Multiple Breast Cancer Subtypes Research Articles

Flavokavain C Suppresses Breast Cancer Cell Viability and Induces Cell Apoptosis by Triggering DNA Damage.

Breast cancer, presented by multiple breast cancer subtypes that coexist within a diagnosed tumor in clinical, has ranked as the most common malignancy in women in recent years. Evidence suggested that limited effective drugs caused the unsatisfactory therapeutic efficacy of breast cancer. Flavokavain C exhibited anticancer activity on colon cancer cells HCT116. It is yet unknown if it can be used to treat breast cancer. This study aims to believe the mechanisms by which Flavokavain C suppresses cell proliferation and the pathways that impact on this effect in breast cancer. 3-(4,5-Dimethythiazol)-2,5-diphenyltetrazolium bromide assay was chosen to evaluate cell cytotoxicity. Colony formation and cell proliferation assays using 5-ethynyl-2'-deoxyuridine staining were performed. Cell cycle progression and apoptosis were examined via flow cytometry and Western blotting, respectively. Five methods (comet assay, immunofluorescence, Western blotting, agarose gel electrophoresis and molecular docking) were used to quantify DNA damage and its cellular response. Compared to cisplatin, Flavokavain C possessed a comparable or more substantial inhibitory effect on breast cancer cell viability while having lower cytotoxicity on human mammary cells. Breast cancer cells treated with Flavokavain C had their colony formation suppressed, DNA replication blocked, the G2/M phase cell cycle arrested, and apoptosis. Furthermore, the results indicated that Flavokavain C would directly interact with DNA and induce DNA cleavage, demonstrating that DNA is an attractive substrate for Flavokavain C. These results suggested that Flavokavain C had strong anticancer activity against multiple subtypes of breast cancer cells.

Abstract P3-07-12: Allogeneic, Antigen-Presenting, GM-CSF-secreting, SV-BR-1-GM Whole Cell Therapeutic Vaccine in Advanced Metastatic Breast Cancer

Abstract Background: SV-BR-1-GM is an irradiated allogeneic cell line derived from a hormone receptor-negative (HR-) HER2-positive (HER2+) breast cancer (BC), now engineered to express HLA class I and II antigens, secrete GM-CSF and function as an antigen-presenting cell. Here we report post-hoc exploratory data for metastatic BC (MBC) patients treated with the SV-BR-1-GM regimen (SV) alone (NCT03066947) and in combination (CO) with immune checkpoint inhibitors (ICIs) (NCT03328026). Methods: SV includes cyclophosphamide 300 mg/m2 i.v. 48-72 hours prior to SV-BR-1-GM (20 × 106 cells) intradermally followed by interferon-alpha-2b at the SV-BR-1-GM inoculation sites on days 2 and 4. SV was given every 2 weeks for 3 cycles and then monthly in NCT03066947, and every 3 weeks in combination with PD-1 inhibitors in NCT03328026. Treatment was continued until disease progression or unacceptable toxicities. Results: A total of 34 refractory MBC patients (pts) were treated, including 24 with SV, and 14 with CO, including 4 who crossed over from SV to CO plus one who restarted the SV after a protocol specified administrative interruption in treatment. Median prior regimens were 5; 55% of pts had hormone receptor-positive (HR+) BC, 42% had HER2+ BC, and 16% were triple-negative BC (TNBC). Objective response rates (ORR) were 4% for monotherapy and 7% for combination. Clinical benefit rate (CBR) was 21% for monotherapy and 29% for combination. Responses and clinical benefits were seen across most BC subtypes (see table). Notably, CBR among 10 pts with HR+ BC (any HER2) who received the combination was 50% (5/10). The duration of response (DOR) among 4 patients treated with monotherapy was 49-223 days and DOR among 6 patients treated with combination was 72-292 days. Median PFS was 2.8 months for monotherapy and 4.2 months for combination. Median OS was 7.0 months for monotherapy, and 12.0 months for combination. Of 28 pts with available prior treatment data, 12 (43%) had PFS on study treatment exceeded PFS on prior treatment, of these 8/12 had >1 HLA match and 5/8 had ≥ 2 loci HLA-matched with SV-BR-1-GM. PFS ratio improvement was independent of the prior number of lines of therapy or BC subtypes. The SV-BR-1GM regimen was well tolerated with the most common treatment-related adverse events (AEs) being injection site reaction in 67%. There was no dose-limiting toxicity, special interest AEs such as cytokine storm, and no grade 5 observed. There were 2 non-treatment-related grade 4 AEs: worsening pleural effusion and altered mental status. Significant improvement in PFS was observed in patients with matched HLA and in association with the delayed-type hypersensitivity skin test, peripheral blood circulating tumor cells, and cancer-associated macrophages. Conclusions: SV-BR-1-GM demonstrated promising activity in patients with MBC. Treatment was well tolerated with no concerning AEs. The PFS ratio compares favorably with prior penultimate standards of care, more notably in patients with matched HLA. Clinical benefits were observed across multiple subtypes of BC, particularly in patients with HR+ disease receiving combination therapy. Phase II clinical trial is currently ongoing to evaluate the efficacy of SV-BR-1-GM in combination with ICIs. Clinical benefit and PFS on SV-BR-1-GM SV-BR-1-GM Whole Cell Therapeutic Vaccine in Heavily Pre-Treated Metastatic Breast Cancer Results Stratified by HER2 and HLA Matching Citation Format: Saranya Chumsri, William Williams, Mingjin Chang, Miguel Lopez-Lago, Charles Wiseman, Jarrod Holmes, Chaitali Nangia, Karim Mohammed, Minal Barve, Shaker Dakhil, Bonnie Guerin, Giuseppe Del Priore, Carmen Calfa. Allogeneic, Antigen-Presenting, GM-CSF-secreting, SV-BR-1-GM Whole Cell Therapeutic Vaccine in Advanced Metastatic Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-07-12.

