Understanding Patterns of Brain Metastasis in Triple-Negative Breast Cancer and Exploring Potential Therapeutic Targets

CD-44 targeted nanoparticles for combination therapy in an in vitro model of triple-negative breast cancer: Targeting the tumour inside out

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer defined by the lack of three key receptors: estrogen, progesterone, and HER2. This lack of receptors makes TNBC difficult to treat with hormone therapy or drugs, and so it is characterised by a poor prognosis compared to other kinds of breast cancer. This study explores photoactive Poly(lactic-co-glycolic acid) (PLGA) nanoparticles as a potential therapeutic strategy for TNBC. The nanoparticles are functionalised with hyaluronic acid (HA) for targeted delivery to CD-44 receptors overexpressed in TNBC cells, especially under hypoxic conditions. Additionally, we co-loaded the nanoparticles with Doxorubicin (Dox) and Indocyanine Green (ICG) to enable combinatorial chemo-photothermal therapy. After carefully optimising the formulation, we propose an effortless and reproducible preparation of the nanodrugs. We demonstrate that HA-conjugated nanoparticles effectively target TNBC cells and inhibit their proliferation while the treatment efficiency is enhanced during near-infrared light irradiation. We also prove that our treatment is effective in a 3D cell culture model, highlighting the importance of tumour architecture and the metabolic stage of the cells in the tumour microenvironment. This approach is promising for a tumour-targeted theragnostic for TNBC with improved efficacy in hypoxic microenvironments.

Mucin 5AC Promotes Breast Cancer Brain Metastasis through cMET/CD44v6

PURPOSE

Breast cancer brain metastasis remains a significant clinical problem. Mucins have been implicated in metastasis; however, whether they are also involved in breast cancer brain metastasis remains unknown. We queried databases of patients with brain metastasis and found mucin 5AC (MUC5AC) to be upregulated and therefore sought to define the role of MUC5AC in breast cancer brain metastasis.

EXPERIMENTAL DESIGN

In silico dataset analysis, RNA-sequence profiling of patient samples and cell lines, analysis of patient serum samples, and in vitro/in vivo knockdown experiments were performed to determine the function of MUC5AC in breast cancer brain metastasis. Coimmunoprecipitation was used to unravel the interactions that can be therapeutically targeted.

RESULTS

Global in silico transcriptomic analysis showed that MUC5AC is significantly higher in patients with breast cancer brain metastasis. Analysis of archived breast cancer brain metastasis tissue further revealed significantly higher expression of MUC5AC in all breast cancer subtypes, and high MUC5AC expression predicted poor survival in HER2+ breast cancer brain metastasis. We validated these observations in breast cancer brain metastatic cell lines and tissue samples. Interestingly, elevated levels of MUC5AC were detected in the sera of patients with breast cancer brain metastasis. MUC5AC silencing in breast cancer brain metastatic cells reduced their migration and adhesion in vitro and in brain metastasis in the intracardiac injection mouse model. We found high expression of cMET and CD44v6 in breast cancer brain metastasis, which increased MUC5AC expression via hepatocyte growth factor signaling. In addition, MUC5AC interacts with cMET and CD44v6, suggesting that MUC5AC promotes breast cancer brain metastasis via the cMET/CD44v6 axis. Inhibition of the MUC5AC/cMET/CD44v6 axis with the blood-brain barrier-permeable cMET inhibitor bozitinib (PLB1001) effectively inhibits breast cancer brain metastasis.

CONCLUSIONS

Our study establishes that the MUC5AC/cMET/CD44v6 axis is critical for breast cancer brain metastasis, and blocking this axis will be a novel therapeutic approach for breast cancer brain metastasis.

Association Between Human Epidermal Growth Factor Receptor 2-Low Status and Time to Development of Brain Metastases Among Patients With Breast Cancer: A Retrospective Cohort Study

PURPOSE

Human epidermal growth factor receptor 2 (HER2)-low is a newly defined subgroup of HER2-negative breast cancer. It is unknown whether HER2-low status is associated with brain metastases (BrM) development. We aimed to determine the association between HER2-low status and the time to developing BrM.

METHODS

HER2 status was determined in a cohort of 689 women with metastatic breast cancer (MBC) who underwent treatment for BrM at Sunnybrook Odette Cancer Centre from 2008 to 2018. In patients with primary breast cancer (PBC) HER2 subclassification available (subgroup 1), we investigated time from PBC diagnosis to BrM diagnosis (PBC-time to brain metastases [TTBM]). In patients with HER2 subclassification available in any tissue (subgroup 2), we investigated time from MBC diagnosis to BrM diagnosis (MBC-TTBM).

RESULTS

In subgroup 1 (n = 175), patients with HER2-low disease (n = 42) had a shorter PBC-TTBM compared with those with HER2-zero disease (n = 77; hazard ratio, 2.4; P = .0003). When stratified by hormone receptor (HR) status, this observation held true in the HR+/HER2- population, but not in the triple-negative breast cancer (TNBC) population. In subgroup 2 (n = 279), patients with HER2-low disease (n = 53) had a shorter MBC-TTBM compared to those with HER2-zero disease (n = 44) in the HR+/HER2- population (hazard ratio, 1.55; P = .036); however, this did not hold true in the TNBC population. Likelihood ratio test revealed significant interaction between HER2 and HR status in subgroup 2 (P = .016), but not subgroup 1 (P = .21).

CONCLUSION

Our findings suggest that among patients with HR+ breast cancer, HER2-low status was associated with shorter TTBM compared with HER2-zero status. In a subset of patients for whom HER2 status of the PBC was available, HER2-low status was associated with shorter PBC-TTBM, irrespective of HR status. This study suggests a previously unrecognized association between HER2-low status and timing of BrM development.

A review of six bioactive compounds from preclinical studies as potential breast cancer inhibitors

Breast cancer is one of the predominant causes of mortality in women worldwide. Although therapeutics such as surgery, chemotherapy, hormonal therapy, and radiotherapy have been used, they are associated with adverse effects or multidrug resistance. The use of natural compounds is a promising strategy, owing to their abundance and medicinal value. This review focuses on six natural compounds, namely cinnamaldehyde, diosmin, taxifolin, phloretin, arctigenin, and eugenol, and details their mechanisms of breast cancer inhibition based on in vitro and in vivo studies. These compounds generally promote apoptosis and cell cycle arrest, hinder metastasis and invasion, and decrease tumor growth. This review reinforces the use of natural compounds as therapeutics for breast cancer from their preclinical studies. These compounds might be promising for drug development due to their abundance, high reliability, and safety.

Acetalax and Bisacodyl for the Treatment of Triple-Negative Breast Cancer: A Combined Molecular and Preclinical Study

SIGNIFICANCE

Acetalax and bisacodyl represent a prospective novel drug mechanism-of-action type, affect mitochondrial function and affect tumor growth in vivo. Their activity may be predicted by TRPM4 but with more accuracy adding other genes in multivariate analysis for triple negative breast cancer (TNBC). Acetalax has a biphasic mean half-life of 5.8 hours.

