Triple-negative Breast Cancer Patients Research Articles

Abstract B012: Understanding the role of VISTA in regulating T cell function and the therapeutic potential of blocking VISTA in triple negative breast cancer

Abstract Triple-negative breast cancer (TNBC) is the most aggressive and highly metastatic breast cancer subtype with limited effective treatment options. Immunotherapy with immune checkpoint inhibitors (ICIs) targeting checkpoint molecules have been widely used and have shown therapeutic efficacy in treating multiple malignancies in the last decade. In TNBC, ICI targeting PD-1, alone or in combination with chemotherapy has been approved for the treatment of patients with both early and advanced stage of the disease. Although, there has been significant clinical benefit achieved from anti-PD-1 and chemotherapy, treatment efficacy is often limited to a subgroup of patients. The limited response to ICIs has been attributed to the increased infiltration of immunosuppressive cells (including MDSCs, neutrophils and tumor-associated macrophages), more importantly, the upregulation of alternative immune checkpoint receptors/ligands that may further suppress cytotoxic T cells (CD8+ T cells) in the tumor microenvironment (TME). Therefore, it has been suggested that targeting other immune checkpoint molecules may be more effective in bolstering anti-tumor immune response. V- domain Ig suppressor of T-cell activation (VISTA) is one of the immune checkpoint molecules attracting increasing attention in the context of anti-tumor immunity due to its broad expression across various cancer types and increased expression upon development of immune checkpoint resistance. However, the role of VISTA in regulating the anti-tumor immune response and its therapeutic potential in TNBC remains unclear. In our study, we observed that VISTA is expressed in TNBC patients, predominantly in neutrophils and macrophages. In the Py230 murine breast cancer model, VISTA expression increased upon paclitaxel (PTX), anti-PD-L1 and paclitaxel combined with anti-PD-L1 treatment compared to the control group, suggesting its potential role as a resistance mechanism in sustaining or further inhibiting T cells. In the Py230 model, VISTA blockade increased the infiltration and activation of CD8+ T cells, as evidenced by the higher number of CD8+ T cells, increased CD69+CD8+ T cells, and Granzyme B production, indicating that VISTA blockade improved CD8+ T cells mediated anti-tumor immunity. To functionally test the role of VISTA, we stimulated CD8+ T cells and co-cultured them with naïve macrophages or tumor educated macrophages in the presence or absence of VISTA blocking antibody. Tumor educated macrophages showed increased immunosuppressive activity which was abrogated with VISTA blockade. Moreover, we found that the immunosuppressive effect of macrophages on T cell activation needs direct cell-cell interaction between VISTA on macrophages and T cells. In conclusion, this study shows the mechanism of action of VISTA in the regulation of T cells mediated anti-tumor immune response and provides the rationale for targeting VISTA in TNBC. Citation Format: Maidinaimu Abudula, Yuliana Astuti, Meirion Raymant Raymant, Vijay Sharma, Michael Schmid, Ainhoa Mielgo. Understanding the role of VISTA in regulating T cell function and the therapeutic potential of blocking VISTA in triple negative breast cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B012.

Abstract A012: Aging drives TNBC lung metastasis dependency on FGFR-triggered metabolic reprogramming exposing an age-induced liability with therapeutic potential

Abstract The clinical manifestation of metastasis in a vital organ is the final stage of breast cancer progression and the main culprit of breast cancer related mortality. This remain especially problematic in the case of triple negative breast cancer (TNBC), the most aggressive type of breast cancer, often diagnosed in its metastatic form and for which chemotherapies are still the major therapeutic option. Typically, TNBC is seen as a disease of younger women, however, 20% of TNBCs occur in patients aged 65 and older, whose prognosis is equally staggering. Unfortunately, due to co-morbidities, tolerability of chemotherapies, as well as severe reduction in quality of life, majority of women above age 65 can’t or decide not to receive chemotherapy ultimately cutting their lives short. Metastatic outgrowth is largely dictated by the ability of TNBC disseminated cancer cells (DCCs) to thrive distal organs and is largely dependent on the physiology of the specific organs. However, how the aging process, a major driver of changes in organismal physiology, affects the interaction between the host organ and TNBC DCCs remains unknown. Here, we adapted several traditional syngeneic models of TNBC metastasis to old mice of different strains and coupled with RNA-seq to unveil molecular adaptations of TNBC DCCs to the aging lung. We show that the changes that occur in the lung with aging drives an increase in mitochondrial fitness in TNBC DCCs, an adaptation that is necessary for metastasis to thrive in the old lung environment. Mechanistically, our data show that the expression of FGF19, a gut hormone not normally expressed in TNBC DCCs, drives this increase in mitochondrial fitness in the old lung through an autocrine signaling axis impinging on activation of FGF-19 cognate receptor family, FGFRs. Inhibition of FGF19-FGFR signaling using an FDA- approved FGFR inhibitor not only blocks the age-induced increase in mitochondrial fitness but also effectively abolishes lung metastasis in old, but not in young, immune competent and immune compromised mice. We traced this to age-specific metastatic adaptation of TNBC lung metastasis to the increase in bile acids, the canonical regulators of FGF19 expression, in the old lung environment. Together, our work demonstrates an important contribution of age-driven metabolic reprogramming of the host to the traits that enable metastasis to thrive in the lung and provides rationale for the use of FDA-approved FGFR inhibitors for the treatment of breast cancer lung metastasis in the most vulnerable of stage IV metastatic TNBC patients, the elderly. Citation Format: Stanislav Drapela, Shiun Chang, Rojan Chimeh Rad, Vanessa Rubio, Didem Ilter, Paulo Rodriguez, Ana P. Gomes. Aging drives TNBC lung metastasis dependency on FGFR-triggered metabolic reprogramming exposing an age-induced liability with therapeutic potential [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A012.