NUF2 Promotes Breast Cancer Development as a New Tumor Stem Cell Indicator

Multiple new subtypes of breast cancer (BRCA) are identified in women each year, rendering BRCA the most common and rapidly expanding form of cancer in females globally. NUF2 has been identified as a prognostic factor in various human cancers, regulating cell apoptosis and proliferation. However, its role in BRCA prognosis has not been clarified. This study explored the role of NUF2 in breast cancer development and prognosis using informatic analysis combined with in vivo intracellular studies. Through the online website TIMER, we evaluated the transcription profile of NUF2 across a variety of different cancer types and found that NUF2 mRNA was highly expressed in BRCA patients. Its transcription level was found to be related to the subtype, pathological stage, and prognosis of BRCA. The R program analysis showed a correlation of NUF2 with cell proliferation and tumor stemness in the BRCA patient samples. Subsequently, the association between the NUF2 expression level and immune cell infiltration was analyzed using the XIANTAO and TIMER tools. The results revealed that NUF2 expression was correlated with the responses of multiple immune cells. Furthermore, we observed the effect of NUF2 expression on tumor stemness in BRCA cell lines in vivo. The experimental results illuminated that the overexpression of NUF2 statistically upregulated the proliferation and tumor stemness ability of the BRCA cell lines MCF-7 and Hs-578T. Meanwhile, the knockdown of NUF2 inhibited the abilities of both cell lines, a finding which was verified by analyzing the subcutaneous tumorigenic ability in nude mice. In summary, this study suggests that NUF2 may play a key role in the development and progression of BRCA by affecting tumor stemness. As a stemness indicator, it has the potential to be one of the markers for the diagnosis of BRCA.

Synthesis and biological evaluation of tert-butyl ester and ethyl ester prodrugs of L-γ-methyleneglutamic acid amides for cancer

In cancer cells, glutaminolysis is the primary source of biosynthetic precursors. Recent efforts to develop amino acid analogues to inhibit glutamine metabolism in cancer have been extensive. Our lab recently discovered many L-γ-methyleneglutamic acid amides that were shown to be as efficacious as tamoxifen or olaparib in inhibiting the cell growth of MCF-7, SK-BR-3, and MDA-MB-231 breast cancer cells after 24 or 72 h of treatment. None of these compounds inhibited the cell growth of nonmalignant MCF-10A breast cells. These L-γ-methyleneglutamic acid amides hold promise as novel therapeutics for the treatment of multiple subtypes of breast cancer. Herein, we report our synthesis and evaluation of two series of tert-butyl ester and ethyl ester prodrugs of these L-γ-methyleneglutamic acid amides and the cyclic metabolite and its tert-butyl esters and ethyl esters on the three breast cancer cell lines MCF-7, SK-BR-3, and MDA-MB-231 and the nonmalignant MCF-10A breast cell line. These esters were found to suppress the growth of the breast cancer cells, but they were less potent compared to the L-γ-methyleneglutamic acid amides. Pharmacokinetic (PK) studies were carried out on the lead L-γ-methyleneglutamic acid amide to establish tissue-specific distribution and other PK parameters. Notably, this lead compound showed moderate exposure to the brain with a half-life of 0.74 h and good tissue distribution, such as in the kidney and liver. Therefore, the L-γ-methyleneglutamic acid amides were then tested on glioblastoma cell lines BNC3 and BNC6 and head and neck cancer cell lines HN30 and HN31. They were found to effectively suppress the growth of these cancer cell lines after 24 or 72 h of treatment in a concentration-dependent manner. These results suggest broad applications of the L-γ-methyleneglutamic acid amides in anticancer therapy.

Abstract 1797: Bcl-2 up-regulation mediates taxane resistance downstream of APC loss

Abstract Patients with triple negative breast cancer (TNBC) are treated with traditional chemotherapy, such as paclitaxel (PTX). Despite the efficacy of taxanes, many tumors will recur due to drug resistance. Therefore, the need to understand the mechanism behind drug resistance is critical to improve patient outcome and survival. Our lab was the first to show that loss of the Adenomatous Polyposis Coli (APC) tumor suppressor caused resistance to PTX in the MDA-MB-157 human TNBC cell line. In the absence of APC, apoptosis induction was decreased, as measured through cleaved caspase 3 and annexin/PI staining. To understand the molecular mechanisms behind APC-mediated PTX response, we analyzed the BCL-2 family of proteins and found a robust increase of the pro-survival family member, Bcl-2. The BH3 mimetic, ABT-199 (Venetoclax), which specifically targets Bcl-2, has been used as a single or combination therapy in multiple hematologic malignancies. In addition, ABT-199 has shown promise in multiple subtypes of breast cancer. Therefore, we used ABT-199 in combination with PTX to address the hypothesis that APC-induced Bcl-2 increase is responsible for PTX resistance. Combination treatment in three CRISPR-mediated APC knockout TNBC cell lines (MDA-MB-157, MDA-MB-231, and SUM159) caused changes in cell proliferation and apoptosis. Combined, these data suggest restored sensitivity to PTX using ABT-199. Our studies are the first to show that Bcl-2 inhibition can restore PTX-sensitivity in APC mutant breast cancer cells. These studies are critical to advance better treatment regimens in patients with TNBC. Citation Format: Sara Maloney, Sarah Zabala, Grace Richmond, Jenifer R. Prosperi. Bcl-2 up-regulation mediates taxane resistance downstream of APC loss [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1797.