Proton pump inhibitor attenuates acidic microenvironment to improve the therapeutic effects of MSLN-CAR-T cells on the brain metastasis

The incidence of brain metastasis (BM) is gradually increasing, and the prognosis and therapeutic effect are poor. The emergence of immunotherapy has brought hope for the development of BM treatments. This study revealed that compared with primary cancers, BMs have a colder and more acidic tumor microenvironment (TME), resulting in reduced protein levels of mesothelin (MSLN), a promising target for chimeric antigen receptor-T (CAR-T) cell therapy for triple-negative breast cancer (TNBC) with BMs. These factors could significantly decrease the efficiency of MSLN-CAR-T cells in TNBC BMs. Pantoprazole (PPZ) administration at the most commonly used dose in the clinic notably increased the pH of the TME, inhibited lysosomal activity, increased the membrane levels of the MSLN protein and improved the killing ability of MSLN-CAR-T cells both in vitro and in vivo. Similar results were obtained in non-small cell lung cancer BMs. Hence, when administered in combination with CAR-T cells, PPZ, which increases the protein levels of target antigens, may constitute a new immunotherapeutic strategy for treating solid tumors with BMs.

Breast Cancer-Derived Extracellular Vesicles Modulate the Cytoplasmic and Cytoskeletal Dynamics of Blood-Brain Barrier Endothelial Cells

Extracellular vesicles (EVs) from brain-seeking breast cancer cells (Br-EVs) breach the blood-brain barrier (BBB) via transcytosis and promote brain metastasis. Here, we defined the mechanisms by which Br-EVs modulate brain endothelial cell (BEC) dynamics to facilitate their BBB transcytosis. BEC treated with Br-EVs show significant downregulation of Rab11fip2, known to promote vesicle recycling to the plasma membrane and significant upregulation of Rab11fip3 and Rab11fip5, which support structural stability of the endosomal compartment and facilitate vesicle recycling and transcytosis, respectively. Using machine learning and quantitative global proteomic, we identified novel Br-EV-induced changes in BECs morphology, motility, and proteome that correlate with decreased BEC cytoplasm and cytoskeletal organization and dynamics. These results define early steps leading to breast-to-brain metastasis and identify molecules that could serve as targets for therapeutic strategies for brain metastasis.

Self-propelling, protein-bound magnetic nanobots for efficient in vitro drug delivery in triple negative breast cancer cells

The emergence of self-propelling magnetic nanobots represents a significant advancement in the field of drug delivery. These magneto-nanobots offer precise control over drug targeting and possess the capability to navigate deep into tumor tissues, thereby addressing multiple challenges associated with conventional cancer therapies. Here, Fe-GSH-Protein-Dox, a novel self-propelling magnetic nanobot conjugated with a biocompatible protein surface and loaded with doxorubicin for the treatment of triple-negative breast cancer (TNBC), is reported. The self-propulsion of magnetic nanobots occurs due to a catalytic interaction between Fe3O4 nanoparticles and hydrogen peroxide. This interaction results in generation of O2 bubbles and high-speed propulsion in blood serum. Cell entry kinetic studies confirmed higher internalization of the drug into TNBC cells with Fe-GSH-Protein-Dox nanobots, resulting in a lower observed IC50 and higher potential to kill cancer cells compared to free doxorubicin. Moreover, fluorescence imaging studies confirmed an increase in the production of reactive oxygen species, leading to maximum cellular damage. Endocytosis studies elucidate the mechanism of cellular internalization, revealing clathrin-mediated endocytosis, while the cell cycle study demonstrates significant cell cycle arrest in the G2-M phase. Thus, the designed protein-conjugated self-propelling magnetic nanobots have the potential to develop into a novel drug delivery platform for clinical applications.

Current Evidence in the Systemic Treatment of Brain Metastases from Breast Cancer and Future Perspectives on New Drugs, Combinations and Administration Routes: A Narrative Review

Breast cancer is the most frequently diagnosed neoplasm all over the world and the second leading cause of cancer death in women. Breast cancer prognosis has significantly improved in the last years due to the advent of novel therapeutic options, both in the early and in advanced stages. However, the spread of the disease to the brain, accounting for 15-30% of the metastatic diagnoses, is challenging, and its poor prognosis represents an unmet medical need, leading to deterioration of quality of life and causing morbidity and mortality. Generally, triple-negative and HER2-positive breast cancer subtypes more frequently spread to the brain or in the leptomeningeal space. Consequently, according to international guidelines, several systemic treatments can be offered as a first option in some subsets of patients. However, a multidisciplinary approach is recommended to offer the most appropriate strategy to patients. Antibody-drug conjugates such as trastuzumab deruxtecan or sacituzumab govitecan along with small molecules have led to important achievements in the treatment of brain metastases from HER2-positive and triple-negative breast cancer. In this narrative review, we will focus on the molecular features leading to the development of brain metastases and explore the risk and the prognostic factors involved in the development of brain metastases. Finally, we will review the major achievements in the treatment landscape of brain metastases from breast cancer and novel medical approaches.

CRISPR/Cas9-mediated knockout strategies for enhancing immunotherapy in breast cancer

Breast cancer, a prevalent disease with significant mortality rates, often presents treatment challenges due to its complex genetic makeup. This review explores the potential of combining Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene knockout strategies with immunotherapeutic approaches to enhance breast cancer treatment. The CRISPR/Cas9 system, renowned for its precision in inducing genetic alterations, can target and eliminate specific cancer cells, thereby minimizing off-target effects. Concurrently, immunotherapy, which leverages the immune system's power to combat cancer, has shown promise in treating breast cancer. By integrating these two strategies, we can potentially augment the effectiveness of immunotherapies by knocking out genes that enable cancer cells to evade the immune system. However, safety considerations, such as off-target effects and immune responses, necessitate careful evaluation. Current research endeavors aim to optimize these strategies and ascertain the most effective methods to stimulate the immune response. This review provides novel insights into the integration of CRISPR/Cas9-mediated knockout strategies and immunotherapy, a promising avenue that could revolutionize breast cancer treatment as our understanding of the immune system's interplay with cancer deepens.

Application of Carbon Nanomaterials to Enhancing Tumor Immunotherapy: Current Advances and Prospects

Recent advances in tumor immunotherapy have highlighted the pivotal role of carbon nanomaterials, such as carbon dots, graphene quantum dots, and carbon nanotubes. This review examines the unique benefits of these materials in cancer treatment, focusing on their mechanisms of action within immunotherapy. These include applications in immunoregulation, recognition, and enhancement. We explore how these nanomaterials when combined with specific biomolecules, can form immunosensors. These sensors are engineered for highly sensitive and specific detection of tumor markers, offering crucial support for early diagnosis and timely therapeutic interventions. This review also addresses significant challenges facing carbon nanomaterials in clinical settings, such as issues related to long-term biocompatibility and the hurdles of clinical translation. These challenges require extensive ongoing research and discussion. This review is of both theoretical and practical importance, aiming to promote using carbon nanomaterials in tumor immunotherapy, potentially transforming clinical outcomes and enhancing patient care.

