UNASSIGNED: PD-1/PD-L1 immune checkpoint blockade can be an effective treatment for advanced breast cancer patients. However, patients with oestrogen receptor positive (ER+) tumors often display only low lymphocyte infiltration, while a large part of triple negative (TN) breast tumors does not generate an effective immunotherapy response. Therefore, new treatment strategies have to be developed. Here, we investigate Siglec-7 and Siglec-9 as novel ITIM-bearing inhibitory immune checkpoint receptors similar to PD-1, but expressed on a broader range of immune cells.
UNASSIGNED: We assessed Siglec-7 and Siglec-9 (ligand) expression in TN and ER+ breast cancer tumors and their breast cancer cell line-induced signalling.
UNASSIGNED: We report that Siglec-7 and Siglec-9 are highly expressed in TN tumors, and to a low extent in ER+ tumors. Siglec-7 was observed on myeloid cells, T cells, and NK cells and Siglec-9 preferentially on myeloid cells. Expression of sialoglycans, including Siglec-7 and Siglec-9 ligands, was observed in both TN and ER+ breast cancer tissue sections. Expression levels of Siglec-7 and Siglec-9 ligands were higher on in vitro cultured TN cell lines than ER+ cell lines. Importantly, by applying chimeric Siglec-7 reporter cells, we showed the induction of Siglec-7 signalling by multiple TN cell lines, but only by one ER+ cell line. Moreover, Siglec-7 signalling is directly related to Siglec-7 ligand expression levels of breast cancer cell lines.
UNASSIGNED: These data imply that immunotherapy targeting Siglec receptors may be particularly interesting for TN breast cancer patients not responding to current treatment strategies with tumors displaying high immune cell infiltration.

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

Triple-negative breast cancer (TNBC) is characterised by the lack or low expression of estrogen, progesterone, and human epidermal growth factor receptor 2 receptors. TNBC has a high recurrence rate, swiftly metastasizes, and has a high mortality rate. Subsequently, the increase in cases of TNBC has signaled the need for treatment strategies with improved drug delivery systems. New diagnostic approaches, chemical entities, formulations particular those in the nanometric range have emerged after extensive scientific research as alternative strategies for TNBC treatment. As compared to contemporary cancer therapy, nanoparticles offer peculiar tunable features namely small size, shape, electrical charge, magnetic and fluorescent properties. Specifically in targeted drug delivery, nanoparticles have been demonstrated to be highly efficient in encapsulating, functionalization, and conjugation. Presently, nanoparticles have ignited and transformed the approach in photodynamic therapy, bioimaging, use of theranostics and precision medicine delivery in breast cancer. Correspondingly, recent years have witnessed a drastic rise in literature pertaining to treatment of TNBC using nanomaterials. Subsequently, this manuscript aims to present a state-of-the-art of nanomaterials advance on TNBC treatment; the ubiquitous utility use of nanomaterials such as liposomes, dendrimers, solid lipid nanomaterials, gold nanomaterials and quantum dots as anticancer agents and drug delivery systems in TNBC.

OBJECTIVE: Triple-negative breast cancer (TNBC) is the deadliest subtype of breast cancer (BC). Tumor-derived extracellular vesicles (EVs) trigger tumor progression by promoting M2 polarization. Some lncRNAs can be encapsulated into EVs for intercellular communication. Herein, we investigated the mechanism of TNBC-derived EV-shuttled lncRNA MALAT1 on macrophage polarization/tumorigenesis.
METHODS: BC-associated targeted EV-derived lncRNAs were screened. Tumor tissues/tissues adjacent to cancer of TNBC patients, and blood samples of all subjects were collected. MALAT1/POSTN mRNA levels in tumor tissues/tissues adjacent to cancer, and MALAT1 expression in EVs and its correlation with TNBC patient overall survival were assessed by RT-qPCR/Kaplan-Meier survival analysis/log-rank test. TNBC patient M2 infiltration was detected by flow cytometry. MALAT1/POSTN levels in EVs/macrophages were regulated by transfection. Hippo/YAP activation was determined by Western blot. Nude mouse xenograft model was established and metastasis was detected by H&E staining.
RESULTS: MALAT1/POSTN were up-regulated and correlated with M2 infiltration/poor prognosis in TNBC patients. TNBC-derived EVs induced M2 polarization. MALAT1 was highly expressed in TNBC-derived EVs and could be transferred to macrophages via EVs to induce M2 polarization. POSTN overexpression diminished the inhibitory effect of MALAT1 knockdown on M2 markers. EVs activated the Hippo/YAP pathway in macrophages. The Hippo/YAP pathway inhibition abrogated the effect of POSTN overexpression on M2 marker expression. TNBC-EV-derived MALAT1 facilitated M2 polarization, and thus promoting occurrence and metastasis of TNBC in vitro and in vivo.
CONCLUSIONS: TNBC-EV-derived MALAT1 activated the Hippo/YAP axis by up-regulating POSTN, thereby inducing M2 polarization to promote TNBC occurrence and metastasis in vivo.

