Metastasis Model Research Articles

Reproducible preclinical models of androgen receptor driven human prostate cancer bone metastasis.

Preclinical models recapitulating the metastatic phenotypes are essential for developing the next-generation therapies for metastatic prostate cancer (mPC). We aimed to establish a cohort of clinically relevant mPC models, particularly androgen receptor positive (AR+) bone metastasis models, from LuCaP patient-derived xenografts (PDX) that reflect the heterogeneity and complexity of mPC. PDX tumors were dissociated into single cells, modified to express luciferase, and were inoculated into NSG mice via intracardiac injection. The progression of metastases was monitored by bioluminescent imaging. Histological phenotypes of metastases were characterized by immunohistochemistry and immunofluorescence staining. Castration responses were further investigated in two AR-positive models. Our PDX-derived metastasis (PDM) model collection comprises three AR+ adenocarcinomas (ARPC) and one AR- neuroendocrine carcinoma (NEPC). All ARPC models developed bone metastases with either an osteoblastic, osteolytic, or mixed phenotype, while the NEPC model mainly developed brain metastasis. Different mechanisms of castration resistance were observed in two AR+ PDM models with distinct genotypes, such as combined loss of TP53 and RB1 in one model and expression of AR splice variant 7 (AR-V7) expression in another model. Intriguingly, the castration-resistant tumors displayed inter- and intra-tumor as well as organ-specific heterogeneity in lineage specification. Genetically diverse PDM models provide a clinically relevant system for biomarker identification and personalized medicine in metastatic castration-resistant prostate cancer.

CEBPB-mediated upregulation of SERPINA1 promotes colorectal cancer progression by enhancing STAT3 signaling

Colorectal cancer (CRC) is a highly malignant carcinoma associated with poor prognosis, and metastasis is one of the most common causes of death in CRC. Serpin Family A Member 1 (SERPINA1) is a serine protease inhibitor from the Serpin family. Till now, the function and mechanism of SERPINA1 in CRC progression have not been fully illustrated. We established highly metastatic colorectal cancer cells named as RKO-H and Caco2-H by mice liver metastasis model. By integrative bioinformatic approaches, we analyzed the prognostic value and clinical significance of SERPINA1 in CRC, and predicted potential transcription factors. Colony formation, EDU, MTS, Transwell and wound healing assay were performed to evaluate the biological functions of SERPINA1 in CRC in vitro. Experiments in vivo were conducted to explore the effects of SERPINA1 on liver metastasis of CRC. ChIP and luciferase reporter gene assays were performed to identify the transcriptional regulatory mechanism of SERPINA1 by CEBPB. Our results show that SERPINA1 is highly expressed in CRC and correlated with poor clinical outcomes. SERPINA1 promotes the proliferation, migration by activating STAT3 pathway. Mechanistically, CEBPB binds SERPINA1 gene promoter sequence and promotes the transcription of SERPINA1. SERPINA1 drives CEBPB-induced tumor cell growth and migration via augmenting STAT3 signaling. Our results suggest that SERPINA1 is a potential prognostic marker and may serve as a novel treatment target for CRC.

CLIP170 inhibits the metastasis and EMT of papillary thyroid cancer through the TGF-β pathway.

Metastasis poses a significant challenge in combating tumors. Even in papillary thyroid cancer (PTC), which typically exhibits a favorable prognosis, high recurrence rates are attributed to metastasis. Cytoplasmic linker protein 170 (CLIP170) functions as a classical microtubule plus-end tracking protein (+TIP) and has shown close association with cell migration. Nevertheless, the specific impact of CLIP170 on PTC cells remains to be elucidated. Our analysis of the GEO and TCGA databases unveiled an association between CLIP170 and the progression of PTC. To explore the impact of CLIP170 on PTC cells, we conducted various assays. We evaluated its effects through CCK-8, wound healing assay, and transwell assay after knocking down CLIP170. Additionally, the influence of CLIP170 on the cellular actin structure was examined via immunofluorescence; we further investigated the molecular expressions of epithelial-mesenchymal transition (EMT) and the transforming growth factor-β (TGF-β) signaling pathways through Western blotting and RT-qPCR. These findings were substantiated through an in vivo nude mouse model of lung metastasis. We observed a decreased expression of CLIP170 in PTC in contrast to normal thyroid tissue. Functionally, the knockdown of CLIP170 (CLIP170KD) notably enhanced the metastatic potential and EMT of PTC cells, both in vitro and in vivo. Mechanistically, CLIP170KD triggered the activation of the TGF-β pathway, subsequently promoting tumor cell migration, invasion, and EMT. Remarkably, the TGF-β inhibitor LY2157299 effectively countered TGF-β activity and significantly reversed tumor metastasis and EMT induced by CLIP170 knockdown. In summary, these findings collectively propose CLIP170 as a promising therapeutic target to mitigate metastatic tendencies in PTC.

Machine-learning and mechanistic modeling of metastatic breast cancer after neoadjuvant treatment.