Breast Tumor Cell Survival and Morphology in a Brain-like Extracellular Matrix Depends on Matrix Composition and Mechanical Properties

Triple-negative breast cancer (TNBC) is the most invasive type of breast cancer with high risk of brain metastasis. To better understand interactions between breast tumors with the brain extracellular matrix (ECM), a 3D cell culture model is implemented using a thiolated hyaluronic acid (HA-SH) based hydrogel. The latter is used as HA represents a major component of brain ECM. Melt-electrowritten (MEW) scaffolds of box- and triangular-shaped polycaprolactone (PCL) micro-fibers for hydrogel reinforcement are utilized. Two different molecular weight HA-SH materials (230 and 420 kDa) are used with elastic moduli of 148 ± 34 Pa (soft) and 1274 ± 440 Pa (stiff). Both hydrogels demonstrate similar porosities. The different molecular weight of HA-SH, however, significantly changes mechanical properties, e.g., stiffness, nonlinearity, and hysteresis. The breast tumor cell line MDA-MB-231 forms mainly multicellular aggregates in both HA-SH hydrogels but sustains high viability (75%). Supplementation of HA-SH hydrogels with ECM components does not affect gene expression but improves cell viability and impacts cellular distribution and morphology. The presence of other brain cell types further support numerous cell-cell interactions with tumor cells. In summary, the present 3D cell culture model represents a novel tool establishing a disease cell culture model in a systematic way.

Demographic and clinical characteristics of patients with metastatic breast cancer and leptomeningeal disease: a single center retrospective cohort study

PURPOSE

Leptomeningeal disease (LMD) is a devastating complication of metastatic breast cancer (MBC). It is critical to better understand the risk factors, natural history, and treatment outcomes, including patients in a modern cohort.

METHODS

In this single center retrospective cohort study, we identified patients with MBC and LMD who received care from 2000 to 2024 and abstracted key clinical, treatment, and survival data.

RESULTS

We identified 111 patients with MBC and LMD, including patients with the following subtypes: HR+/HER2- (n = 53, 47.7%), HER2+ (n = 30, 27.0%), and triple negative breast cancer (TNBC; n = 28, 25.2%). Median time from the diagnosis of MBC to LMD was 16.4 months (range 0-101.3 months). After the diagnosis of LMD, most patients received systemic therapy (n = 66, 59.5%) and/or central nervous system (CNS)-directed therapy (n = 94, 84.7%) including intrathecal therapy (n = 42, 37.8%) and/or CNS-directed radiation therapy (n = 70, 63.1%). In all patients, median overall survival (OS) from the diagnosis of LMD to death was 4.1 months (range 0.1-78.1 months) and varied by subtype, with HR+/HER2- or HER2+ MBC patients living longer than those with TNBC (4.2 and 6.8 months respectively vs. 2.0 months, p < 0.01, HR 2.15, 95% CI 1.36-3.39). Patients who received CNS-directed therapy lived longer than those who did not (4.2 vs. 1.3, p = 0.02 HR 0.54, 0.32-0.91). Patients diagnosed with LMD from 2015 to 2024 lived longer than those diagnosed from 2000 to 2014 (6.4 vs. 2.9 months, p = 0.04, HR 0.67, 95% CI 0.46-0.99). On multivariable analysis, having TNBC was associated with shorter OS from time of LMD to death (p = 0.004, HR 2.03, 95% CI 1.25-3.30).

CONCLUSION

This is one of the largest case series of patients with MBC and LMD. Patients diagnosed with LMD from 2015 to 2024 lived longer than those diagnosed from 2000 to 2014, although median OS was short overall. Patients with TNBC and LMD had particularly short OS. Novel therapeutic strategies for LMD remain an area of unmet clinical need.

Risk factors and prognostic factors of brain metastasis of triple-negative breast cancer: A single-center retrospective study

OBJECTIVE

This retrospective study is to explore the risk factors and prognostic factors of brain metastases of triple-negative breast cancer (TNBC) in a single center.

METHODS

Clinical data of patients with stages I-III TNBC were collected. The Kaplan-Meier method, log-rank test, and stepwise COX regression were performed.

RESULTS

The 437 patients with stages I-III TNBC were followed up for five years. Among them, 89 cases (20.4%) developed brain metastases, and they were followed up for 2 years after brain metastasis. The cumulative brain metastasis rates of TNBC patients at six months, one year, two years, three years, and five years were 1.38%, 5.75%, 12.94%, 17.63%, and 21.26%, respectively. Multivariate analysis suggested that the first diagnosis age ≤35 years old, advanced pathological stage, lymph node metastasis, and Ki-67 ≥30% represented the risk factors for brain metastasis. In contrast, the surgical method was a protective factor for brain metastasis. The median survival time after brain metastasis was 4.87 months. The survival rates at one, three, six, 12, and 24 months were 84.27%, 60.67%, 34.83%, 15.69%, and 6.64%, respectively. The age >60 years at first diagnosis, Ki-67 ≥30%, local recurrence, and distant metastasis were closely related to the poor prognosis of TNBC patients with brain metastases, while radiotherapy alone, systemic therapy, and combined chemotherapy and radiotherapy represented the prognostic protective factors.

CONCLUSIONS

Patient age, Ki-67 level, metastasis, and treatment methods are the risk factors and prognostic factors for brain metastasis of TNBC. Surgical resection of the primary lesion during the first treatment is essential to reduce the incidence of brain metastases. Close postoperative follow-up (such as brain magnetic resonance imaging [MRI]) within 2-3 years after surgery is recommended to improve the prognosis.

Impact of brain organoid-derived sEVs on metastatic adaptation and invasion of breast carcinoma cells through a microphysiological system

Brain metastases are common in triple-negative breast cancer (TNBC), suggesting a complex process of cancer spread. The mechanisms enabling TNBC cell adaptation and proliferation in the brain remain unclear. Small extracellular vesicles (sEVs) play a crucial role in communication between breast carcinoma cells and the brain. However, the lack of relevant models hinders understanding of sEV-mediated communication. The present study assesses the impact of brain organoid-derived sEVs (BO-sEVs) on various behaviours of the MDA-MB-231 cell line, chosen as a representative of TNBC in a 3D microfluidic model. Our results demonstrate that 150-200 nm sEVs expressing CD63, CD9, and CD81 from brain organoid media decrease MDA-MB-231 cell proliferation, enhance their wound-healing capacity, alter their morphology into more mesenchymal mode, and increase their stemness. BO-sEVs led to heightened PD-L1, CD49f, and vimentin levels of expression in MDA-MB-231 cells, suggesting an amplified immunosuppressive, stem-like, and mesenchymal phenotype. Furthermore, these sEVs also induced the expression of neural markers such as GFAP in carcinoma cells. The cytokine antibody profiling array also showed that BO-sEVs enhanced the secretion of MCP-1, IL-6, and IL-8 by MDA-MB-231 cells. Moreover, sEVs significantly enhance the migration and invasion of carcinoma cells toward brain organoids in a 3D organoid-on-a-chip system. Our findings emphasize the potential significance of metastatic site-derived sEVs as pivotal mediators in carcinoma progression and adaptation to the brain microenvironment, thereby unveiling novel therapeutic avenues.