Abstract B022: Investigating how monocytes impair NK cell cytotoxicity in lung metastasis of triple-negative breast cancer

Abstract Triple-negative breast cancer (TNBC) accounts for 20% of breast cancer (BC) cases worldwide, yet due to its aggressive phenotype and lack of targeted therapies it has the worst prognosis amongst BC subtypes. Up to 40% of TNBC patients will relapse after treatment and develop distant metastasis. Metastasis is the complex process by which disseminated tumor cells (DTCs) leave the primary tumor and grow at distal sites. Since most metastases occur within 3 years of diagnosis, the rapid onset and lack of effective treatments in metastatic TNBC (mTNBC) means less than 20% of patients survive after 4 years. Even though it is the most “immune-activated” BC subtype, and immune checkpoint blockade (ICB) has shown clinical benefits in early TNBC, there is a clear need for novel immunotherapeutic approaches for patients with mTNBC. Natural killer (NK) cells are innate lymphocytes that function as the body’s first line defense against metastatic cancer cells. NK cells eliminate DTCs in the blood or at distal sites via NK cell cytotoxicity (NKCC) and this process is known to be impaired in successful metastasis. We hypothesized that other cells within the tumor microenvironment (TME) can inhibit NKCC at the earliest stages of metastatic outgrowth. We have used Cherry-niche, an in vivo labelling tool, to characterize how TME cells change in early and established lung micro-metastases by single-cell RNA sequencing (scRNA-seq) and flow cytometry. Our initial analyses showed that monocytes are highly enriched, not only in the entire metastatic lung, but specifically in the established niche surrounding DTCs. Although we detected a slight increase in total NK cells, there was a shift in maturation status with fewer mature NK cells (CD27-CD11b+) and more immature NK cells (CD27+/-CD11b-) in the metastatic lung. Furthermore, NK cells were largely absent from the metastatic niche and those that were present displayed a dysfunctional phenotype. CellChat and NicheNet analyses of our scRNA-seq data predicted that several receptor-ligand interactions, including the cytokine macrophage migration inhibitory factor (MIF), can mediate the crosstalk between NK cells and monocytes. Next, we developed an in vitro 3D co-culture system to study the effect of blood-derived monocytes on human NKCC against mTNBC cells. We found that monocytes can suppress NKCC against MDA-MB-231 cells and decrease the viability of mature NK cells. Furthermore, recombinant MIF was able to directly inhibit NKCC, whilst a selective MIF antagonist was able to rescue monocyte-induced impairment of NKCC. These data implicate MIF as a critical monocyte-derived factor in the suppression of NK cell function against mTNBC cells. Future work will aim to identify the exact mechanism by which MIF inhibits NKCC, whilst also evaluate the effect of monocyte depletion and MIF inhibition on metastatic outgrowth and NK cell activation/maturation in vivo. This study will reveal novel inter-cellular dynamics occurring in the metastatic lung, as well as immunotherapeutic targets that may restore NKCC in mTNBC. Citation Format: Christos Ermogenous, Luigi Ombrato, Gordon Beattie. Investigating how monocytes impair NK cell cytotoxicity in lung metastasis of triple-negative breast cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B022.

Abstract A034: Single cell RNA sequencing of triple negative breast cancer patient-derived xenograft model identifies CRABP1 of cancer-associated fibroblast as a key regulator of breast cancer metastasis

Abstract Triple-negative breast cancer (TNBC) is associated with a high risk of distant metastasis, particularly to the lung and liver. Both intrinsic characteristics of cancer cells and the tumor microenvironment (TME) influence TNBC growth and metastasis. The TME, comprising stromal, immune, and endothelial cells, exhibits heterogeneity both between and within cell types. Identifying the molecular characteristics of TME cells that affect cancer progression is crucial. We aim to investigate this using single-cell RNA sequencing of patient-derived xenograft (PDX) models to explore TME cells and genes involved in TNBC metastasis. We established PDX models by transplanting tumor tissues from 26 TNBC patients into immunodeficient mice. These models were categorized based on their metastatic potential and patient outcomes: non-metastatic (n=5) and metastatic (n=4). Single-cell RNA sequencing of nine PDX tumors revealed significant differences in gene expression of murine stromal cells between metastatic and non-metastatic models. We identified ten genes (Serpinb2, Spp1, Tnc, Thbs1, Timp1, Il11, Mt2, Crabp1, Cck, Mt1) that were highly expressed in the stromal cells of metastatic PDX models. To test if TNBC cells influence these fibroblast genes, we exposed NIH3T3 fibroblasts to conditioned media from the 4T1 TNBC cell line. In three independent experiments, only Crabp1 expression in NIH3T3 cells was consistently increased by 4T1- conditioned media. CRABP1, a retinoic acid-binding protein, is known for its role in differentiation and proliferation by regulating MAPK signaling. Although Crabp1-positive cancer-associated fibroblasts have been noted, its role in TNBC metastasis was previously unexplored. We investigated CRABP1 function using a CRABP1 knockdown NIH3T3 cell line. CRABP1 knockdown led to reduced invasion and migration of 4T1 cells in trans-well assays and decreased invasiveness of 4T1 spheroids in a collagen matrix. Additionally, CRABP1 knockdown NIH3T3 cells showed reduced proliferation in vitro and fewer alpha-SMA positive cancer-associated fibroblasts in co-injected 4T1 tumors in BALB/C mice. In summary, CRABP1, identified through single-cell RNA sequencing of stromal cells in TNBC PDX models, is a potential regulator of TNBC metastasis, affecting cancer cell migration, invasion, and fibroblast proliferation. Citation Format: Woohang Heo, Yujeong Her, Sieun Yang, Dakyung Lee, Rokhyun Kim, Jong-Il Kim, Hyeong-Gon Moon. Single cell RNA sequencing of triple negative breast cancer patient-derived xenograft model identifies CRABP1 of cancer-associated fibroblast as a key regulator of breast cancer metastasis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A034.