Radiotherapy (RT) is one of major therapeutic modalities in combating breast cancer. In RT, ionizing radiation is employed to induce DNA double-strand breaks (DSBs) as a primary mechanism that causes cancer cell death. However, the induced DNA damage can also trigger the activation of DNA repair mechanisms, reducing the efficacy of RT treatment. Given the pivotal role of RAD50 protein in the radiation-responsive DNA repair pathways involving DSBs, we developed a novel polymer-lipid based nanoparticle formulation containing RAD50-silencing RNA (RAD50-siRNA-NPs) and evaluated its effect on the RAD50 downregulation as well as cellular and tumoral responses to ionizing radiation using human triple-negative breast cancer as a model. The RAD50-siRNA-NPs successfully preserved the activity of the siRNA, facilitated its internalization by cancer cells via endocytosis, and enabled its lysosomal escape. The nanoparticles significantly reduced RAD50 expression, whereas RT alone strongly increased RAD50 levels at 24 h. Pretreatment with RAD50-siRNA-NPs sensitized the cancer cells to RT with ∼2-fold higher level of initial DNA DSBs as determined by a γH2AX biomarker and a 2.5-fold lower radiation dose to achieve 50 % colony reduction. Intratumoral administration of RAD50-siRNA-NPs led to a remarkable 53 % knockdown in RAD50. The pretreatment with RAD50-siRNA-NPs followed by RT resulted in approximately a 2-fold increase in DNA DSBs, a 4.5-fold increase in cancer cell apoptosis, and 2.5-fold increase in tumor growth inhibition compared to RT alone. The results of this work demonstrate that RAD50 silencing by RAD50-siRNA-NPs can disrupt RT-induced DNA damage repair mechanisms, thereby significantly enhancing the radiation sensitivity of TNBC MDA-MB-231 cells in vitro and in orthotopic tumors as measured by colony forming and tumor regrowth assays, respectively.

Breast cancer is one of the most common malignant tumors in women in the world, and its incidence is increasing year by year, which seriously threatens the physical and mental health of women. Triple negative breast cancer (TNBC) is a special molecular type of breast cancer in which estrogen receptor, progesterone receptor and human epidermal growth factor receptor-2 are negative. Compared with other molecular types of breast cancer, triple-negative breast cancer (TNBC) has high aggressiveness and metastasis, high recurrence rate, lack of effective therapeutic targets, and usually poor clinical treatment effect. Chemotherapy was the main therapeutic means used in the past. With the advent of the immune era, immunotherapy has made a lot of progress in the treatment of triple-negative breast cancer (TNBC), bringing new therapeutic hope for the treatment of triple-negative breast cancer. This review combines the results of cutting-edge medical research, mainly summarizes the research progress of immunotherapy, and summarizes the main treatment methods of triple-negative breast cancer (TNBC) immunotherapy, including immune checkpoint inhibitors, tumor vaccines, adoptive immunotherapy and the application of traditional Chinese and western medicine. It provides a new idea for the treatment of triple negative breast cancer (TNBC).

BACKGROUND: Older breast cancer patients represent a heterogeneous population. Studies demonstrate that sentinel lymph node biopsy (SLNB) omission may be appropriate in some clinical scenarios, yet patients with triple-negative breast cancer (TNBC) are often excluded from these studies. This study evaluated differences in treatment and survival for older patients with TNBC based on SLNB receipt and result.
METHODS: Patients 70 years old or older with a diagnosis of cT1-2/cN0/M0 TNBC (2010-2019) who underwent surgery were selected from the National Cancer Database. Logistic regression estimated the association of SLNB with therapy, and Cox proportional hazards models estimated the association of SLNB with overall survival (OS) after adjustment for select factors.
RESULTS: Of the 15,167 patients included in the study (median age, 77 years), 13.02% did not undergo SLNB, 5.14% had pN1 disease, 0.12% had pN2 disease, and 0.01% had pN3 disease. Most of the patients (83.9%) underwent surgery first, and 16.1% received neoadjuvant chemotherapy. Of those who underwent surgery first and SLNB, 6.2% had pN+ disease. Receipt of SLNB was associated with a higher likelihood of chemotherapy (odds ratio [OR] 1.85; 95% confidence interval [CI] 1.55-2.21), regardless of pN status. Compared with those who did not undergo a SLNB, a negative SLNB was significantly associated with lower mortality (hazard ratio [HR] 0.68; 95% CI 0.63-0.75), although there was no difference for a positive SLNB (HR 1.14; 95% CI 0.98-1.34). The patients receiving chemotherapy first showed no difference in survival based on SLNB receipt or result (p = 0.23).
CONCLUSIONS: Most older patients with TNBC do not have nodal involvement and do not receive chemotherapy. The receipt and results of SLNB may be associated with outcomes for some who undergo surgery first, but not for those who receive neoadjuvant chemotherapy.

