBC using bioinformatics. Co-immunoprecipitation and GST pull-down assays were then conducted to determine the presence of a gankyrin and MDM2 complex. RT-qPCR and immunoblotting were used to examine molecules related to ferroptosis, such as gankyrin, p53, MDM2, SLC7A11, and GPX4. Additionally, cell death was evaluated using flow cytometry detection of 7-AAD and a lactate dehydrogenase release assay, as well as lipid peroxide C11-BODIPY. Results showed that the expression of gankyrin is significantly higher in TNBC tissues and cell lines, and is associated with a poor prognosis for patients. Subsequent studies revealed that inhibiting gankyrin activity triggered ferroptosis in TNBC cells. Additionally, silencing gankyrin caused an increase in the expression of the p53 protein, without altering its mRNA expression. Co-immunoprecipitation and GST pull-down experiments indicated that gankyrin and MDM2 form a complex. In mouse embryonic fibroblasts lacking both MDM2 and p53, this gankyrin/MDM2 complex was observed to ubiquitinate p53, thus raising the expression of molecules inhibited by ferroptosis, such as SLC7A11 and GPX4. Furthermore, silencing gankyrin in TNBC cells disrupted the formation of the gankyrin/MDM2 complex, hindered the degradation of p53, increased SLC7A11 expression, impeded cysteine uptake, and decreased GPX4 production. Our findings suggest that TNBC cells are able to prevent cell ferroptosis through the gankyrin/p53/SLC7A11/GPX4 signaling pathway, indicating that gankyrin may be a useful biomarker for predicting TNBC prognosis or a potential therapeutic target.

FXYD3 functionally demarcates an ancestral breast cancer stem cell subpopulation with features of drug-tolerant persisters

The heterogeneity of cancer stem cells (CSCs) within tumors presents a challenge in therapeutic targeting. To decipher the cellular plasticity that fuels phenotypic heterogeneity, we undertook single-cell transcriptomics analysis in triple-negative breast cancer (TNBC) to identify subpopulations in CSCs. We found a subpopulation of CSCs with ancestral features that is marked by FXYD domain-containing ion transport regulator 3 (FXYD3), a component of the Na+/K+ pump. Accordingly, FXYD3+ CSCs evolve and proliferate, while displaying traits of alveolar progenitors that are normally induced during pregnancy. Clinically, FXYD3+ CSCs were persistent during neoadjuvant chemotherapy, hence linking them to drug-tolerant persisters (DTPs) and identifying them as crucial therapeutic targets. Importantly, FXYD3+ CSCs were sensitive to senolytic Na+/K+ pump inhibitors, such as cardiac glycosides. Together, our data indicate that FXYD3+ CSCs with ancestral features are drivers of plasticity and chemoresistance in TNBC. Targeting the Na+/K+ pump could be an effective strategy to eliminate CSCs with ancestral and DTP features that could improve TNBC prognosis.

Zhuidu Formula suppresses the migratory and invasive properties of triple-negative breast cancer cells via dual signaling pathways of RhoA/ROCK and CDC42/MRCK

ETHNOPHARMACOLOGICAL RELEVANCE

Zhuidu Formula (ZDF) is composed of triptolide, cinobufagin and paclitaxel, which are the active ingredients of Tripterygium wilfordii Hook. F, dried toad skin and Taxus wallichiana var. chinensis (Pilg) Florin, respectively. Modern pharmacological studies show that triptolide, cinobufagin, and paclitaxel are well-known natural compounds that exert anti-tumor effects by interfering with DNA synthesis, inducing tumor cell apoptosis, and inhibiting the dynamic balance of the tubulin. However, the mechanism by which the three compounds inhibit triple-negative breast cancer (TNBC) metastasis is unknown.

OBJECTIVE

The objective of this investigation was to examine the inhibitory essences of ZDF on the metastasis of TNBC and elucidate its potential mechanism.