Clinical trials involving systemic neoadjuvant treatments in breast cancer aim to shrink tumors before surgery while simultaneously allowing for controlled evaluation of biomarkers, toxicity, and suppression of distant (occult) metastatic disease. Yet neoadjuvant clinical trials are rarely preceded by preclinical testing involving neoadjuvant treatment, surgery, and post-surgery monitoring of the disease. Here we used a mouse model of spontaneous metastasis occurring after surgical removal of orthotopically implanted primary tumors to develop a predictive mathematical model of neoadjuvant treatment response to sunitinib, a receptor tyrosine kinase inhibitor (RTKI). Treatment outcomes were used to validate a novel mathematical kinetics-pharmacodynamics model predictive of perioperative disease progression. Longitudinal measurements of presurgical primary tumor size and postsurgical metastatic burden were compiled using 128 mice receiving variable neoadjuvant treatment doses and schedules (released publicly at https://zenodo.org/records/10607753). A non-linear mixed-effects modeling approach quantified inter-animal variabilities in metastatic dynamics and survival, and machine-learning algorithms were applied to investigate the significance of several biomarkers at resection as predictors of individual kinetics. Biomarkers included circulating tumor- and immune-based cells (i.e., circulating tumor cells and myeloid-derived suppressor cells) as well as immunohistochemical tumor proteins (i.e., CD31 and Ki67). Our computational simulations show that neoadjuvant RTKI treatment inhibits primary tumor growth but has little efficacy in preventing (micro)-metastatic disease progression after surgery and treatment cessation. Machine learning algorithms that included support vector machines, random forests, and artificial neural networks, confirmed a lack of definitive biomarkers, which shows the value of preclinical modeling studies to identify potential failures that should be avoided clinically.

Prostate-Specific Membrane Antigen Targeted StarPEG Nanocarrier for Imaging and Therapy of Prostate Cancer.

The uptake of large (>10nm) non-targeted nanocarriers by bulk tumors is thought to be dominated by passive extravasation through porous tumor vessels and limited lymphatic drainage, the enhanced permeability and retention (EPR) effect. Prior studies demonstrated radiolabeled tumor-targeted and non-targeted 4-arm 40kDa star polyethylene glycol (StarPEG) polymers for cancer imaging. By adding small molecule ligands targeting prostate-specific membrane antigen (PSMA) to the StarPEG polymer, marked increase in tumor uptake, penetration and retention in the tumor core was observed. These prior studies support the application of imaging surrogates for the evaluation of targeted delivery of chemotherapeutic nanomedicines and the potential for therapy using analogous β-emitting radiopharmaceuticals. To evaluate the delivery and therapeutic efficacy of PSMA-targeted StarPEG nanocarriers, StarPEG nanodrugs with or without three copies of PSMA-targeting, ACUPA, ligands were designed and synthesized. One copy of the radiometal chelator, DOTA, was conjugated to each nanocarrier for labelling with b-emitting 177Lu, providing non-targeted [177Lu]PEG-(DOTA)1 and PSMA targeting [177Lu]PEG-(DOTA)1(ACUPA)3, for SPECT imaging and therapy. The radiolabeled nanodrugs were evaluated in vitro and in vivo using PSMA+ PC3-Pip and/or PSMA- PC3-Flu cell lines, subcutaneous xenografts and disseminated metastatic models. The nanocarriers PEG-(DOTA)1 and PEG-(DOTA)1(ACUPA)3 were efficiently radiolabeled with 177Lu with molar activities of 10.8-15.8 MBq/nmol. Along with excellent in vitro PSMA binding affinity (kD = 51.7nM in PC3-Pip cells), the targeted nanocarrier [177Lu]PEG-(DOTA)1(ACUPA)3 demonstrated excellent in vivo single-photon emission computed tomography (SPECT) imaging contrast with 21.3% ID/g uptake in PC3-Pip tumors at 192h post injection. Single doses of 18.5 MBq [177Lu]PEG-(DOTA)1(ACUPA)3 showed complete resolution of the PC3-Pip xenografts, without any regrowth up to 138 days. The StarPEG nanocarriers demonstrated high PSMA-targeted delivery of the therapeutic isotope 177Lu with excellent imaging contrast. The targeted nanocarrier eliminated subcutaneous and metastatic PC3-Pip tumors. Overall, these preclinical results demonstrated high treatment efficacy of the PSMA-targeted nanocarrier [177Lu]PEG-(DOTA)1(ACUPA)3 for prostate cancer, with potential for clinical translation. This article is protected by copyright. All rights reserved.

Abstract PO4-07-07: The construction and clinical research value of the prediction model of sentinel lymph node metastasis based on indocyanine green fluorescence quantification in breast cancer

Abstract Objective: To establish a prediction model of sentinel lymph node metastasis by quantitative indocyanine green fluorescence analysis in breast cancer. Methods: From May 2023 to June 2023, 20 patients with breast cancer underwent modified radical mastectomy in the General Surgery Department of Jiangsu Provincial People's Hospital were chosen for research and analysis. Sentinel lymph node were taken from all the patients. The sentinel lymph nodes were located by using the double staining method of subcutaneous injection of Methylene blue and intravenous injection of indocyanine green. The postoperative pathology is used as the standard for evaluating the presence or absence of metastatic cancer in lymph nodes. At the same time, the transcutaneous fluorescence of sentinel lymph node was recorded and the peak time of fluorescence intensity curve was plotted. To establish a logistic diagnostic prediction model and fluorescence threshold, the sentinel lymph node was incised during operation and the fluorescence of sentinel lymph node was recorded again. The criteria for ICG positive determination are determined by the Youden index, which was used to judge the lymph nodes above the threshold in the Logistic diagnostic prediction model. Lymph nodes below the threshold determined in the Logistic diagnostic prediction model are the criteria for ICG negative determination. Cases with less than 3 sentinel lymph node were excluded. Results: 19 cases were ultimately selected. Methylene blue staining data was taking as the judgment standard of sentinel lymph node. Fluorescence imaging was 100% in 14 patients, 66.7% (2/3) in 1 patient, and 125%-150% (5/4-6/4) in 4 patients. Fluorescence quantification values below 2.91 are negative lymph nodes, and values above 4.69 are positive lymph nodes. Moreover, caution is required between 2.91 and 4.69. Combining with the fluorescence dynamic attenuation curve, the positive group has a plateau curve, while the negative group mostly has a decline curve. Combining fluorescence quantification with fluorescence dynamic attenuation curve, the diagnostic rate of positive lymph nodes has a lower false negative rate compared to simple fluorescence quantification and fluorescence dynamic attenuation curve. Conclusion: The quantitative difference value of indocyanine green fluorescence angiography can be used to predict the positive metastasis of sentinel lymph node in breast cancer, making it an attempt to exempt sentinel lymph node biopsy. Citation Format: Yang Wu, Wei Zhang, Jinhai Tang. The construction and clinical research value of the prediction model of sentinel lymph node metastasis based on indocyanine green fluorescence quantification in breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-07-07.