The use of a selective, nontoxic dual-acting peptide for breast cancer patients with brain metastasis

Triple-negative breast cancer (TNBC) is an aggressive subtype characterized by the absence of commonly targeted receptors. Unspecific chemotherapy is currently the main therapeutic option, with poor results. Another major challenge is the frequent appearance of brain metastasis (BM) associated with a significant decrease in patient overall survival. The treatment of BM is even more challenging due to the presence of the blood-brain barrier (BBB). Here, we present a dual-acting peptide (PepH3-vCPP2319) designed to tackle TNBC/BM, in which a TNBC-specific anticancer peptide (ACP) motif (vCPP2319) is joined to a BBB peptide shuttle (BBBpS) motif (PepH3). PepH3-vCPP2319 demonstrated selectivity and efficiency in eliminating TNBC both in monolayers (IC50≈5.0 µM) and in spheroids (IC50≈25.0 µM), with no stringent toxicity toward noncancerous cell lines and red blood cells (RBCs). PepH3-vCPP2319 was also able to cross the BBB in vitro and penetrate the brain in vivo, and was stable in serum with a half-life above 120 min. Tumor cell-peptide interaction is fast, with quick peptide internalization via clathrin-mediated endocytosis without membrane disruption. Upon internalization, the peptide is detected in the nucleus and the cytoplasm, indicating a multi-targeted mechanism of action that ultimately induces irreversible cell damage and apoptosis. In conclusion, we have designed a dual-acting peptide capable of brain penetration and TNBC cell elimination, thus expanding the drug arsenal to fight this BC subtype and its BM.

GLUT and HK: Two primary and essential key players in tumor glycolysis

Cancer cells reprogram their metabolism to become "glycolysis-dominant," which enables them to meet their energy and macromolecule needs and enhancing their rate of survival. This glycolytic-dominancy is known as the "Warburg effect", a significant factor in the growth and invasion of malignant tumors. Many studies confirmed that members of the GLUT family, specifically HK-II from the HK family play a pivotal role in the Warburg effect, and are closely associated with glucose transportation followed by glucose metabolism in cancer cells. Overexpression of GLUTs and HK-II correlates with aggressive tumor behaviour and tumor microenvironment making them attractive therapeutic targets. Several studies have proven that the regulation of GLUTs and HK-II expression improves the treatment outcome for various tumors. Therefore, small molecule inhibitors targeting GLUT and HK-II show promise in sensitizing cancer cells to treatment, either alone or in combination with existing therapies including chemotherapy, radiotherapy, immunotherapy, and photodynamic therapy. Despite existing therapies, viable methods to target the glycolysis of cancer cells are currently lacking to increase the effectiveness of cancer treatment. This review explores the current understanding of GLUT and HK-II in cancer metabolism, recent inhibitor developments, and strategies for future drug development, offering insights into improving cancer treatment efficacy.

Improved outcomes for triple negative breast cancer brain metastases patients after stereotactic radiosurgery and new systemic approaches

PURPOSE

Although ongoing studies are assessing the efficacy of new systemic therapies for patients with triple negative breast cancer (TNBC), the overwhelming majority have excluded patients with brain metastases (BM). Therefore, we aim to characterize systemic therapies and outcomes in a cohort of patients with TNBC and BM managed with stereotactic radiosurgery (SRS) and delineate predictors of increased survival.

METHODS

We used our prospective patient registry to evaluate data from 2012 to 2023. We included patients who received SRS for TNBC-BM. A competing risk analysis was conducted to assess local and distant control.

RESULTS

Forty-three patients with 262 tumors were included. The median overall survival (OS) was 16 months (95% CI 13-19 months). Predictors of increased OS after initial SRS include Breast GPA score > 1 (p < 0.001) and use of immunotherapy such as pembrolizumab (p = 0.011). The median time on immunotherapy was 8 months (IQR 4.4, 11.2). The median time to new CNS lesions after the first SRS treatment was 17 months (95% CI 12-22). The cumulative rate for development of new CNS metastases after initial SRS at 6 months, 1 year, and 2 years was 23%, 40%, and 70%, respectively. Thirty patients (70%) underwent multiple SRS treatments, with a median time of 5 months (95% CI 0.59-9.4 months) for the appearance of new CNS metastases after second SRS treatment.

CONCLUSIONS

TNBC patients with BM can achieve longer survival than might have been previously anticipated with median survival now surpassing one year. The use of immunotherapy is associated with increased median OS of 23 months.

Synthesis and mechanism of action of new purine derivatives against triple negative breast cancer

Triple negative breast cancer (TNBC) is considered to be the most difficult subtype of breast cancer to treat because of its extremely prone to metastasis and the lack of targeted therapy drugs. New purine derivatives were synthesized and evaluated in a series of kinases and cell lines. The most active compounds 3g and 3j were selected based on their antiproliferative activities, then their pharmaceutical activity and mechanism in MDA-MB-231 cells were analyzed. The results in vitro indicated that compounds 3g and 3j can induce MDA-MB-231 cells apoptosis, and inhibit its migration and angiogenesis through influencing protein expression such as Bcl-2, Bax, Bcl-xl, P38, MMP2, MMP9, AKT and EGFR. In vivo results indicate that compounds 3g and 3j can inhibit tumor growth and metastasis and reduce the expression of Ki67 and CD31 protein in TNBC xenograft models. These findings not only broaden our understanding of the anti-TNBC effects and mechanisms of compounds 3g and 3j, but also provide new ideas and reference directions for the treatment of TNBC.

Brain metastasis in de novo stage IV breast cancer

OBJECTIVES

Information of brain metastasis (BM) in de novo stage IV breast cancer is lacking, which is an unavoidable problem and dilemma in practice. Understanding the current situation is helpful for the clinical cognition and decision-making.

METHODS

We retrospectively analyzed the clinical and survival information of de novo stage IV breast cancer with BM between 2015 and 2019 from the Surveillance, Epidemiology, and End Results (SEER) database. Multivariable logistic and Cox regression analyses were performed to identify predictors of BM and factors associated with all-cause mortality in de novo stage IV breast cancer, respectively. Overall survival (OS) was calculated using Kaplan-Meier and log-rank tests.

RESULTS

Our cohort consisted of 1366 patients with BM in de novo stage IV breast cancer, with an incidence of 8.38% in patients with metastatic disease to any distant site. Incidence was highest among patients with metastatic disease with HR-HER2+ (12.95%) and HR-HER2- (13.40%) subtypes. The higher the number of extracranial metastases, the higher the BM incidence. The median OS was 12.0 (95%CI: 10.426-13.574) months in BM group; it was longest in HR + HER2+ (19.0[95%CI: 11.793-26.207] months), and shortest in HR-HER2- (7.0 [95%CI:5.354-8.646] months). Marital status, subtype, and abundance of metastatic sites influenced morbidity and OS of BM in de novo stage IV breast cancer.

CONCLUSIONS

Population-based estimates of the incidence and prognosis for patients with BM in de novo stage IV breast cancer were closely associated with subtype and metastatic burden. These findings may be helpful in developing diagnostic strategies, especially for brain screening.

