bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract PS15-03: Breast complications in patients who received intraoperative radiation therapy compared to other forms of radiation therapy following breast conserving surgery
Authors: Wheeler James , Vaghefi Houman , Morris Laura , Liu Fang , Sparks Irina , Denham Fiona , Henry Leonard , Hardy Ashley , Schrock Meghan , DePue Vanessa , Coody Leon
Published: February 2021

Introduction: Intraoperative radiation therapy (IORT) is a convenient treatment option for appropriate women with early stage breast cancer. Some patients undergoing IORT also need adjuvant whole breast radiation therapy due to adverse final pathologic features. Although there are various reports of the complication rates with patients undergoing IORT, comparisons with patients undergoing other forms of radiation therapy such as whole breast or accelerated partial breast radiation are sparse. Methods: A total of 293 patients underwent breast conserving surgery at the study institution between January 2016 and December 2019 for either ductal carcinoma in situ (DCIS) or invasive breast cancer. Three patients had bilateral breast cancer and one patient had a local recurrence having refused adjuvant treatment following breast conserving surgery, for a total of 297 treated breasts. 124 received whole breast radiation therapy, 70 did not receive radiation therapy, 47 received IORT alone, 15 received IORT and whole breast radiation therapy, 30 received accelerated partial breast radiation using external beam radiation (APBI-EB), and 9 received Ir-192 based high dose rate accelerated partial breast radiation (APBI-HDR). One patient with bilateral breast cancer did not complete whole breast radiation therapy to either breast. Complications included cellulitis, wound drainage, symptomatic seroma, delayed wound healing, and wet desquamation. Interventions included observation, antibiotics, wound packing, debridement, fluid aspiration, hydrogel dressings, and wound vacuums. Results: For the entire group, the incidence of wound complications was 20%. The risk of complications was 27.4% for those undergoing IORT (with or without whole breast radiation) compared to 18.3% for those not receiving IORT, which was not statistically different at the 5% significance level. For those who received both IORT and whole breast radiation, however, the proportion having complication was 53.3% versus 18.4% in the other groups. The difference was significant with a p-value 0.0032. Conclusion: Patients who undergo both IORT and whole breast radiation have an increased risk for wound complications.

Citation Format: James Wheeler, Houman Vaghefi, Laura Morris, Fang Liu, Irina Sparks, Fiona Denham, Leonard Henry, Ashley Hardy, Meghan Schrock, Vanessa DePue, Leon Coody. Breast complications in patients who received intraoperative radiation therapy compared to other forms of radiation therapy following breast conserving surgery [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS15-03.
Abstract PS15-11: Intraoperative radiation therapy (IORT) for1200 early breast tumors
Authors: Epstein Melinda , Silverstein Melvin , Chen Peter , Lin Kevin , Kim Brian , Khan Sadia , Snyder Lincoln , Guerra Lisa E. , Coleman Colleen
Published: February 2021

Introduction: Two prospective randomized trials, TARGIT-A and ELIOT, have shown intraoperative radiation therapy (IORT) to be a safe alternative with a low-risk of local recurrence compared to whole breast radiation therapy following breast conserving surgery for selected low-risk patients. We report the first 1200 tumors treated with this modality at our facility.Methods: 1200 distinct breast cancers in 1169 patients (31 bilateral) were treated with breast conserving surgery and X-ray IORT, using the Xoft Accent System from June 2010 to November 2018. Patients were enrolled in an IORT registry trial and data were collected at 1 week, 1 month, 6 months, 1 year, and yearly thereafter. The primary endpoint was local recurrence.Results: To date, there have been 61 events in 54 patients: 50 ipsilateral local recurrences (14 DCIS and 36 invasive), 7 regional nodal recurrences and 4 distant recurrences. Of local recurrences, 9 were within the IORT field, 21 outside of the IORT field but within the same quadrant as the index cancer, and 20 were new cancers in different quadrants. There has been no breast cancer related deaths and 27 non-breast cancer deaths. Currently, with a median follow-up of 52 months, Kaplan Meier analysis projects 5.2 % local recurrence rate at 5 years. In the table below, the five-year probability of local recurrence is analyzed by quadrant and/or type of recurrence (all recurrences or just invasive). Using the 2017, ASTRO Categories, 520 patients (43%) were suitable for IORT, 415 (35%) were cautionary, and 265 (22%) were unsuitable for IORT after final histopathology was evaluated.Conclusion: IORT is profoundly convenient. When used as the only adjuvant breast irradiation, it eliminates approximately 15-35 outpatient visits. This has become increasingly important during the current COVID-19 pandemic. In the group of patients described here, more that 100,000 patient-hours were saved. The local, regional, and distant recurrence rates observed in this trial were slightly higher than those of the prospective randomized TARGIT-A and ELIOT Trials. This may be explained by 22% of our patients being considered unsuitable for IORT by ASTRO Criteria. The low complication rates previously reported by our group as well as the low recurrence rates reported in this study support the cautious use and continued study of X-ray IORT in women with low-risk breast cancer.