Abstract PO5-24-05: The Metabolic and Epigenetic Contributions of Fibroblast Growth Factor Receptor-Mediated Breast Cancer Progression

Abstract Despite recent improvements in treatment options, breast cancer remains the second leading cause of cancer-related deaths among women, with metastasis of the primary tumor accounting for most of these deaths. Signaling by fibroblast growth factor receptors (FGFRs) is active in 85% of breast cancers and results in enhanced proliferation, migration, invasion, and therapeutic resistance of tumor cells. A common feature of breast cancer is altered cholesterol metabolism including an increase in cholesterol stored intracellularly as cholesteryl esters (CEs). In breast cancer cells, high levels of CEs are associated with aggressive disease and CEs are essential for growth and migration of cancer cells. Furthermore, there is mounting evidence that modifications to metabolic pathways impact epigenetic processes including DNA methylation and histone post-translational modifications. These epigenetic changes support tumor progression and metastasis through oncogene activation and silencing of tumor suppressors. While there have been numerous studies focused on the role of metabolic and epigenetic changes in breast cancer, none have attempted to connect these altered pathways to upstream growth factor receptor pathways, such as the FGFR pathway, in cancer cells. We hypothesize that FGFR signaling promotes changes to cholesterol metabolism and epigenetic regulation which lead to breast cancer progression. To study the proposed roles of FGFR signaling, we utilized murine mammary cells of differing metastatic abilities with inducible, oncogenic FGFR1 signaling. We also included the FGFR-dependent murine mammary tumor lines 4T1 and 4T07 which demonstrate differing metastatic capabilities. Through gene expression studies, we found an FGFR-mediated increase in cholesterol metabolic processes including cholesterol storage, uptake, and synthesis. Along with this, we found an FGFR-mediated increase in CE content in our models. Interestingly, these changes were exclusive to our highly metastatic models. Additionally, we have identified FGFR-mediated changes in the expression of histone modifying enzymes in our cell lines. Many of the enzymes modified by FGFR have been previously reported to play a role in breast cancer metastasis. To further elucidate the role of enhanced cholesterol storage in breast cancer progression, we treated cells with pharmacological inhibitors of cholesterol storage. Using in vitro assays, we demonstrate that cell survival, migration, and invasion all decrease when cholesterol storage is inhibited. Again, we observe that our highly metastatic cell line models are more sensitive to this inhibition. Taken together, these data suggest a role for FGFR signaling in promoting breast cancer progression and metastasis. With further studies, this connection may inform the development of novel therapeutic strategies to combat therapeutic resistance in breast cancer. Citation Format: Jennifer Tuokkola, Lyndsay Reese, Kaylee Schwertfeger. The Metabolic and Epigenetic Contributions of Fibroblast Growth Factor Receptor-Mediated Breast Cancer Progression [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-24-05.

New Evidence on the Antiproliferative Activity of Campomanesia Adamantium (Cambess.) O. Berg Extracts in Melanoma Lung Metastasis.

Given the importance of discovering plant species from the Brazilian Cerrado biome with anticancer potential, this study evaluated the antitumor activity of two extracts of Campomanesi adamantium fruits in in vitro and invivo models of melanoma lung metastasis. Pulp and peel extracts (DEGPU and DEGPE, respectively) were extracted from fresh fruit using dichloromethane as a solvent. As cytotoxicity parameter, concentration values that inhibited 50% cell growth (GI50), total growth inhibition (TGI), and selectivity index (SI) were established. The melanoma lung metastasis model was obtained by injecting 5 × 105/50 μL B16-F10 cells via the tail vein of mice, which received treatment on the 15th day. Metastatic lungs were collected for fluorescence analysis with the IR-780 marker and also macro- and microscopic assessment. In vitro analyses showed that DEGPU was active in K562 (GI50 32.99; TGI 47.93) and U-251 (GI50 32.10; TGI 249.92), whereas DEGPE showed better cytotoxicity results for all tumor cell lines, but was more efficient in K562 (GI50 27.42; TGI 40.20) and U-251 (GI50 4.89; TGI 12.77). Both showed a cytocidal effect on B16F10 at the highest concentration tested, with approximately 25% (DEGPU) and 88% (DEGPE) of cell death. In vivo analyzes showed that both extracts showed significant activity in metastatic lung. Fluorescence images showed differences in intensity between groups owing to greater tumor involvement. Macro- and microscopic images showed that treatments with extracts limited tumor growth and prevented proliferation. The extracts tested have promising activity, thus requiring further research on their active compounds.