MATERIALS AND METHODS

Cell viability of triptolide (TPL), cinobufagin (CBF), and paclitaxel (PTX) on MDA-MB-231 cells was assessed employing a CCK-8 assay. The drug interactions of the three drugs on MDA-MB-231 cells were determined in vitro utilizing the Chou-Talalay method. MDA-MB-231 cells were identified for migration, invasion and adhesion in vitro through the implementation of the scratch assay, transwell assay and adhesion assay, respectively. The formation of cytoskeleton protein F-actin was detected by immunofluorescence assay. The expressions of MMP-2 and MMP-9 in the supernatant of the cells were determined by ELISA analysis. The Western blot and RT-qPCR were employed to explore the protein expressions associated with the dual signaling pathways of RhoA/ROCK and CDC42/MRCK. The anti-tumor efficacy of ZDF in vivo and its preliminary mechanism were investigated in the mouse 4T1 TNBC model.

RESULTS

The results demonstrated that ZDF could significantly reduce the viability of the MDA-MB-231 cell, and the combination index (CI) values of actual compatibility experimental points were all less than 1, demonstrating a favorable synergistic compatibility relationship. It was found that ZDF reduces RhoA/ROCK and CDC42/MRCK dual signaling pathways, which are responsible for MDA-MB-231cell migration, invasion, and adhesion. Additionally, there has been a significant reduction in the manifestation of cytoskeleton-related proteins. Furthermore, the expression levels of RhoA, CDC42, ROCK2, and MRCKβ mRNA and protein were down-regulated. ZDF significantly decreased the protein expressions of vimentin, cytokeratin-8, Arp2 and N-WASP, and inhibited actin polymerization and actomyosin contraction. Furthermore, MMP-2 and MMP-9 levels in the high-dose ZDF group were decreased by 30% and 26%, respectively. ZDF significantly reduced the tumor volume and protein expressions of ROCK2 and MRCKβ in tumor tissues without eliciting any perceptible alterations in the physical mass of the mice, and the reduction was more pronounced than that of the BDP5290 treated group.

CONCLUSION

The current investigation demonstrates that ZDF exhibits a proficient inhibitory impact on TNBC metastasis by regulating cytoskeletal proteins through the dual signaling pathways of RhoA/ROCK and CDC42/MRCK. Furthermore, the findings indicate that ZDF has significant anti-tumorigenic and anti-metastatic characteristics in breast cancer animal models.

Nanodrug regulates ROS homeostasis via enhancing fatty acid oxidation and inhibiting autophagy to overcome tumor drug resistance

The treatment of drug-resistant tumors poses a significant challenge in the field of tumor therapy. Disrupting the homeostasis of reactive oxygen species (ROS) within tumor cells may represent a pivotal strategy for overcoming the prevalent issue of drug resistance. However, the restricted sustainability of ROS generation and the increased autophagy capacity exhibited by tumor cells hinder the application of ROS-based therapies. In this study, we developed liposome nanoparticles (Ato/CQ@L) for co-encapsulation of atorvastatin (Ato), an activator of AMP-activated protein kinase (AMPK), and chloroquine (CQ), an autophagy inhibitor. Upon internalization by tumor cells, Ato upregulated carnitine palmitoyltransferase 1(CPT1) concentration and promoted fatty acid oxidation (FAO) within the tumor cells. The process of FAO coupled with an abundance of fatty acid substrates, facilitates a sustained generation of ROS production. Concurrently, a positive feedback loop is established between escalated concentration of ROS and AMPK protein levels, resulting in a persistent elevation in ROS levels. In addition, CQ disrupted lysosomes, leading to an increased lysosomal pH and reducing autophagy in tumor cells. In both in vivo and in vitro experiments, the Ato/CQ@L treatment group exhibited a considerable enhancement in tumor cell apoptosis, validating the efficacy of this combined therapy. In summary, the combined therapy involving Ato and CQ addresses the inherent limitations of conventional ROS therapy, which include insufficient ROS production and increased autophagy. This approach holds significant potential as a treatment strategy for drug-resistant triple-negative breast cancer.

