Triple-negative Breast Cancer Models Research Articles

Discovery of Pyrido[2,3-d]pyrimidin-7-one Derivatives as Highly Potent and Efficacious Ectonucleotide Pyrophosphatase/Phosphodiesterase 1 (ENPP1) Inhibitors for Cancer Treatment.

Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) is an extracellular enzyme responsible for hydrolyzing cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), the endogenous agonist for the stimulator of interferon genes (STING) pathway. Inhibition of ENPP1 can trigger STING and promote antitumor immunity, offering an attractive therapeutic target for cancer immunotherapy. Despite progress in the discovery of ENPP1 inhibitors, the diversity in chemical structures and the efficacy of the agents are far from desirable, emphasizing the demand for novel inhibitors. Herein, we describe the design, synthesis, and biological evaluation of a series of ENPP1 inhibitors based on the pyrido[2,3-d]pyrimidin-7-one scaffold. Optimization efforts led to compound 31 with significant potency in both ENPP1 inhibition and STING pathway stimulation in vitro. Notably, 31 demonstrated in vivo efficacy in a syngeneic 4T1 mouse triple negative breast cancer model. These findings provide a promising lead compound with a novel scaffold for further drug development in cancer immunotherapy.

Structural optimization of siRNA conjugates for albumin binding achieves effective MCL1-directed cancer therapy

The high potential of siRNAs to silence oncogenic drivers remains largely untapped due to the challenges of tumor cell delivery. Here, divalent lipid-conjugated siRNAs are optimized for in situ binding to albumin to improve pharmacokinetics and tumor delivery. Systematic variation of the siRNA conjugate structure reveals that the location of the linker branching site dictates tendency toward albumin association versus self-assembly, while the lipid hydrophobicity and reversibility of albumin binding also contribute to siRNA intracellular delivery. The lead structure increases tumor siRNA accumulation 12-fold in orthotopic triple negative breast cancer (TNBC) tumors over the parent siRNA. This structure achieves approximately 80% silencing of the anti-apoptotic oncogene MCL1 and yields better survival outcomes in three TNBC models than an MCL-1 small molecule inhibitor. These studies provide new structure-function insights on siRNA-lipid conjugate structures that are intravenously injected, associate in situ with serum albumin, and improve pharmacokinetics and tumor treatment efficacy.

S100A8/A9 predicts response to PIM kinase and PD-1/PD-L1 inhibition in triple-negative breast cancer mouse models

BackgroundUnderstanding why some triple-negative breast cancer (TNBC) patients respond poorly to existing therapies while others respond well remains a challenge. This study aims to understand the potential underlying mechanisms distinguishing early-stage TNBC tumors that respond to clinical intervention from non-responders, as well as to identify clinically viable therapeutic strategies, specifically for TNBC patients who may not benefit from existing therapies.MethodsWe conducted retrospective bioinformatics analysis of historical gene expression datasets to identify a group of genes whose expression levels in early-stage tumors predict poor clinical outcomes in TNBC. In vitro small-molecule screening, genetic manipulation, and drug treatment in syngeneic mouse models of TNBC were utilized to investigate potential therapeutic strategies and elucidate mechanisms of drug action.ResultsOur bioinformatics analysis reveals a robust association between increased expression of immunosuppressive cytokine S100A8/A9 in early-stage tumors and subsequent disease progression in TNBC. A targeted small-molecule screen identifies PIM kinase inhibitors as capable of decreasing S100A8/A9 expression in multiple cell types, including TNBC and immunosuppressive myeloid cells. Combining PIM inhibition and immune checkpoint blockade induces significant antitumor responses, especially in otherwise resistant S100A8/A9-high PD-1/PD-L1-positive tumors. Notably, serum S100A8/A9 levels mirror those of tumor S100A8/A9 in a syngeneic mouse model of TNBC.ConclusionsOur data propose S100A8/A9 as a potential predictive and pharmacodynamic biomarker in clinical trials evaluating combination therapy targeting PIM and immune checkpoints in TNBC. This work encourages the development of S100A8/A9-based liquid biopsy tests for treatment guidance.