Abstract PO5-25-01: Treating liver metastases by reversing cell competition between metastatic cancer cells and hepatocytes

Abstract Background: Although breast cancer liver metastases (BCLM) are common events, with 40-50% of patients with metastatic breast cancer developing liver metastases, their development indicates poor prognosis. Patients with BCLM have a 5-year survival rate of 8%. Specific treatments for liver metastases are virtually non-existent, partly because the key events of early liver metastasis formation remain unknown. The liver is a dense organ, and metastatic breast cancer cells (MCC) must clear space among hepatocytes, the primary cell population in the liver, during metastatic formation. Cell competition is a developmentally conserved process that explains how organs or primary tumors form when cells within those tissues have varying fitness and compete with one another. This competition can result in the survival and expansion of one cell population, and the induction of cell death through apoptosis in the other. We hypothesized that MCC use cell competition with hepatocytes to create space and expand within the liver. Objectives: In this study, we tested the hypothesis that MCC use cell competition with hepatocytes to create space and expand within the liver, resulting in hepatocyte apoptosis. Methods: We develop new in-vitro and mouse lineage-traced models to assay cell competition between MCC and hepatocytes, initially using balb/c derived breast cancer (4T1) and hepatocyte (H2.35) cells and syngeneic mouse models of liver metastasis. These models directly capture MCC and hepatocyte interactions, and we can assess modes of cell competition, including apoptosis, through immunostaining. Because prior literature suggests that the developing mammary gland informs both cell competition and metastasis, we next performed a bioinformatics screen to identify potential signals that contribute to cell competition between MCC and hepatocytes. We generated a new single-cell RNA-seq dataset that incorporates information from the developing mammary gland and breast cancer cells. This dataset includes 3264 primary breast cancer cells across 3 models of aggressive breast cancers, encompassing HER2+ and TNBC subtypes, as well as 526 embryonic mammary gland cells. Using this platform, we identify genes enriched in both breast cancer and the developing mammary gland. Next, we validate genes by testing for their high expression in MCC when compared to hepatocytes. Then, we determine the impact of target genes on cell competition in our models. Results/Discussion: Our models demonstrate that MCC use cell competition to create space in the liver by inducing apoptosis in neighboring hepatocytes. MCC induce apoptosis in neighboring hepatocytes through cell competition in in-vitro co-cultures by 11.7-fold compared to MCC apoptosis. Hydrodynamic tail-vein engraftment in NOD-scid-gamma mice livers with MCC also resulted in increased neighboring hepatocyte apoptosis. Using our bioinformatics screen, we identified 5 potential targets that could drive breast cancer metastasis and cell competition. Using our competition models, perturbation of SerpinE2, a protease inhibitor which was one of the top gene targets, successfully modulated competition between MCC and hepatocytes. Knock-out of SerpinE2 in MCC did not affect their viability or growth but resulted in MCC apoptosis adjacent to hepatocyte neighbors by 16.9-fold when compared to wild type conditions. Further, co-culture of MCC that lacked SerpinE2 with hepatocytes resulted in decreased hepatocyte apoptosis by 2.3-fold compared to hepatocytes co-cultured with wild-type (WT) MCC. These findings suggest that hepatocytes cannot outcompete or kill WT MCC, but they can outcompete and kill MCC that lack SerpinE2. Future work focused on the perturbation of SerpinE2 may lead to novel therapies for patients at risk for or with BCLM. Our findings suggest that restoring the competitiveness of the liver parenchyma could be a new treatment modality for treating liver metastases. Citation Format: Katherine Lake, Sakshi Mohta, Clayton Smith, Venkata Repaka, Lily Xu, Kaitlyn Saunders, Vrushali Pandit, Emily Goff, Christine Zhang, Jacob Pena, Christine Hodgdon, Julia Maues, Elizabeth Chen, Isaac Chan. Treating liver metastases by reversing cell competition between metastatic cancer cells and hepatocytes [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-25-01.

Abstract PO5-05-05: Clinical outcomes of CDK4/6 inhibitors in patients with bone only metastatic breast cancer