Hope and Hype around Immunotherapy in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) holds a poor prognosis compared to other breast cancer subtypes, and the development of new effective treatment strategies is an unmet medical need. TNBC has traditionally been considered not amenable to treatment with targeted agents due to a lack of actionable targets. Therefore, chemotherapy has remained the mainstay of systemic treatment for many decades. The advent of immunotherapy raised very hopeful expectations in TNBC, possibly due to higher levels of tumor-infiltrating lymphocytes, PD-L1 expression and tumor mutational burden compared to other breast cancer subtypes, that predict an effective anti-tumor immune-engagement. The results of clinical trials testing immunotherapy in TNBC led to the approval of the combination of immune checkpoint inhibitors and chemotherapy in both early and advanced settings. However, some open questions about the use of immunotherapy in TNBC still exist. These include a deeper understanding of the heterogeneity of the disease, identification of reliable predictive biomarkers of response, determination of the most appropriate chemotherapy backbone and appropriate management of potential long-term immune-related adverse events. In this review we aim to examine the available evidence on the use of immunotherapy strategies in both early and advanced TNBC, to critically discuss some of the limitations encountered in clinical research and to summarize data on novel promising immunotherapeutic strategies beyond PD-(L)1 blockade that have been investigated in the most recent trials.

Research Status of Systemic Adjuvant Therapy for Early Breast Cancer

Breast cancer has surpassed lung cancer as the most common cause of cancer deaths, worldwide. Early breast cancers are treatment sensitive and patients under standardized treatment have prolonged. Breast cancer treatment has significantly evolved from the conventional surgical approach and radiotherapy to local and systemic adjuvant therapies. Though localized breast cancers are clinically manageable, distant recurrence is a cause of morbid concern. Adjuvant systemic therapy is effective in both distant and local recurrences and hence gained significant attention. Early breast cancer prognosis has greatly improved in the past 3 decades with reduced mortality rates due to the widespread use of adjuvant therapy. It can markedly increase the cure rate of breast cancers, and postoperative adjuvant therapy became a part of comprehensive breast cancer treatment. Further research to understand the early breast cancer characteristics could expand the treatment modalities that can improve the outcomes and survival benefits of breast cancer patients.

A novel conditional survival nomogram for monitoring real-time prognosis of non-metastatic triple-negative breast cancer

BACKGROUND

Conditional survival (CS) is defined as the possibility of further survival after patients have survived for several years since diagnosis. This may be highly valuable for real-time prognostic monitoring, especially when considering individualized factors. Such prediction tools were lacking for non-metastatic triple-negative breast cancer (TNBC). Therefore, this study estimated CS and developed a novel CS-nomogram for real-time prediction of 10-year survival.

METHODS

We recruited 32,836 non-metastatic TNBC patients from the Surveillance, Epidemiology, and End Results (SEER) database (2010-2019), who were divided into training and validation groups according to a 7:3 ratio. The Kaplan-Meier method estimated overall survival (OS), and the CS was calculated using the formula CS(y|x) =OS(y+x)/OS(x), where OS(x) and OS(y+x) were the survival of x- and (x+y)-years, respectively. The least absolute shrinkage and selection operator (LASSO) regression identified predictors to develop the CS-nomogram.

RESULTS

CS analysis reported gradual improvement in real-time survival over time since diagnosis, with 10-year OS updated annually from an initial 69.9% to 72.8%, 78.1%, 83.0%, 87.0%, 90.3%, 93.0%, 95.0%, 97.0%, and 98.9% (after 1-9 years of survival, respectively). The LASSO regression identified age, marriage, race, T status, N status, chemotherapy, surgery, and radiotherapy as predictors of CS-nomogram development. This model had a satisfactory predictive performance with a stable 10-year time-dependent area under the curves (AUCs) between 0.75 and 0.86.

CONCLUSIONS

Survival of non-metastatic TNBC survivors improved dynamically and non-linearly with survival time. The study developed a CS-nomogram that provided more accurate prognostic data than traditional nomograms, aiding clinical decision-making and reducing patient anxiety.