CD24 negativity reprograms mitochondrial metabolism to PPARα and NF-κB-driven fatty acid β-oxidation in triple-negative breast cancer

CD24 is a well-characterized breast cancer (BC) stem cell (BCSC) marker. Primary breast tumor cells having CD24-negativity together with CD44-positivity is known to maintain high metastatic potential. However, the functional role of CD24 gene in triple-negative BC (TNBC), an aggressive subtype of BC, is not well understood. While the significance of CD24 in regulating immune pathways is well recognized in previous studies, the significance of CD24 low expression in onco-signaling and metabolic rewiring is largely unknown. Using CD24 knock-down and over-expression TNBC models, our in vitro and in vivo analysis suggest that CD24 is a tumor suppressor in metastatic TNBC. Comprehensive in silico gene expression analysis of breast tumors followed by lipidomic and metabolomic analyses of CD24-modulated cells revealed that CD24 negativity induces mitochondrial oxidative phosphorylation and reprograms TNBC metabolism toward the fatty acid beta-oxidation (FAO) pathway. CD24 silencing activates PPARα-mediated regulation of FAO in TNBC cells. Further analysis using reverse-phase protein array and its validation using CD24-modulated TNBC cells and xenograft models nominated CD24-NF-κB-CPT1A signaling pathway as the central regulatory mechanism of CD24-mediated FAO activity. Overall, our study proposes a novel role of CD24 in metabolic reprogramming that can open new avenues for the treatment strategies for patients with metastatic TNBC.

An inflamed tumor cell subpopulation promotes chemotherapy resistance in triple negative breast cancer

Individual cancers are composed of heterogeneous tumor cells with distinct phenotypes and genotypes, with triple negative breast cancers (TNBC) demonstrating the most heterogeneity among breast cancer types. Variability in transcriptional phenotypes could meaningfully limit the efficacy of monotherapies and fuel drug resistance, although to an unknown extent. To determine if transcriptional differences between tumor cells lead to differential drug responses we performed single cell RNA-seq on cell line and PDX models of breast cancer revealing cell subpopulations in states associated with resistance to standard-of-care therapies. We found that TNBC models contained a subpopulation in an inflamed cellular state, often also present in human breast cancer samples. Inflamed cells display evidence of heightened cGAS/STING signaling which we demonstrate is sufficient to cause tumor cell resistance to chemotherapy. Accordingly, inflamed cells were enriched in human tumors taken after neoadjuvant chemotherapy and associated with early recurrence, highlighting the potential for diverse tumor cell states to promote drug resistance.

High-nuclearity Luminescent Lanthanide Nanocages for Tumor Drug Delivery.

There is an unmet need for easy-to-visualize drug carriers that can deliver therapeutic cargoes deep into solid tumors. Herein, we report the preparation of ultrasmall luminescent imine-based lanthanide nanocages, Eu60 and Tb60 (collectively Ln60 ), designed to encapsulate anticancer chemotherapeutics for tumor therapy. The as-prepared nanocages possess large cavities suitable for the encapsulation of doxorubicin (DOX), yielding DOX@Ln60 nanocages with diameters around 5 nm. DOX@Ln60 are efficiently internalized by breast cancer cells, allowing the cells to be visualized via the intrinsic luminescent property of Ln(III). Once internalized, the acidic intracellular microenvironment promotes imine bond cleavage and the release of the loaded DOX. DOX@Ln60 inhibits DNA replication and triggers tumor cell apoptosis. In a murine triple negative breast cancer (TNBC) model, DOX@Ln60 was found to inhibit tumor growth with negligible side effects on normal tissues. It proved more effective than various controls, including DOX and Ln60 . The present nanocages thus point the way to the development of precise nanomedicines for tumor imaging and therapy.

High Intensity Focused Ultrasound-Driven Nanomotor for Effective Ferroptosis-Immunotherapy of TNBC.