Abstract Background: CDK4/6 inhibitors (CDK 4/6i) have significantly advanced the treatment of hormone receptor-positive (HR+) metastatic breast cancer in the last decade. Several clinical trials including PALOMA, MONALEESA, and MONARCH have shown improved progression-free survival (PFS) rates when CDK4/6i were combined with endocrine therapy (ET). These results led to recommending their use in combination with ET as the first line of therapy in the metastatic settings. Bone metastasis is the most common site of disease in patients with HR+ metastatic breast cancer, about 40% of whom have bone as the only site of metastasis (bone-only disease [BoD]). While previous studies have shown that BoD can have a unique clinical course and a more favorable prognosis compared to non-BoD metastasis, most of the aforementioned CDK 4/6i clinical trials have not shown significant improvements in PFS in BoD subset of patients. Here we aimed to investigate the survival outcomes of BoD patients at a single institution center and evaluate CDK 4/6i activity in preclinical models of bone metastasis in breast cancer. Patients and methods: Patients with HR+, HER2-negative metastatic breast cancer from a retrospective CDK4/6i study at Washington University School of Medicine were included in this analysis. We selected all the patients who received CDK4/6i in the first- or second-line settings from June 2014 to March 2020. Outcomes were collected through June 10, 2023. The Kaplan-Meier method with log rank test and multivariable cox model were used for survival analysis. Results: 114 female patients (n=75 first line, n=39 second line, n=20 African American, n=94 Caucasian) were included in this study. All patients received Palbociclib as the first exposure to CDK4/6 inhibitor in combination with ET for at least two months. Median age was 60 years (range, 28-87) and forty-seven patients (41%) were in the BoD group. Survival outcomes for BoD group were compared to the rest of patients who had either bone and visceral or visceral only metastatic lesions (BV group). Our results demonstrated a significantly reduced median PFS in BoD group compared to BV group (13.1 months [95%CI:8-18.2] vs 19.6 months [95%CI:6.8-32.4], p=0.01) respectively. There was no significant difference in overall survival between BoD and BV groups (36.6 months [95%CI:32.2-41] vs 41.7 months [95%CI 36.1-47.2] p=0.74) respectively. In multivariate analysis regarding the associated risk factors with PFS, after adjusting for age and race, BoD had a HR of 1.62 (95%CI:1.04-2.54) for PFS. Among the 75 patients who received CDK4/6i as their first line of therapy, BoD (n=32 patients [42.7%]) also showed an inferior (p=0.05) median PFS (20 months [95%CI 12.9-27]) compared to BV group (n=43 patients [57.3%], median PFS=28.4 months [95%CI: 16.3-40.4]). To investigate potential treatment resistance mechanisms in bone metastases, we used the triple negative 4T1 and the ER+ luminal B PyMT Bo1 breast tumor cell line derived mammary gland models in immunocompetent mice. Single agent CDK4/6i, ribociclib, decreased primary mammary gland tumor burden. This effect was abrogated when CD8+ T-cells were depleted. In the bone colonization model using these cell lines, ribociclib had little effect on bone tumor burden. Arg1+ immune suppressive macrophages were significantly decreased in the primary mammary tumor but not in the bone tumor after ribociclib administration, suggesting a relative treatment resistance and immune suppression in the bone tumor microenvironment compared to the primary mammary gland. Conclusion: CDK4/6i play a significant role in the treatment of patients with HR+ metastatic breast cancer. Our single institution, retrospective study and preclinical data suggests that CDK4/6i may not be as effective for the treatment of tumors residing in the bone microenvironment, warranting future studies to understand the mechanisms of CDK4/6 inhibitors action in bone versus visceral metastases. Citation Format: Mahta Mardani, Suleyman Noordeen, Katherine Clifton, Cynthia Ma, Jingqin Luo, Jing Xi, Nusayba Bagegni, Foluso Ademuyiwa, Rama Suresh, Ashley Frith, Andrew Davis, Ron Bose, Lindsay Peterson, Shana Thomas, Yu Tao, Takayuki Kobayashi, Jingyu Xiang, Yalin Xu, Xinming Su, Katherine Weilbaecher. Clinical outcomes of CDK4/6 inhibitors in patients with bone only metastatic breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-05-05.

Abstract PO2-27-06: ANXA9 facilitates the exocrine secretion of S100A4 and promotes pleural metastasis in breast cancer

Abstract Metastasis to distant organs stands as the primary contributor to mortality in cases of breast cancer. While localized breast cancer boasts a 5-year survival rate of roughly 99%, this figure drastically declines to approximately 26% for patients afflicted with distant metastasis. Regrettably, the current therapeutic landscape lacks efficacious and targeted interventions for the treatment of metastatic breast cancer. Our investigation has revealed a significant upregulation of S100A4 in metastatic breast cancer tissues, with notably high expression observed in the malignant pleural effusion of patients in advanced stages of the disease. Upon acceptance of the effective treatment, the expression of S100A4 in malignant pleural effusion decreased, along with a decrease in several cytokines, including IL-6, IL-8, CCL2, and CCL5. The breast cancer cellular models demonstrated that ANXA9 has the ability to regulate the excretion of S100A4 from cells into the surrounding medium. Similarly, the mice model of pleural metastasis indicated that the downregulation of ANXA9 (sh-ANXA9) resulted in decreased levels of S100A4 and cytokines IL-6, IL-8, CCL2, and CCL5 in the mice's hydrothorax. Additionally, our findings suggest that ANXA9 regulates the excretion of S100A4 through phosphorylation of ANXA9. The cellular membrane harbored phosphorylated ANXA9, which exhibited two phosphorylation sites. Upon mutation of these sites, the level of ANXA9 phosphorylation decreased, leading to a reduction in the exocrine release of ANXA9 from cells into the medium. Our research further revealed the significant involvement of ANXA9 in facilitating the progression of breast cancer, thereby suggesting that therapeutic interventions targeting ANXA9 could prove efficacious in treating metastatic breast cancer. This work was supported by Shanghai Sailing Program to Dengfeng Li (No. 20YF1437800), grant from the National Natural Science Foundation of China to Dengfeng li (No. 82103454) and grant from the National Natural Science Foundation of China to Lin Fang (No. 82073204). Citation Format: Xiqian Zhou, Dengfeng Li, Lin Fang, Junyong Zhao. ANXA9 facilitates the exocrine secretion of S100A4 and promotes pleural metastasis in breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-27-06.

Abstract PO3-18-07: Therapeutic Potential of Combining Eltanexor with Tamoxifen to Treat Primary and Metastatic Estrogen Receptor Positive (ER+) Breast Cancers

Abstract Estrogen receptors are key pathway initiators in the aggressive development of more than two-thirds of all breast cancers. Tamoxifen (TAM) is a selective estrogen receptor modulator that disables the ER pathway and inhibits the progression of ER+ breast cancer. Unfortunately, 10-40% of patients with ER+ breast cancer who were treated with TAM experience recurrence and metastasis within 10 years. We have previously identified exportin 1 (XPO1) to be more highly expressed in breast cancers with acquired TAM resistance compared to TAM-sensitive counterparts and showed that a combination treatment of TAM with an XPO1 inhibitor, selinexor, is an effective method of tumor suppression in preclinical models. In this study we investigated the activity of eltanexor, an investigational second generation XPO1 inhibitor with minimal penetration of the blood-brain barrier, to inhibit cancer growth without leading to weight loss. Our results show that mice harboring MCF7-ESR1Y537Sxenograft tumors had significantly less (P < .05) flank tumor growth when administered a treatment regimen of TAM and eltanexor compared to control mice. In metastatic tumor models, we observed decreased metastatic burden in mice harboring MCF7-ESR1 D538G and MCF7-ESR1Y537S tumors when co-administered TAM and eltanexor. We did not observe weight changes in either model. Our findings suggest that eltanexor may be a relevant treatment for further exploration in the context of a TAM combination therapy for treatment of ER+ breast cancer. Citation Format: Vedant Jain, Myra Kamdar, Hannah McGee, Qianying Zuo, Jin Young Yoo, Yosef Landesman, Christopher Walker, Zeynep Madak-Erdogan. Therapeutic Potential of Combining Eltanexor with Tamoxifen to Treat Primary and Metastatic Estrogen Receptor Positive (ER+) Breast Cancers [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-18-07.