Inflammasome activation in peritumoral astrocytes is a key player in breast cancer brain metastasis development

Inflammasomes, primarily responsible for the activation of IL-1β, have emerged as critical regulators of the tumor microenvironment. By using in vivo and in vitro brain metastasis models, as well as human samples to study the role of the NLRP3 inflammasome in triple-negative breast cancer (TNBC) brain metastases, we found NLRP3 inflammasome components and IL-1β to be highly and specifically expressed in peritumoral astrocytes. Soluble factors from TNBC cells induced upregulation and activation of NLRP3 and IL-1β in astrocytes, while astrocyte-derived mediators augmented the proliferation of metastatic cells. In addition, inhibition of NLRP3 inflammasome activity using MCC950 or dampening the downstream effect of IL-1β prevented the proliferation increase in cancer cells. In vivo, MCC950 reduced IL-1β expression in peritumoral astrocytes, as well as the levels of inflammasome components and active IL-1β. Most importantly, significantly retarded growth of brain metastatic tumors was observed in mice treated with MCC950. Overall, astrocytes contribute to TNBC progression in the brain through activation of the NLRP3 inflammasome and consequent IL-1β release. We conclude that pharmacological targeting of inflammasomes may become a novel strategy in controlling brain metastatic diseases.

Abrogating Metastatic Properties of Triple-Negative Breast Cancer Cells by EGFR and PI3K Dual Inhibitors

Triple-negative breast cancer (TNBC) is a devastating BC subtype. Its aggressiveness, allied to the lack of well-defined molecular targets, usually culminates in the appearance of metastases that account for poor prognosis, particularly when they develop in the brain. Nevertheless, TNBC has been associated with epidermal growth factor receptor (EGFR) overexpression, leading to downstream phosphoinositide 3-kinase (PI3K) signaling activation. We aimed to unravel novel drug candidates for TNBC treatment based on EGFR and/or PI3K inhibition. Using a highly metastatic TNBC cell line with brain tropism (MDA-MB-231 Br4) and a library of 27 drug candidates in silico predicted to inhibit EGFR, PI3K, or EGFR plus PI3K, and to cross the blood-brain barrier, we evaluated the effects on cell viability. The half maximal inhibitory concentration (IC50) of the most cytotoxic ones was established, and cell cycle and death, as well as migration and EGFR pathway intervenient, were further evaluated. Two dual inhibitors emerged as the most promising drugs, with the ability to modulate cell cycle, death, migration and proliferation, morphology, and PI3K/AKT cascade players such as myocyte enhancer factor 2C (MEF2C) and forkhead box P1 (FOXP1). This work revealed EGFR/PI3K dual inhibitors as strong candidates to tackle brain metastatic TNBC cells.

Anti-CD47 immunotherapy as a therapeutic strategy for the treatment of breast cancer brain metastasis

The presence of cell surface protein CD47 allows cancer cells to evade innate and adaptive immune surveillance resulting in metastatic spread. CD47 binds to and activates SIRPα on the surface of myeloid cells, inhibiting their phagocytic activity. On the other hand, CD47 binds the matricellular protein Thrombospondin-1, limiting T-cell activation. Thus, blocking CD47 is a potential therapeutic strategy for preventing brain metastasis. To test this hypothesis, breast cancer patient biopsies were stained with antibodies against CD47 to determine differences in protein expression. An anti-CD47 antibody was used in a syngeneic orthotopic triple-negative breast cancer model, and CD47 null mice were used in a breast cancer brain metastasis model by intracardiac injection of the E0771-Br-Luc cell line. Immunohistochemical staining of patient biopsies revealed an 89% increase in CD47 expression in metastatic brain tumors compared to normal adjacent tissue (p ≤ 0.05). Anti-CD47 treatment in mice bearing brain metastatic 4T1br3 orthotopic tumors reduced tumor volume and tumor weight by over 50% compared to control mice (p ≤ 0.05) and increased IBA1 macrophage/microglia marker 5-fold in tumors compared to control (p ≤ 0.05). Additionally, CD47 blockade increased the M1/M2 macrophage ratio in tumors 2.5-fold (p ≤ 0.05). CD47 null mice had an 89% decrease in metastatic brain burden (p ≤ 0.05) compared to control mice in a brain metastasis model. Additionally, RNA sequencing revealed several uniquely expressed genes and significantly enriched genes related to tissue development, cell death, and cell migration tumors treated with anti-CD47 antibodies. Thus, demonstrating that CD47 blockade affects cancer cell and tumor microenvironment signaling to limit metastatic spread and may be an effective therapeutic for triple-negative breast cancer brain metastasis.

Updates on Triple-Negative Breast Cancer in Type 2 Diabetes Mellitus Patients: From Risk Factors to Diagnosis, Biomarkers and Therapy

Triple-negative breast cancer (TNBC) is usually the most malignant and aggressive mammary epithelial tumor characterized by the lack of expression for estrogen receptors and progesterone receptors, and the absence of epidermal growth factor receptor (HER)2 amplification. Corresponding to 15-20% of all breast cancers and well-known by its poor clinical outcome, this negative receptor expression deprives TNBC from targeted therapy and makes its management therapeutically challenging. Type 2 diabetes mellitus (T2DM) is the most common ageing metabolic disorder due to insulin deficiency or resistance resulting in hyperglycemia, hyperinsulinemia, and hyperlipidemia. Due to metabolic and hormonal imbalances, there are many interplays between both chronic disorders leading to increased risk of breast cancer, especially TNBC, diagnosed in T2DM patients. The purpose of this review is to provide up-to-date information related to epidemiology and clinicopathological features, risk factors, diagnosis, biomarkers, and current therapy/clinical trials for TNBC patients with T2DM compared to non-diabetic counterparts. Thus, in-depth investigation of the diabetic complications on TNBC onset, development, and progression and the discovery of biomarkers would improve TNBC management through early diagnosis, tailoring therapy for a better outcome of T2DM patients diagnosed with TNBC.

Molecular signaling network and therapeutic developments in breast cancer brain metastasis

Breast cancer (BC) is one of the most frequently diagnosed cancers in women worldwide. It has surpassed lung cancer as the leading cause of cancer-related death. Breast cancer brain metastasis (BCBM) is becoming a major clinical concern that is commonly associated with ER-ve and HER2+ve subtypes of BC patients. Metastatic lesions in the brain originate when the cancer cells detach from a primary breast tumor and establish metastatic lesions and infiltrate near and distant organs via systemic blood circulation by traversing the BBB. The colonization of BC cells in the brain involves a complex interplay in the tumor microenvironment (TME), metastatic cells, and brain cells like endothelial cells, microglia, and astrocytes. BCBM is a significant cause of morbidity and mortality and presents a challenge to developing successful cancer therapy. In this review, we discuss the molecular mechanism of BCBM and novel therapeutic strategies for patients with brain metastatic BC.

Triple Negative Breast Cancer Treatment Options and Limitations: Future Outlook

Triple negative breast cancer (TNBC) has a negative expression of estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptors (HER2). The survival rate for TNBC is generally worse than other breast cancer subtypes. TNBC treatment has made significant advances, but certain limitations remain. Treatment for TNBC can be challenging since the disease has various molecular subtypes. A variety of treatment options are available, such as chemotherapy, immunotherapy, radiotherapy, and surgery. Chemotherapy is the most common of these options. TNBC is generally treated with systemic chemotherapy using drugs such as anthracyclines and taxanes in neoadjuvant or adjuvant settings. Developing resistance to anticancer drugs and off-target toxicity are the primary hindrances to chemotherapeutic solutions for cancer. It is imperative that researchers, clinicians, and pharmaceutical companies work together to develop effective treatment options for TNBC. Several studies have suggested nanotechnology as a potential solution to the problem of suboptimal TNBC treatment. In this review, we summarized possible treatment options for TNBC, including chemotherapy, immunotherapy, targeted therapy, combination therapy, and nanoparticle-based therapy, and some solutions for the treatment of TNBC in the future. Moreover, we gave general information about TNBC in terms of its characteristics and aggressiveness.