BACKGROUND: Pembrolizumab combined with neoadjuvant chemotherapy (NAC) is the current standard of care in early stage triple-negative breast cancer (TNBC) based on higher event-free survival and pathological complete response (pCR) in Keynote-522 (KN-522) clinical trial. However, this aggressive five-drug regimen is associated with increased risks for immune-related adverse events (irAEs). We investigated real-world clinical outcomes and toxicity of this regimen as well as factors predictive of pCR and irAEs.
METHODS: We identified and abstracted data from 153 early-stage TNBC patients treated with the KN-522 regimen between July 1, 2021, and December 31, 2023, at 4 academic institutions in the U.S. Descriptive analysis was conducted, univariate and multivariate analyses were performed to identify factors associated with pCR and irAEs.
RESULTS: The median age was 52 years (interquartile range, 42-60years), with 66% White and 24% Black patients with stage I/II (67%), node-negative disease (58%), grade 3 (86%) tumors, and ≥1 comorbidities (68%). Approximately 21% discontinued pembrolizumab, because of toxicity; ∼50% received a lower relative dose intensity (RDI) of chemotherapy (dose reduction or discontinuation). Of the 153 patients, 99 (64.7%) achieved pCR and 83 (54%) experienced an irAE, with 18 (12%) having ≥ grade 3 irAE. The majority (90%) of the irAEs were observed during neoadjuvant phase. Stage I/II versus stage III disease (OR 1.55, CI 1.04-2.33, P = .03), age (OR 0.96, CI 0.93-0.99, P = .01) and full versus reduced RDI of NAC (OR 1.53, CI 1.04-2.26, P = .03) were associated with higher pCR rates on multivariate analyses. Fewer cycles of pembrolizumab were associated with a higher likelihood of irAEs (OR 1.52, CI 1.07-2.16, P = .02), likely explained by the early discontinuation and receipt of less than 8 cycles of pembrolizumab in patients who experienced irAEs.
CONCLUSIONS: Our study validates the clinical efficacy of KN-522 regimen; however, we observed a higher incidence of irAEs (54%) in this real-world population. Lower stage and younger age were associated with higher likelihood of achieving pCR. Toxicity-related chemotherapy dose reduction or discontinuation was observed to adversely impact the likelihood of achieving pCR.

OBJECTIVE: Matrix metalloproteinase-2 (MMP-2) has been implicated in the pathogenesis of breast cancer (BC). However, there is limited research on the role of MMP-2 genotypes in BC risk. This study aimed to investigate the associations between two MMP-2 promoter polymorphisms, rs243865 and rs2285053, and BC risk.
METHODS: MMP-2 genotypes were analyzed using PCR-based RFLP methodology in a cohort comprising 1,232 BC cases and 1,232 controls.
RESULTS: Genotypic frequencies of MMP-2 rs243865 and rs2285053 in controls were consistent with Hardy-Weinberg equilibrium (p=0.3702 and 0.2036, respectively). There were no significant differences in the distribution of rs243865 and rs2285053 genotypes between BC cases and controls (p for trend=0.1602 and 0.2170, respectively). Variant genotypes at rs243865 and rs2285053 appeared to confer a protective effect, although not statistically significant (all p>0.05). Similarly, the variant T allele at rs243865 and rs2285053 showed a non-significant trend towards decreased BC risk (OR=0.84 and 0.89, 95%CI=0.69-1.02 and 0.78-1.02, p=0.0811 and 0.1043, respectively). There was no interaction observed between MMP-2 rs243865 or rs2285053 genotypes and age. Stratified analysis did not reveal significant associations between MMP-2 rs243865 or rs2285053 genotypes and triple-negative breast cancer (TNBC) (p=0.6458 and 0.8745, respectively). Among both TNBC and non-TNBC cases, none of the variant genotypes at rs243865 or rs2285053 showed significant associations with TNBC (all p>0.05).
CONCLUSIONS: MMP-2 rs243865 and rs2285053 genotypes appear to have a minimal impact on individual susceptibility to BC or TNBC.

In breast cancer, triple negative (TN) breast cancer has most responses to immune checkpoint inhibitor (ICI) therapy. Lymphocyte infiltrate does not impact prognosis in Hormone receptor positive HER2 negative (HR + HER2-) breast tumors and few HR + HER2- tumors respond to ICI. We contrasted immune-associated gene expression between 119 TN and 475 HR + HER2- breast tumors from The Cancer Genome Atlas (TCGA) and confirmed our findings in 299 TN and 1369 HR + HER2- breast tumors in the METABRIC database. TN and HR+ HER2- tumors grouped into immune-high or -low tumors, both subtypes were represented in the immune-high group. The largest difference between the immune-high TN and HR + HER2- tumors was TN tumors had more abundant Th1 and Th2 CD4+ T cells while HR + HER2- tumors had more abundant fibroblasts (log2FC > 0.3; p < 10×10-10). This suggests an immune-high signature is not dictated by breast cancer subtype, but fibroblast subsets associated with worse outcome were higher in the immune-high HR + HER2- tumors.