Systemic therapy for early-stage breast cancer: learning from the past to build the future

The treatment of breast cancer has improved dramatically over the past century, from a strictly surgical approach to a coordinated one, including local and systemic therapies. Systemic therapies for early-stage disease were initially tested against observation or placebo only in adjuvant trials. Subsequent clinical trials focusing on treatment 'fine-tuning' had a marked increase in cohort size, duration and costs, leading to a growing interest in the neoadjuvant setting in the past decade. Neoadjuvant trial designs have the advantages of enabling the direct evaluation of treatment effects on tumour diameter and offer unique translational research opportunities through the comparative analysis of tumour biology before, during and after treatment. Current technologies enabling the identification of better predictive biomarkers are shaping the new era of (neo)adjuvant trials. An urgent need exists to reinforce collaboration between the pharmaceutical industry and academia to share data and thus establish large databases of biomarker data coupled with patient outcomes that are easily accessible to the scientific community. In this Review, we summarize the evolution of (neo)adjuvant trials from the pre-genomic to the post-genomic era and provide critical insights into how neoadjuvant studies are currently designed, discussing the need for better end points and treatment strategies that are more personalized, including in the post-neoadjuvant setting.

The tumor microenvironment and triple-negative breast cancer aggressiveness: shedding light on mechanisms and targeting

INTRODUCTION

In contrast to other breast cancer subtypes, there are currently limited options of targeted therapies for triple-negative breast cancer (TNBC). Immense research has demonstrated that not only cancer cells but also stromal cells and immune cells in the tumor microenvironment (TME) play significant roles in the progression of TNBC. It is thus critical to understand the components of the TME of TNBC and the interactions between the various cell populations.

AREAS COVERED

The components of the TME of TNBC identified by single-cell technologies are reviewed. Furthermore, the molecular interactions between the cells and the potential therapeutic targets contributing to the progression of TNBC are discussed.

EXPERT OPINION

Single-cell omics studies have contributed to the classification of cells in the TME and the identification of important cell types involved in the progression and the treatment of the tumor. The interactions between cancer cells and stromal cells/immune cells in the TME have led to the discovery of potential therapeutic targets. Experimental data with spatial and temporal resolution will further boost the understanding of the TME of TNBC.

Ceramide Synthase 6 Mediates Triple-Negative Breast Cancer Response to Chemotherapy Through RhoA- and EGFR-Mediated Signaling Pathways

PURPOSE

Limited treatment options and lack of treatment sensitivity biomarkers make the clinical management of triple-negative breast cancer (TNBC) challenging. Ceramide synthase 6 (CERS6) generates ceramides, which are key intermediates in sphingolipid biosynthesis and play important roles in cancer progression and resistance.

METHODS

CERS6 was analyzed to determine its potential as a treatment sensitivity biomarker. CERS6 levels were determined in patients with breast cancer, and the roles and downstream signaling of CERS6 were analyzed using cellular and biochemical assays.

RESULTS

Analysis of CERS6 expression in 195 patients with TNBC and their clinical response to chemotherapy revealed that individuals with CERS6 overexpression experienced significantly inferior responses to chemotherapy than those without CERS6 overexpression. Functional analysis demonstrated that although CERS6 overexpression did not affect TNBC cell growth and migration, it conferred chemoresistance. CERS6 inhibition significantly reduced growth, migration, and survival by suppressing the RhoA- and EGFR-mediated signaling pathways. Compared to control cells, CERS6-depleted cells were consistently less viable at different concentrations of chemotherapeutic agents.

CONCLUSION

Our study is the first to demonstrate that CERS6 may serve as a treatment sensitivity biomarker in patients with TNBC in response to chemotherapy. In addition, our findings suggested that CERS6 may be a therapeutic target for TNBC treatment.

PD-L1-Positive High-Grade Triple-Negative Breast Cancer Patients Respond Better to Standard Neoadjuvant Treatment-A Retrospective Study of PD-L1 Expression in Relation to Different Clinicopathological Parameters

