Invasive Breast Research Articles

Abstract LB159: Overcoming immunosuppression and therapeutic resistance to PARP inhibition in BRCA1-deficient breast cancer with STING agonists

Abstract PARP inhibitors (PARPi) have drastically changed the treatment landscape of advanced ovarian tumors with BRCA mutations. However, the impact of this class of inhibitor is relatively modest in patients with advanced BRCA-mutant breast cancer, as shown by the final reports on overall survival described by the OlympiAD and EMBRACA clinical trials. We have recently generated in parallel two syngeneic genetically engineered mouse (GEM) models of BRCA1/p53-deficient high-grade serous ovarian cancer (HGSOC) and invasive basal-like breast cancer. Notably, our pre-clinical results of PARPi in these two models are in line with clinical outcomes showing different responses to PARPi between breast and ovarian tumors, which cannot be explained by synthetic lethality alone. Here, we uncovered a major mechanism by which BRCA1-deficient breast tumors typically progress through treatment with PARPi as monotherapy or in combination with PD-1 blockade, in contrast to the much higher rates of success observed for BRCA1-deficient ovarian cancer. Using our syngeneic GEM model of breast cancer driven by Brca1 deficiency, we show that tumor-associated macrophages (TAMs) abrogate PARPi efficacy both in vivo and in vitro. Mechanistically, BRCA1-deficient breast tumor cells induce protumor polarization of TAMs, which in turn suppress PARPi-elicited DNA damage in tumor cells, leading to reduced production of cytosolic double-stranded DNA (dsDNA) and synthetic lethality, hence impairing STING-dependent antitumor immunity. STING agonists reprogram M2-like TAMs into an M1-like anti-tumor state in a macrophage STING-dependent fashion. Systemic administration of STING agonists breaches multiple layers of tumor cell-mediated suppression on macrophages and dendritic cells, and synergizes with PARPi. Notably, while STING-deficient/BRCA1-deficient breast tumors fail to respond to the combination of PARPi and STING agonists administered intratumorally, they respond effectively to systemic delivery of STING agonists in combination with PARPi. Our data is thus different from the majority of other studies suggesting that STING agonists act in the tumor cells but is consistent with a rising tide of work pointing to the importance of STING activation in macrophages and DCs. This finding also suggests a novel therapeutic approach for treating a significant fraction of patients with cancers deficient in tumor cell-intrinsic STING. Together, our study provides an important conceptual shift in understanding the resistance to PARP inhibitors, which has mostly been described in terms of restoration of homologous recombination. Our mechanism-based, novel therapeutic approach to circumvent the refractory nature of BRCA1-deficient breast cancers should prove instrumental in guiding the design of clinical trials evaluating PARPi-based rational combination therapy in the near future. Citation Format: Qiwei Wang, Johann S. Bergholz, Liya Ding, Ziying Lin, Shaozhen Xie, Tao Jiang, Hye-Jung Kim, Thomas M. Roberts, Jean J. Zhao. Overcoming immunosuppression and therapeutic resistance to PARP inhibition in BRCA1-deficient breast cancer with STING agonists [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 LB159.

Abstract LB207: Glutamine transporter SLC38A3 promotes breast cancer migration via GSK3beta/beta-catenin/EMT pathway