Abstract C045: The extracellular matrix glycoprotein periostin supports chemotherapy resistance by modulating macrophage recruitment and phagocytosis in triple negative breast cancer

Abstract Triple-negative breast cancer (TNBC) accounts for approximately 15–20% of all breast cancer cases and is notoriously aggressive, often developing resistance to standard chemotherapy thus leading to a high rate of metastatic relapse. Evidence suggests that this resistance is linked to changes in the extracellular matrix (ECM) composition, particularly an increase in periostin (POSTN) expression, which is also associated with poor prognosis in breast cancer. Our recent publication showed that the ECM alone can influence macrophage phenotypes. Furthermore, another study from our lab has demonstrated that POSTN mediates resistance to anti-angiogenic therapy by recruiting macrophages in pancreatic neuroendocrine tumors. Notably, POSTN deletion reduced monocyte/macrophage recruitment and enhanced cytotoxic CD8+ T-cell infiltration. Based on these findings, we hypothesized that paclitaxel (PTX), a widely used chemotherapeutic drug for the management of TNBC, may stimulate POSTN production by fibroblasts leading to the recruitment of pro-tumoral macrophages that facilitate tumor growth resulting into therapy resistance. In this study, we showed that PTX induces increased POSTN expression in mouse models of TNBC through immunohistochemistry, and in both 2D and 3D in vitro models via interactions between TNBC cell lines and mammary fibroblasts, as demonstrated by immunofluorescence. An in vitro migration assay confirmed that PTX-induced POSTN enhances the recruitment of human monocytes and macrophages, which display a mixed immunosuppressive and inflammatory phenotype, as revealed by flow cytometry. Not only did these recruited macrophages exhibit a reduced phagocytic capacity against labelled TNBC cells in an in vitro phagocytosis assay, but we also found that POSTN plays a crucial role in inducing SIRPα expression, that may diminish macrophage phagocytic potential. Increased sialylation and Siglec-1 expression are known to be linked to poor prognosis and polarization towards a more immunosuppressive macrophage phenotype in TNBC. Interestingly in our model, we observed that higher concentrations of recombinant human POSTN induce increased Siglec-1 expression on macrophages, a receptor that interacts with sialic acids in the tumor ECM. Further work using a decellularized tissue model that preserves only the ECM from patient-derived tumor biopsies pre- and post-chemo, aims to further explore the correlation between PTX-induced POSTN, ECM sialylation, and Siglec-1 expression on macrophages. Additionally, we have developed POSTN-knockout murine cancer cells and fibroblasts using CRISPR/Cas9, allowing us to investigate how POSTN influences macrophage phenotypes and chemotherapy responses in vivo. Understanding the mechanisms behind chemotherapy resistance in TNBC is crucial for developing effective treatments for this aggressive cancer subtype. By elucidating the intricate interplay between POSTN, macrophages, and chemotherapy response, we aim to identify new therapeutic strategies to improve outcomes for TNBC patients. Citation Format: Ludovica Tarantola, Ioanna Keklikoglou, Oliver M. Pearce. The extracellular matrix glycoprotein periostin supports chemotherapy resistance by modulating macrophage recruitment and phagocytosis in triple negative breast cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C045.

Neoantigen DNA vaccines are safe, feasible, and induce neoantigen-specific immune responses in triple-negative breast cancer patients

Abstract Background Neoantigen vaccines can induce or enhance highly specific antitumor immune responses with minimal risk of autoimmunity. We have developed a neoantigen DNA vaccine platform capable of efficiently presenting both HLA class I and II epitopes and performed a phase 1 clinical trial in triple-negative breast cancer patients with persistent disease on surgical pathology following neoadjuvant chemotherapy, a patient population at high risk of disease recurrence. Methods Expressed somatic mutations were identified by tumor/normal exome sequencing and tumor RNA sequencing. The pVACtools software suite of neoantigen prediction algorithms was used to identify and prioritize cancer neoantigens and facilitate vaccine design for manufacture in an academic GMP facility. Neoantigen DNA vaccines were administered via electroporation in the adjuvant setting (i.e., following surgical removal of the primary tumor and completion of standard of care therapy). Vaccines were monitored for safety and immune responses via ELISpot, intracellular cytokine production via flow cytometry, and TCR sequencing. Results Eighteen subjects received three doses of a neoantigen DNA vaccine encoding on average 11 neoantigens per patient (range 4–20). The vaccinations were well tolerated with relatively few adverse events. Neoantigen-specific T cell responses were induced in 14/18 patients as measured by ELISpot and flow cytometry. At a median follow-up of 36 months, recurrence-free survival was 87.5% (95% CI: 72.7–100%) in the cohort of vaccinated patients. Conclusion Our study demonstrates neoantigen DNA vaccines are safe, feasible, and capable of inducing neoantigen-specific immune responses. Clinical trial registration number NCT02348320.