Abstract P5-08-05: Preclinical activity of KB-0742, an oral, highly selective, CDK9 inhibitor, in cell lines and in MYC-high expressing, patient-derived models of multiple breast cancer subtypes

Abstract KB-0742 is an orally available, potent, and selective inhibitor of cyclin-dependent kinase 9 (CDK9). Sensitivity profiling across a panel of 800 adherent and suspension immortalized pan-cancer cell lines using the Broad Institute PRISM platform had previously demonstrated MYC amplification as being a driver of KB-0742 sensitivity. We sought to further determine the activity of KB-0742 in breast cancer cell lines, patient-derived cell and organoid cultures, and patient-derived xenograft (PDX) models. KB-0742 decreased the viability of cell lines derived from primary and metastatic breast cancers, including triple-negative breast cancers (TNBCs). In a panel of 17 breast cancer cell lines, including 2 human epidermal growth factor receptor 2-positive (HER2+), 7 estrogen-receptor positive (ER+), 1 HER2+/ER+ and 7 TNBCs, the effect of KB-0742 on viability was either cytostatic or cytotoxic over the duration of the culture period. KB-0742 was also tested in patient-derived cell lines derived from primary and metastatic tumors including TNBC, and in 2 TNBC MYC-high expressing patient-derived organoid cultures. KB-0742 demonstrated cytostatic and cytotoxic effects on cell growth and superior inhibitory effects on cell growth in the TNBC organoid cultures as compared with paclitaxel and gemcitabine. Since sensitivity to KB-0742 was observed in breast cancer cell lines and patient-derived models, including TNBCs, we evaluated efficacy and target engagement in several MYC-high expressing TNBC PDX animal models. Treatment with KB-0742 using an intermittent dosing schedule (3-days on/4-days off) was well tolerated and resulted in anti-tumor activity comparable to that observed with standard of care chemotherapeutic agents. Tumors collected at 2 and 8 hours post-final dose displayed a decrease in phosphorylated serine residue 2 (pSER2) in the C-terminal domain of RNA polymerase II (RNA pol-II) and decreased MYC protein levels consistent with CDK9 inhibition. These data demonstrate the efficacy of KB-0742 in preclinical models of breast cancer and supports clinical testing in TNBC patients. KB-0742 is currently being evaluated in a phase I dose-escalation trial in patients with relapsed or refractory solid tumors or non-Hodgkin lymphoma (NCT04718675). Citation Format: Douglas C. Saffran, Melinda A.L. Day, Nathalie Rioux, Tom Chen, Christina Lee, Suha Naffar-Abu Amara, David B. Freeman, Tressa Hood, Charles Y. Lin, Pavan Kumar, Jorge DiMartino. Preclinical activity of KB-0742, an oral, highly selective, CDK9 inhibitor, in cell lines and in MYC-high expressing, patient-derived models of multiple breast cancer subtypes [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-08-05.

HSP90 inhibitors induce GPNMB cell-surface expression by modulating lysosomal positioning and sensitize breast cancer cells to glembatumumab vedotin.

Transmembrane glycoprotein NMB (GPNMB) is a prognostic marker of poor outcome in patients with triple-negative breast cancer (TNBC). Glembatumumab Vedotin, an antibody drug conjugate targeting GPNMB, exhibits variable efficacy against GPNMB-positive metastatic TNBC as a single agent. We show that GPNMB levels increase in response to standard-of-care and experimental therapies for multiple breast cancer subtypes. While these therapeutic stressors induce GPNMB expression through differential engagement of the MiTF family of transcription factors, not all are capable of increasing GPNMB cell-surface localization required for Glembatumumab Vedotin inhibition. Using a FACS-based genetic screen, we discovered that suppression of heat shock protein 90 (HSP90) concomitantly increases GPNMB expression and cell-surface localization. Mechanistically, HSP90 inhibition resulted in lysosomal dispersion towards the cell periphery and fusion with the plasma membrane, which delivers GPNMB to the cell surface. Finally, treatment with HSP90 inhibitors sensitizes breast cancers to Glembatumumab Vedotin in vivo, suggesting that combination of HSP90 inhibitors and Glembatumumab Vedotin may be a viable treatment strategy for patients with metastatic TNBC.

Enhancing the Antitumor Effect of Doxorubicin with Photosensitive Metal-Organic Framework Nanoparticles against Breast Cancer.

Breast cancer is one of the most common malignant tumors in women. The existence of multiple breast cancer subtypes often leads to chemotherapy failure or the development of drug resistance. In recent years, photodynamic therapy has been proven to enhance the sensitivity of tumors to chemotherapeutic drugs. Porphyrin-based metal-organic framework (MOF) materials could simultaneously be used as carriers for chemotherapy and photosensitizers in photodynamic therapy. In this paper, doxorubicin hydrochloride (DOX) was loaded in porphyrin MOFs, and the mechanism of the synergistic effect of the DOX carriers and photodynamic therapy on breast cancer was investigated. In vitro and in vivo experiments have shown that MOFs could prolong the residence time of DOX in tumor tissues and promote the endocytosis of DOX by tumor cells. In addition, adjuvant treatment with photodynamic therapy can promote breast cancer tumors to resensitize to DOX and synergistically enhance the chemotherapy effect of DOX. Therefore, this study can provide effective development ideas for reversing drug resistance during breast cancer chemotherapy and improving the therapeutic effect of chemotherapy on breast cancer.