Abstract Breast cancer is one of the most commonly diagnosed cancers and the leading cause of cancer-related death among women. Triple negative breast cancer (TNBC) is a subtype of breast cancer characterized by the absence of estrogen receptor, progesterone receptor and HER2 expression. TNBC shows a high capacity for early metastasis and leads to worse clinical outcomes than other breast cancer subtypes due to the lack of specific therapeutic targets. We are looking to develop cancer-specific therapeutic targets for TNBC. Many types of cancer cells including TNBC cells rely on glutamine as carbon and nitrogen source to fuel unchecked growth. We screened for key genes in regulating glutamine metabolism in a panel of breast cancer cell lines. This screen identified the mRNA and protein levels of solute carrier family 38 member 3 (SLC38A3), a glutamine transporter, to be upregulated in human breast cancer cell lines, especially in TNBC cell lines. The TCGA breast cancer patient database also showed that SLC38A3 mRNA is overexpressed in invasive ductal breast carcinoma tissues, and it is even higher in TNBC relative to other breast cancer subtypes. To test the biological role of SLC38A3 protein in TNBC cells, we performed loss-of-function experiments in multiple TNBC cell lines. Silencing of SLC38A3 decreased cellular glutamate, glutamine and alanine levels. Silencing of SLC38A3 also activated apoptosis, and suppressed cell viability, migration and invasion in several TNBC cell lines. Interestingly, silencing of SLC38A3 increased the activity of glycogen synthase kinase 3-β (GSK3β) which promoted the degradation of β-catenin, leading to the decrease of the mRNA levels of epithelial-to-mesenchymal-transition (EMT)-associated transcription factors in TNBC cell lines. In summary, we showed that SLC38A3 is overexpressed in TNBC and promotes breast cancer migration and invasion via GSK3β/β-catenin/EMT pathway, which could be a novel therapeutic target for breast cancer. Citation Format: Zheqiong Tan, Caitlin M. Tressler, Kanchan Sonkar, Kristine Glunde. Glutamine transporter SLC38A3 promotes breast cancer migration via GSK3beta/beta-catenin/EMT pathway [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 LB207.

Expression of Androgen Receptor in Invasive Triple Negative Breast Carcinoma

Expression of Androgen Receptor in Invasive Triple Negative Breast Carcinoma

Co-expression of transcription factor AP-2beta (TFAP2B) and GATA3 in human mammary epithelial cells with intense, apicobasal immunoreactivity for CK8/18

AP-2β is a new mammary epithelial differentiation marker and its expression is preferentially retained and enhanced in lobular carcinoma in situ and invasive lobular breast cancer. In normal breast epithelium AP-2β is expressed in a scattered subpopulation of luminal cells. So far, these cells have not been further characterized. Co-expression of AP-2β protein and luminal epithelium markers (GATA3, CK8/18), hormone receptors [estrogen receptor (ER), androgen receptor (AR)] and candidate stem cells markers (CK5/14, CD44) were assessed by double-immunofluorescence staining in normal mammary gland epithelium. The subpopulation of AP-2β-positive mammary epithelial cells showed an almost complete, superimposable co-expression with GATA3 and a peculiar intense, ring-like appearing immunoreactivity for CK8/18. Confocal immunofluorescence microscopy revealed an apicobasal staining for CK8/18 in AP-2β-positive cells, which was not seen in in AP-2β-negative cells. Furthermore, AP-2β-positive displayed a partial co-expression with ER and AR, but lacked expression of candidate stem cell markers CK5/14 and CD44. In summary, AP-2β is a new luminal mammary epithelial differentiation marker, which is expressed in the GATA3-positive subpopulation of luminal epithelial cells. These AP-2β-positive/GATA3-positive cells also show a peculiar CK8/18-expression which may indicate a previously unknown functionally specialized mammary epithelial cell population.

IL-9 Abrogates the Metastatic Potential of Breast Cancer by Controlling Extracellular Matrix Remodeling and Cellular Contractility.

IL-9 is produced by Th9 cells and is classically known as a growth-promoting cytokine. Although protumorigenic functions of IL-9 are described in T cell lymphoma, recently, we and others have reported anti-tumor activities of IL-9 in melanoma mediated by mast cells and CD8+ T cells. However, involvement of IL-9 in invasive breast and cervical cancer remains unexplored. In this study, we demonstrate IL-9-dependent inhibition of metastasis of both human breast (MDA-MB-231 and MCF-7) and cervical (HeLa) tumor cells in physiological three-dimensional invasion assays. To dissect underlying mechanisms of IL-9-mediated suppression of invasion, we analyzed IL-9-dependent pathways of cancer cell metastasis, including proteolysis, contractility, and focal adhesion dynamics. IL-9 markedly blocked tumor cell-collagen degradation, highlighting the effects of IL-9 on extracellular matrix remodeling. Moreover, IL-9 significantly reduced phosphorylation of myosin L chain and resultant actomyosin contractility and also increased focal adhesion formation. Finally, IL-9 suppressed IL-17- and IFN-γ-induced metastasis of both human breast (MDA-MB-231) and cervical (HeLa) cancer cells. In conclusion, IL-9 inhibits the metastatic potential of breast and cervical cancer cells by controlling extracellular matrix remodeling and cellular contractility.