Triple negative breast cancer (TNBC) is typically a high-grade breast cancer with poorest clinical outcome despite available treatment modalities with chemo-, immuno- and radiotherapy. The status of tumor-infiltrating lymphocytes (TILs) is a prognostic factor closely related to programmed death ligand 1 (PD-L1) expressed on T lymphocytes modulating antitumor immunity. Immune-checkpoint inhibitors (ICI) are showing promising results in a subset of breast cancer patients in both neo- and adjuvant settings. Pathologic complete response (pCR) after neoadjuvant treatment was found to be associated with better prognosis. We analyzed the prognostic and predictive significance of PD-L1 (SP142 assay) immunohistochemical expression on TNBC patients' samples as illustrated by pCR with regard to its relation to treatment regimen, stage, BRCA mutational status and outcome. Furthermore, we analyzed a few other clinicopathological parameters such as age, TILs and proliferation index. The study highlighted a positive role of PD-L1 evaluation for personalized pCR probability assessment. Although considerable research was made on comparison of PD-L1 level in TNBC with different patient parameters, to our best knowledge, the relation of PD-L1 status to pCR while taking treatment regimen and stage into consideration was so far not investigated.

Serotonin 5-HT7 receptor is a biomarker poor prognostic factor and induces proliferation of triple-negative breast cancer cells through FOXM1

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive type of breast cancer and associated with poor prognosis and shorter survival due to significant genetic heterogeneity, drug resistance and lack of effective targeted therapeutics. Therefore, novel molecular targets and therapeutic strategies are needed to improve patient survival. Serotonin (5-hydroxytryptamine, 5-HT) has been shown to induce growth stimulatory effects in breast cancer. However, the molecular mechanisms by which 5-HT exerts its oncogenic effects in TNBC still are not well understood.

METHODS

Normal breast epithelium (MCF10A) and two TNBC cells (MDA-MB-231, BT-546) and MCF-7 cells (ER +) were used to investigate effects of 5-HT7 receptor. Small interfering RNA (siRNA)-based knockdown and metergoline (5-HT7 antagonist) were used to inhibit the activity of 5-HT7. Cell proliferation and colony formation were evaluated using MTS cell viability and colony formation assays, respectively. Western blotting was used to investigate 5-HT7, FOXM1 and its downstream targets protein expressions.

RESULTS

We demonstrated that 5-HT induces cell proliferation of TNBC cells and expression of 5-HT7 receptor and FOXM1 oncogenic transcription factor. We found that expression of 5-HT7 receptor is up-regulated in TNBC cells and higher 5-HT7 receptor expression is associated with poor patient prognosis and shorter patient survival. Genetic and pharmacological inhibition of 5-HT7 receptor by siRNA and metergoline, respectively, suppressed TNBC cell proliferation and FOXM1 and its downstream mediators, including eEF2-Kinase (eEF2K) and cyclin-D1.

CONCLUSION

Our findings suggest for the first time that the 5-HT7 receptor promotes FOXM1, eEF2K and cyclin D1 signaling to support TNBC cell proliferation; thus, inhibition of 5-HT7 receptor/FOXM1 signaling may be used as a potential therapeutic strategy for targeting TNBC. 5-HT induces cell proliferation of TNBC cells through 5-HT7 receptor signaling. Also, genetic and pharmacological inhibition of 5-HT7 by RNAi (siRNA) and metergoline HTR7 antagonist, respectively inhibits FOXM1 oncogenic transcription factor and suppresses TNBC cell proliferation.

Heterogeneity of triple-negative breast cancer: understanding the Daedalian labyrinth and how it could reveal new drug targets

INTRODUCTION

Triple-negative breast cancer (TNBC) is considered the most aggressive breast cancer subtype with the least favorable outcomes. However, recent research efforts have generated an enhanced knowledge of the biology of the disease and have provided a new, more comprehensive understanding of the multifaceted ecosystem that underpins TNBC.

AREAS COVERED

In this review, the authors illustrate the principal biological characteristics of TNBC, the molecular driver alterations, targetable genes, and the biomarkers of immune engagement that have been identified across the subgroups of TNBC. Accordingly, the authors summarize the landscape of the innovative and investigative biomarker-driven therapeutic options in TNBC that emerge from the unique biological basis of the disease.

EXPERT OPINION

The therapeutic setting of TNBC is rapidly evolving. An enriched understanding of the tumor spatial and temporal heterogeneity and the surrounding microenvironment of this complex disease can effectively support the development of novel and tailored opportunities of treatment.