Functionalized liposomes for targeted breast cancer drug delivery

Despite the exceptional progress in breast cancer pathogenesis, prognosis, diagnosis, and treatment strategies, it remains a prominent cause of female mortality worldwide. Additionally, although chemotherapies are effective, they are associated with critical limitations, most notably their lack of specificity resulting in systemic toxicity and the eventual development of multi-drug resistance (MDR) cancer cells. Liposomes have proven to be an invaluable drug delivery system but of the multitudes of liposomal systems developed every year only a few have been approved for clinical use, none of which employ active targeting. In this review, we summarize the most recent strategies in development for actively targeted liposomal drug delivery systems for surface, transmembrane and internal cell receptors, enzymes, direct cell targeting and dual-targeting of breast cancer and breast cancer-associated cells, e.g., cancer stem cells, cells associated with the tumor microenvironment, etc.

High percentage of Cancer Stem cells in metastatic locations: Upregulation of cicBIRC6 in highly metastatic breast Cancer Subline

BACKGROUND

Metastasis is a devastating complication of breast cancer. Cancer relapse and metastasis are associated with cancer stem cells. CicBIRC6 is a circular RNA that is proposed to be involved in the stemness of stem cells. In breast cancer, metastatic tumor cells have higher stem cell properties. In the present study, we evaluate the expression of cicBIRC6 in these cells.

METHODS

After the development of a syngeneic animal model of TNBC, primary breast cancer cells named 4T1T were isolated from the tumor mass. Highly metastatic tumor cells named 4T1B and 4T1L were isolated and expanded from brain metastasis lesions and lungs of cancerous mice respectively. Sphere formation ability in metastatic and primary tumor cells was evaluated separately. The quantitative real-time polymerase chain reaction was performed to analyze the expression of cicBIRC6 in primary and metastatic tumor cells.

RESULTS

Our data revealed that, sphere formation ability among metastatic tumor cells was significantly higher. Surprisingly expression of cicBIRC6 was significantly upregulated in these metastatic tumor cells. In comparison with 4T1T, cicBIRC6 was upregulated 5.7 and 3.5 times in 4T1B and 4T1L respectively.

CONCLUSION

These findings provided important insights regarding the molecular properties of metastatic tumor cells and can be used for designing a targeted therapeutic strategy in combat with these cells.

Tumor Suppressive Role of MicroRNAs in Triple Negative Breast Cancer

Triple-negative breast cancers are highly aggressive, a heterogeneous form of breast cancer with a high re-occurrence rate that further lacks an efficient treatment strategy and prognostic marker. The tumor microenvironment of the disease comprises cancer-associated fibroblasts, cancer stem cells, immunological molecules, epithelial-mesenchymal transition, and a metastatic microenvironment that contributes to disease progression and metastasis to distant sites. Emerging evidence indicated that miRNA clusters would be of clinical utility as they exert an oncogenic or tumor suppressor role in TNBC. The present review article aims to highlight the therapeutic significance of miRNA in targeting the above-mentioned signaling cascades and modulating the intracellular crosstalk in the tumor microenvironment of TNBC. Prognostic implications of miRNAs to depict disease-free survival, distant metastasis-free survival, relapse-free survival, and overall survival outcome were also unveiled.

Silencing TRAIP suppresses cell proliferation and migration/invasion of triple negative breast cancer via RB-E2F signaling and EMT

TRAIP, as a 53 kDa E3 ubiquitin protein ligase, is involved in various cellular processes and closely related to the occurrence and development of tumors. At present, few studies on the relationship between TRAIP and triple negative breast cancer (TNBC) were reported. Bioinformatic analysis and Western blot, immunohistochemistry (IHC), CCK-8, colony formation, flow cytometry, wound healing, Transwell, and dual-luciferase reporter assays were performed, and xenograft mouse models were established to explore the role of TRAIP in TNBC. This study showed that the expression of TRAIP protein was upregulated in TNBC tissues and cell lines. Silencing of TRAIP significantly inhibited the proliferation, migration, and invasion of TNBC cells, whereas opposite results were observed in the TRAIP overexpression. In addition, TRAIP regulated cell proliferation, migration, and invasion through RB-E2F signaling and epithelial mesenchymal transformation (EMT). MiR-590-3p directly targeted the TRAIP 3'-UTR, and its expression were lower in TNBC tissues. Its mimic significantly downregulated the expression of TRAIP and subsequently suppressed cell proliferation, migration, and invasion. Rescue experiments indicated that TRAIP silencing reversed the promotion of miR-590-3p inhibitor on cell proliferation, migration, and invasion. TRAIP overexpression could also reverse the inhibition of miR-590-3p mimic on tumorigenesis. Finally, TRAIP knockdown significantly inhibited tumor growth and metastasis in animal experiments. In conclusion, TRAIP is an oncogene that influences the proliferation, migration, and invasion of TNBC cells through RB-E2F signaling and EMT. Therefore, TRAIP may be a potential therapeutic target for TNBC.

Natural Blockers of PD-1/PD-L1 Interaction for the Immunotherapy of Triple-Negative Breast Cancer-Brain Metastasis

The limited treatment options for triple-negative breast cancer with brain metastasis (TNBC-BM) have left the door of further drug development for these patients wide open. Although immunotherapy via monoclonal antibodies has shown some promising results in several cancers including TNBC, it cannot be considered the most effective treatment for brain metastasis. This is due to the protective role of the blood-brain barrier (BBB) which limits the entrance of most drugs, especially the bulky ones such as antibodies, to the brain. For a drug to traverse the BBB via passive diffusion, various physicochemical properties should be considered. Since natural medicine has been a key inspiration for the development of the majority of current medicines, in this paper, we review several naturally-derived molecules which have the potential for immunotherapy via blocking the interaction of programmed cell death protein-1 (PD-1) and its ligand, PD-L1. The mechanism of action, physicochemical properties and pharmacokinetics of these molecules and their theoretical potential to be used for the treatment of TNBC-BM are discussed.

Characterization of triple negative breast cancer gene expression profiles in Mexican patients

Triple negative breast cancer (TNBC) is an aggressive type of cancer that accounts for ~23% of breast tumors in Mexico. In an attempt to understand in an improved way the behavior of TNBC, throughout the years, gene expression in these tumors has been studied. Lehman et al identified 6 subtypes of gene expression in TNBC with distinct characteristics. In the present study, it was aimed to assess clinical, pathological and prognostic characteristics of TNBC in a Mexican-based cohort. A total of 55 patients diagnosed with TNBC at Mexico's National Institute of Cancer (INCan) were included. Tumor needle biopsy samples were obtained and subjected to microarray analysis. Patients were thus classified into one of the 6 TNBC molecular subtypes. The prognostic, clinical and pathological information of patients was obtained, and differences across molecular subtypes were sought. Out of the 55 included patients, the following subtypes were identified: 9 basal-like-1, 11 basal-like-2 (BSL2), 16 immunomodulatory (IM), 12 mesenchymal, 6 androgen receptor-like and 1 mesenchymal stem-like. Mean follow-up time was 47.1 months. The IM molecular subtype had the best overall survival (OS) (median OS was not reached). BSL2 had the worst OS (15 months). A complete pathologic response to neoadjuvant chemotherapy was obtained more often in the IM subtype (P=0.032). No significant associations were found between any of the clinical or pathological characteristics and the TNBC molecular subtypes. The results obtained from the present study should be considered when seeking to implement a clinical-molecular model for TNBC patient care, particularly in Hispanic-based populations, as they have been frequently underrepresented in clinical studies assessing TNBC molecular subtypes.