Abstract 2576: Calorie restriction reverses the tumorigenic effects of obesity to a greater extent than bariatric surgery in a murine model of breast cancer

Abstract Obesity is an established risk and prognostic factor for multiple breast cancer (BC) subtypes. Epidemiologic studies suggest that weight loss via bariatric surgery results in metabolic reprogramming that reverses systemic aberrations as well as the protumorigenic effects of obesity; however, data on the effects of nonsurgical weight loss interventions in obese women remain inconclusive. We previously established that diet-induced obesity (DIO) increases tumor progression in murine models of basal-like BC. The purpose of this study was to determine if surgical and dietary weight loss interventions could effectively reduce obesity-associated tumor progression. Our first experiment directly compared mammary tumor growth following weight loss in DIO mice. Female C57BL/6 mice were randomized to a low-fat control (CON; 10 kcal% fat) diet or DIO regimen (60 kcal% fat) for 15 weeks. DIO mice were then randomized to either remain on DIO diet (DIO-DIO) or initiate weight loss either via vertical sleeve gastrectomy (DIO-SURG, with concurrent switch to control diet) or switch to control diet without surgery (DIO-DIET). CON mice remained on the 10 kcal% fat diet throughout the study. Eight weeks later, all mice were orthotopically injected with E0771 basal-like mammary tumor cells and were euthanized when tumors from the DIO-DIO group reached 1.5cm3. Body weights were not significantly different between DIO-SURG and DIO-DIET mice but both groups weighed significantly less than DIO-DIO mice. Compared with CON mice, tumor burden was not different in DIO-SURG mice but was significantly greater in DIO-DIET mice, suggesting that surgical weight loss more effectively reverses the protumorigenic effects of obesity than a low-fat diet. We next sought to determine how the anticancer effects of calorie restricted diets compared with bariatric surgery. Another group of female C57BL/6 received DIO diet for 16 weeks, then randomized to the same CON or DIO-SURG interventions as above, or to receive one of two calorie restriction (CR) diets—chronic CR (DIO-CCR; 30% daily calorie reduction) or intermittent CR (DIO-ICR; 14% calorie reduction 5 days per week, 70% calorie reduction on 2 nonconsecutive days per week). At time of tumor collection, DIO-SURG, DIO-CCR, and DIO-ICR mice weighed significantly less than DIO-DIO mice; however, only DIO-CCR and DIO-ICR mice achieved body weights significantly lower than CON mice. Tumor weights were significantly reduced in DIO-CCR and DIO-ICR fed mice, relative to CON mice, while tumor weights of DIO-SURG mice were intermediate. Moreover, multiple linear regression indicated weight loss, irrespective of intervention, was the strongest predictor of tumor mass. Our results in a murine model of basal-like BC suggest that weight loss via CR regimens (CCR, ICR) and, to a lesser extent, bariatric surgery, mitigates the pro-tumorigenic effects of obesity. Citation Format: Kristina K. Camp, Emily Rossi, Tori L. McFarlane, Steven Doerstling, Subreen Khatib, Elaine Glenny, Michael Coleman, Laura Bowers, Erika Rezeli, Randy J. Seeley, Alfor G. Lewis, Joel Parker, Anthony Fodor, Farnaz Fouladi, Stephen Hursting. Calorie restriction reverses the tumorigenic effects of obesity to a greater extent than bariatric surgery in a murine model of breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2576.

Machine learning integrated ensemble of feature selection methods followed by survival analysis for predicting breast cancer subtype specific miRNA biomarkers

Breast cancer is the second leading cancer type among females. In this regard, it is found that microRNAs play an important role by regulating the gene expressions at the post-transcriptional phase. However, identification of the most influencing miRNAs in breast cancer subtypes is a challenging task, while the recent advancement in Next Generation Sequencing techniques allows analyzing high throughput expression data of miRNAs. Thus, we have conducted this research with the help of NGS data of breast cancer in order to identify the most significant miRNA biomarkers. The selected miRNA biomarkers are highly associated with the multiple breast cancer subtypes. For this purpose, a two-phase technique, called Machine Learning Integrated Ensemble of Feature Selection Methods, followed by survival analysis, is proposed. In the first phase, we have selected the best among seven machine learning techniques based on classification accuracy using the entire set of features (in this case miRNAs). Subsequently, eight different feature selection methods are used separately in order to rank the features and validate each set of top features using the selected machine learning technique by considering a multi-class classification task of the breast cancer subtypes. In the second phase, based on the classification accuracy values, the top features from each feature selection method are considered to make an ensemble to provide further categorization of the miRNAs as 8*, 7* up to 1*. The 8* miRNAs provide the highest average classification accuracy of 86% after 10-fold cross-validation. Thereafter, 27 miRNAs are identified from the list that is confined within 8* to 4* miRNAs based on their importance in survival for breast cancer subtypes using Cox regression based survival analysis. Moreover, expression analysis, regulatory network analysis, protein-protein interaction analysis, KEGG pathway and gene ontology enrichment analysis are performed in order to validate biological significance of the proposed solution. Additionally, we have prepared a miRNA-protein-drug interaction network to identify possible drug for the selected miRNAs. Thus, our findings may be considered during a clinical trial for the treatment of breast cancer patients.