The heterogeneity of triple-negative breast cancers (TNBC) remains challenging for various treatments. Ferroptosis, a recently identified form of cell death resulting from the unrestrained peroxidation of phospholipids, represents a potential vulnerability in TNBC. In this study, a high intensity focused ultrasound (HIFU)-driven nanomotor is developed for effective therapy of TNBC through induction of ferroptosis. Through bioinformatics analysis of typical ferroptosis-associated genes in the FUSCCTNBC dataset, gambogic acid is identified as a promising ferroptosis drug and loaded it into the nanomotor. It is found that the rapid motion of nanomotors propelled by HIFU significantly enhanced tumor accumulation and penetration. More importantly, HIFU not only actuated nanomotors to trigger effective ferroptosis of TNBC cells, but also drove nanomotors to activate ferroptosis-mediated antitumor immunity in primary and metastatic TNBC models, resulting in effective tumor regression and prevention of metastases. Overall, HIFU-driven nanomotors show great potential for ferroptosis-immunotherapy of TNBC.

Antibodies toward Na+,HCO3--cotransporter NBCn1/SLC4A7 block net acid extrusion and cause pH-dependent growth inhibition and apoptosis in breast cancer.

Na+,HCO3--cotransporter NBCn1/Slc4a7 accelerates murine breast carcinogenesis. Lack of specific pharmacological tools previously restricted therapeutic targeting of NBCn1 and identification of NBCn1-dependent functions in human breast cancer. We develop extracellularly-targeted anti-NBCn1 antibodies, screen for functional activity on cells, and evaluate (a) mechanisms of intracellular pH regulation in human primary breast carcinomas, (b) proliferation, cell death, and tumor growth consequences of NBCn1 in triple-negative breast cancer, and (c) association of NBCn1-mediated Na+,HCO3--cotransport with human breast cancer metastasis. We identify high-affinity (KD ≈ 0.14 nM) anti-NBCn1 antibodies that block human NBCn1-mediated Na+,HCO3--cotransport in cells, without cross-reactivity towards human NBCe1 or murine NBCn1. These anti-NBCn1 antibodies abolish Na+,HCO3--cotransport activity in freshly isolated primary organoids from human breast carcinomas and lower net acid extrusion effectively in primary breast cancer tissue from patients with macrometastases in axillary lymph nodes. Inhibitory anti-NBCn1 antibodies decelerate tumor growth in vivo by ~50% in a patient-derived xenograft model of triple-negative breast cancer and pH-dependently reduce colony formation, cause G2/M-phase cell cycle accumulation, and increase apoptosis of metastatic triple-negative breast cancer cells in vitro. Inhibitory anti-NBCn1 antibodies block net acid extrusion in human breast cancer tissue, particularly from patients with disseminated disease, and pH-dependently limit triple-negative breast cancer growth.

Abstract B031: Localized cytokine immunotherapy with a novel injectable hydrogel confers immune memory in murine triple negative breast cancer tumors