Immunotherapy for HER2-Positive Breast Cancer: Clinical Evidence and Future Perspectives

Breast cancer is the most common malignancy among women worldwide, and HER2-positive breast cancer accounts for approximately 15% of all breast cancer diagnoses. The advent of HER2-targeting therapies has dramatically improved the survival of these patients, significantly reducing their risk of recurrence and death. However, as a significant proportion of patients ultimately develop resistance to these therapies, it is extremely important to identify new treatments to further improve their clinical outcomes. Immunotherapy has revolutionized the treatment and history of several cancer types, and it has already been approved as a standard of care for patients with triple-negative breast cancer. Based on a strong preclinical rationale, immunotherapy in HER2-positive breast cancer represents an intriguing field that is currently under clinical investigation. There is a close interplay between HER2-targeting therapies (both approved and under investigation) and the immune system, and several new immunotherapeutic strategies, including immune checkpoint inhibitors, CAR-T cells and therapeutic vaccines, are being studied in this disease. In this narrative review, we discuss the clinical evidence and the future perspectives of immunotherapy for patients with HER2-positive breast cancer.

Progress and pitfalls in the use of immunotherapy for patients with triple negative breast cancer

INTRODUCTION

Triple negative breast cancer (TNBC) is an area of high unmet medical need in terms of new effective treatment strategies. Although breast cancer is traditionally considered a 'cold' tumor type, TNBC is the most appropriate subtype for immunotherapeutic strategies; this is due to the high level of tumor infiltrating lymphocytes, PD-L1 expression and tumor mutational burden relative to other breast cancer subtypes.

AREAS COVERED

This review examines the use of immunotherapeutic strategies in early and advanced TNBC. The paper summarizes data on novel promising immunomodulatory approaches that have been explored in early phase trials and discusses the pitfalls and limitations often encountered in clinical research.

EXPERT OPINION

PD-1-blockade is approved for stage II/III TNBC and for first-line treatment of PD-L1-positive TNBC patients with metastatic disease and should be considered standard of care. However, question marks and difficulties remain; these include the identification of predictive biomarkers to select patients who benefit from the addition of PD1-blockade and the balance between efficacy and long-term toxicity for an individual patient. Numerous treatment combinations and new immunotherapeutic strategies beyond PD1 blockade are being evaluated, thus reflecting a promising evolution of a more personalized approach, and extended clinical benefit in TNBC.

TrMab-6 Exerts Antitumor Activity in Mouse Xenograft Models of Breast Cancers

Trophoblast cell surface antigen 2 (TROP2) has been reported to be overexpressed in many cancers, and is involved in cancer cell proliferation, invasion, and metastasis. We previously developed a highly sensitive anti-TROP2 monoclonal antibody (mAb) (clone TrMab-6; mouse IgG_2b, kappa) using a Cell-Based Immunization and Screening method. TrMab-6 is useful for investigations using flow cytometry, Western blotting, and immunohistochemistry and possesses antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) against TROP2-expressing triple-negative breast cancer (TNBC) cell lines, such as MDA-MB-231 and MDA-MB-468. This study investigated whether TrMab-6 possesses in vivo antitumor activities via ADCC/CDC activities using mouse xenograft models of TNBC cell lines. In vivo experiments on MDA-MB-231 and MDA-MB-468 xenografts revealed that TrMab-6 significantly reduced tumor growth compared with normal mouse IgG treatment. The findings of this study suggest that TrMab-6 is a promising treatment option for TROP2-expressing TNBC.

New insights into the discovery of drugs for triple-negative breast cancer metastasis

INTRODUCTION

Triple-negative breast cancer (TNBC) is of great concern due to its aggressiveness and lack of targeted therapy. For these reasons, TNBC is one of the main causes of death in women, mainly due to metastases. Tumor dissemination has highlighted a set of possible targets, with extensive research into new single-target drugs, in addition to drug repurposing strategies, being undertaken to discover new classes of potential inhibitors of metastasis.

AREAS COVERED

The authors here describe the main proposed targets and the bases of their pharmacological inhibition with different chemical compounds. The authors also discuss the state-of-the-art from the latest clinical trials and highlight other potential targets for metastatic TNBC.