Recent advances in neoadjuvant therapy for breast cancer.

Neoadjuvant trials for early breast cancer have accelerated the identification of novel active agents, enabling streamlined conduct of registration trials with fewer subjects. Measurement of neoadjuvant drug effects has also enabled the identification of patients with high risk of distant recurrence and has justified development of additional adjuvant approaches to improve outcomes. Neoadjuvant evaluation of new drugs was significantly improved by the introduction of pathologic complete response (pCR) rate as a quantitative surrogate endpoint for distant disease-free survival (DDFS) and event free survival (EFS). The neoadjuvant phase 2 platform trial I-SPY 2 simultaneously tests multiple drugs across multiple breast cancer subtypes using Bayesian methods of adaptive randomization for assessment of drug efficacy. In addition to the pCR endpoint, the I-SPY 2 trial has demonstrated that the residual cancer burden (RCB) score measures gradations of tumor response that correlate with DDFS and EFS across treatments and subtypes. For HER2-positive and triple-negative breast cancers that have failed to attain pCR with neoadjuvant chemotherapy (NAC), effective modifications of adjuvant treatment have improved outcomes and changed the standard of care for these subtypes. Neoadjuvant therapy is therefore preferred for stage II and III, as well as some stage I, HER2-positive and triple-negative tumors. Neoadjuvant endocrine therapy (NET) strategies have also emerged from innovative trials for stage II and III estrogen receptor (ER)-positive/HER2-negative tumors, as in the ALTERNATE trial. From neoadjuvant trials, opportunities have emerged to de-escalate therapy on the basis of metrics of response to chemotherapy or hormonal therapy. Neoadjuvant therapy for early breast cancer is therefore emerging as a promising approach to accelerate new drug development, optimize treatment strategies, and (where appropriate) de-escalate neoadjuvant therapy.

An efficient synthetic route to l-γ-methyleneglutamine and its amide derivatives, and their selective anticancer activity.

In cancer cells, glutaminolysis is the primary source of biosynthetic precursors, fueling the TCA cycle with glutamine-derived α-ketoglutarate. The enhanced production of α-ketoglutarate is critical to cancer cells as it provides carbons for the TCA cycle to produce glutathione, fatty acids, and nucleotides, and contributes nitrogens to produce hexosamines, nucleotides, and many nonessential amino acids. Efforts to inhibit glutamine metabolism in cancer using amino acid analogs have been extensive. l-γ-Methyleneglutamine was shown to be of considerable biochemical importance, playing a major role in nitrogen transport in Arachis and Amorpha plants. Herein we report for the first time an efficient synthetic route to l-γ-methyleneglutamine and its amide derivatives. Many of these l-γ-methyleneglutamic acid amides were shown to be as efficacious as tamoxifen or olaparib at arresting cell growth among MCF-7 (ER+/PR+/HER2-), and SK-BR-3 (ER-/PR-/HER2+) breast cancer cells at 24 or 72 h of treatment. Several of these compounds exerted similar efficacy to olaparib at arresting cell growth among triple-negative MDA-MB-231 breast cancer cells by 72 h of treatment. None of the compounds inhibited cell growth in benign MCF-10A breast cells. Overall, N-phenyl amides and N-benzyl amides, such as 3, 5, 9, and 10, arrested the growth of all three (MCF-7, SK-BR-3, and MDA-MB-231) cell lines for 72 h and were devoid of cytotoxicity on MCF-10A control cells; N-benzyl amides with an electron withdrawing group at the para position, such as 5 and 6, inhibited the growth of triple-negative MDA-MB-231 cells commensurate to olaparib. These compounds hold promise as novel therapeutics for the treatment of multiple breast cancer subtypes.

The FGF/FGFR System in Breast Cancer: Oncogenic Features and Therapeutic Perspectives.

Simple SummaryThe fibroblast growth factor/fibroblast growth factor receptor (FGF/FGFR) system represents an emerging therapeutic target in breast cancer. Here, we discussed previous studies dealing with FGFR molecular aberrations, the alterations in the FGF/FGFR signaling across the different subtypes of breast cancer, the functional interplay between the FGF/FGFR axis and important components of the breast microenvironment, the therapeutic usefulness of FGF/FGFR inhibitors for the treatment of breast cancer.One of the major challenges in the treatment of breast cancer is the heterogeneous nature of the disease. With multiple subtypes of breast cancer identified, there is an unmet clinical need for the development of therapies particularly for the less tractable subtypes. Several transduction mechanisms are involved in the progression of breast cancer, therefore making the assessment of the molecular landscape that characterizes each patient intricate. Over the last decade, numerous studies have focused on the development of tyrosine kinase inhibitors (TKIs) to target the main pathways dysregulated in breast cancer, however their effectiveness is often limited either by resistance to treatments or the appearance of adverse effects. In this context, the fibroblast growth factor/fibroblast growth factor receptor (FGF/FGFR) system represents an emerging transduction pathway and therapeutic target to be fully investigated among the diverse anti-cancer settings in breast cancer. Here, we have recapitulated previous studies dealing with FGFR molecular aberrations, such as the gene amplification, point mutations, and chromosomal translocations that occur in breast cancer. Furthermore, alterations in the FGF/FGFR signaling across the different subtypes of breast cancer have been described. Next, we discussed the functional interplay between the FGF/FGFR axis and important components of the breast tumor microenvironment. Lastly, we pointed out the therapeutic usefulness of FGF/FGFR inhibitors, as revealed by preclinical and clinical models of breast cancer.