Abstract PO3-26-08: Genetic modification of tumor associated macrophages using CRISPR lipid nanoparticle platform altered tumor microenvironment and induced cancer cell elimination

Abstract More than half of patients with stage IV breast cancer will eventually develop liver metastasis. Due to their nature, liver metastases are hard to treat, and the five-year survival rate for stage IV breast cancer is very low (~11%). In the recent years, vital roles macrophages play in cancer progression and immune evasion have become increasingly clear, making them an appealing target for therapeutic intervention. As one of the most abundant cell populations recruited to the tumor microenvironment, tumor-associated macrophages (TAM) are typically immunosuppressive Arg1+ M2-like macrophages, which support cancer growth, metastasis progression, and drug resistance. Numerous studies, including from our laboratory, have shown that reversal of the macrophage phenotype to the classical inflammatory CD80+ M1-like macrophages is very promising for cancer eradication. In this study, we used CRISPR loaded into lipid nanoparticles (CRISPR-LNP) to modulate macrophage polarization in breast cancer metastasis in vivo. We hypothesize that CRISPR-mediated gene editing through lipid nanoparticle (LNP) delivery of CRISPR enzyme and target gRNA (CRISPR-LNP) is a highly effective and safe approach. Using our CRISPR-LNP platform, we screened multiple genes with significant roles in macrophage polarization and found that targeting the RICTOR gene alone enabled reprograming of pro-tumorigenic M2 TAMs to anti-tumorigenic M1 phenotype in vitro and in vivo. We administered the CRISPR-LNP targeting RICTOR (CRISPR-RIC-LNP) on a syngeneic liver metastasis mouse model via intravenous injection. Single dose studies were conducted to determine biodistribution, treatment efficacy, and shift in immune landscape of the tumor after treatment via immunofluorescence staining, Imaging Mass Cytometry, and single cell RNA sequencing. A spatial map was built using digital pathology analysis for investigation of the interactions amongst immune and tumor cells within the tumor immune microenvironment. In 4T1 breast cancer liver metastatic model, we observed that CRISPR-RIC-LNP treatment: (i) accumulated in the liver metastases lesions in vivo 24 hours after injection. ~0.5% of total injected dose, which corresponds to ~75% of fluorescence from the whole body at 24h time point was confined only in the metastatic regions; (ii) led to modest increase of macrophage number, and (iii) significant shift of macrophage phenotype from immunosuppressive, pro-tumorigenic Arg1+, CD206+ macrophages to inflammatory, anti-tumor CD80+ phenotype (from ~5 to ~9% of total cell in the tumor lesions) 24 hours after injection; (iv) reduced the cancer cell number by almost 80%; and (v) dramatically reduced exhausted T-cell and regulatory T-cell population, as determined by single cell RNA sequencing analysis. We plan to validate our preliminary finding with flow cytometry analysis of metastatic lesions, and evalute the efficacy of CRISPR-RIC-LNP as single and in combinatorial therapies in survival studies. These data showed that reprograming macrophages from cancer-supporting to cancer-eliminating phenotype is a promising tool to suppress cancer cell growth and increase the presence of cytotoxic CD8+ T-cells. We propose that this approach can be efficiently used as single therapy or as combination with immune checkpoint inhibitors to obtain synergistic effects and efficiently eradicate cancer cells. We will assess the safety, optimize the accumulation in TME, and devise methods to limit exposure to healthy cells. In the future, we also aim to expand scope of our candidate therapy as therapeutics for other types of breast cancer metastases. Citation Format: Fransisca Leonard, Tyler Galbraith, Nourhan Abdelfattah, Arturas Ziemys, Chihiro Hashimoto, Harlan Cook, Yitian Xu, Shu-Hsia Chen, Roberto Rosato, Kyuson Yun. Genetic modification of tumor associated macrophages using CRISPR lipid nanoparticle platform altered tumor microenvironment and induced cancer cell elimination [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-26-08.

Abstract PO3-18-09: OPERA-01: A randomized, open-label, phase 3, study of palazestrant (OP-1250) vs standard-of-care treatment for ER+, HER2- advanced or metastatic breast cancer after endocrine and CDK4/6 inhibitor therapy