EXPERT OPINION

In the last decade, oncology research has changed its focus from primary tumors to moving tumor cells, their products, and to the secondary tumor and its surroundings, for the purpose of finding targets to treat metastasis. Consequently, our comprehension of the complexity of the metastatic process has increased drastically, with, furthermore, the discovery of new potential targets. Although promising, the wide range of strategies is still not effective to suppress TNBC metastasis in terms of increasing patient survival or decreasing the number of metastases. Treating or preventing metastasis continues to be a great challenge.

ADRB2 is a potential protective gene in breast cancer by regulating tumor immune microenvironment

Background

Breast cancer (BRCA) is the leading cause of cancer death among females. Studies suggested that β-adrenoceptors involved in tumor progression by regulating immune system. However, how ADRB2 affects the immune infiltration in BRCA is still being unraveled.

Methods

Expressions of ADRB2 in multiple tissues, cancers and blood cells were analyzed by using the Human Protein Atlas and UALCAN database. Expression differentiation of ADRB2 in tumor microenvironment (TME) of BRCA was detected in TISCH database. Correlations between ADRB2 and immune cell infiltration were analyzed by TIMER 2.0, and co-expression genes of ADRB2 were obtained from the cBioPortal website. Functional enrichment analyses and protein-protein interactions were constructed as well. Finally, the potential mechanisms of ADRB2 and candidate drugs targeting BRCA were discussed by using the Metascape, STITCH and Cmap tools.

Results

ADRB2 was significantly down-regulated in BRCA, and lower ADRB2 expression often resulted in worse prognosis in BRCA patients. ADRB2 was mainly expressed in breast tissue and blood. Among blood cell subtypes and TME of BRCA, ADRB2 was specifically expressed in T cell subtypes. Also, ADRB2 expression level was positively correlated with the infiltration levels of immune cells such as CD4+ T cell, CD8+ T cell, Tγδ and myeloid DC while negatively correlated with Treg, Tfh and myeloid-derived suppressor cell. Furthermore, functional enrichment analyses revealed that most enriched pathways were immune-related, especially in T cell-related pathways. Also, transcription factors (TFs) analyses showed that most downstream TFs regulated by ADRB2 were immune-related, and most candidate drugs had promising anti-tumor effects.

Conclusions

In conclusion, ADRB2 was a potential protective gene in BRCA, and it might play a vital role in regulating immune responses. The expression level of ADRB2 was positively correlated with immune cells infiltration in BRCA, especially for T cells. Therefore, ADRB2 would be a target for boosting immunotherapy effects in BRCA.

Micellar paclitaxel boosts ICD and chemo-immunotherapy of metastatic triple negative breast cancer

Triple negative breast cancer (TNBC) with easy metastasis, "cold" tumor immune microenvironment, and lack of targeted therapy remains poorly prognosed. Chemo-immunotherapy deemed as a potential treatment for TNBC is however confronted by low TNBC selectivity, pronounced systemic toxicity, and limited immunogenic cell death (ICD) induction. Here, employing clinically validated ATN peptide as a ligand and reduction-sensitive biodegradable micelles as a vehicle we constructed α₅β₁ integrin-targeted micellar paclitaxel (ATN-MPTX) to elicit strong and selective ICD and chemo-immunotherapy of TNBC. ATN-MPTX exhibited evident targetability and prominent uptake in α₅β₁ integrin-positive 4 T1 cells and induced significantly stronger ICD than free PTX and non-targeted MPTX. The therapeutic studies in 4 T1 TNBC model demonstrated that ATN-MPTX caused superior tumor accumulation and treatment efficacy to all controls. Of note, ATN-MPTX plus nano-STING agonist further augmented the immunotherapeutic effects by increasing secretion of proinflammatory cytokines and CD4⁺ and CD8⁺ T cells in the tumor and spleen while reducing T_reg, leading to significantly improved inhibition of 4 T1 primary tumor and more interestingly mitigated lung metastases. This strong and selective ICD induction of ATN-MPTX renders it an interesting tool to enhance chemo-immunotherapy of TNBC.