Citation Format: Melinda Epstein, Melvin Silverstein, Peter Chen, Kevin Lin, Brian Kim, Sadia Khan, Lincoln Snyder, Lisa E. Guerra, Colleen Coleman. Intraoperative radiation therapy (IORT) for1200 early breast tumors [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS15-11.
Abstract PS15-13: Safe margins for delineation of left anterior descending artery (LAD) using cardiac-gated CT-scan (CG-CT) in left side breast cancer patients
Authors: Nicolas Eliot , Khalifa Nadjoua , Bouhroum Sabrina , Laporte Cyril , Kirova Youlia
Published: February 2021

Background: Cardiac toxicity after breast cancer (BC) radiotherapy (RT) is partly due to the large radiation doses to coronary arteries. The left anterior descending artery (LAD) is particularly exposed. A first step in achieving robustly proven dose constraints to the LAD during treatment planning is homogeneous delineation based on guidelines. LAD delineation can be problematic due to heart movements.Purpose/Objective(s): The aim of the study was to establish a safety margin for delineation of the LAD in BC patients.Materials/Methods: We studied 45 left-sided BC patients who had an indication for adjuvant radiotherapy between 2015 and 2018. They all underwent cardiac-gated computed tomography scan (CG-CT), as well as planning CT scans (P-CT) with or without contrast agents, to assess LAD diameter and movements. CG-CT was performed while monitoring the cardiac cycle. Acquisition was launched immediately after contrast injection (arterial sequence), with deep inspiration breath hold and use of a beta-receptor blocking agent. By manually reviewing each scan, the LAD positions and diameter were defined at 20 different phases of the cardiac cycle at 5 different sites: ostium, circumflex (Cx) bifurcation (bfc), first diagonal (D1) bfc, second diagonal (D2) bfc and apex (right coronary anastomosis). Next step is to introduce it in softwear of automatic delineation to improve the atlas of cardiac structures.Results: Movement of the LAD is maximal at the ostium, then constant overall even when far from its origin. The diameter decreases with the distance from ostium: 4.9 mm (OS), 3.9 mm (Cx), 3.5 mm (D2) and 3.1 mm (D2).Conclusion: We suggest using a safety delineation margin consisting of a cylinder with a diameter of 10 mm surrounding the LAD. These findings must be validated in independent series of patients treated for BC.

Citation Format: Eliot Nicolas, Nadjoua Khalifa, Sabrina Bouhroum, Cyril Laporte, Youlia Kirova. Safe margins for delineation of left anterior descending artery (LAD) using cardiac-gated CT-scan (CG-CT) in left side breast cancer patients [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS15-13.
Abstract PS16-10: Tao kinase 3 augment the resistance to microtubule-disrupting agents in breast cancer cells
Authors: Fang Chih-Yeu , Lai Tsung-Ching , Hsiao Michael
Published: February 2021

Breast cancer is the leading type of cancer in women worldwide. It is a heterogeneous disease that contains several subtypes with substantial differences in pathology and clinical outcome. With the advancements in imaging and targeted therapy, many patients with early stages of this disease have a great opportunity to be cured. However, recurrence or metastasis of tumor still occurs in patients even after successful primary treatment. Chemotherapy remains one of the most important treatment for advanced breast cancer. Anti-microtubule agents including taxanes, eribulin and vinca-alkaloids constitutes the major anti-breast cancer chemotherapeutic category, while chemoresistance remains a thorny issue for advanced disease. We aimed to discover novel candidate regulators for chemoresistance in breast cancer. A lentiviral-based, high-throughput shRNA platform was developed for screening the variation of global kinome to find new therapeutic targets in paclitaxel-resistant breast cancer cells. The underlying molecular mechanisms was further explored by global phosphoprotein array and expression microarray. The serine/threonine kinase, TAO Kinase 3 (TAOK3), was identified from 724 kinase genes. Knockdown of TAOK3 exhibited the most profound reduction of IC50 values in response to paclitaxel treatment in breast cancer cells. High expression of TAOK3 was related to poor prognosis in breast cancer patients after adjuvant chemotherapy. Furthermore, the expression of TAOK3 also decreased the sensitivity to other anti-microtubule drugs, including eribulin and vinorelbine. Expression microarray analysis revealed that NF-κB signaling plays the major regulation roles in TAOK3-associated resistance. Taken together, our results showed that TAOK3 increases resistance to anti-microtubule drug through upregulating the NF-κB signaling in breast cancer. Inhibitors that disrupt TAOK3 and NF-κB signaling pathway may overcome the drug resistance for patients treated with anti-microtubule agents.

Citation Format: Chih-Yeu Fang, Tsung-Ching Lai, Michael Hsiao. Tao kinase 3 augment the resistance to microtubule-disrupting agents in breast cancer cells [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS16-10.
Abstract PS16-16: B-catenin-ccl2 axis regulates breast cancer stem cells via crosstalk between cancer cells and tumor-associated macrophages
Authors: Liu Hao , Liu Bolin
Published: February 2021

Breast cancer is most frequently diagnosed cancer among women worldwide. Though advance in diagnosis and treatment strategies have prolonged disease-free survival (DFS) and overall survival (OS) for different molecular types of breast cancer patients, many patients initially benefit from chemotherapy but experience recurrence, metastasis, and ultimately death. Breast cancer stem cells (BCSCs) are tumor initiating cells with self-renewal, low differentiation, and high tumorigenicity and metastasis abilities. The ineffectiveness of conventional chemotherapy to eradicate BCSCs frequently results in therapy failure. Therefore, understanding the molecular pathways sustaining BCSC characteristics and targeting BCSCs will ultimately improve breast cancer treatments. Here, we found that activation of β-Catenin directly regulated CCL2 expression at the transcriptional level, and in turn, promoted tumor-associated macrophage (TAM) infiltration and M2 polarization. Moreover, crosstalk between the TAM and breast cancer cells increased secretion of CCL2, which promoted cancer progression by regulating BCSCs characteristics through feedback activation of β-Catenin. The combined inhibition of CCR2 and β-catenin synergistically suppressed breast cancer growth. The results described herein provide novel insights into our understanding how the β-Catenin-CCL2 feedback loop mediates the crosstalk between cancer stem cells and tumor-associated macrophages. They may also facilitate the development of useful therapeutic targets against BCSCs for breast cancer therapy.