Enhanced Therapeutic Effect of Optimized Melittin-dKLA, a Peptide Agent Targeting M2-like Tumor-Associated Macrophages in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is characterized by a high possibility of metastasis. M2-like tumor-associated macrophages (TAMs) are the main components of the tumor microenvironment (TME) and play a key role in TNBC metastasis. Therefore, TAMs may be a potential target for reducing TNBC metastasis. Melittin-dKLA, a peptide composed of fused melittin and pro-apoptotic peptide d(KLAKLAK)2 (dKLA), showed a potent therapeutic effect against cancers by depleting TAMs. However, melittin has a strong adverse hemolytic effect. Hence, we attempted to improve the therapeutic potential of melittin-dKLA by reducing toxicity and increasing stability. Nine truncated melittin fragments were synthesized and examined. Of the nine peptides, the melittin-dKLA8-26 showed the best binding properties to M2 macrophages and discriminated M0/M1/M2. All fragments, except melittin, lost their hemolytic effects. To increase the stability of the peptide, melittin-dKLA8-26 fragment was conjugated with PEGylation at the amino terminus and was named PEG-melittin-dKLA8-26. This final drug candidate was assessed in vivo in a murine TNBC model and showed superior effects on tumor growth, survival rates, and lung metastasis compared with the previously used melittin-dKLA. Taken together, our study showed that the novel PEG-melittin-dKLA8-26 possesses potential as a new drug for treating TNBC and TNBC-mediated metastasis by targeting TAMs.

Enhanced delivery of antibodies across the blood-brain barrier via TEMs with inherent receptor-mediated phagocytosis

BACKGROUND

The near impermeability of the blood-brain barrier (BBB) and the unique neuroimmune environment of the CNS prevents the effective use of antibodies in neurological diseases. Delivery of biotherapeutics to the brain can be enabled through receptor-mediated transcytosis via proteins such as the transferrin receptor, although limitations such as the ability to use Fc-mediated effector function to clear pathogenic targets can introduce safety liabilities. Hence, novel delivery approaches with alternative clearance mechanisms are warranted.

METHODS

Binders that optimized transport across the BBB, known as transcytosis-enabling modules (TEMs), were identified using a combination of antibody discovery techniques and pharmacokinetic analyses. Functional activity of TEMs were subsequently evaluated by imaging for the ability of myeloid cells to phagocytose target proteins and cells.

FINDINGS

We demonstrated significantly enhanced brain exposure of therapeutic antibodies using optimal transferrin receptor or CD98 TEMs. We found that these modules also mediated efficient clearance of tau aggregates and HER2+ tumor cells via a non-classical phagocytosis mechanism through direct engagement of myeloid cells. This mode of clearance potentially avoids the known drawbacks of FcγR-mediated antibody mechanisms in the brain such as the neurotoxic release of proinflammatory cytokines and immune cell exhaustion.

CONCLUSIONS

Our study reports a new brain delivery platform that harnesses receptor-mediated transcytosis to maximize brain uptake and uses a non-classical phagocytosis mechanism to efficiently clear pathologic proteins and cells. We believe these findings will transform therapeutic approaches to treat CNS diseases.

FUNDING

This research was funded by Janssen, Pharmaceutical Companies of Johnson & Johnson.

New Achievements for the Treatment of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) constitutes a heterogeneous group of malignancies that are often aggressive and associated with a poor prognosis. The development of new TNBC treatment strategies has become an urgent clinical need. Diagnosis and subtyping of TNBC are essential to establish alternative treatments and targeted therapies for every TNBC patient. Chemotherapy, particularly with anthracycline and taxanes, remains the backbone for medical management for both early and metastatic TNBC. More recently, immune checkpoint inhibitors and targeted therapy have revolutionized cancer treatment. Included in the different strategies studied for TNBC treatment is drug repurposing. Despite the numerous medications available, numerous studies in medicinal chemistry are still aimed at the synthesis of new compounds in order to find new antiproliferative agents capable of treating TNBC. Additionally, some supplemental micronutrients, nutraceuticals and functional foods can potentially reduce the risk of developing cancer or can retard the rate of growth and metastases of established malignant diseases. Finally, nanotechnology in medicine, termed nanomedicines, introduces nanoparticles of variable chemistry and architecture for cancer treatment. This review highlights the most recent studies in search of new therapies for the treatment of TNBC, along with nutraceuticals and repositioning of drugs.

SEOM-GEINO clinical guideline of systemic therapy and management of brain central nervous system metastases (2021)

Central nervous system (CNS) dissemination is a severe complication in cancer and a leading cause of cancer-related mortality. Brain metastases (BMs) are the most common types of malignant intracranial tumors and are reported in approximately 25% of patients with metastatic cancers. The recent increase in incidence of BMs is due to several factors including better diagnostic assessments and the development of improved systemic therapies that have lower activity on the CNS. However, newer systemic therapies are being developed that can cross the blood-brain barrier giving us additional tools to treat BMs. The guidelines presented here focus on the efficacy of new targeted systemic therapies and immunotherapies on CNS BMs from breast, melanoma, and lung cancers.

Glycosylation as a regulator of site-specific metastasis

Metastasis is considered to be responsible for 90% of cancer-related deaths. Although it is clinically evident that metastatic patterns vary by primary tumor type, the molecular mechanisms underlying the site-specific nature of metastasis are an area of active investigation. One mechanism that has emerged as an important player in this process is glycosylation, or the addition of sugar moieties onto protein and lipid substrates. Glycosylation is the most common post-translational modification, occurring on more than 50% of translated proteins. Many of those proteins are either secreted or expressed on the cell membrane, thereby making glycosylation an important mediator of cell-cell interactions, including tumor-microenvironment interactions. It has been recently discovered that alteration of glycosylation patterns influences cancer metastasis, both globally and in a site-specific manner. This review will summarize the current knowledge regarding the role of glycosylation in the tropism of cancer cells for several common metastatic sites, including the bone, lung, brain, and lymph nodes.

Central Nervous System Metastases from Triple-Negative Breast Cancer: Current Treatments and Future Prospective

It is estimated that approximately one-third of patients with triple-negative breast cancer (TNBC) will develop brain metastases. The prognosis for patients with breast cancer brain metastasis has improved in the recent past, especially for hormone receptor and human epidermal growth factor receptor 2 (HER) positive subtypes. However, the overall survival rate for patients with triple-negative subtype remains poor. The development of newer treatment options, including antibody-drug conjugates such as Sacituzumab govitecan, is particularly encouraging. This article reviews the clinical outcomes, challenges, and current approach to the treatment of brain metastasis in TNBC. We have also briefly discussed newer treatment options and ongoing clinical trials. The development of brain metastasis significantly decreases the quality of life of patients with TNBC, and newer treatment strategies and therapeutics are the need of the hour for this disease subgroup.

