Triple-negative Breast Cancer Models Research Articles

Evaluating immunotherapeutic outcomes in triple-negative breast cancer with a cholesterol radiotracer in mice.

Evaluating the response to immune checkpoint inhibitors (ICIs) remains an unmet challenge in triple-negative breast cancer (TNBC). The requirement for cholesterol in the activation and function of T cells led us to hypothesize that quantifying cellular accumulation of this molecule could distinguish successful from ineffective checkpoint immunotherapy. To analyze accumulation of cholesterol by T cells in the immune microenvironment of breast cancer, we leveraged the PET radiotracer, eFNP-59. eFNP-59 is an analog of cholesterol that our group validated as an imaging biomarker for cholesterol uptake in preclinical models and initial human studies. In immunocompetent mouse models of TNBC, we found that elevated uptake of exogenous labeled cholesterol analogs functions as a marker for T cell activation. When comparing ICI-responsive and -nonresponsive tumors directly, uptake of fluorescent cholesterol and eFNP-59 increased in T cells from ICI-responsive tumors. We discovered that accumulation of cholesterol by T cells increased in ICI-responding tumors that received anti-PD-1 checkpoint immunotherapy. In patients with TNBC, tumors containing cycling T cells had features of cholesterol uptake and trafficking within those populations. These results suggest that uptake of exogenous cholesterol analogs by tumor-infiltrating T cells allows detection of T cell activation and has potential to assess the success of ICI therapy.

Vitamin D suppresses CD133+/CD44 + cancer stem cell stemness by inhibiting NF-κB signaling and reducing NLRP3 expression in triple-negative breast cancer.

This study aims to investigate the role of Vitamin D (VD) in regulating the stemness and survival of CD133+/CD44 + breast cancer stem cells, and to explore the role of NLRP3 in this process. Breast cancer tissues were collected for RXRα and VDR expression analysis. A triple-negative breast cancer cell line was cultured and stem-like cells (CD133 + CD44+) isolated using flow cytometry. These cells were treated with VD, analyzing their stem-like properties, apoptosis and proliferation, as well as P65 nuclear expression and NLRP3 expression. After NLRP3 inflammasome activator treatment, the parameters were reassessed. RXRα and VDR interaction was confirmed using co-immunoprecipitation (CoIP). Finally, a subcutaneous xenograft model of triple-negative breast cancer was treated with VD and subsequently analyzed for stem-like properties, proliferation, apoptosis, and NLRP3 expression levels. CD133+/CD44 + stem cells expressed high levels of SOX2 and OCT4. VD treatment resulted in a significant decrease in SOX2 and OCT4 expression, fewer sphere-forming colonies, lower proliferation ability, and more apoptosis. Additionally, VD treatment inhibited NF-κB signaling and reduced NLRP3 expression. The NLRP3 activator BMS-986,299 counteracted the effects of VD in vitro. In vivo, VD inhibited the growth of breast cancer stem cells, reducing both tumor volume and weight, and decreased NLRP3, SOX2, and OCT4 expression within tumor tissues. Findings elucidate that VD mediates the modulation of stemness in CD133+/CD44 + breast cancer stem cells through the regulation of NLRP3 expression. The research represents novel insights on the implications for the application of VD in cancer therapies.

Cholesterol-modified sphingomyelin chimeric lipid bilayer for improved therapeutic delivery

Cholesterol (Chol) fortifies packing and reduces fluidity and permeability of the lipid bilayer in vesicles (liposomes)-mediated drug delivery. However, under the physiological environment, Chol is rapidly extracted from the lipid bilayer by biomembranes, which jeopardizes membrane stability and results in premature leakage for delivered payloads, yielding suboptimal clinic efficacy. Herein, we report a Chol-modified sphingomyelin (SM) lipid bilayer via covalently conjugating Chol to SM (SM-Chol), which retains membrane condensing ability of Chol. Systemic structure activity relationship screening demonstrates that SM-Chol with a disulfide bond and longer linker outperforms other counterparts and conventional phospholipids/Chol mixture systems on blocking Chol transfer and payload leakage, increases maximum tolerated dose of vincristine while reducing systemic toxicities, improves pharmacokinetics and tumor delivery efficiency, and enhances antitumor efficacy in SU-DHL-4 diffuse large B-cell lymphoma xenograft model in female mice. Furthermore, SM-Chol improves therapeutic delivery of structurally diversified therapeutic agents (irinotecan, doxorubicin, dexamethasone) or siRNA targeting multi-drug resistant gene (p-glycoprotein) in late-stage metastatic orthotopic KPC-Luc pancreas cancer, 4T1-Luc2 triple negative breast cancer, lung inflammation, and CT26 colorectal cancer animal models in female mice compared to respective FDA-approved nanotherapeutics or lipid compositions. Thus, SM-Chol represents a promising platform for universal and improved drug delivery.

EPAC inhibitor suppresses angiogenesis and tumor growth of triple-negative breast cancer

AimsExchange protein directly activated by cAMP 1 (EPAC1), a major isoform of guanine nucleotide exchange factors, is highly expressed in vascular endothelia cells and regulates angiogenesis in the retina. High intratumor microvascular densities (MVD) resulting from angiogenesis is responsible for breast cancer development. Downregulation of EPAC1 in tumor cell reduces triple-negative breast cancer (TNBC)-induced angiogenesis. However, whether Epac1 expressed in vascular endothelial cells contributes to angiogenesis and tumor development of TNBC remains elusive. Main methodsWe employed NY0123, a previously identified potent EPAC inhibitor, to explore the anti-angiogenic biological role of EPAC1 in vitro and in vivo through vascular endothelial cells, rat aortic ring, Matrigel plug, and chick embryo chorioallantoic membrane (CAM) and yolk sac membrane (YSM) assays, as well as the in vivo xenograft tumor models of TNBC in both chick embryo and mice. Key findingsInhibiting EPAC1 in vascular endothelial cells by NY0123 significantly suppresses angiogenesis and tumor growth of TNBC. In addition, NY0123 possesses a better inhibitory efficacy than ESI-09, a reported specific EPAC inhibitor tool compound. Importantly, inhibiting EPAC1 in vascular endothelia cells regulates the typical angiogenic signaling network, which is associated with not only vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor-2 (VEGFR2) signaling, but also PI3K/AKT, MEK/ERK and Notch pathway. ConclusionsOur findings support that EPAC1 may serve as an effective anti-angiogenic therapeutic target of TNBC, and EPAC inhibitor NY0123 has the therapeutic potential to be developed for the treatment of TNBC.