Citation Format: Hao Liu, Bolin Liu. B-catenin-ccl2 axis regulates breast cancer stem cells via crosstalk between cancer cells and tumor-associated macrophages [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS16-16.
Abstract PS16-27: Small extracellular vesicle-mediated intercellular TGF-β1 transferring promotes adriamycin-resistant transmission in breast cancer cells
Authors: Xu Zhi , Tang JInhai
Published: February 2021

Chemotherapeutic resistance is a major obstacle to control of advanced breast cancer (BCa). We have previously shown that small extracellular vesicles (sEVs) can transmit adriamycin resistance between BCa cells. Here, we demonstrate that sEV-TGF-involves in intercellular drug-resistant transmission from adriamycin-resistant cells to adriamycin-sensitive cells. sEVs were isolated and characterized form the both sensitive and resistant cells. sEVs derived from the resistant cells were incubated with the sensitive cells and resulted in transmitting the resistant phenotype to the recipient cells. Cytokine antibody microarray revealed that most metastasis associated cytokines present at the high levels in sEVs from the resistant cells compared to their levels in sEVs from the sensitive cells, particularly TGF-β1. The sEV-TGF-β1 led to phosphorylation of Smad2/3 and remarkably changed the phenotypes of the recipient cells by suppressing apoptosis and enhancing cell movability. Finally, the sEV-TGF-mediated drug-resistance transmission was validated using a zebrafish xenograft tumor model. The results from this study elaborated that sEV-TGF-β1 intercellular transfer contributes to adriamycin resistance in BCa.

Citation Format: Zhi Xu, JInhai Tang. Small extracellular vesicle-mediated intercellular TGF-β1 transferring promotes adriamycin-resistant transmission in breast cancer cells [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS16-27.
Abstract PS16-32: Obg-like ATPase 1 enhances chemoresistance of breast cancer via activation of TGF-β/Smad axis cascades
Authors: Xiao Gary , Liu Jianzhou , Miao Xiaoyu
Published: February 2021

Background: Understanding the molecular mechanism of drug resistance helps identify aneffective target for therapy of breast cancer. We investigated in this study the regulatory role ofObg-like ATPase 1 playing in multiple drug resistance of breast cancer.Methods: Paclitaxel resistant cell line (MCF-7-PTR) was developed by a continuous increasingpaclitaxel concentration. MTT assay was used to validate either acquired resistant or OLA1modified cell lines. qRT-PCR, immunoblot, apoptosis and cell cycle assays were performed toassess expression of genes and proteins in cell lines. A series of in vitro assays was performed inthe cells with RNAi-mediated knockdown to elucidate the regulatory role of OLA1 in breast cancer.Findings: We demonstrated that OLA1 was highly correlated with either acquired or intrinsicresistance of breast cancer. Further study showed that escalated expression of OLA1 promotedEMT process in tumor cells through TGF-β/Smad signaling cascades, resulting in the enhancedexpression of anti-apoptosis-related proteins (cleaved caspase3, Bax, Bcl-2) and the strengthendepolymerization of microtubules in tumor cells. Our findings revealed that OLA1 enhanced theanti-apoptotic ability and elucidated a regulatory role of OLA1 in promoting drug resistance ofbreast cancer.Interpretation: OLA1 is highly correlated with drug resistance of breast cancer. Chemo-sensitivity of the disease can be thus enhanced significantly by knocked down OLA1,which ledto inactivation of the TGF-β/Smad signaling cascades, polymerized microtubules, and promotedcell apoptosis. Our data suggest that OLA1 may be developed as a potential target to improvechemotherapy of patients with breast cancer.Keywords: breast cancer; Obg-like ATPase 1; multidrug resistance; γ-tubulin; paclitaxel

Citation Format: Gary Xiao, Jianzhou Liu, Xiaoyu Miao. Obg-like ATPase 1 enhances chemoresistance of breast cancer via activation of TGF-β/Smad axis cascades [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS16-32.
Abstract PS16-33: Niclosamide reverses cisplatin resistance by inhibiting Bcl-2 and Stat3 in HER2-positive breast cancer
Authors: Liu Junjun
Published: February 2021