Clinical considerations of CDK4/6 inhibitors in triple-negative breast cancer

The formation of cyclinD-CDK4/6 complex plays vital roles in the cell cycle transition from G1 phase to S phase which is characterized by vigorous transcription and synthesis. Through cyclinD-CDK4/6-Rb axis, CDK4/6 inhibitors arrest the cell cycle in the G1 phase and block the proliferation of aggressive cells, exhibiting promising effects in containing the aggressiveness of breast cancers. To date, there are three CDK4/6 inhibitors approved by the U.S. Food and Drug Administration in treating advanced hormone receptor-positive breast cancer, including palbociclib, abemaciclib, and ribociclib. In fact, several preclinical experiments and clinical trials presented therapeutic effects of CDK4/6 inhibitor-based treatment in triple-negative breast cancer.

Tumour-infiltrating lymphocytes in non-invasive breast cancer: A systematic review and meta-analysis

Background

The role of tumour infiltrating lymphocytes (TILs) as a biomarker in non-invasive breast cancer is unclear. This meta-analysis assessed the prognostic impact of TIL levels in patients with non-invasive breast cancer.

Methods

Systematic literature search was performed to identify studies assessing local recurrence in patients with non-invasive breast cancer according to TIL levels (high vs. low). Subgroup analyses per local recurrence (invasive and non-invasive) were performed. Secondary objectives were the association between TIL levels and non-invasive breast cancer subtypes, age, grade and necrosis. Odds ratios (ORs) and 95% confidence intervals (CI) were extracted from each study and a pooled analysis was conducted with random-effect model.

Results

Seven studies (N = 3437) were included in the present meta-analysis. High-TILs were associated with a higher likelihood of local recurrence (invasive or non-invasive, N = 2941; OR 2.05; 95%CI, 1.03–4.08; p = 0.042), although with a lower likelihood of invasive local recurrence (N = 1722; OR 0.69; 95%CI, 0.49–0.99; p = 0.042). High-TIL levels were associated with triple-negative (OR 3.84; 95%CI, 2.23–6.61; p < 0.001) and HER2-positive (OR 6.27; 95%CI, 4.93–7.97; p < 0.001) subtypes, high grade (OR 5.15; 95%CI, 3.69–7.19; p < 0.001) and necrosis (OR 3.09; 95%CI, 2.33–4.10; p < 0.001).

Conclusions

High-TIL levels were associated with more aggressive tumours, a higher likelihood of local recurrence (invasive or non-invasive) but a lower likelihood of invasive local recurrence in patients with non-invasive breast cancer.

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The prognostic role of TILs in non-invasive breast cancer is unknown.

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We observed an association between high-TILs and local recurrence.

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High-TILs were associated with triple-negative and HER2+ subtypes, high grade and necrosis.

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Non-invasive lesions with aggressive characteristics may also be more immunogenic.

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Patients with low-TILs showed a higher likelihood of presenting an invasive recurrence.

VISTA: A Promising Target for Cancer Immunotherapy?

Agents targeting the B7 family co-inhibitory receptors cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed cell death protein-1 (PD-1), or its ligand (PD-L1), have a pivotal role in clinical practice. V-domain Ig suppressor of T-cell activation (VISTA) is a protein highly conserved between species, with a similar amino acid sequence to the B7 family members, characterized by a particularly structural homology to PD-1. It has been counted as an emerging target within the list of novel targetable immune checkpoints in oncology. Physiologically, VISTA exerts a regulatory function on the immune system at several levels, particularly by modulating T cells activation. Its altered activity plays a role in many autoimmune diseases, and its expression has been found to be prognostically implicated in different cancer types in preclinical models. We hereby present the main evidence on the value of VISTA as an immune checkpoint in solid and hematological malignancies. We also review its value as a potential target for cancer immunotherapy, by reporting the results of Phase I and II clinical trials assessing the use of drugs targeting VISTA. The complexity of its pathway, along with some unclear biological aspects concerning its molecular interactions, currently represent a limit to the applicability of VISTA as an effective biomarker for immunotherapy in oncology. A deeper characterization of this immune checkpoint may help defining its value within immune signatures of solid and hematological malignancies, and to design future therapeutic strategies.