Abstract Introduction. Triple negative breast cancer (TNBC), representing 10-15% of all diagnosed breast cancer (BC) cases, is the most aggressive BC subtype and has higher recurrence rates and therapy resistance. It typically has an inflamed tumor microenvironment and relatively high tumor infiltrating lymphocyte levels. However, T cells are typically less activated compared to non-invasive BC. Hence, we hypothesize that local delivery of immunotherapeutics to activate and reinvigorate T cells can restore the anti-tumor immune response. To this end, we have developed an injectable delivery medium to effectively localize immune agonists to activate, expand, and reinvigorate T cells at the site of the tumor. Methods. The naturally occurring polysaccharide chitosan was crosslinked to form a novel injectable hydrogel (XCSgel). For in vivo tumor treatment, 2.5 × 105 E0771 murine breast cancer cells were implanted subcutaneously on the right flank of C57BL/6 mice. When tumors grew to be 50-100mm3, 5ug and 20ug of interleukin-12 (IL-12) co-formulated in 50uL of XCSgel was delivered intratumorally, with additional treatment groups of 5ug IL-12 in saline, XCSgel alone, and an untreated control. For re-challenge studies, 2.5 × 105 E0771 murine breast cancer cells were implanted subcutaneously on the left flank of mice, with a naïve cohort as a control. For the second tumor study to reinvigorate T cells in mice with larger tumor burdens, 5 × 105 E0771 murine breast cancer cells were implanted subcutaneously on the right flank of C57BL/6 mice. When tumors reach 100-150mm3, 5ug IL-12 in XCSgel, 20ug IL-10 in XCSgel, 5ug IL-12 + 20ug IL-10 in XCSgel, 5ug IL-12 + 20ug IL-10 in saline, and XCSgel will be delivered intratumorally, with an untreated control. Tumor sizes and Kaplan-Meier survival curves were/will be collected across all cohorts. All experiments involving laboratory animals were approved by the Institutional Animal Care and Use Committee at North Carolina State University. Results and Discussion. In the first tumor study, 5ug IL-12 in XCSgel eliminated tumors in 5/5 mice, while 20ug IL-12 in XCSgel eliminated tumors in 4/5 mice and IL-12 in saline eliminated 2/5 tumors. No tumor delay or elimination was observed in untreated and gel alone groups. Upon re-challenge, 5/5 mice in the 5ug IL-12 in XCSgel remained tumor-free over 40 days post-re-challenge, as did 3/4 of the 20ug in XCSgel and 2/2 in IL-12 saline treatment groups. The second intratumoral study is ongoing. Conclusions. A single injection of IL-12 formulated in a novel injectable hydrogel was found to eliminate tumors and stimulate immune memory in a murine triple negative breast cancer model. Results from localized IL-12 and IL-10 cytokine treatment of tumors with larger tumor burdens are ongoing. Given the ability of this localized immunotherapy to induce systemic antitumor immunity, it deserves further consideration as a neoadjuvant treatment prior to breast conserving surgery.Acknowledgements. This work is supported by the NSF Graduate Research Fellowship. Citation Format: Siena M Mantooth, David A Zaharoff. Localized cytokine immunotherapy with a novel injectable hydrogel confers immune memory in murine triple negative breast cancer tumors [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr B031.

Achieving anticancer peptides: Peptide-lipid interactions in triple negative breast cancer models

Achieving anticancer peptides: Peptide-lipid interactions in triple negative breast cancer models

Efficient Sequential Co-Delivery Nanosystem for Inhibition of Tumor and Tumor-Associated Fibroblast-Induced Resistance and Metastasis.

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer. However, the effect of current treatment strategies by inducing tumor cell apoptosis alone is not satisfactory. The growth, metastasis and treatment sensitivity of tumors can be strongly influenced by cancer-associated fibroblasts (CAFs) in the microenvironment. Effective cancer therapies may need to target not only the tumor cells directly but also the CAFs that protect them. Celastrol and small-sized micelles containing betulinic acid were co-encapsulated into liposomes using the thin-film hydration method (CL@BM). Folic acid was further introduced to modify liposomes as the targeting moiety (F/CL@BM). We established a novel NIH3T3+4T1 co-culture model to mimic the tumor microenvironment and assessed the nanocarrier's inhibitory effects on CAFs-induced drug resistance and migration in the co-culture model. The in vivo biological distribution, fluorescence imaging, biological safety evaluation, and combined therapeutic effect evaluation of the nanocarrier were carried out based on a triple-negative breast cancer model. In the present study, a novel multifunctional nano-formulation was designed by combining the advantages of sequential release, co-loading of tretinoin and betulinic acid, and folic acid-mediated active targeting. As expected, the nano-formulation exhibited enhanced cytotoxicity in different cellular models and effectively increased drug accumulation at the tumor site by disrupting the cellular barrier composed of CAFs by tretinoin. Notably, the co-loaded nano-formulations proved to be more potent in inhibiting tumor growth in mice and also showed better anti-metastatic effects in lung metastasis models compared to the formulations with either drug alone. This novel drug delivery system has the potential to be used to develop more effective cancer therapies. Targeting CAFs with celastrol sensitizes tumor cells to chemotherapy, increasing the efficacy of betulinic acid. The combination of drugs targeting tumor cells and CAFs may lead to more effective therapies against various cancers.