Preclinical Efficacy of Cabazitaxel Loaded Poly(2-alkyl cyanoacrylate) Nanoparticle Variants.

Biodegradable poly(alkyl cyanoacrylate) (PACA) nanoparticles (NPs) are receiving increasing attention in anti-cancer nanomedicine development not only for targeted cancer chemotherapy, but also for modulation of the tumor microenvironment. We previously reported promising results with cabazitaxel (CBZ) loaded poly(2-ethylbutyl cyanoacrylate) NPs (PEBCA-CBZ NPs) in a patient derived xenograft (PDX) model of triple-negative breast cancer, and this was associated with a decrease in M2 macrophages. The present study aims at comparing two endotoxin-free PACA NP variants (PEBCA and poly(2-ethylhexyl cyanoacrylate); PEHCA), loaded with CBZ and test whether conjugation with folate would improve their effect. Cytotoxicity assays and cellular uptake of NPs by flow cytometry were performed in different breast cancer cells. Biodistribution and efficacy studies were performed in PDX models of breast cancer. Tumor associated immune cells were analyzed by multiparametric flow cytometry. In vitro studies showed similar NP-induced cytotoxicity patterns despite difference in early NP internalization. On intravenous injection, the liver cleared the majority of NPs. Efficacy studies in the HBCx39 PDX model demonstrated an enhanced effect of drug-loaded PEBCA variants compared with free drug and PEHCA NPs. Furthermore, the folate conjugated PEBCA variant did not show any enhanced effects compared with the unconjugated counterpart which might be due to unfavorable orientation of folate on the NPs. Finally, analyses of the immune cell populations in tumors revealed that treatment with drug loaded PEBCA variants affected the myeloid cells, especially macrophages, contributing to an inflammatory, immune activated tumor microenvironment. We report for the first time, comparative efficacy of PEBCA and PEHCA NP variants in triple negative breast cancer models and show that CBZ-loaded PEBCA NPs exhibit a combined effect on tumor cells and on the tumor associated myeloid compartment, which may boost the anti-tumor response.

Apigenin: a natural molecule at the intersection of sleep and aging.

NAD+, a pivotal coenzyme central to metabolism, exhibits a characteristic decline with age. In mice, NAD+ levels can be elevated via treatment with apigenin, a natural flavonoid that inhibits the NAD+-consuming glycoprotein CD38. In animal models, apigenin positively impacts both sleep and longevity. For example, apigenin improves learning and memory in older mice, reduces tumor proliferation in a mouse xenograft model of triple-negative breast cancer, and induces sedative effects in mice and rats. Moreover, apigenin elongates survival in fly models of neurodegenerative disease and apigenin glycosides increase lifespan in worms. Apigenin's therapeutic potential is underscored by human clinical studies using chamomile extract, which contains apigenin as an active ingredient. Collectively, chamomile extract has been reported to alleviate anxiety, improve mood, and relieve pain. Furthermore, dietary apigenin intake positively correlates with sleep quality in a large cohort of adults. Apigenin's electron-rich flavonoid structure gives it strong bonding capacity to diverse molecular structures across receptors and enzymes. The effects of apigenin extend beyond CD38 inhibition, encompassing agonistic and antagonistic modulation of various targets, including GABA and inflammatory pathways. Cumulatively, a large body of evidence positions apigenin as a unique molecule capable of influencing both aging and sleep. Further studies are warranted to better understand apigenin's nuanced mechanisms and clinical potential.

Breast Cancer Treatment Using the Magneto-Hyperthermia Technique Associated with Omega-3 Polyunsaturated Fatty Acids' Supplementation and Physical Training.

Breast cancer (BC) presents a growing global concern, mainly for the female population of working age. Their pathophysiology shows challenges when attempting to ensure conventional treatment efficacy without adverse effects. This study aimed to evaluate the efficacy of magneto-hyperthermia (MHT) therapy associated with supplementation with omega-3 polyunsaturated fatty acid (w-3 PUFA) and engagement in physical training (PT) for the triple-negative BC (TNBC) model. First, we assessed the physicochemical properties of iron oxide nanoparticles (ION) in biological conditions, as well as their heating potential for MHT therapy. Then, a bioluminescence (BLI) evaluation of the best tumor growth conditions in the TNBC model (the quantity of implanted cells and time), as well as the efficacy of MHT therapy (5 consecutive days) associated with the previous administration of 8 weeks of w-3 PUFA and PT, was carried out. The results showed the good stability and potential of ION for MHT using 300 Gauss and 420 kHz. In the TNBC model, adequate tumor growth was observed after 14 days of 2 × 106 cells implantation by BLI. There was a delay in tumor growth in animals that received w-3 and PT and a significant decrease associated with MHT. This pioneering combination therapy approach (MHT, omega-3, and exercise) showed a positive effect on TNBC tumor reduction and demonstrated promise for pre-clinical and clinical studies in the future.

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.