Background: Breast cancer is the second leading cause of cancer-related deaths. Chemotherapy resistant breast cancer is poorly differentiated and displays aggressive clinical behavior. These tumors become resistant to cytotoxic agents and tumor relapse has been attributed to the presence of epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs). Niclosamide has been shown to have broad clinical applications for the treatment of malignant tumors other than those caused by parasites. However, the specific functions and molecular mechanisms of niclosamide in chemo-resistant HER2 positive breast cancer are still unknown. Methods: HER2 positive breast cancer cell line, BT474, was continuously exposed to increasing concentrations of cisplatin (5-20 μM) to establish stable cell line resistant to cisplatin, BT-CR. Cell viability was determined by alamar blue. Apoptosis was determined by flow cytometry. Mammosphere formation assay was conducted to observe the self-renewal potential. Invasion ability was analyzed by transwell assay. Protein expression was determined by western-blot. Results: BT-CR had EMT and stem-like phenotype with higher invasion ability compared to naive sensitive cells. Alamar Blue assay showed combination of niclosamide with cisplatin could reverse cisplatin resistance. The combination index value of niclosamide combined with cisplatin was less than 1. Niclosamide in combination with cisplatin significantly enhanced apoptosis of BT-CR cells to over 50%. Western-blot showed niclosamide and cisplatin could reverse the EMT phenotype of BT-CR with E-cadherin up-regulated and N-cadherin and vimentin down-regulated. A significant reduction of Bcl-2 and Stat3 phosphorylation (Tyr705) levels was also confirmed. After treatment of niclosamide combined with cisplatin, the inhibition of mammosphere forming efficiency and capability of invasion was also observed in BT-CR. Conclusion: Our results revealed that niclosamide combined with cisplatin inhibited cell growth, invasion, EMT and stem-like phenotype in cisplatin resistant BT474 cells. The inhibitory effect of niclosamide was exerted by increasing apoptosis and down-regulated Bcl-2 expression, whilst inhibiting phosphorylation levels of STAT3. The results suggested that niclosamide combined with cisplatin appears to be a novel therapeutic way in chemo-resistant breast cancer.

Citation Format: Junjun Liu. Niclosamide reverses cisplatin resistance by inhibiting Bcl-2 and Stat3 in HER2-positive breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS16-33.
Abstract PS17-16: Sar439859, a novel selective estrogen receptor degrader (serd), demonstrates effective and broad antitumor activity in wild-type and mutant er-positive breast cancer models
Authors: Shomali Maysoun , Sun Fangxian , Levit Mikhail , Pollard Jack , Lee Joon Sang , Schio Laurent , El-Ahmad Youssef , Soria Chris , Cohen Patrick , Debussche Laurent , Bouaboula Monsif
Published: February 2021

Primary treatment for estrogen receptor-positive (ER+) breast cancer is endocrine therapy. However, substantial evidence indicates a continued role for ER signaling in tumor progression. Selective estrogen receptor degraders (SERDs), such as fulvestrant, induce effective ER signaling inhibition, although clinical studies with fulvestrant report insufficient blockade of ER signaling, possibly due to suboptimal pharmaceutical properties. Furthermore, activating mutations in the ER have emerged as a resistance mechanism to current endocrine therapies. New oral SERDs with improved drug properties are under clinical investigation, but the biological profile that could translate to improved therapeutic benefit remains unclear. Here we describe the discovery of SAR439859, a novel, orally bioavailable SERD with potent antagonist and degradation activities against both wild-type and mutant Y537S ER. Driven by its fluoropropyl pyrrolidinyl side chain, SAR439859 has demonstrated broader and superior ER antagonist and degrader activities across a large panel of ER+ cells, compared with other SERDs characterized by a cinnamic acid side chain, including improved inhibition of ER signaling and tumor cell growth. Similarly, in vivo treatment with SAR439859 demonstrated significant tumor regression in ER+ breast cancer models including MCF7-ESR1 wild type and mutant-Y537S mouse tumors, and HCI013, a patient-derived tamoxifen-resistant xenograft tumor. These findings indicate that SAR439859 may provide therapeutic benefit to patients with ER+ breast cancer, including those have resistance to endocrine therapy with both wild-type and mutant ER. This presentation will highlight the global profile and key features of new SERD and its translation to patient.

Citation Format: Maysoun Shomali, Fangxian Sun, Mikhail Levit, Jack Pollard, Joon Sang Lee, Laurent Schio, Youssef El-Ahmad, Chris Soria, Patrick Cohen, Laurent Debussche, Monsif Bouaboula. Sar439859, a novel selective estrogen receptor degrader (serd), demonstrates effective and broad antitumor activity in wild-type and mutant er-positive breast cancer models [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-16.
Abstract PS17-39: Inhibition of acetate metabolism enhances host anti-tumor immunity
Authors: Miller Katelyn , Schug Zachary T.
Published: February 2021

Acquired resistance to anti-cancer therapy is an enormous challenge. One of the main factors contributing to therapy resistance is tumor hypoxia. The stress imposed by tumor hypoxia forces cancer cells to adapt in order to survive. These metabolically adapted cancer cells are often more invasive, more malignant, and more drug resistant. As a result, the cancer cells that emerge from hypoxic tumor regions are more likely to cause patient relapse. There is therefore a critical need to understand the mechanisms that promote the survival of cancer cells in stressful tumor microenvironments. We previously showed that the enzyme acetyl-CoA synthetase 2 (ACSS2) supports cancer cell metabolism in hypoxic and nutrient-depleted environments. ACSS2 endows cancer cells with the ability to use acetate as an alternative nutrient source to drive acetyl-CoA biosynthesis during stress and genetic silencing of ACSS2 inhibits human breast tumor growth in xenograft models. Given the important role of acetate metabolism in breast cancer we expanded upon our studies by using immunocompetent hosts and syngeneic mouse tumor models. Our results revealed a previously unknown role of ACSS2 in modulating host anti-tumor immunity. We found that ACSS2 deficient tumors are unable to grow when host immunity is intact. Depletion of host immunity (T cells) using genetic or pharmacological models rescues the growth of ACSS2 deficient tumors. Pharmacological inhibition of ACSS2 in tumors in vivo displayed gene signatures associated immune infiltration and activation within the tumor microenvironment. Moreover, ACSS2 deficient breast cancer cell lines show a marked susceptibility to T cell killing in vitro. Our current research demonstrates a novel role for acetate metabolism in supporting tumor extrinsic modulation of host anti-tumor immunity. Since activation of acetate metabolism via ACSS2 is a near universal hallmark of metabolically stressed cancer cells, targeting acetate metabolism represents an unrealized opportunity with significant upside for improving current therapeutic modalities in breast cancer.