Abstract B032: Compromised TGFβ signaling and DNA repair primes response to immune checkpoint inhibition by activating NK cells in immunologically cold breast cancers

Abstract We investigated the interplay between immunosuppressive TGFβ signaling and immunogenic DNA repair in response to immune checkpoint inhibition (ICI) in a new model of breast cancer. Transforming growth factor beta (TGFβ) is a canonical suppressor. Cancer cells evade TGFβ either by selectively overcoming TGFβ proliferative barrier or completely shutting down signaling. Loss of TGFβ signaling is accompanied by high immunosuppressive TGFβ activity. We have shown that loss of TGFβ is critical to genomic integrity. It endorses classical DNA repair and inhibits error-prone repair. We described a score, βAlt, that reports the TGFβ/DNA repair functional relationship. Pan-cancer analysis showed that high βAlt cancers, in which the TGFβ target signature is low and DNA repair signature is high, use error-prone DNA repair, are sensitive to chemoradiation and have a greater fraction of the genome altered compared to low βAlt cancers, which maintain TGFβ signaling. We established a novel murine tumor derived transplant model (mTDT) of triple-negative breast cancer, similar to a human PDX, in immunocompetent BALB/cJ mice. Transcriptomics analysis showed that mTDT range from high to low βAlt and from immune poor to immune rich, which was confirmed by multiplex immunstaining. Unsupervised clustering of mTDT based on βAlt score demonstrated that low βAlt was associated with immune rich tumors while high βAlt was associated with immune poor tumors. A similar relationship is evident in the TCGA breast cancers. We then asked how mTDT respond to ICI. Mice bearing mTDT were randomized to monotherapy consisting of single fraction 10 Gy radiation, anti-PD-L1 or TGFβ inhibition, dual or triple treatment. Neither anti-PD-L1 or TGFβ inhibition affected survival, alone or in combination, whereas radiation significantly increased survival. Unexpectedly immune poor, high βAlt mTDT were the most responsive. To evaluate biological correlates, mice were stratified as a function of treatment as responders, in which tumor growth was controlled for 7 days post-treatment, or non-responders, in which tumor growth was uncontrolled. Tumor infiltrating CD45+ cells increased (P=0.02) as did circulating CD8 T cells (P<0.001) in responders. Natural killer (NK) cells were also significantly expanded in responders (P<0.001). TGFβ broadly downregulates chemokine receptor expression necessary to recruit NK cells and impairs NK cell cytotoxic effector function. We depleted NK cells to test whether they were necessary for the pronounced response to triple treatment. NK depletion was completely abrogated response (P<0.00001) indicating NK cells can provoke an ICI response in high βAlt mammary tumors devoid of lymphocytes. This preclinical model and human breast cancer shows that loss of TGFβ signaling resulting in error-prone DNA damage response is strongly associated with immune poor tumors, and suggests that TGFβ inhibition can override NK cell dysfunction to create vulnerability to ICI and anti-tumor immunity. Citation Format: Jade Moore, Jim Gkantalis, Ines Guix, Colin Foster, Mary Helen Barcellos-Hoff. Compromised TGFβ signaling and DNA repair primes response to immune checkpoint inhibition by activating NK cells in immunologically cold breast cancers [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr B032.

Anti-cathepsin D immunotherapy triggers both innate and adaptive anti-tumour immunity in breast cancer.

Triple-negative breast cancer (TNBC) has poorer outcomes than other breast cancers (BC), including HER2+ BC. Cathepsin D (CathD) is a poor prognosis marker overproduced by BC cells, hypersecreted in the tumour microenvironment with tumour-promoting activity. Here, we characterized the immunomodulatory activity of the anti-CathD antibody F1 and its improved Fab-aglycosylated version (F1M1) in immunocompetent mouse models of TNBC (C57BL/6 mice harbouring E0771 cell grafts) and HER2-amplified BC (BALB/c mice harbouring TUBO cell grafts). CathD expression was evaluated by western blotting and immunofluorescence, and antibody binding to CathD by ELISA. Antibody anti-tumour efficacy was investigated in mouse models. Immune cell recruitment and activation were assessed by immunohistochemistry, immunophenotyping, and RT-qPCR. F1 and F1M1 antibodies remodelled the tumour immune landscape. Both antibodies promoted innate antitumour immunity by preventing the recruitment of immunosuppressive M2-polarized tumour-associated macrophages (TAMs) and by activating natural killer cells in the tumour microenvironment of both models. This translated into a reduction of T-cell exhaustion markers in the tumour microenvironment that could be locally supported by enhanced activation of anti-tumour antigen-presenting cell (M1-polarized TAMs and cDC1 cells) functions. Both antibodies inhibited tumour growth in the highly-immunogenic E0771 model, but only marginally in the immune-excluded TUBO model, indicating that anti-CathD immunotherapy is more relevant for BC with a high immune cell infiltrate, as often observed in TNBC. Anti-CathD antibody-based therapy triggers the anti-tumour innate and adaptive immunity in preclinical models of BC and is a promising immunotherapy for immunogenic TNBC.

