Triple-Negative Breast Cancer: Breast Tumors With an Identity Crisis

Deciphering the landscape of triple negative breast cancer from microenvironment dynamics and molecular insights to biomarker analysis and therapeutic modalities

Triple negative breast cancer (TNBC) displays a notable challenge in clinical oncology due to its invasive nature which is attributed to the absence of progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor (HER-2). The heterogenous tumor microenvironment (TME) of TNBC is composed of diverse constituents that intricately interact to evade immune response and facilitate cancer progression and metastasis. Based on molecular gene expression, TNBC is classified into four molecular subtypes: basal-like (BL1 and BL2), luminal androgen receptor (LAR), immunomodulatory (IM), and mesenchymal. TNBC is an aggressive histological variant with adverse prognosis and poor therapeutic response. The lack of response in most of the TNBC patients could be attributed to the heterogeneity of the disease, highlighting the need for more effective treatments and reliable prognostic biomarkers. Targeting certain signaling pathways and their components has emerged as a promising therapeutic strategy for improving patient outcomes. In this review, we have summarized the interactions among various components of the dynamic TME in TNBC and discussed the classification of its molecular subtypes. Moreover, the purpose of this review is to compile and provide an overview of the most recent data about recently discovered novel TNBC biomarkers and targeted therapeutics that have proven successful in treating metastatic TNBC. The emergence of novel therapeutic strategies such as chemoimmunotherapy, chimeric antigen receptor (CAR)-T cells-based immunotherapy, phytometabolites-mediated natural therapy, photodynamic and photothermal approaches have made a significant positive impact and have paved the way for more effective interventions.

Deep Learning and Radiomics in Triple-Negative Breast Cancer: Predicting Long-Term Prognosis and Clinical Outcomes

Triple-negative breast cancer (TNBC) is a unique breast cancer subtype characterized by the lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression in tumor cells. TNBC represents about 15% to 20% of all breast cancers and is aggressive and highly malignant. Currently, TNBC diagnosis primarily depends on pathological examination, while treatment efficacy is assessed through imaging, biomarker detection, pathological evaluation, and clinical symptom improvement. Among these, biomarker detection and pathological assessments are invasive, time-intensive procedures that may be difficult for patients with severe comorbidities and high complication risks. Thus, there is an urgent need for new, supportive tools in TNBC diagnosis and treatment. Deep learning and radiomics techniques represent advanced machine learning methodologies and are also emerging outcomes in the medical-engineering field in recent years. They are extensions of conventional imaging diagnostic methods and have demonstrated tremendous potential in image segmentation, reconstruction, recognition, and classification. These techniques hold certain application prospects for the diagnosis of TNBC, assessment of treatment response, and long-term prognosis prediction. This article reviews recent progress in the application of deep learning, ultrasound, MRI, and radiomics for TNBC diagnosis and treatment, based on research from both domestic and international scholars.

Association between Toll-like receptor 2 rs4696483 and rs1898830 polymorphisms and the risk of triple-negative breast cancer

PURPOSE

Breast cancer (BC) is heterogeneous in clinical manifestation, of which the triple-negative (TNBC) subtype is the most aggressive. This study examines the associations between Toll-Like Receptor (TLR)-2 polymorphisms and the susceptibility to BC and TNBC.

METHODS

Genotyping of TLR-2 rs1898830 and rs4696483 polymorphisms was done by real-time PCR in 488 women with BC (130 TNBC, 358 non-TNBC) and 476 cancer-free control women.

RESULTS

The minor allele frequency (MAF) of rs4696483 was significantly lower in BC cases compared to controls, and significantly lower frequencies of rs4696483 C/T and higher frequencies of rs1898830 G/G genotypes were seen in BC cases. Significantly higher MAF of rs4696483 and higher C/T and T/T rs4696483 genotypes frequencies were seen in TNBC than in non-TNBC cases. Considering the prevalent AC haplotype as a reference, 2-locus TLR-2 haplotype analysis did not identify any 2-locus TLR-2 haplotype associated with an altered risk of BC or TNBC. Positive associations of rs1898830 and rs4966483 were seen with the histological type in TNBC and negatively with distant metastasis and HR status in TNBC and non-TNBC rs1898830 carriers. In addition, rs4696483 was positively correlated with hormonotherapy and surgery in non-TNBC cases, while rs1898830 was negatively associated with hormonotherapy. Furthermore, rs1898830 was negatively and positively correlated with BMI in TNBC and TNBC cases, respectively, but positively with Ki-67 status.