Citation Format: Katelyn Miller, Zachary T. Schug. Inhibition of acetate metabolism enhances host anti-tumor immunity [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-39.
Abstract PS18-09: Novel chimeric small molecule AC682 potently degrades estrogen receptor with oral anti-tumor efficacy superior to fulvestrant
Authors: He Wei , Zhang Hui , Perkins Lorena , Bouza Lissette , Liu Ke , Qian Yimin , Fan Jie
Published: February 2021

Modulation of estrogen activity and/or synthesis has been the mainstay therapeutic strategy for estrogen receptor (ER)-positive breast cancer. Fulvestrant, which provides superior clinical benefit over aromatase inhibitors and selective ER modulators, achieves its potent ER signaling inhibition through unique ER degradation activity beyond direct antagonism. Despite this superiority, the efficacy of fulvestrant appears limited by poor drug exposure through intramuscular injection. Up to 50% of ER baseline levels remained after 6 months of fulvestrant treatment. Therefore, an oral ER degrader with optimal pharmacokinetic profile may lead to better convenience and efficacy than fulvestrant. Here we report preclinical characterization of our novel oral ER degrader development candidate, AC682, a chimeric small molecule containing both ligands of ER and E3 ligase discovered with our ACCU-Degron technology. Through engaging E3 ligase and ER simultaneously, AC682 induced potent ER degradation with a sub-nanomolar half-maximal degradation concentration (DC50) in multiple ER-positive breast cancer cell lines tested, including a tamoxifen-resistant long-term estrogen deprived (LTED) cell line and cell lines expressing clinically-relevant ESR1 variants (Y537S and D538G). Proteasome-dependent ER degradation by AC682 peaked after a few hours of treatment, resulting in diminished expression of ER-regulated genes and subsequent cell growth inhibition. In the in vivo setting, oral dosing of AC682 achieved substantial drug exposure and oral bioavailability, with well tolerance in multiple animal species. In estradiol-dependent MCF7 xenograft tumors, oral daily dosing of AC682 led to dose-dependent tumor growth inhibition/regression and concomitant tumor ER protein reduction more than 90% at study termination. In particular, 3 mg/kg oral daily dosing achieved tumor stasis. When administrated in combination with CDK4/6 inhibitor Palbociclib, AC682 showed clear synergy in both the estradiol-dependent MCF7 model and a tamoxifen-resistant MCF7 model. In a patient-derived xenograft model, which bears ESR1 Y537S mutation and is hormone-independent, AC682 significantly inhibited tumor growth whereas fulvestrant only showed weak efficacy. In conclusion, oral chimeric ER degrader AC682 demonstrated robust ER degradation and anti-tumor efficacy in preclinical models, supporting its continued investigation in the clinic.

Citation Format: Wei He, Hui Zhang, Lorena Perkins, Lissette Bouza, Ke Liu, Yimin Qian, Jie Fan. Novel chimeric small molecule AC682 potently degrades estrogen receptor with oral anti-tumor efficacy superior to fulvestrant [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS18-09.
Abstract PS18-24: Impact of protein corona formation on Fn14-targeted DART nanoparticle selectivity, uptake, and cytotoxicity on TNBC cells
Authors: Carney Christine P , Kapur Anshika , Pandey Nikhil , Dancy Jimena G , Wadajkar Aniket S , Woodworth Graeme F , Winkles Jeffrey A , Kim Anthony J
Published: February 2021

Despite dramatic improvements in the treatment of primary breast cancers, there currently are no effective targeted therapeutics for women diagnosed with metastatic triple negative breast cancer (mTNBC), resulting in an overall survival of just ~13 months in these patients. Drug-loaded nanoparticles (NPs) offer the potential to improve the therapeutic efficacy and pharmacokinetic profile of drugs through use of passive and active targeting to metastatic tumors. However, effective and active targeting of nanodrug formulations to tumor cells is complicated by the adsorption of proteins to NP surfaces upon exposure to the systemic circulation. Termed ‘protein coronas’, this protein coat can drastically reduce the blood circulation time and targeting capability of NPs in vivo. We have developed paclitaxel (PTX)-loaded NPs that are engineered for decreased non-specific adhesivity and receptor-targeting (‘DART’) characteristics, which balance minimal recognition by circulating immune cells and low non-specific binding to tumor extracellular matrix proteins with maximal targeting to tumor tissues. These DARTs selectively bind the fibroblast growth factor-inducible 14 (Fn14) cell surface receptor, which is overexpressed in over a dozen solid cancers and their metastases, including mTNBC tumors. We recently demonstrated the enhanced therapeutic efficacy of Fn14-targeted DARTs in comparison to a non-targeted nanoformulation and Abraxane, an FDA-approved nanoformulation for mTNBC, in xenograft models of primary and intracranial TNBC. In addition, we found that these DARTs retain targeting capability and traffic to Fn14+ tumors in the presence of an endogenous protein corona in vitro and in vivo. This encouraged further investigation into the specific mechanisms of DART NP uptake in tumor cells in both the presence and absence of protein coronas using surface plasmon resonance, flow cytometry, total internal reflection fluorescence and confocal microscopy, and cytotoxicity assays. Understanding the role of protein coronas on this drug delivery platform is crucial for its clinical development and these results provide valuable new information pertaining to the optimization of NP surface properties for minimizing the impact of protein coronas and improving mTNBC tumor targeting in vivo.