Injectable Nano-in-Gel Vaccine for Spatial and Temporal Control of Vaccine Kinetics and Breast Cancer Postsurgical Therapy.

Breast cancer is the most commonly diagnosed cancer, and surgical resection is the first choice for its treatment. With the development of operation techniques, surgical treatment for breast cancer is evolving toward minimally invasive and breast-conserving approaches. However, breast-conserving surgery is prone to an increased risk of cancer recurrence and is becoming a key challenge that needs to be solved. In this study, we introduce a one-shot injectable nano-in-gel vaccine (NIGel-Vax) for postoperative breast cancer therapy. The NIGel-Vax was constructed by mixing protein antigens with PEI-4BImi-Man adjuvant and then encapsulated in a hydrogel made with oxidized dextran (ODEX) and 4-arm PEG-ONH2. Using 4T1 tumor-extracted proteins as antigen, the NIGel-Vax achieved a 92% tumor suppression rate and a 33% cure rate as a postoperative therapy in the 4T1 tumor model. Using the tumor-associated antigen trophoblast cell-surface antigen 2 (TROP2) protein as the antigen, NIGel-Vax achieved a 96% tumor suppression rate and a 50% cure rate in triple-negative breast cancer (TNBC) models. This design provides an encouraging approach for breast cancer postoperative management.

NUPR1 packaged in extracellular vesicles promotes murine triple-negative breast cancer in a type 1 interferon-independent manner.

This study aims to elucidate the involvement of triple-negative breast cancer (TNBC)-derived extracellular vesicles in metastasis. The loss of components in the type 1 interferon (IFN1) signaling pathway has been linked to the promotion of metastasis. However, IFN1 signaling induces immunological dormancy and promotes tumorigenesis. Our hypothesis was that TNBC cells release tumor-derived extracellular vesicles (TEVs) that promote metastasis in an IFN1-independent manner. Two murine TNBC models and transgenic mice were used to examine the role of IFN1 in TNBC progression to metastasis. Reserpine was employed to determine the effect of TEV education on TNBC progression and overall survival. EVs from cancer cells treated with vehicle and reserpine and from the serum of tumor-bearing mice receiving reserpine were examined to determine changes in EV release and EV content. TNBC cells progress to metastasis in mice lacking the IFN1-induced gene cholesterol-25 hydroxylase (CH25H) or expressing the IFNAR1S526 knock-in that cannot be downregulated. Reserpine suppresses EV release from TNBC cells in vitro and in vivo. Western blot analysis demonstrated reserpine decreased NUPR1 protein levels in EVs. RNAseq analysis demonstrated that endothelial cells lacking CH25H treated with TEVs exhibited increased NUPR1 expression that was decreased by adding reserpine with the TEVs. NUPR1 overexpression upregulated genes that mediate TEV biogenesis and incorporation. Knockdown of NUPR1 with shRNA decreased the release of TEVs. In conclusion, our study suggests that TNBC is driven by aberrant packaging of NUPR1 into TEVs which were transferred into recipient cells to activate pro-metastatic transcription driven by NUPR1.

Enhancing therapeutic efficacy in triple-negative breast cancer and melanoma: synergistic effects of modulated electro-hyperthermia (mEHT) with NSAIDs especially COX-2 inhibition in in vivo models.