CONCLUSIONS

Our study highlights the association between TLR-2 genetic polymorphisms and BC and TNBC susceptibility, suggesting these variants' diagnostic/prognostic capacity in BC patients and patient subgroups.

Basal-like mammary carcinomas stimulate cancer stem cell properties through AXL-signaling to induce chemotherapy resistance

Basal-like breast cancer (BLBC) is the most aggressive and heterogeneous breast cancer (BC) subtype. Conventional chemotherapies represent next to surgery the most frequently employed treatment options. Unfortunately, resistant tumor phenotypes often develop, resulting in therapeutic failure. To identify the early events occurring upon the first drug application and initiating chemotherapy resistance in BLBC, we leveraged the WAP-T syngeneic mammary carcinoma mouse model and we developed a strategy combining magnetic-activated cell sorting (MACS)-based tumor cell enrichment with high-throughput transcriptome analyses. We discovered that chemotherapy induced a massive gene expression reprogramming toward stemness acquisition to tolerate and survive the cytotoxic treatment in vitro and in vivo. Retransplantation experiments revealed that one single cycle of cytotoxic drug combination therapy (Cyclophosphamide, Adriamycin and 5-Fluorouracil) suffices to induce resistant tumor cell phenotypes in vivo. We identified Axl and its ligand Pros1 as highly induced genes driving cancer stem cell (CSC) properties upon chemotherapy in vivo and in vitro. Furthermore, from our analysis of BLBC patient datasets, we found that AXL expression is also strongly correlated with CSC-gene signatures, a poor response to conventional therapies and worse survival outcomes in those patients. Finally, we demonstrate that AXL inhibition sensitized BLBC-cells to cytotoxic treatment in vitro. Together, our data support AXL as a promising therapeutic target to optimize the efficiency of conventional cytotoxic therapies in BLBC.

Novel Association of IGF2BP2 Gene Variants With Altered Risk of Breast Cancer and as Potential Molecular Biomarker of Triple Negative Breast Cancer

BACKGROUND

Several studies documented that insulin-like growth factor-2 mRNA-binding protein 2 (IGF2BP2) contributes to carcinogenesis, and 1 report documented the association of IGF2BP2 rs4402960 with increased risk of breast cancer (BC). This study investigated the association of rs4402960 and rs1470579 IGF2BP2 variants with BC and triple negative BC (TNBC).

MATERIALS AND METHODS

This case-control study included 488 BC patients comprising 130 TNBC and 358 non-TNBC patients, and 476 cancer-free controls. Genomic DNA was obtained from peripheral venous blood, and genotyping was done by allelic exclusion method on real-time PCR.

RESULTS

The rs440960, but not rs1470579, minor allele was significantly associated with BC, and significantly higher rs4402960 T/T genotype frequency was noted in BC patients than controls; the distribution of rs1470579 genotypes were comparable between BC patients and controls. In contrast, significantly lower rs1470579 minor allele frequency, and reduced rs1470579 A/C and C/C, and rs4402960 T/T genotype frequencies were seen in TNBC cases. Among TNBC cases, rs4402960 and rs1470579 correlated with menses pattern, histological type, breastfeeding, oral contraceptive use and hormonotherapy. Among non-TNBC patients, and rs1470579 correlated significantly with breast feeding, oral contraceptive use, hormonotherapy, and nodal status; rs4402960 also correlated with menses pattern. Two-locus (rs440960-rs1470579) haplotype analysis confirmed the positive association of TC, and negative association of GC and TA haplotypes with BC, while TC and GC haplotypes were negatively associated with TNBC.