Abstract B012: HNRNPL-mediated mRNA stability underlies metastasis triggered by resistance to radiation therapy

Abstract The high rate of locoregional/distant recurrence in triple-negative breast cancer (TNBC) is a major driver of the decreased survival observed in breast cancer patients. Radiation therapy is a reliable treatment modality to limit recurrence for many cancers, but TNBC patients have a higher chance for relapse despite receiving increased doses of radiation compared to patients with other breast cancer subtypes. This study investigated the differential pathways in radioresistant TNBC tumors that impact recurrence. We developed two radioresistant cell line models (468-RR and 4T1-RR) by administering a radiation dose of 50Gy over the course of 8 weeks to the human TNBC cell line, MDA-MB-468, and the mouse TNBC cell line, 4T1, respectively. Migration and invasion were assessed using the scratch-wound assay and transwell assay, respectively. We assessed in vivo metastasis by injecting the cells in the mammary fat pad, tail vein, or left ventricle. RNA-sequencing of the cell lines was done to identify global transcriptomic changes and regulatory pathways induced by radiation therapy. The mRNA stability of integrin b3 was assessed by inhibiting transcription using actinomycin D. Moreover, we implemented the newly developed InduroRT-mediated circRNA-sequencing (IMRT-seq) to identify the circular RNAs processed by HNRNPL that are present in radioresistant cells. We observed enhanced lung and bone metastasis, based on bioluminescent imaging, in both the spontaneous and vascular metastasis models for the radioresistant cells compared to the parental cells. Genset enrichment analysis identified mRNA stability and metabolism as upregulated pathways in radioresistant cells with HNRNPL, a ribonucleoprotein involved in mRNA stability, as one of the top genes. By knocking down HNRNPL, we observed decreased migration capacity of the radioresistant cells. Given the role of HNRNPL in integrin and extracellular matrix genes, which are key components associated with metastasis in cancer cells, we screened for these genes in our RNA-seq dataset and identified integrin b3 as a possible target. More specifically, knocking down HNRNPL decreased the mRNA stability of integrin b3 as assessed by actinomycin d treatment. By expressing integrin b3 in the HNRNPL-depleted cells, we were able to rescue the migration capacity of these cells. We believe a subset of HNRNPL-mediated circular RNAs are responsible for integrin b3 mRNA stability by sequestering miRNAs that target integrin b3. With IMRT-seq we are exploring the potential circRNA-miRNA interactions present in radioresistant TNBC responsible for its metastatic phenotype. The radioresistant cells derived from TNBC cell lines have an enhanced metastatic potential than the treatment-naive cell lines and our data suggest that RNA metabolism is pivotal to this phenotype. The upregulation of HNRNPL upon radiation by Nrf2 increases integrin b3 expression by stabilizing its transcripts and preventing its degradation. This novel mechanism of radioresistant metastasis provides a therapeutic approach to minimize TNBC recurrence. Citation Format: Ayush Kumar, Kensei Kishimoto, Christi Wisniewski, Shivam Goel, Arthur Mercurio. HNRNPL-mediated mRNA stability underlies metastasis triggered by resistance to radiation therapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr B012.

Abstract B008: Evaluating ctDNA as a risk-stratifying biomarker in non-metastatic triple-negative breast cancer treated with neoadjuvant chemotherapy

Abstract Introduction: Patients with triple-negative breast cancer (TNBC) who respond well to neoadjuvant chemotherapy (NACT) generally experience favorable outcomes. However, those with residual disease after NACT face a higher risk of relapse and exhibit varying outcomes. Therefore, additional tools for assessing relapse risk are critical for guiding personalized treatment strategies. We aim to investigate the role of circulating tumor DNA (ctDNA) in conjunction with homologous recombination deficiency (HRD) as a risk-stratifying biomarker in TNBC patients with residual disease. Methods: TNBC were classified as HRD-Hereditary or Sporadic using multi-gene genetic testing. Comprehensive Genomic Profiling (CGP) was performed and tumor acquired small variants were tracked in plasma samples by a personalized-amplicontarget-sequencing (PATS) approach. Plasma samples were collected at six key time points: before treatment (BT), after the first block of NACT (ab1Neo), post-completion of NACT (aNeo), after tumor resection (aSur), and at two monitoring intervals every three months (M3m and M6m). Results: Of 105 TNBC patients tested for germline variants, 26% were classified as HRD-Hereditary, primarily due to BRCA1 mutations. CGP was performed on 73 tumors, with 12.5% displaying high tumor mutation burden (TMB), not associated with HRD- Hereditary status. Tumor-specific variants were identified in 95% (69/73) of cases, with TP53 variants being the most frequent (84%). Regarding response to NACT, 55% (58/105) achieved pathological complete response (RCB=0), while 11% (12/105) had RCB=I, 16% (17/105) RCB=II, 10% (11/105) RCB=III and 7% (7/105) unavailable RCB score. ctDNA analysis was feasible for 62% (65/105) of cases. Positive ctDNA (ctDNApos) was detected in 66.2% (43/65) at BT, 48.4% (30/62) at ab1Neo, 25.4% (15/59) at aNeo, 32.8% (20/61) at aSur, 18.6% (11/59) at M3m and 28.6% (14/49) at M6m. Interestingly, sporadic tumor patients exhibited significantly higher ctDNApos rates compared with HRD-Hereditary tumors at BT, aNeo, and aSur. No significant association was found between ctDNApos at any timepoint and RCB scores. Strong negative predictive value of RCB=0/1 and ctDNAneg aSur for progression was observed (94.2% - 65/69 and 85.4% - 35/41, respectively; mean follow-up 39.7 months, median 36.9 months). In contrast, the positive predictive value for both RCB=2/3 and ctDNApos aSur was relatively low (50% - 14/28; 50% - 10/20, respectively). However, when ctDNApos at aSur were combined with RCB=2/3, the PPV improved to 77.8%. Moreover, ctDNApos was significantly associated with clinical progression at BT (p=0.0359) and aSur (p=0.0053) and consistently anticipated progression detected by standard imaging, with a mean lead-time of 4.7 months. Patients with ctDNApos also demonstrated worse progression-free survival, strongly suggesting its potential as a prognostic marker. Conclusions: ctDNA appears to be a promising risk-stratifying biomarker for TNBC patients with residual cancer, offering valuable insights for tailoring patient management and improving outcomes. Citation Format: Rafael Canfield Brianese, Karina Miranda Santiago, Nathalia de Angelis de Carvalho, Marina de Brot Andrade, Giovana Tardin Torrezan, Vladmir Claudio Cordeiro de Lima, Solange Moraes Sanches, Maria Nirvana da Cruz Formiga, Fabiana Baroni Alves Makdissi, Dirce Maria Carraro. Evaluating ctDNA as a risk-stratifying biomarker in non-metastatic triple-negative breast cancer treated with neoadjuvant chemotherapy [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr B008.