CXCR2 Mediates Distinct Neutrophil Behavior in Brain Metastatic Breast Tumor

Brain metastasis is one of the main causes of mortality among breast cancer patients, but the origins and the mechanisms that drive this process remain poorly understood. Here, we report that the upregulation of certain CXCR2-associated ligands in the brain metastatic variants of the breast cancer cells (BrM) dynamically activate the corresponding CXCR2 receptors on the neutrophils, thereby resulting in the modulation of certain key functional neutrophil responses towards the BrM. Using established neutrophil-tumor biomimetic co-culture models, we show that the upregulation of CXCR2 increases the recruitment of Tumor-Associated Neutrophils (TANs) towards the BrM, to enable location-favored formation of Neutrophil Extracellular Traps (NETs). Inhibition of CXCR2 using small molecule antagonist AZD5069 reversed this behavior, limiting the neutrophil responses to the BrM and retarding the reciprocal tumor development. We further demonstrate that abrogation of NETs formation using Neutrophil Elastase Inhibitor (NEI) significantly decreases the influx of neutrophils towards BrM but not to their parental tumor, suggesting that CXCR2 activation could be used by the brain metastatic tumors as a mechanism to program the tumor-infiltrating TANs into a pro-NETotic state, so as to assume a unique spatial distribution that assists in the subsequent migration and invasion of the metastatic tumor cells. This new perspective indicates that CXCR2 is a critical target for suppressing neutrophilic inflammation in brain metastasis.

From blood to brain: blood cell-based biomimetic drug delivery systems

Brain drug delivery remains a major difficulty for several challenges including the blood-brain barrier, lesion spot targeting, and stability during circulation. Blood cells including erythrocytes, platelets, and various subpopulations of leukocytes have distinct features such as long-circulation, natural targeting, and chemotaxis. The development of biomimetic drug delivery systems based on blood cells for brain drug delivery is growing fast by using living cells, membrane coating nanotechnology, or cell membrane-derived nanovesicles. Blood cell-based vehicles are superior delivery systems for their engineering feasibility and versatile delivery ability of chemicals, proteins, and all kinds of nanoparticles. Here, we focus on advances of blood cell-based biomimetic carriers for from blood to brain drug delivery and discuss their translational challenges in the future.

Brain and Breast Cancer Cells with PTEN Loss of Function Reveal Enhanced Durotaxis and RHOB Dependent Amoeboid Migration Utilizing 3D Scaffolds and Aligned Microfiber Tracts

BACKGROUND

Glioblastoma multiforme (GBM) and metastatic triple-negative breast cancer (TNBC) with PTEN mutations often lead to brain dissemination with poor patient outcome, thus new therapeutic targets are needed. To understand signaling, controlling the dynamics and mechanics of brain tumor cell migration, we implemented GBM and TNBC cell lines and designed 3D aligned microfibers and scaffolds mimicking brain structures.

METHODS

3D microfibers and scaffolds were printed using melt electrowriting. GBM and TNBC cell lines with opposing PTEN genotypes were analyzed with RHO-ROCK-PTEN inhibitors and PTEN rescue using live-cell imaging. RNA-sequencing and qPCR of tumor cells in 3D with microfibers were performed, while scanning electron microscopy and confocal microscopy addressed cell morphology.

RESULTS

In contrast to the PTEN wildtype, GBM and TNBC cells with PTEN loss of function yielded enhanced durotaxis, topotaxis, adhesion, amoeboid migration on 3D microfibers and significant high RHOB expression. Functional studies concerning RHOB-ROCK-PTEN signaling confirmed the essential role for the above cellular processes.

CONCLUSIONS

This study demonstrates a significant role of the PTEN genotype and RHOB expression for durotaxis, adhesion and migration dependent on 3D. GBM and TNBC cells with PTEN loss of function have an affinity for stiff brain structures promoting metastasis. 3D microfibers represent an important tool to model brain metastasizing tumor cells, where RHO-inhibitors could play an essential role for improved therapy.

A common goal to CARE: Cancer Advocates, Researchers, and Clinicians Explore current treatments and clinical trials for breast cancer brain metastases

Breast cancer is the most commonly diagnosed cancer in women worldwide. Approximately one-tenth of all patients with advanced breast cancer develop brain metastases resulting in an overall survival rate of fewer than 2 years. The challenges lie in developing new approaches to treat, monitor, and prevent breast cancer brain metastasis (BCBM). This review will provide an overview of BCBM from the integrated perspective of clinicians, researchers, and patient advocates. We will summarize the current management of BCBM, including diagnosis, treatment, and monitoring. We will highlight ongoing translational research for BCBM, including clinical trials and improved detection methods that can become the mainstay for BCBM treatment if they demonstrate efficacy. We will discuss preclinical BCBM research that focuses on the intrinsic properties of breast cancer cells and the influence of the brain microenvironment. Finally, we will spotlight emerging studies and future research needs to improve survival outcomes and preserve the quality of life for patients with BCBM.

Glucose Transporters as a Target for Anticancer Therapy

Simple Summary

For mammalian cells, glucose is a major source of energy. In the presence of oxygen, a complete breakdown of glucose generates 36 molecules of ATP from one molecule of glucose. Hypoxia is a hallmark of cancer; therefore, cancer cells prefer the process of glycolysis, which generates only two molecules of ATP from one molecule of glucose, and cancer cells need more molecules of glucose in comparison with normal cells. Increased uptake of glucose by cancer cells is due to increased expression of glucose transporters. However, overexpression of glucose transporters, promoting the process of carcinogenesis, and increasing aggressiveness and invasiveness of tumors, may have also a beneficial effect. For example, upregulation of glucose transporters is used in diagnostic techniques such as FDG-PET. Therapeutic inhibition of glucose transporters may be a method of treatment of cancer patients. On the other hand, upregulation of glucose transporters, which are used in radioiodine therapy, can help patients with cancers.

Abstract

Tumor growth causes cancer cells to become hypoxic. A hypoxic condition is a hallmark of cancer. Metabolism of cancer cells differs from metabolism of normal cells. Cancer cells prefer the process of glycolysis as a source of ATP. Process of glycolysis generates only two molecules of ATP per one molecule of glucose, whereas the complete oxidative breakdown of one molecule of glucose yields 36 molecules of ATP. Therefore, cancer cells need more molecules of glucose in comparison with normal cells. Increased uptake of glucose by these cells is due to overexpression of glucose transporters, especially GLUT1 and GLUT3, that are hypoxia responsive, as well as other glucose transport proteins. Increased expression of these carrier proteins may be used in anticancer therapy. This phenomenon is used in diagnostic techniques such as FDG-PET. It is also suggested, and there are observations, that therapeutic inhibition of glucose transporters may be a method in treatment of cancer patients. On the other hand, there are described cases, in which upregulation of glucose transporters, as, for example, NIS, which is used in radioiodine therapy, can help patients with cancer. The aim of this review is the presentation of possibilities, and how glucose transporters can be used in anticancer therapy.