CONCLUSION

Whereas rs440960 was positively associated with BC, both rs4402960 and rs1470579 were negatively associated with TNBC, suggesting potential diagnostic/prognostic role in BC and its complications.

Gene Expression Profiles in Cancers and Their Therapeutic Implications

ABSTRACT

The vast amount of gene expression profiling data of bulk tumors and cell lines available in the public domain represents a tremendous resource. For any major cancer type, expression data can identify molecular subtypes, predict patient outcome, identify markers of therapeutic response, determine the functional consequences of somatic mutation, and elucidate the biology of metastatic and advanced cancers. This review provides a broad overview of gene expression profiling in cancer (which may include transcriptome and proteome levels) and the types of findings made using these data. This review also provides specific examples of accessing public cancer gene expression data sets and generating unique views of the data and the resulting genes of interest. These examples involve pan-cancer molecular subtyping, metabolism-associated expression correlates of patient survival involving multiple cancer types, and gene expression correlates of chemotherapy response in breast tumors.

Genetic and functional homologous repair deficiency as biomarkers for platinum sensitivity in TNBC: A case report

Triple-negative breast cancer is the most aggressive subtype of mammary carcinoma. In the early stage, neoadjuvant chemotherapy (NAC) is the standard of care for prognostic stratification and the best adjuvant treatment strategy. A 30-year-old female presented in the emergency room because of a gigantic right breast associated with an ulcerated lump at the upper quadrants. The right axillary nodes were palpable. An ultrasound was performed, showing the ulcerated neoformation with enlarged right axillary lymph nodes observed to level III. A core biopsy of the breast lesion was performed, and the pathological examination revealed a nonspecial type, grade 3, invasive, triple-negative breast cancer. No distant disease was found in the PET-CT scan. A germline genetic panel by next-generation sequencing identified a likely pathogenic variant in RAD51D (c.898C>T). Assessment of the functionality of the DNA homologous recombination repair pathway by RAD51 foci in the tumor revealed a profile of homologous recombination deficiency. NAC consisting of weekly carboplatin and paclitaxel followed by dose-dense doxorubicin/cyclophosphamide was performed with a complete metabolic response achieved in the PET-CT scan. The patient underwent a modified radical mastectomy plus axillary lymphadenectomy with a pathological complete response in the breast and axilla and remains disease-free after 2 years of follow-up. We report a young female with a triple-negative breast cancer stage cT4bN3M0 and a hereditary pathogenic mutation in RAD51D. The tumor was highly proliferative and homologous recombination-deficient by RAD51. The patient received platinum-based NAC, achieving a pathologic complete response. More effort should be made to identify predictive functional biomarkers of treatment response, such as RAD51 foci, for platinum sensitivity.

Outcomes of Immediate Breast Reconstruction in Triple Negative Breast Cancer: A Propensity Score-Matched Analysis

PURPOSE

Triple negative breast cancer (TNBC) patients have a significantly worse prognosis and survival compared to non-TNBC patients. Mastectomy and immediate breast reconstruction (MIBR) is associated with higher rates of complications overall, but whether MIBR significantly increases oncological risk in TNBC patients has not been fully elucidated. Our study aimed to evaluate the oncological safety of MIBR in patients with TNBC compared to non-TNBC.

METHODS

A 6-year prospectively maintained retrospective database at The Ottawa Hospital was reviewed from January 1, 2013 to May 31, 2019. Propensity score-matching was performed using the nearest-neighbour method with a matching ratio of 2:1. Kaplan-Meier and log rank tests were performed to provide statistical comparison of disease-free interval (DFI). DFI was defined as time from MIBR to locoregional recurrence or disease-specific mortality. P-value < 0.05 indicated statistical significance.