Phytochemicals as Novel Therapeutics for Triple-Negative Breast Cancer: A Comprehensive Review of Current Knowledge.

Triple-negative breast cancer is a characteristic subtype of breast cancer that lacks the estrogen receptor, human epidermal growth factor receptor 2, and progesterone receptor. Because of its highly diverse subtypes, increased metastasis capability, and poor prognosis, the risk of mortality for people with triple-negative breast cancers is high as compared with other cancers. Chemotherapy is currently playing a major role in treating triple-negative breast cancer patients; however, poor prognosis due to drug resistance is causing serious concern. Recent studies on several phytochemicals derived from various plants being used in Traditional Chinese Medicine, Traditional Korean Medicine, Ayurveda (Traditional Indian Medicine), and so on, have demonstrated to be a promising agent as a viable therapy against triple-negative breast cancer. Phytochemicals categorized as alkaloids, polyphenols, terpenoids, phytosterols, and organosulfur compounds have been demonstrated to reduce cancer cell proliferation and metastasis by activating various molecular pathways, thereby reducing the spread of triple-negative breast cancer. This review analyzes the molecular mechanisms by which various phytochemicals fight triple-negative breast cancer and offers a perspective on the difficulties and potential prospects for treating triple-negative breast cancer with various phytochemicals.

Comprehensive analysis of the metabolomics and transcriptomics uncovers the dysregulated network and potential biomarkers of Triple Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is known for its aggressive nature, lack of effective diagnostic tools and treatments, and generally poor prognosis. The objective of this study was to investigate metabolic changes in TNBC using metabolomics approaches and explore the underlying mechanisms through integrated analysis with transcriptomics. In this study, serum untargeted metabolic profiles were first examined between 18 TNBC patients and 21 healthy control (HC) subjects using liquid chromatography-mass spectrometry (LC-MS), identifying a total of 22 significantly differential metabolites (DMs). Subsequently, receiver operating characteristic analysis revealed that 7-methylguanine could serve as a potential biomarker for TNBC in both the discovery and validation sets. Additionally, transcriptomic datasets were retrieved from the GEO database to identify differentially expressed genes (DEGs) between TNBC and normal tissues. An integrative analysis of the DMs and DEGs was conducted, uncovering potential molecular mechanisms underlying TNBC. Notably, three pathways-tyrosine metabolism, phenylalanine metabolism, and glycolysis/gluconeogenesis-were enriched, providing insight into the energy metabolism disorders in TNBC. Within these pathways, two DMs (4-hydroxyphenylacetaldehyde and oxaloacetic acid) and six DEGs (MAOA, ADH1B, ADH1C, AOC3, TAT, and PCK1) were identified as key components. In summary, this study highlights metabolic biomarkers that could potentially be used for the diagnosis and screening of TNBC. The comprehensive analysis of metabolomics and transcriptomics data offers a validated and in-depth understanding of TNBC metabolism.

Outcome of Triple Negative Breast Cancer(TNBC) as compared to other breast cancers in Bir Hospital, National Academy of Medical Sciences

Introduction: In Nepal, breast cancer is the second most common cancer accounting for a large number of deaths.The subtype Triple-negative breast cancer (TNBC) is linked to poor prognosis and is characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2). This study describes the outcome of women with TNBC as compared to other breast cancers in Bir Hospital in Nepal. Methods: This was a cross-sectional study conducted in Bir Hospital, National Academy of Medical Sciences. The breast cancer data in Department of Surgery and Department of Oncology were collected from July 2021 to June 2024. The study data on demographic details, clinical findings, radiological and pathological investigations, operative procedures, neoadjuvant/adjuvant therapy, surgical and oncological outcomeswere collected. The study approval was taken from Institutional Review Board of National Academy of Medical Sciences. Results: There were 72 breast cancer patientsout of which 10 (13.8 %) were TNBC. Majority of the cases (70%) underwent modified radical mastectomy and 60% of them had received neoadjuvant therapy in TNBC cases. One out of 10 had positive margin post mastectomy. The proportion of TNBC patients with postoperative wound infection, seroma and flap necrosis were 10% each. The mean lymph node positivity was less in TNBC group as compared to other breast cancers.There was one recurrence, one metastasis and no mortality till one year follow up. Conclusion: The surgical outcome was satisfactory and with neo-adjuvant, surgery and adjuvant therapy, there is less tumor recurrence and satisfactory disease free survival and overall survival.