Single-cell RNA-sequencing reveals distinct patterns of cell state heterogeneity in mouse models of breast cancer.

Breast cancer stem cells (BCSCs) contribute to intra-tumoral heterogeneity and therapeutic resistance. However, the binary concept of universal BCSCs co-existing with bulk tumor cells is over-simplified. Through single-cell RNA-sequencing, we found that Neu, PyMT and BRCA1-null mammary tumors each corresponded to a spectrum of minimally overlapping cell differentiation states without a universal BCSC population. Instead, our analyses revealed that these tumors contained distinct lineage-specific tumor propagating cells (TPCs) and this is reflective of the self-sustaining capabilities of lineage-specific stem/progenitor cells in the mammary epithelial hierarchy. By understanding the respective tumor hierarchies, we were able to identify CD14 as a TPC marker in the Neu tumor. Additionally, single-cell breast cancer subtype stratification revealed the co-existence of multiple breast cancer subtypes within tumors. Collectively, our findings emphasize the need to account for lineage-specific TPCs and the hierarchical composition within breast tumors, as these heterogenous sub-populations can have differential therapeutic susceptibilities.

Abstract P6-05-08: Progesterone receptor membrane component 1 controls cellular proliferation and plays a key role in the molecular circuitry of both ER positive and triple negative breast cancers

Abstract Introduction: Increased expression of progesterone receptor membrane component 1 (PGRMC1), has been linked to breast cancer cell proliferation and tumor growth via epidermal growth factor receptor (EGFR) dependent interaction. As estrogen receptor positive breast cancers receive endocrine therapy and triple negative breast cancers (TNBC) rely on chemotherapeutic agents and or small molecule inhibitors. PGRMC1 could be a potential therapeutic target for both estrogen receptor positive and TNBCs, however its mechanism of action remains elusive. We, aim to understand the signaling mechanism behind PGRMC1 and its potential as viable target for the treatment of breast cancers. Materials and Methods: A panel of non-malignant and malignant breast cell lines were cultured and screened for PGRMC1 expression. PGRMC1 overexpressing breast cancer cell lines were treated with AG-205 (PGRMC1 inhibitor) and PGRMC1 targeting siRNAs. MTS, qRT-PCR, Western blot, immunofluorescence, flow cytometry assays and phospho explorer antibody array analysis were performed. Results: Increased PGRMC1 mRNA and protein levels were observed in estrogen receptor positive ZR-75-1 and TNBC MDA-MB-468 cells, these results were validated and compared to online RNA-seq based gene expression analysis of breast cell lines and breast tumor data sets. Data from online databases also demonstrated PGRMC1 overexpression in multiple breast cancer subtypes (Luminal, Basal B and Basal A). Immunohistochemistry demonstrated strong staining for PGRMC1 in human breast cancer tissue compared to normal tissue. Both AG-205 treatment and PGRMC1 silencing decreased cell proliferation, induced cell cycle arrest at the G0/G1 phase, promoted apoptosis and reduced the capability of the cells to migrate and invade. Phospho-specific antibody array data demonstrated overall downregulation of the EGFR/PI3K/AKT signaling mechanisms following AG-205 and PGRMC1 silencing. Alteration in the expression of key markers of cell proliferation, apoptosis and cell cycle revealed that PGRMC1 inhibition decreases breast cancer proliferation. Conclusion: Our data demonstrate that PGRMC1 plays a prominent role in regulating breast cancer growth and progression by altering the EGFR/PI3K/AKT signaling mechanisms. Citation Format: Diego A Pedroza, Alejandra Bencomo, Adriana Galvez, Ramadevi Subramani, Venkatesh Rajamanickam, Rajkumar Lakshmanaswamy. Progesterone receptor membrane component 1 controls cellular proliferation and plays a key role in the molecular circuitry of both ER positive and triple negative breast cancers [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-05-08.

Abstract OT1-08-01: A phase Ib trial of sequential combinations of BN-brachyury, entinostat, ado-trastuzumab emtansine (T-DM1) and bintrafusp alfa (M7824) in advanced stage breast cancer (BrEAsT)