Citation Format: Christine P Carney, Anshika Kapur, Nikhil Pandey, Jimena G Dancy, Aniket S Wadajkar, Graeme F Woodworth, Jeffrey A Winkles, Anthony J Kim. Impact of protein corona formation on Fn14-targeted DART nanoparticle selectivity, uptake, and cytotoxicity on TNBC cells [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS18-24.
Abstract PS18-39: Estrogen receptor beta agonists for triple negative breast cancer
Authors: Datta Jharna , Willingham Natalie , Manouchehri Jasmine , David Joel , Sheth Mirisha , Ramaswamy Bhuvaneswari , Ganju Ramesh , Cherian Mathew A
Published: February 2021

Background:Triple negative breast cancer (TNBC) represents about 10-15% of all breast cancers. Given the lack of targeted therapies, chemotherapy and immunotherapy are the only treatment options. The five-year survival rate of TNBC patients is approximately 15% less than other forms of breast cancer. Therefore, there is an urgent need to develop novel effective therapeutics for TNBC.Material and Methods:RNA isolated from human immortalized mammary epithelial MCF10A, and various TNBC cell lines was DNase treated and quantitative RT-PCR (qRT-PCR) performed using gene-specific primers spanning exon-exon junctions that include introns in the corresponding genomic sequence to avoid genomic DNA amplification. Gene expression was calculated by ΔΔCt method using GAPDH as an internal control. Immuno-blot analyses were performed on lysates prepared from cells in log phase of growth. Proteins were detected by Enhanced Chemi-Luminescence (ECL) method. Viability of cells treated with ERβ specific agonists was determined by using CellTiter-Glo® 2.0 assay. MB231 cells were treated with ERβ agonists following transfection with pcDNA3 (vector) or Flag-tagged ESR2 plasmids. Western blot analyses using specific antibodies and qRT-PCR were performed with the protein extracts and RNA isolated from the cells, respectively. Results:Our experiments demonstrate that ESR2 (ERβ) is differentially expressed and its level of expression is about 3 to 22-fold higher in TNBC cell lines tested than MCF10A. We have shown that viability of estrogen receptor (ER) positive breast cancer cell lines can be significantly inhibited by selective activation of ERβ. A highly selective ERβ agonist has been invented in the Drug Development Institute at the Ohio State University. Treatment of TNBC lines with these ERβ agonists exhibited a dramatic reduction of cell viability. While comparable IC50 values were observed with our in house and commercially available compounds, TNBC had 2-3-fold lesser IC50 values than ER-positive cell lines. Increased expression of FOXO3 and c-Myc1 and decreased expression of c-Myc2 isoform was noted in ERβ overexpressing MB231 cells upon treatment with ERβ agonists.Conclusion:Our results demonstrate that treatment with highly selective ERβ agonists could be an effective therapeutic strategy for TNBC patients. To improve and develop novel therapeutics for TNBC understanding the mechanism of action of these compounds will be crucial.

Citation Format: Jharna Datta, Natalie Willingham, Jasmine Manouchehri, Joel David, Mirisha Sheth, Bhuvaneswari Ramaswamy, Ramesh Ganju, Mathew A Cherian. Estrogen receptor beta agonists for triple negative breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS18-39.
Abstract PS19-08: Intratumoral heterogeneity of second-harmonic generation scattering from tumor collagen and its effects on metastatic risk prediction
Authors: Brown Edward , Desa Danielle , Wu Wencheng , Hill Robert , Martens John , Strawderman Robert , Turner Bradley
Published: February 2021

Second harmonic generation (SHG) is an intrinsic optical signal that can be generated from fibrillar collagen. The directionality of SHG emission is influenced by the diameter and spacing of collagen fibrils, and the disorder in their packing within collagen fibers. One measure of SHG directionality is the ratio of forward- to backward-scattered SHG, or “F/B”. F/B has been used to assess healthy vs diseased tissue in breast, ovarian, and lung cancer, and is an independent prognostic indicator of metastasis free survival time in ER+, lymph node-negative (N0), invasive ductal carcinoma (IDC). Here we assess the heterogeneity in F/B within tumor sections from ER+ N0 IDC, and its effect on the use of F/B for metastatic risk prediction. We find that F/B of tumor collagen varies between the tumor/host interface and the more cellular tumor bulk (p<0.0001, Student’s t-test), and that F/B from the tumor/host interface, but not tumor bulk, is prognostic of metastasis free survival in 95 IDC ER+ N0 patients (p=0.0020 and 0.10, respectively, log rank test for trend). This result was repeated with two additional image analysis procedures to generate F/B with reduced user input and hence reduced possibility of bias. Using Random Survival Forests to generate a data-driven predictive model, we find that F/B from the tumor/host interface, but not bulk, as well as a 21-gene prognostic score inferred from Affymetrix data, both contribute to predicting metastasis-free survival in this cohort. Any tool to help predict metastasis and assist with treatment decisions is likely to be applied in combination with the now well-established genomic scores. To understand how F/B can support genomic methods for guiding treatment decisions we divided our patient samples into two cohorts based upon the value of their 21-gene score relative to the TAILORx cutoff of 26 (separating low-intermediate and high-risk groups). The F/B value from tumor-host interface identifies a subgroup of patients in the low-intermediate risk group with poor clinical outcome (p=0.045, log rank test for trend). Overall, this data reveals that intratumor heterogeneity can impact the ability of F/B to predict patient outcome, and that F/B specifically from the tumor-host interface may provide a tool to better identify patients in need of adjuvant treatment or enrollment in clinical trials.