PTPN20 promotes metastasis through activating NF-κB signaling in triple-negative breast cancer

BackgroundCancer metastasis remains a major challenge in the clinical management of triple-negative breast cancer (TNBC). The NF-κB signaling pathway has been implicated as a crucial factor in the development of metastases, but the underlying molecular mechanisms remain largely unclear.MethodsPTPN20 expression was evaluated using data from the Sweden Cancerome Analysis Network-Breast and The Cancer Genome Atlas database, as well as by western blotting and immunohistochemistry in 88 TNBC patients. The ability of PTPN20 to activate NF-κB was assessed by luciferase reporter assays. The effects of PTPN20 overexpression and knockdown via short hairpin RNA were examined in TNBC cell lines by wound healing and transwell matrix penetration assays. Additionally, we analyzed the growth and metastasis abilitiy of 4T1 xenograft tumors in nude mice.ResultsPTPN20 levels were elevated in TNBC cell lines and patient samples compared to controls, and higher protein levels correlated with metastasis-free survival. Overexpression of PTPN20 enhanced migration and invasion in vitro, and promoted lung metastasis in vivo. Our finding revealed that PTPN20 activates NF-κB signaling by dephosphorylating p65 at Ser468, preventing its binding to COMMD1, thereby protecting p65 from degradation. Downregulation of PTPN20 effectively inhibit, while p65 S468A mutant restored the migratory and invasive abilities of TNBC cells.ConclusionsCollectively, our results demonstrate that PTPN20 plays a critical role in TNBC metastasis through the activation of NF-κB signaling. We propose that PTPN20 may serve as a novel prognostic marker and potential therapeutic target for the treatment of TNBC.

Glucocorticoid Receptor Isoforms in Breast Cancer Raise Implications for Personalised Supportive Therapies.

Glucocorticoid receptor (GR) activation may promote metastasis in oestrogen receptor-negative and triple-negative breast cancer (TNBC). However, the role of the GRβ isoform, which has opposing effects to the main isoform, has not been studied in clinical samples. We aimed to analyse the intracellular localisation of total GR and GRβ in vitro using plasmid constructs and fluorescent immunocytochemistry. Additionally, our goal was to perform immunostaining for total GR and GRβ on two cohorts: (i) on 194 clinical breast cancer samples to compare the expression in different molecular subtypes, and (ii) on 161 TNBC samples to analyse the association of GR with survival. We supplemented our analysis with RNA data from 1097 TNBC cases. We found that in the absence of the ligand, GR resided in the cytoplasm of breast cancer cells, while upon ligand activation, it translocated to the nucleus. A negative correlation was found between cytoplasmic GRtotal and Ki67 in luminal A tumours, while the opposite trend was observed in TNBC samples. Tumours with strong lymphoid infiltration showed higher cytoplasmic GRtotal staining compared to those with weaker infiltration. Patients with high nuclear GRtotal staining had shorter progression-free survival in univariate analysis. High cytoplasmic GRβ was a marker for better overall survival in multivariate analysis (10-year overall survival HR [95% CI]: 0.46 [0.22-0.95], p = 0.036). As a conclusions, this study is the first to investigate GRβ expression in breast tumours. Different expression and cellular localisation of GRtotal and GRβ were observed in the context of molecular subtypes, underscoring the complex role of GR in breast cancer. An inverse association between cytoplasmic GRtotal and the Ki67 proliferation index was observed in luminal A and TNBC. Regarding the impact of GR on outcomes in TNBC patients, while cytoplasmic GRβ was associated with a better prognosis, patients with nuclear GRtotal staining may be at a higher risk of disease progression, as it negatively affects survival. Caution should be exercised when using glucocorticoids in patients with nuclear GR staining, as it may negatively impact survival.

Olaparib monotherapy in advanced triple-negative breast cancer patients with homologous recombination deficiency and without germline mutations in BRCA1/2: The NOBROLA phase 2 study

PurposeTo evaluate olaparib in advanced triple negative breast cancer (TNBC) patients with homologous recombination deficiency (HRD) and no germline BRCA1/2 mutations (gBRCA1/2mut). MethodsNOBROLA (NCT03367689) is a single-arm, open-label, multicenter, phase IIa trial, enrolling adult patients with advanced TNBC without gBRCA1/2mut and with HRD, who were treated with olaparib. The primary endpoint was clinical benefit rate (CBR) per RECIST v.1.1. ResultsSix of 114 patients were eligible and received olaparib. Median follow up was 8.5 months. CBR and overall response rate (ORR) were 50 % (95 % CI, 11.8–88.2). ConclusionsThe observed results could prompt further investigation. TrialClinicalTrials.gov identifier NCT03367689.