Abstract Background: In estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC), adding a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor to endocrine therapy (ET) has improved outcomes and is the current standard-of-care treatment in the first-line setting. However, resistance to first-line treatment develops in most patients (pts), which is often attributed to acquired mutations in ESR1. Limited data exist for ET-based treatment options after progression on prior ET and CDK4/6 inhibitors, and most pts will transition to chemotherapy for further treatment. Therefore, there is a significant unmet need for more effective ET in pts with ER-positive, HER2-negative MBC to improve outcomes and delay time to chemotherapy. Palazestrant (OP-1250) is a small molecule oral complete ER antagonist (CERAN) and selective ER degrader (SERD) that binds the ligand binding domain of ER and completely blocks ER-driven transcriptional activity in both wild-type (ESR1-wt) and mutant (ESR1-mut) forms of ER. In preclinical studies, palazestrant demonstrated better tumor shrinkage in ESR1-wt and ESR1-mut models when compared to fulvestrant; it also showed efficacy in brain metastasis models. In a phase 1/2 monotherapy study in pts with heavily pretreated ER-positive, HER2-negative advanced breast cancer (BC) or MBC (NCT04505826), palazestrant showed a tolerable safety profile, promising antitumor efficacy, and favorable pharmacokinetics (PK) supporting once a day (qd) dosing. The recommended Phase 2 dose of palazestrant is 120 mg qd. Methods: The OPERA-01 trial is an international, multicenter, randomized, open-label, phase 3 clinical trial comparing the efficacy and safety of palazestrant as a single agent to standard-of-care ET (fulvestrant, anastrozole, letrozole, or exemestane) in pts with ER-positive, HER2-negative advanced BC or MBC that has relapsed or progressed on 1 or 2 prior lines of ET for MBC, which includes a CDK4/6 inhibitor. Eligible pts are women (pre- or post-menopausal) or men who have a confirmed diagnosis of ER-positive, HER2-negative locally advanced evaluable BC or MBC not amenable to curative therapy. ER and HER2 status are determined according to the American Society of Clinical Oncology/College of American Pathologists guidelines. Patients must have Eastern Cooperative Oncology Group performance status 0 or 1. Prior treatments must include 1 or 2 prior lines of ET as monotherapy or in combination with a CDK4/6 inhibitor for MBC; must have received CDK4/6 inhibitor in combination with ET and have disease progression during or within 28 days of completion of each line of prior treatment for MBC; most recent ET given for ≥6 months. Prior chemotherapy in the metastatic setting is not permitted. Patients (N∼500) are randomized to palazestrant or standard-of-care ET monotherapy, and are stratified by ESR1 mutation status, prior lines of ET for advanced disease (1 vs 2 lines), and presence or absence of visceral disease. The primary endpoint of progression-free survival will be assessed by blinded independent central review in pts with and without ESR1 mutations in the intent-to-treat population. Secondary endpoints include overall survival, antitumor activity (objective response rate, clinical benefit rate, and duration of response), safety, patient-reported outcomes, and PK in pts with and without ESR1 mutations. The study is planned to be conducted globally. Citation Format: Arlene Chan, Jane Meisel, Komal Jhaveri, Joo Hyuk Sohn, Meritxell Bellet- Ezquerra, Jason Schroeder, Mark Shilkrut, Barbara Pistilli. OPERA-01: A randomized, open-label, phase 3, study of palazestrant (OP-1250) vs standard-of-care treatment for ER+, HER2- advanced or metastatic breast cancer after endocrine and CDK4/6 inhibitor therapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-18-09.

Genetically Edited Cascade Nanozymes for Cancer Immunotherapy.

Immune checkpoint blockade (ICB) has brought tremendous clinical progress, but its therapeutic outcome can be limited due to insufficient activation of dendritic cells (DCs) and insufficient infiltration of cytotoxic T lymphocytes (CTLs). Evoking immunogenic cell death (ICD) is one promising strategy to promote DC maturation and elicit T-cell immunity, whereas low levels of ICD induction of solid tumors restrict durable antitumor efficacy. Herein, we report a genetically edited cell membrane-coated cascade nanozyme (gCM@MnAu) for enhanced cancer immunotherapy by inducing ICD and activating the stimulator of the interferon genes (STING) pathway. In the tumor microenvironment (TME), the gCM@MnAu initiates a cascade reaction and generates abundant cytotoxic hydroxyl (•OH), resulting in improved chemodynamic therapy (CDT) and boosted ICD activation. In addition, released Mn2+ during the cascade reaction activates the STING pathway and further promotes the DC maturation. More importantly, activated immunogenicity in the TME significantly improves gCM-mediated PD-1/PD-L1 checkpoint blockade therapy by eliciting systemic antitumor responses. In breast cancer subcutaneous and lung metastasis models, the gCM@MnAu showed synergistically enhanced therapeutic effects and significantly prolonged the survival of mice. This work develops a genetically edited nanozyme-based therapeutic strategy to improve DC-mediated cross-priming of T cells against poorly immunogenic solid tumors.

Arenobufagin inhibits lung metastasis of colorectal cancer by targeting c-MYC/Nrf2 axis

Colorectal cancer (CRC) is one of the commonest cancers worldwide. Metastasis is the most common cause of death in patients with CRC. Arenobufagin is an active component of bufadienolides, extracted from toad skin and parotid venom. Arenobufagin reportedly inhibits epithelial-to-mesenchymal transition (EMT) and metastasis in various cancers. However, the mechanism through which arenobufagin inhibits CRC metastasis remains unclear. This study aimed to elucidate the molecular mechanisms by which arenobufagin inhibits CRC metastasis. Wound-healing and transwell assays were used to assess the migration and invasion of CRC cells. The expression of nuclear factor erythroid-2-related factor 2 (Nrf2) in the CRC tissues was assessed using immunohistochemistry. The protein expression levels of c-MYC and Nrf2 were detected by immunoblotting. A mouse model of lung metastasis was used to study the effects of arenobufagin on CRC lung metastasis in vivo. Arenobufagin observably inhibited the migration and invasion of CRC cells by downregulating c-MYC and inactivating the Nrf2 signaling pathway. Pretreatment with the Nrf2 inhibitor brusatol markedly enhanced arenobufagin-mediated inhibition of migration and invasion, whereas pretreatment with the Nrf2 agonist tert‑butylhydroquinone significantly attenuated arenobufagin-mediated inhibition of migration and invasion of CRC cells. Furthermore, Nrf2 knockdown with short hairpin RNA enhanced the arenobufagin-induced inhibition of the migration and invasion of CRC cells. Importantly, c-MYC acts as an upstream modulator of Nrf2 in CRC cells. c-MYC knockdown markedly enhanced arenobufagin-mediated inhibition of the Nrf2 signaling pathway, cell migration, and invasion. Arenobufagin inhibited CRC lung metastasis in vivo. Together, these findings provide evidence that interruption of the c-MYC/Nrf2 signaling pathway is crucial for arenobufagin-inhibited cell metastasis in CRC. Collectively, our findings show that arenobufagin could be used as a potential anticancer agent against CRC metastasis. The arenobufagin-targeted c-MYC/Nrf2 signaling pathway may be a novel chemotherapeutic strategy for treating CRC.