Triple-negative breast cancer (TNBC) is a leading cause of cancer mortality and lacks modern therapy options. Modulated electro-hyperthermia (mEHT) is an adjuvant therapy with demonstrated clinical efficacy for the treatment of various cancer types. In this study, we report that mEHT monotherapy stimulated interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) expression, and consequently cyclooxygenase 2 (COX-2), which may favor a cancer-promoting tumor microenvironment. Thus, we combined mEHT with nonsteroid anti-inflammatory drugs (NSAIDs): a nonselective aspirin, or the selective COX-2 inhibitor SC236, in vivo. We demonstrate that NSAIDs synergistically increased the effect of mEHT in the 4T1 TNBC model. Moreover, the strongest tumor destruction ratio was observed in the combination SC236 + mEHT groups. Tumor damage was accompanied by a significant increase in cleaved caspase-3, suggesting that apoptosis played an important role. IL-1β and COX-2 expression were significantly reduced by the combination therapies. In addition, a custom-made nanostring panel demonstrated significant upregulation of genes participating in the formation of the extracellular matrix. Similarly, in the B16F10 melanoma model, mEHT and aspirin synergistically reduced the number of melanoma nodules in the lungs. In conclusion, mEHT combined with a selective COX-2 inhibitor may offer a new therapeutic option in TNBC.

Preclinical evaluation of the theranostic potential of 89Zr/177Lu-labeled anti-TROP-2 antibody in triple-negative breast cancer model

BackgroundTriple-negative breast cancer (TNBC) is one of the most lethal malignant tumors among women, characterized by high invasiveness, high heterogeneity, and lack of specific therapeutic targets such as estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Trophoblast cell-surface antigen-2 (TROP-2) is a transmembrane glycoprotein over-expressed in 80% of TNBC patients and is associated with the occurrence, progress, and poor prognosis of TNBC. The TROP-2 targeted immunoPET imaging allows non-invasive quantification of the TROP-2 expression levels of tumors, which could help to screen beneficiaries most likely to respond to SG and predict the response. This study aimed to develop a 89Zr/177Lu-radiolabeled anti-TROP-2 antibody (NY003) for immunoPET and SPECT imaging, as well as radioimmunotherapy (RIT) in TROP-2 (+)TNBC tumor-bearing model. Based on the camelid antibody, we developed a TROP-2 targeted recombinant antibody NY003. NY003 was conjugated with DFO and DTPA for 89Zr and 177Lu radiolabelling, respectively. The theranostic potential of [89Zr]Zr-DFO-NY003/[177Lu]Lu-DTPA-NY003 was evaluated through immunoPET, SPECT imaging, and RIT studies in the subcutaneous TROP-2 positive TNBC xenograft mice model.ResultsThe high binding affinity of NY003 to TROP-2 was verified through ELISA. The radiochemical purity of [89Zr]Zr-DFO-NY003/[177Lu]Lu-DTPA-NY003 exceeded 95% and remained stable within 144h p.i. in vitro. ImmunoPET and SPECT imaging showed the specific accumulation of [89Zr]Zr-DFO-NY003/[177Lu]Lu-DTPA-NY003 in MDA-MB-231 tumors and gradually increased with the time tested, significantly higher than that in control groups (P < 0.05). The strongest anti-tumor efficacy was observed in the high-dose of [177Lu]Lu-DTPA-NY003 group, followed by the low-dose group, the tumor growth was significantly suppressed by [177Lu]Lu-DTPA-NY003, the tumor volumes of both high- and low-dose groups were smaller than the control groups (P < 0.05). Ex vivo biodistribution and histological staining verified the results of in vivo imaging and RIT studies.ConclusionAs a drug platform for radiotheranostics, 89Zr/177Lu-radiolabeled anti-TROP-2 antibody NY003 could not only non-invasively screen the potential beneficiaries for optimizing SG ADC treatment but also suppressed the growth of TROP-2 positive TNBC tumors, strongly supporting the theranostic potential of [89Zr]Zr-DFO-NY003/[177Lu]Lu-DTPA-NY003.