A study of the role of androgen receptor and androgen receptor variant 7 in TNBC patients and the effect of their targeting by Enzalutamide and EPI-001 in MDA-MB-231

The lack of targeted therapy for triple-negative breast cancer (TNBC) is among the mainsprings of its poor prognosis. This study aimed to elucidate the role of the androgen receptor (AR) and its splice variant 7 (ARv7) in TNBC patients. Further, the molecular impact of their blockers, Enzalutamide and EPI-001, on the TNBC cell line MDA-MB-231 was investigated. Thereby, immunohistochemical expression of AR/ARv7 was assessed for TNBC Egyptian patients. Moreover, bioinformatics analysis of AR/ARv7 RNA status was carried out on TNBC patients from The Cancer Genome Atlas Breast Carcinoma project (TCGA-BRCA). Data from both groups was correlated with patients’ clinicopathological features. Besides, scratch wound healing assay and ELISA were employed to assess the effect of AR/ARv7 blockers on several metastasis markers in MDA-MB-231 cell line. In the Egyptian-TNBC patients, AR expression was associated with worse 7-year DFS (40.6±18.6%). In addition, ARv7 showed cytoplasmic and nuclear patterns, and both cytoplasmic and nuclear ARv7+ patients demonstrated a worse 7-year DFS (22.7±17.7% and 20±17.9%) and overall survival (63.6±14.5% and 40±21.8%). Importantly, 80% of the nuclear ARv7+ patients developed distant metastasis. The data of the TCGA-TNBC patients showed a tendency for poor outcomes in the high ARv7-expressing patients. Molecularly, in MDA-MB-231, both inhibitors modulated metastasis and epithelial to mesenchymal transition (EMT) markers ROCK1, ROCK2, c-Myc, E-cadherin and N-cadherin, with EPI-001 downregulating NF-ĸB level as well. We concluded that ARv7 indicated poor prognosis in the studied cohorts and that blocking of AR/ARv7 abated metastasis and key regulators of EMT in MDA-MB-231, at least in part by targeting ROCK/NF-ĸB/c-Myc axis.

Clinical Significance of FAM83G in Breast Cancer: Association With Triple-negative Subtype and Prognosis.

Family with sequence similarity 83 member G (FAM83G) plays an important role in cancer aggressiveness and patients' prognosis across various types of cancer. However, the association of FAM83G protein expression in breast cancer with clinicopathologic factors, breast cancer subtypes, and prognosis is not well characterized. This study aimed to elucidate the clinical significance of FAM83G protein expression in breast cancer. Immunohistochemistry was employed to examine FAM83G protein expression in 75 breast cancer tissues, assessing its potential as a biomarker for breast cancer patients. The Kaplan-Meier plotter was used to estimate the correlation between FAM83G mRNA expression and survival outcomes in TNBC patients. FAM83G protein was predominantly localized in the cytoplasm of breast cancer cells, exhibiting uniform expression throughout tumor tissues. FAM83G expression was significantly higher in cancerous areas compared to non-cancerous areas. High FAM83G expression was more prevalent in triple-negative breast cancer (TNBC) cases than in hormone receptor-positive cases. Although high FAM83G protein expression did not significantly impact prognosis in our cohort, a large-scale database analysis revealed an association between high FAM83G expression and poor prognosis in TNBC cases. This study demonstrates an association between high FAM83G expression in breast cancer tissues and TNBC. FAM83G may serve as a promising biomarker and therapeutic target for breast cancer patients.

Chaperonin‐containing TCP1 subunit 6A inhibition via TRIM21‐mediated K48‐linked ubiquitination suppresses triple‐negative breast cancer progression through the AKT signalling pathway

AbstractBackgroundTriple‐negative breast cancer (TNBC) is distinguished by a significant likelihood of distant recurrence and an unfavourable prognosis. However, the underlying molecules and mechanisms have not been fully elucidated.MethodsWe investigated the expression profile and clinical relevance of chaperonin‐containing TCP1 subunit 6A (CCT6A) in TNBC. We performed cell function assays on TNBC cells with CCT6A knockdown or overexpression. To further explore the mechanism of action of CCT6A, RNA sequencing and co‐immunoprecipitation–mass spectrometry analyses were utilized. Rescue and ubiquitination assays evaluated the impact of TRIM21‐mediated CCT6A ubiquitination and degradation on TNBC progression in vitro and in vivo. Finally, we studied the potential of Ipatasertib, a pharmacological AKT inhibitor, and/or anti‐PD1 therapy in inhibiting TNBC progression.ResultsElevated CCT6A expression in TNBC patients was associated with an adverse prognosis and lymph node metastasis. Mechanistically, CCT6A facilitated cell migration, invasion, epithelial‐mesenchymal transition and proliferation by activating the phosphatidylinositol 3‐kinase (PI3K)/AKT pathway. The TRIM21 RING domain is an E3 ligase, facilitating the K48‐linked ubiquitination‐mediated degradation of CCT6A, thereby impeding TNBC progression. Moreover, in the tumour tissues of the CCT6A‐overexpressing mice, the quantity of CD8+ T cells and the concentration of secreted interferon‐gamma were decreased, whereas in the group double‐overexpression of CCT6A and TRIM21, they were elevated; the opposite was observed in the knockdown and double‐knockdown groups. Ipatasertib demonstrated enhanced efficacy in inhibiting cell proliferation, invasion and migration in TNBC cells ectopically expressing CCT6A. When Ipatasertib and anti‐PD1 therapies were combined, both the tumour volume and mass exhibited a notable reduction, while the expression of CD45+CD8+ T cells increased, and that of CD45+CD4+CTLA4+ and CD45+CD4+PD1+ T cells decreased.ConclusionsOur findings indicate that TRIM21 inhibits TNBC progression by facilitating the K48‐linked ubiquitination‐mediated degradation of CCT6A via the PI3K/AKT signalling pathway. This highlights the potential of Ipatasertib and/or anti‐PD1 as therapeutic strategies, particularly for TNBC patients overexpressing CCT6A.Key points Chaperonin TCP1 subunit 6A (CCT6A) plays an oncogenic role in triple‐negative breast cancer (TNBC) through the AKT signaling pathway. TRIM21 facilitated K48‐linked ubiquitination‐mediated degradation of CCT6A, thereby impeding TNBC progression. Our study collectively underscores the potential of Ipatasertib in conjunction with anti‐PD1 therapy as a promising strategy to counteract CCT6A/AKT hyperactivity‐driven TNBC progression.