RESULTS

Of 277 eligible patients, 153 patients were matched. The cohort consisted of 51(33%) TNBC patients and 102 (67%) non-TNBC patients after 2:1 propensity score-matching. The rates of delays to first radiochemotherapy [17 (33%) vs.14 (14%), p = 0.10], postoperative complications [13 (26%) vs. 34 (33%), p = 0.50], and locoregional recurrence [2 (1.96%) vs. 1 (1.96%), p = 1.0] were statistically similar in TNBC and non-TNBC, respectively. DFI was not significantly different in TNBC compared to non-TNBC patients (log-rank p = 1.0). There was no mortality in this cohort.

CONCLUSIONS

This 6-year retrospective 2:1 propensity score-matched cohort study demonstrated similar oncological safety for MIBR in patients with TNBC and non-TNBC.. Overall, these findings provide additional support for the oncological safety of MIBR in TNBC. . Therefore, MIBR remains a therapeutic option for patients with TNBC.

Nano to rescue: repository of nanocarriers for targeted drug delivery to curb breast cancer

Breast cancer is a heterogeneous disease with different intrinsic subtypes. The conventional treatment of surgical resection, chemotherapy, immunotherapy and radiotherapy has not shown significant improvement in the survival rate of breast cancer patients. The therapeutics used cause bystander toxicities deteriorating healthy tissues. The breakthroughs of nanotechnology have been a promising feat in selective targeting of tumor site thus increasing the therapeutic gain. By the application of nanoenabled carriers, nanomedicines ensure targeted delivery, stability, enhanced cellular uptake, biocompatibility and higher apoptotic efficacy. The present review focuses on breakthrough of nanoscale intervention in targeted drug delivery as novel class of therapeutics. Nanoenabled carriers like polymeric and metallic nanoparticles, dendrimers, quantum dots, liposomes, solid lipid nanoparticles, carbon nanotubes, drug-antibody conjugates and exosomes revolutionized the targeted therapeutic delivery approach. These nanoassemblies have shown additional effect of improving the solubility of drugs such as paclitaxel, reducing the dose and toxicity. The present review provides an insight on the different drug conjugates employed/investigated to curb breast cancer using nanocarrier mediated targeted drug delivery. However, identification of appropriate biomarkers to target, clearer insight of the biological processes, batch uniformity, reproducibility, nanomaterial toxicity and stabilities are the hurdles faced by nanodrugs. The potential of nano-therapeutics delivery necessitates the agglomerated efforts of research community to bridge the route of nanodrugs for scale-up, commercialization and clinical applications.

HDAC8 suppresses the epithelial phenotype and promotes EMT in chemotherapy-treated basal-like breast cancer

BACKGROUND

Basal-like breast cancer (BLBC) is one of the most aggressive malignant diseases in women with an increased metastatic behavior and poor prognosis compared to other molecular subtypes of breast cancer. Resistance to chemotherapy is the main cause of treatment failure in BLBC. Therefore, novel therapeutic strategies counteracting the gain of aggressiveness underlying therapy resistance are urgently needed. The epithelial-to-mesenchymal transition (EMT) has been established as one central process stimulating cancer cell migratory capacity but also acquisition of chemotherapy-resistant properties. In this study, we aimed to uncover epigenetic factors involved in the EMT-transcriptional program occurring in BLBC cells surviving conventional chemotherapy.

RESULTS

Using whole transcriptome data from a murine mammary carcinoma cell line (pG-2), we identified upregulation of Hdac4, 7 and 8 in tumor cells surviving conventional chemotherapy. Subsequent analyses of human BLBC patient datasets and cell lines established HDAC8 as the most promising factor sustaining tumor cell viability. ChIP-sequencing data analysis identified a pronounced loss of H3K27ac at regulatory regions of master transcription factors (TFs) of epithelial phenotype like Gata3, Elf5, Rora and Grhl2 upon chemotherapy. Interestingly, impairment of HDAC8 activity reverted epithelial-TFs levels. Furthermore, loss of HDAC8 activity sensitized tumor cells to chemotherapeutic treatments, even at low doses.