Citation Format: Edward Brown, Danielle Desa, Wencheng Wu, Robert Hill, John Martens, Robert Strawderman, Bradley Turner. Intratumoral heterogeneity of second-harmonic generation scattering from tumor collagen and its effects on metastatic risk prediction [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-08.
Abstract PS19-14: Matrin3 inhibits breast cancer growth by suppressing microtubule nucleation protein MZT2B
Authors: Subbarayalu Panneerdoss , Rajamanickam Subapriya , Viswanadhapalli Suryavathi , Li Fuyang , Eedunuri Vijay , Yadav Pooja , Reddy Esha , Timilsina Santosh , Nirzhor Saif SR , Onyeagucha Benjamin C , Wang Li-Ju , Chiu Yu-Chiao , Mohammad Tabrez , Abdelfattah Nourhan , Dybdal-Hargreaves Nicholas , Chen Yidong , Vadlamudi Ratna , Rao Manjeet
Published: February 2021

Despite improvement in overall survival, many patients with breast cancers still succumb to this disease. Identification of new biomarkers and safe therapeutic targets are urgently needed to improve the overall clinical outcome of breast cancer patients. Our studies discovered a RNA binding protein, MATRIN3 (MATR3), as a novel tumor suppressor. MATR3 is expressed at a significantly reduced levels in breast tumors. MATR3 inhibited short and long-term viability as well as migration and invasion of breast cancer cells. Further, MATR3 overexpression suppressed tumor growth, while its depletion induced tumor growth in orthotopic mouse tumor models. RNA seq and RNA immunoprecipitation analyses revealed that MATR3 binds and directly regulates the expression of several microtubule-associated proteins. Mechanistic studies identified MZT2B, a mitotic spindle organizing protein as a down stream effector of MATR3. MZT2B knockdown or knockout using CRISPR-CAS9 resulted in significantly decreased short and long term viability as well as reduced migration and invasion of breast cancer cells. Notably, MZT2B overexpression rescued the inhibitory effect of MATR3 overexpression on breast cancer growth. Furthermore, MATR3 overexpression downregulated expression of key microtubule nucleation protein complex including γ-tubulin and γ-tubulin ring complex protein (TUBGCP). Our data suggest that MATR3 inhibits breast cancer growth and progression by inhibiting MZT2B and consequently microtubule nucleation in breast cancers.

Citation Format: Panneerdoss Subbarayalu, Subapriya Rajamanickam, Suryavathi Viswanadhapalli, Fuyang Li, Vijay Eedunuri, Pooja Yadav, Esha Reddy, Santosh Timilsina, Saif SR Nirzhor, Benjamin C Onyeagucha, Li-Ju Wang, Yu-Chiao Chiu, Tabrez Mohammad, Nourhan Abdelfattah, Nicholas Dybdal-Hargreaves, Yidong Chen, Ratna Vadlamudi, Manjeet Rao. Matrin3 inhibits breast cancer growth by suppressing microtubule nucleation protein MZT2B [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-14.
Abstract PS19-15: N-RAS as a marker for DCIS progression
Authors: Chang Eric C , Zheng Zeyi , Elsarraj Hanan , Hong Yan , Shen Yichao Shen , Lo Flora , Feng Long , Zhang Xian H.-F. , Behbod Fariba
Published: February 2021

Background: Ductal carcinoma in situ (DCIS) is a key premalignant stage. Approximately 50% of the DCIS cases will advance to invasive ductal carcinoma (IDC); however, they are usually universally treated leading to overtreatment. While earlier premalignant breast lesions, such as atypical ductal hyperplasia, are nearly all luminal and positive for estrogen receptor α (ER+), up to 8% DCIS are basal-like, which is more aggressive. We have previously shown that N-Ras, which is highly expressed selectively in the basal-like subtype, can promote the growth and transforming activity of basal-like breast cancer (PMID 26166574). In this study we investigate whether NRAS expression at DCIS can promote basal-like properties and the progression to invasiveness.

Methods: NRAS mRNA levels in normal, DCIS, and IDC patient-derived microarray databases and tissue microarrays (TMAs) were compared using student t-test. Correlation between NRAS mRNA levels and basal-like properties was assessed by Pearson Correlation. ER protein levels were assessed by IHC. NRAS was expressed in a luminal DCIS cell line model SUM225PE cells and the resulting cells were injected intraductally into mice to assess expression of basal-like markers and invasiveness in vivo. Conversely, NRAS expression was silenced in a DCIS-like basal-like cell line SUM102 and increased expression of luminal markers was assessed by RNA-seq and western blot.