DHDH-mediated D-xylose metabolism induces immune evasion in triple-negative breast cancer.

Although the prognosis of triple-negative breast cancer (TNBC) has significantly improved in the era of immunotherapy, many TNBC patients are resistant to therapies, and their disease progresses rapidly. Deciphering the metabolic mechanisms regulating anticancer immunity will provide new insights into therapeutic strategies for TNBC. In this study, we performed bioinformatics analysis in our multi-omics TNBC database and identified that a metabolic enzyme, dihydrodiol dehydrogenase (DHDH), might promote the phenotype of "cold tumor" in TNBC. The biological function of DHDH was verified by invitro and invivo functional experiments, and the potential molecular mechanism of DHDH promoting TNBC immune escape was further explored. Mechanistically, DHDH mediated the synthesis and depletion of the substrate D-xylose and inhibited the activation of the proteasome subunit beta type 9 (PSMB9) and further induction of the immune response. We demonstrated that D-xylose supplementation could enhance the proliferation of CD8+ Tcells and the expression of cytotoxic markers against cocultured DHDH-wild type (WT) cells. Consistently, D-xylose supplementation invivo promoted CD8+ Tcell infiltration and the expression of cytotoxic markers and increased the sensitivity of DHDH-overexpressing tumors to immune checkpoint blockade (ICB). Our findings reveal that a D-xylose-regulated PSMB9-dependent pathway governs tumor-intrinsic immunogenicity and, hence, the sensitivity to ICB, which may provide approaches to promote the "cold-to-hot" transition in TNBC. This study was funded by the National Key Research and Development Plan of China, Shanghai Science and Technology Commission, National Natural Science Foundation of China, and China Postdoctoral Science Foundation.

Leveraging chemotherapy-induced PD-L1 upregulation to potentiate targeted PD-L1 degradation using nanoparticle-based targeting chimeras

The combination of nab-paclitaxel and the programmed death-ligand 1(PD-L1) antibody atezolizumab showed limited benefits in clinical trials involving PD-L1-positive triple-negative breast cancer patients. This observed lack of success is attributed to the upregulation of PD-L1 on tumor cells induced by paclitaxel, leading to resistance against PD-L1 antibodies. Here, we introduce nanoparticle-based PD-L1 targeting chimeras (NanoTACPD-L1) to induce PD-L1 degradation instead of blockade. NanoTACPD-L1 initiates endocytosis independent of specific lysosome-targeting receptors, and delivers membrane-bound PD-L1 to lysosomes for targeted degradation. Furthermore, the efficiency of degradation is directly correlated with the PD-L1 expression level. NanoTACPD-L1 effectively leverages paclitaxel-induced PD-L1 upregulation to enhance PD-L1 degradation, employing a “Meet-Plot-With-Plot” strategy. In a series of in vivo models, NanoTACPD-L1 demonstrates superior therapeutic efficacy and immune activation, both when administered individually and in combination with paclitaxel, surpassing the effects of anti-PD-L1 antibody treatment. Collectively, our study provides a nanotechnology-based tool that can be enhanced by paclitaxel for PD-L1 degradation and validates its potential application in overcoming chemo-immunotherapy resistance.

AXL/GAS6 signaling governs differentiation of tumor-associated macrophages in breast cancer

Most epithelial cancers are infiltrated by prognostically relevant myelomonocytic cells. Immunosuppressive tumor associated macrophages (TAMs) and their precursor monocytic-MDSCs have previously been associated with worse outcomes in human breast cancer (BCa), yet the mechanism of immunosuppressive TAMs-polarization from myelomonocytic precursors is not completely understood. In this study, we show that persuaded AXL/GAS6 pathway alters macrophage phenotype from HLA-DRhighCD206low CD163low classical phagocytic into HLA-DRlowCD206highCD163high immunosuppressive ones with accelerated BCa progression, and increased angiogenesis signature and invasion ability of cancer cells at tumor beds. Notably, both AXL and GAS6 expressions are upregulated in human invasive breast carcinoma, with maximum expression in triple negative histology type. Mechanistically, we demonstrate that AXL/GAS6 signaling drives immunosuppression by governing increased immunosuppressive IL10 production while dampening IL-1β expression within the tumor microenvironment (TME) of BCa. Further, AXL/GAS6 signaling promotes angiogenesis through the activation of PI3K/AKT and NF-κB signaling pathways. Our results unveil role of AXL/GAS6 axis in the differentiation of TAMs, which governs malignant growth, and suggest that therapies that uncouple AXL/GAS6 axis may exhibit therapeutic opportunity for otherwise undruggable Triple Negative Breast Cancer (TNBC) patients.