Abstract Immune checkpoint blockade (ICB) monotherapy has produced limited benefit in breast cancer (BC) with response rates (RR) ranging from 5 to 23%. Combination ICB improved RR and progression free survival (PFS) resulting in atezolizumab + nab-paclitaxel receiving FDA accelerated approval for programmed cell death ligand 1 (PD-L1) positive, triple negative breast cancers (TNBC). BC has historically been considered immunologically quiet with most having a low mutational burden, low PD-L1 expression, defective antigen presentation machinery, and immuosuppressive signals in the tumor microenvironment (TME). An approach using a combination of immuno-oncology (IO) agents including ICB, immunomodulators and vaccines may shift the TME to allow for improved antigen presentation, the release of immunostimulatory cytokines, more immunogenic cell death and increased PD-L1 expression. The transcription factor brachyury plays an important role in breast tumor plasticity. High brachyury expression is associated with treatment resistance and a worse prognosis. Entinostat is a histone deacetylase inhibitor that has activity in multiple breast cancer subtypes. Preclinical data demonstrates entinostat upregulates MHC, enhances immune-mediated lysis and upregulates PD-L1 expression through epigenetic modification. Bintrafusp alfa is a bifunctional protein composed of the extracellular domain of the TGF-βRII receptor (TGF-β“trap”) fused to a human IgG1. Preclinical data shows bintrafusp alpha treatment increases T-cell trafficking, antigen-specific CD8+ T-cell lysis and NK cell activation. Monotherapy clinical studies with these agents have produced modest results in solid tumors, including BC. Preclinical data evaluating combinations of these agents shows a reduction in in tumor size, improved antigen-specific T-cell responses, reduced regulatory T cells, increased CD8+T-cells, and increased PD-L1 expression. We propose the stepwise addition of BN-Brachyury, Bintrafusp alfa, T-DM1 and Entinostat in advanced BC. This phase Ib study will assess efficacy and safety of the regimen and has three cohorts: Cohort 1(TNBC) will receive BN-Brachyury + Bintrafusp alfa. Cohort 2 (HER2+) will receive T-DM1 + BN-Brachyury + Bintrafusp alfa +/- entinostat. After safety is established in Cohort 2, patients in Cohort 3 (HER2+) will be assigned to receive T-DM1 + BN-Brachyury + Bintrafusp alfa +/- entinostat. Responses are evaluated every 2 cycles (6 weeks). Patients in Cohorts 2 and 3 will undergo research biopsies -baseline and after 2 cycles to evaluate changes within TME. Peripheral immune responses will be evaluated at selected time points. All patients must have measurable disease and HER2+ patients must have biopsiable disease. >1 prior treatment is required. Asymptomatic or brain metastases treated > 6 weeks are allowed. Well controlled HIV, HBV or treated HCV is allowed. Exclusion criteria include symptomatic brain metastases or clinically significant bleeding (<3 months from study entry). Co-primary objectives are RR and safety. Secondary objectives include PFS and changes in tumor infiltrating lymphocytes (Cohorts 2 and 3). Exploratory analyses include changes in immune cells and cytokines in the peripheral blood. Analyses performed will be descriptive, reporting the outcome measure for each treatment arm indicated along with two-tailed 80% and 95% confidence intervals. All cohorts employ a safety assessment in the initial 6 patients and a Simon minimax 2-stage design for clinical efficacy. We plan to recruit 51 patients: 13 patients with TNBC, 38 patients with HER2+BC. This trial will open Fall 2019 at the National Institutes of Health (Bethesda, MD). For more information contact the PI, Margaret.gatti-mays@nih.gov. Citation Format: Margaret E Gatti-Mays, Claudia Palena, Sofia R Gameiro, Renee N Donahue, Caroline Jochems, Seth Steinberg, Stan Lipkowitz, Alexandra Zimmer, Deneise Francis, Julius Strauss, Houssein Abdul Sater, Lisa Cordes, Jason Redman, Fatima Karzai, Marijo Bilusic, Ravi A Madan, James L Gulley, Jeffrey Schlom. A phase Ib trial of sequential combinations of BN-brachyury, entinostat, ado-trastuzumab emtansine (T-DM1) and bintrafusp alfa (M7824) in advanced stage breast cancer (BrEAsT) [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT1-08-01.

Human Tumor-Lymphatic Microfluidic Model Reveals Differential Conditioning of Lymphatic Vessels by Breast Cancer Cells.

Breast tumor progression is a complex process involving intricate crosstalk between the primary tumor and its microenvironment. In the context of breast tumor-lymphatic interactions, it is unclear how breast cancer cells alter the gene expression of lymphatic endothelial cells and how these transcriptional changes potentiate lymphatic dysfunction. Thus, there is a need for in vitro lymphatic vessel models to study these interactions. In this work, a tumor-lymphatic microfluidic model is developed to study the differential conditioning of lymphatic vessels by estrogen receptor-positive (i.e., MCF7) and triple-negative (i.e., MDA-MB-231) breast cancer cells. The model consists of a lymphatic endothelial vessel cultured adjacently to either MCF7 or MDA-MB-231 cells. Quantitative transcriptional analysis reveals expression changes in genes related to vessel growth, permeability, metabolism, hypoxia, and apoptosis in lymphatic endothelial cells cocultured with breast cancer cells. Interestingly, these changes are different in the MCF7-lymphatic cocultures as compared to the 231-lymphatic cocultures. Importantly, these changes in gene expression correlate to functional responses, such as endothelial barrier dysfunction. These results collectively demonstrate the utility of this model for studying breast tumor-lymphatic crosstalk for multiple breast cancer subtypes.

Comparison of Clinical Features and Treatment Results of Mix Mucinous Carcinomas and Other Atypical Carcinomas of the Breast.