Overexpressing Bcl-2 enhances murine chimeric antigen receptor T cell therapy against solid tumor.

Chimeric antigen receptor T (CART) cell therapy has demonstrated promising potential in the treatment of hematologic malignancies. However, its application to solid tumors is limited due to the restrictive nature of the tumor microenvironment, resulting in functional failure and poor persistence of CART cells. Overexpression of Bcl-2 in human CART cells (hCART) has been found to significantly enhance their anti-apoptotic effects both in vitro and in vivo. Nevertheless, the evaluation of hCART cells in preclinical studies has predominantly relied on immunodeficient mice xenograft tumor models, making it challenging to assess the impact of hCART cells on normal tissues and the immune system. We established a murine CART (mCART) that overexpresses Bcl-2 and targets the epidermal growth factor receptor variant III (EGFRvIII), named EGFRvIII·mCART-Bcl2. It demonstrated superior proliferation, cytotoxicity, and anti-apoptotic capabilities in vitro. In an immunocompetent mouse model of abdominal metastasis of colorectal cancer, EGFRvIII·mCART-Bcl2 exhibited improved survival of CART in the abdomen, increased tumor clearance, and significantly prolonged overall mouse survival. In summary, our study provides evidence that the introduction of Bcl-2 into mCART cells can enhance their therapeutic efficacy against solid tumors while ensuring safety.

Ferric Oxide Nanoparticles Enhance Cytotoxicity and Reduce the Occurrence and Development of Cervical Cancer Metastases

Fe3O4 nanoparticles can be used in diagnostic imaging and therapeutic applications. However, poor solubility limits its use in tumors. In this study, we used ferric oxide and nanoparticles to covalently bind ferric oxide nanoparticles as a strategy for treatment of cervical cancer metastases. We aimed to evaluate their biological effects on cervical cancer metastases in vivo. Confocal microscopy was used to detect transfection efficiency, ferric oxide or ferric oxide nanoparticles were used to intervene cervical cancer cell lines, and flow cytometry explored cell apoptosis. The mouse model of cervical cancer metastasis was further treated with ferric oxide or ferric tetroxide nanoparticles through intraperitoneal injection. The tumor volume was counted and size was measured. Cell proliferation and apoptosis were detected by IHC and Western-blot was used to detect protein expression. Nanoparticles significantly enhanced the cellular uptake of Fe3O4, which inhibited cell proliferation and promoted cell apoptosis. In the in vivo transplanted tumor model, the same was observed in mice. In the mice model, ferric oxide nanoparticles significantly inhibited the growth of tumors, slowed down tumor growth rate, and accelerated apoptosis. Our research results showed that nanoparticles contributed to the uptake of oxidized particles, and Fe3O4 nanoparticles regulated studied tumors by enhancing cytotoxicity, thereby inhibiting cell proliferation and promoting cell apoptosis, achieving Fe3O4 nanoparticles. The particles significantly inhibited tumor growth, slowed down multiplication rate, and accelerated apoptosis, suggesting that Fe3O4 nanoparticles have a significant inhibitory effect on cervical cancer transplanted tumors.

Next-generation anti-PD-L1/IL-15 immunocytokine elicits superior antitumor immunity in cold tumors with minimal toxicity

Next-generation anti-PD-L1/IL-15 immunocytokine elicits superior antitumor immunity in cold tumors with minimal toxicity

Inhalable nanoparticles with enhanced cuproptosis and cGAS–STING activation for synergistic lung metastasis immunotherapy

Due to the insufficient Cu+ accumulation, Cu+ efflux mechanism, and highly immunosuppressive tumor microenvironment (TME) in lung metastasis, the cuproptosis efficacy is limited. Herein, an inhalable nanodevice (CLDCu) is constructed to successfully overcome the drawbacks of cuproptosis. CLDCu consists of a Cu2+-chitosan shell and low molecular weight heparin-tocopherol succinate (LMWH-TOS, LT) core with disulfiram (DSF) loading. The prepared CLDCu can be inhaled and accumulate in large amounts in lung lesions (63.6%) with 56.5 times higher than intravenous injection. Within tumor cells, the mild acidity triggers the co-release of DSF and Cu2+, thus generating bis(diethyldithiocarbamate)-copper (CuET) to block Cu+ efflux protein ATP7B and forming toxic Cu+, leading to enhanced cuproptosis. Meanwhile, the released chitosan cooperates with CLDCu-induced cuproptosis to activate stimulator of interferon genes (STING) pathway, which significantly potentiates dendritic cells (DCs) maturation, as wells as evokes innate and adaptive immunity. In lung metastatic mice model, CLDCu is found to induce cuproptosis and reverse the immunosuppressive TME by inhalation administration. Moreover, CLDCu combined with anti-programmed cell death protein ligand-1 antibody (aPD-L1) provokes stronger antitumor immunity. Therefore, nanomedicine that combines cuproptosis with STING activation is a novel strategy for tumor immunotherapy.