Digoxin-Mediated Inhibition of Potential Hypoxia-Related Angiogenic Repair in Modulated Electro-Hyperthermia (mEHT)-Treated Murine Triple-Negative Breast Cancer Model.

Triple-negative breast cancer (TNBC) is a highly aggressive breast cancer type with no targeted therapy and hence limited treatment options. Modulated electrohyperthermia (mEHT) is a novel complementary therapy where a 13.56 MHz radiofrequency current targets cancer cells selectively, inducing tumor damage by thermal and electromagnetic effects. We observed severe vascular damage in mEHT-treated tumors and investigated the potential synergism between mEHT and inhibition of tumor vasculature recovery in our TNBC mouse model. 4T1/4T07 isografts were orthotopically inoculated and treated three to five times with mEHT. mEHT induced vascular damage 4-12 h after treatment, leading to tissue hypoxia detected at 24 h. Hypoxia in treated tumors induced an angiogenic recovery 24 h after the last treatment. Administration of the cardiac glycoside digoxin with the potential hypoxia-inducible factor 1-α (HIF1-α) and angiogenesis inhibitory effects could synergistically augment mEHT-mediated tumor damage and reduce tissue hypoxia signaling and consequent vascular recovery in mEHT-treated TNBC tumors. Conclusively, repeated mEHT induced vascular damage and hypoxic stress in TNBC that promoted vascular recovery. Inhibiting this hypoxic stress signaling enhanced the effectiveness of mEHT and may potentially enhance other forms of cancer treatment.

Characterization of immunomodulating agents from Staphylococcus aureus for priming immunotherapy in triple-negative breast cancers

Immunotherapy, specifically immune checkpoint blockade (ICB), has revolutionized the treatment paradigm of triple-negative breast cancers (TNBCs). However, a subset of TNBCs devoid of tumor-infiltrating T cells (TILs) or PD-L1 expression generally has a poor response to immunotherapy. In this study, we aimed to sensitize TNBCs to ICB by harnessing the immunomodulating potential of S. aureus, a breast-resident bacterium. We show that intratumoral injection of spent culture media from S. aureus recruits TILs and suppresses tumor growth in a preclinical TNBC model. We further demonstrate that α-hemolysin (HLA), an S. aureus-produced molecule, increases the levels of CD8+ T cells and PD-L1 expression in tumors, delays tumor growth, and triggers tumor necrosis. Mechanistically, while tumor cells treated with HLA display Gasdermin E (GSDME) cleavage and a cellular phenotype resembling pyroptosis, splenic T cells incubated with HLA lead to selective expansion of CD8+ T cells. Notably, intratumoral HLA injection prior to ICB augments the therapeutic efficacy compared to ICB alone. This study uncovers novel immunomodulatory properties of HLA and suggests that intratumoral administration of HLA could be a potential priming strategy to expand the population of TNBC patients who may respond to ICB.

Adoptive cell transfer therapy with ex vivo primed peripheral lymphocytes in combination with anti-PDL1 therapy effectively inhibits triple-negative breast cancer growth and metastasis

BackgroundAdoptive cell transfer cancer immunotherapy holds promise for treating disseminated disease, yet generating sufficient numbers of lymphocytes with anti-cancer activity against diverse specificities remains a major challenge. We recently developed a novel procedure (ALECSAT) for selecting, expanding and maturating polyclonal lymphocytes from peripheral blood with the capacity to target malignant cells.MethodsImmunodeficient mice were challenged with triple-negative breast cancer cell lines or patient-derived xenografts (PDX) and treated with allogeneic or autologous ALECSAT cells with and without anti-PDL1 therapy to assess the capacity of ALECSAT cells to inhibit primary tumor growth and metastasis.ResultsALECSAT mono therapy inhibited metastasis, but did not inhibit primary tumor growth or prolong survival of tumor-bearing mice. In contrast, combined ALECSAT and anti-PDL1 therapy significantly inhibited primary tumor growth, nearly completely blocked metastasis, and prolonged survival of tumor-bearing mice.ConclusionsCombined ALECSAT and anti-PDL1 therapy results in favorable anti-cancer responses in both cell line-derived xenograft and autologous PDX models of advanced triple-negative breast cancer.