There are multiple subtypes of breast cancer with different biological and pathological features and accordingly exhibit different clinical behaviors. The aim of this study was to compare the treatment modalities, clinical features and prognostic characteristics of Mix Mucinous Carcinomas (MMBC) and other rare tumors of the breast. A total of 2152 patients who were operated on for breast cancer in our clinic between 2010-2019, with pathological diagnoses of tubular, pure mucinous, mix mucinous or papillary carcinoma were enrolled in the study. Patients were divided into two groups as mix mucinous patients (Group1) and other rare tumors (Group2). The demographic, clinical and prognostic characteristics and treatment approaches were compared between Groups, and additionally between the subtypes of Group 2. 42 patients participated in our study. Group 1 consisted of 7 patients, and Group2 consisted of 35 patients. The subtypes in Group2 were papillary (n=21), pure mucinous (n=10) and tubular (n=4). Progesterone Receptor Positivity was found to be significantly higher in Group 2 patients than in Group1 patients (p=0.005, p<0.05). Multicentricity rates in the tumors of the patients in Group1 were found to be statistically significantly higher than the patients in Group 2 (p=0.024, p<0.05). In subtype analysis in Group2, there were no statistically significant differences parameters in the subgroups (p>0.05). Mean survival was 19.5+5.6 (8.5-30.5) months in Group 1 and 46.3+5.2 (36.1-56.6) months, in Group2 when evaluated separately (p:0.002). The prognosis of pure mucinosis (PMBC) and other atypical cancers of the breast compared to the (MMBC) is quite good. Rare pathological types of breast cancer can have favorable outcomes when treated with necessary oncological principles.

High expression of PRKDC promotes breast cancer cell growth via p38 MAPK signaling and is associated with poor survival.

BackgroundDNA‐Dependent Protein Kinase Catalytic Subunit (PRKDC), a key component of the DNA damage repair pathway, is associated with chemotherapy resistance and tumor progression.MethodsHere we analyzed transcriptome data of ~2,000 breast cancer patients and performed functional studies in vitro to investigate the function of PRKDC in breast cancer.ResultsOur results revealed overexpression of PRKDC in multiple breast cancer subtypes. Consistent with patients’ data, overexpression of PRKDC was also observed in breast cancer cell lines compared to normal breast epithelial cells. Knockdown of PRKDC in MCF‐7 and T47D breast cancer cell lines resulted in proliferation inhibition, reduced colony formation and G2/M cell cycle arrest. Furthermore, we showed that PRKDC knockdown induced proliferation inhibition through activation of p38 MAPK, but not ERK MAPK, signaling pathway in breast cancer cells. Blockage of p38 MAPK signaling could largely rescue proliferation inhibition and cell cycle arrest induced by PRKDC knockdown. Moreover, we analyzed gene expression and clinical data from six independent breast cancer cohorts containing ~1,000 patients. In all cohorts, our results consistently showed that high expression of PRKDC was significantly associated with poor survival in both treated and untreated breast cancer patients.ConclusionTogether, our results suggest that high expression of PRKDC facilitates breast cancer cell growth via regulation of p38 MAPK signaling, and is a prognostic marker for poor survival in breast cancer patients.

Abstract P5-17-01: Patient-derived organoid models of inflammatory breast cancer

Abstract Background: Inflammatory Breast Cancer (IBC) is an aggressive subtype of breast cancer that is associated with an increased likelihood of early metastasis and a poor prognosis, accounting for approximately 10% of all breast cancer mortality. Currently, there is limited availability of cell line and patient-derived xenograft (PDX) models of IBC. As a result, there is an urgent need for additional model systems to facilitate our understanding of this disease. Organoids have been used to grow breast cancer cells with high efficiency, resulting in long-term cultures with genetic and phenotypic stability; however, the extent to which IBC can be modeled using this system is unknown. We undertook an evaluation of organoid culture technology for growing IBC patient samples, with the goal of generating a model of IBC that more faithfully recapitulates the key features of the disease. Methods: Tumor samples (taken from lumpectomy, mastectomy, PDX, or core biopsy samples), were digested to the organoid level using collagenase, and were grown in three dimensional cultures using a basement membrane extract and a fully-defined organoid medium, as described (Sachs et al. Cell 2018). First, we surveyed non-IBC metastatic breast cancer samples to determine the efficiency of growth of multiple breast cancer subtypes under these conditions. Then, we assessed the efficiency of growth of IBC samples taken after treatment, at the time of mastectomy. Co-culture experiments in which IBC organoids were grown in the presence of human endothelial cells were performed in three dimensional culture using a mixture of type I collagen and basement membrane extract. Results: Our success rate for establishing organoid cultures from breast cancer samples in general was 75% (33 out of 44 samples), and for triple-negative breast cancers, the success rate for establishment of organoid cultures was 100% (14 out of 14 samples). Expansion of ER+ tumor organoids (16 of 26 samples) was primarily restricted by a slow growth rate in culture, as compared to triple-negative tumor organoids. We were able to establish 12 breast cancer organoids from core biopsies of multiple metastatic sites, including brain, liver, bone, breast, and skin. We subsequently were able to establish organoid cultures from five out of five IBC tumor samples. Our IBC organoids preserved histopathologic features of the original tumor, and expressed key markers, such as E-cadherin, that are known to be associated with IBC. In addition, our IBC organoids interacted with human endothelial cells under co-culture conditions designed to model lymphovascular invasion, an essential feature of IBC. Conclusion: We have shown that organoid cultures can be established to propagate IBC tumors with high efficiency, preserve key pathologic features of IBC in vitro, and model interactions between tumor cells and the microenvironment. Thus, organoids are useful complements to existing IBC models, and can be used to identify potential therapeutic vulnerabilities associated with this particularly aggressive breast cancer subtype. Citation Format: Rosenbluth JM, Zervantonakis I, Boedicker M, Wagle N, Dillon D, Nakhlis F, Brugge JS, Overmoyer B. Patient-derived organoid models of inflammatory breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-17-01.