CONCLUSION

The current study reveals a previously unknown transcriptional repressive function of HDAC8 exerted on a panel of transcription factors involved in the maintenance of epithelial cell phenotype, thereby supporting BLBC cell survival to conventional chemotherapy. Our data establish HDAC8 as an attractive therapeutically targetable epigenetic factor to increase the efficiency of chemotherapeutics.

Varying outcomes of triple-negative breast cancer in different age groups-prognostic value of clinical features and proliferation

PURPOSE

Triple-negative breast cancer (TNBC) is an aggressive disease lacking specific biomarkers to guide treatment decisions. We evaluated the combined prognostic impact of clinical features and novel biomarkers of cell cycle-progression in age-dependent subgroups of TNBC patients.

METHODS

One hundred forty seven TNBC patients with complete clinical data and up to 18 year follow-up were collected from Turku University Hospital, Finland. Eight biomarkers for cell division were immunohistochemically detected to evaluate their clinical applicability in relation to patient and tumor characteristics.

RESULTS

Age at diagnosis was the decisive factor predicting disease-specific mortality in TNBC (p = 0.002). The established prognostic features, nodal status and Ki-67, predicted survival only when combined with age. The outcome and prognostic features differed significantly between age groups, middle-aged patients showing the most favorable outcome. Among young patients, only lack of basal differentiation predicted disease outcome, indicating 4.5-fold mortality risk (p = 0.03). Among patients aged > 57, the established prognostic features predicted disease outcome with up to 3.0-fold mortality risk for tumor size ≥ 2 cm (p = 0.001). Concerning cell proliferation, Ki-67 alone was a significant prognosticator among patients aged > 57 years (p = 0.009). Among the studied cell cycle-specific biomarkers, only geminin predicted disease outcome, indicating up to 6.2-fold increased risk of mortality for tumor size < 2 cm (p = 0.03).

CONCLUSION

Traditional clinical features do not provide optimal prognostic characterization for all TNBC patients. Young age should be considered as an additional adverse prognostic feature in therapeutic considerations. Increased proliferation, as evaluated using Ki-67 or geminin immunohistochemistry, showed potential in detecting survival differences in subgroups of TNBC.

TH1902, a new docetaxel-peptide conjugate for the treatment of sortilin-positive triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous subgroup of cancers which lacks the expression and/or amplification of targetable biomarkers (ie, estrogen receptor, progestrogen receptor, and human epidermal growth factor receptor 2), and is often associated with the worse disease-specific outcomes than other breast cancer subtypes. Here, we report that high expression of the sortilin (SORT1) receptor correlates with the decreased survival in TNBC patients, and more importantly in those bearing lymph node metastases. By exploiting SORT1 function in ligand internalization, a new anticancer treatment strategy was designed to target SORT1-positive TNBC-derived cells both in vitro and in two in vivo tumor xenografts models. A peptide (TH19P01), which requires SORT1 for internalization and to which many anticancer drugs could be conjugated, was developed. In vitro, while the TH19P01 peptide itself did not exert any antiproliferative or apoptotic effects, the docetaxel-TH19P01 conjugate (TH1902) exerted potent antiproliferative and antimigratory activities when tested on TNBC-derived MDA-MB-231 cells. TH1902 triggered faster and more potent apoptotic cell death than did unconjugated docetaxel. The apoptotic and antimigratory effects of TH1902 were both reversed by two SORT1 ligands, neurotensin and progranulin, and on siRNA-mediated silencing of SORT1. TH1902 also altered microtubule polymerization and triggered the downregulation of the anti-apoptotic Bcl-xL biomarker. In vivo, both i.p. and i.v. administrations of TH1902 led to greater tumor regression in two MDA-MB-231 and HCC-70 murine xenograft models than did docetaxel, without inducing neutropenia. Altogether, the data demonstrates the high in vivo efficacy and safety of TH1902 against TNBC through a SORT1 receptor-mediated mechanism. This property allows for selective treatment of SORT1-positive TNBC and makes TH1902 a promising avenue for personalized therapy with the potential of improving the therapeutic window of cytotoxic anticancer drugs such as docetaxel.