Results: In microarray databases, DCIS samples with higher NRAS mRNA levels are enriched with basal-like gene expression signature; furthermore, NRAS mRNA levels appear to increase progressively from normal to DICS and from DCIS to IDC. A similar correlation between high NRAS levels and invasiveness and high Ki67 levels in TMAs was observed by RNA FISH. High levels of NRAS mRNAs also correlated with low ER levels.

Conclusions: How to identify the subset of DCIS cases that will become invasive is critical for addressing the current problem of overtreatment. Our data support the hypothesis that high N-RAS levels in DCIS mark invasiveness, by presumably inducing basal-like more aggressive tumor activities. On-going studies will further delineate whether N-Ras is also responsible for driving DCIS to the invasive state.

Citation Format: Eric C Chang, Zeyi Zheng, Hanan Elsarraj, Yan Hong, Yichao Shen Shen, Flora Lo, Long Feng, Xian H.-F. Zhang, Fariba Behbod. N-RAS as a marker for DCIS progression [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-15.
Abstract PS19-17: The role of myoglobin in breast cancer
Authors: Aboouf Mostafa A. , Armbruster Julia , Guscetti Franco , Thiersch Markus , Gassmann Max , Gorr Thomas A.
Published: February 2021

Breast cancer today is typically seen as malignancy with longer survival due to early-detection diagnostics, yet the cancer remains by far the most common tumor type in adult females. Recently, our group co-discovered myoglobin (MB) to be expressed in luminal cells of healthy and cancerous breast epithelia of human and mice. In human patients, MB positivity emerged as hallmark of the luminal subtype and was directly correlated with estrogen receptor alpha positivity and hence a significantly better prognosis. Cancerous cells’ MB also appears to interact with the known tumor suppressor p53. However, if and how myoglobin itself restricts mammary tumorigenesis is completely unclear. To understand how MB exerts its alleged tumor-suppressive effects and if it impacts response of mammary tumors to chemo- and/or radiotherapy, we examine the molecular role of MB in breast tumor formation and progression through a) in vitro studies (MCF7 breast cancer BrCa cell clones; wildtype (wt) controls versus CRISPR/Cas9-engineered clones of a MB and/or p53 knockout (MBko/p53ko), b) in vivo mouse models to obtain spontaneously forming breast tumors, with or without MB, in a p53 deficient background. Comparing MCF7 BrCa MBko and p53ko clones vs. their corresponding wildtype counterpart supports our hypothesis of a feed forward loop between MB and p53 proteins, besides interfering with estrogen receptor expression. In addition to that, loss of MB was noticed to exert p53-independent upregulation on cell cyclins with more S phase cell population. That was reflected by a significant increase in survival of the MBko cells, in presence or absence of p53. Hypoxic MBko cells exhibited a partial epithelial to mesenchymal transition and hence a more migratory phenotype, relative to MBwt controls. Additionally, MB seems to stimulate apoptosis of the normoxic cancer cells. On the other hand, murine tumors were found to phenocopy human BrCa in the extent of their MB expression. Interestingly, MB-devoid tumors showed a significantly higher proliferation index and fat accumulation. Further studies will look into the clinical significance of that. In conclusion, MB seems to occupy unknown roles in cancer cells beyond or different from its classical O2 storage/transport functions. Unraveling these novel roles in governing tumor development and virulence will hopefully provide innovative strategies for future breast cancer interventions.

Citation Format: Mostafa A. Aboouf, Julia Armbruster, Franco Guscetti, Markus Thiersch, Max Gassmann, Thomas A. Gorr. The role of myoglobin in breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-17.
Abstract PS19-21: Tak1 signaling regulates p53 through a mechanism involving ribosomal stress
Authors: Bakin Andrei , Zonneville Justin
Published: February 2021

Triple-negative breast cancer (TNBC) is among the most aggressive forms of breast cancer with limited therapeutic options. TAK1 is implicated in aggressive behavior of TNBC, while means are not fully understood. Here, we report that pharmacological blockade of TAK1 signaling hampered ribosome biogenesis (RBG) by reducing expression of RBG regulators such as RRS1, while not changing expression of ribosomal core proteins. Importantly, TAK1 blockade upregulated expression of p53 target genes in cell lines carrying wild type (wt) TP53 but not in p53-mutant cells. By examining involvement of the ribosomal stress response, we found that p53 activation by blockade of TAK1 was prevented by depletion of ribosomal protein RPL11. Further, siRNA-mediated depletion of TAK1 or RELA resulted in activation of p53 signaling and this response was dependent on RPL11. Knockdown of RRS1 disrupted nucleolar organization and resulted in activation of p53. Genomic TCGA data showed that TNBCs express high levels of ribosome biogenesis regulators, and elevated RRS1 levels correlate with unfavorable prognosis. Cytotoxicity data showed that TNBC cell lines are more sensitive to TAK1 inhibitor compared to luminal and HER2+ cell lines. Together, the data indicate that TAK1 regulates p53 activation by controlling ribosome biogenesis factors, and the TAK1-ribosome axis is a potential therapeutic target in TNBC.

Citation Format: Andrei Bakin, Justin Zonneville. Tak1 signaling regulates p53 through a mechanism involving ribosomal stress [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-21.