Gene methylation and cytological atypia in random fine needle aspirates for assessment of breast cancer risk: 10-year follow up in average risk women.

10520 Background: Alterations in DNA methylation occur early in tumorigenesis, and are a potential breast cancer risk biomarker. We previously reported a study where healthy volunteers underwent random fine needle aspiration (rFNA) of the breasts; cumulative methylation index of eight preselected tumor suppressor genes (CMI) was associated with the presence of cytological atypia in rFNA samples. We now report 10-year follow-up of this population, to evaluate whether increased CMI is associated with subsequent breast cancer development. Methods: 380 women, unselected by breast cancer risk, were enrolled. Demographics, breast cancer risk factors, lifetime Gail model risk estimates (Gail-LR), and %breast density were obtained at baseline. rFNA samples were assessed for cytopathology (Masood Score, MS) and CMI. Patients were contacted annually for 10 years to ascertain development of invasive or non-invasive breast cancer. In univariate analysis, log-rank test was used to compare breast cancer incidence rates between individuals with high and low baseline measures (separated by median). Area under the ROC curve was used to evaluate the cancer prediction accuracy. In multivariate analysis, the effect of CMI (after log-transformation to reduce skewness) was further studied using Cox regression model adjusting for confounding baseline variables. Results: 362 women participated in follow up. At a median follow up time of 9.5 years after rFNA sampling, 16 women developed invasive or non-invasive breast cancer. There were no significant differences between women who developed cancer and those that did not in regard to demographic factors, %breast density, MS, or Gail-LR. On univariate analysis, Gail-LR was higher in women who developed cancer (13.0 vs. 16.5, p=0.08). The largest hazard ratios were observed from high breast density (2.30, 95% CI 0.8, 6.6) and high CMI (2.26, 95% CI 0.8, 6.6, p=0.07). In breast cancer prediction, the AUC for CMI was 0.64 (95% CI 0.51, 0.77). In separate bivariable models that adjusted for age, Gail-LR, MS, and %breast density, the HR for log CMI was consistently above unity, with a p value consistently below 0.1, except for the model that included MS (see Table). Conclusions: Elevated CMI has potential as a robust predictor of future breast cancer occurrence in average risk women, even when adjusted for breast density or cytologic atypia. Our prior analysis established that CMI is not susceptible to variation with menstrual cycle phase and menopausal status. These features support its further evaluation in larger trials. Clinical trial information: NCT00896636 .[Table: see text]

Germline pathogenic variants in cancer predisposition genes among women with invasive lobular cancer of breast.

10581 Background: The prevalence of germline pathogenic variants (PVs) in cancer predisposition genes among women with invasive lobular breast cancer (ILC) and the risk of ILC in PV carriers is not well-defined. Methods: The study included 2,999 women with ILC and 32,544 unaffected controls from a population-based cohort; 3,796 women with ILC and 20,323 women with invasive ductal carcinoma (IDC) undergoing clinical multigene panel testing (clinical cohort); and 125,748 exome sequences from unrelated women without a cancer diagnosis in the gnomAD 3.0 dataset. Frequencies of germline PVs in breast cancer predisposition genes ( ATM, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, PALB2, PTEN, RAD51C, RAD51D, and TP53) were compared between women with ILC and unaffected controls in both cohorts and between women with ILC and IDC in the clinical cohort. Results: The frequency of PVs in breast cancer predisposition genes among women with ILC was 6.5% in the clinical cohort and 5.2% in the population-based cohort. In case-control analyses, CDH1 and BRCA2 PVs were associated with high risks of ILC (Odds ratio (OR) > 4), and CHEK2, ATM and PALB2 PVs were associated with moderate (OR = 2-4) risks. BRCA1 PVs and CHEK2 p.Ile157Thr were not associated with clinically relevant risks (OR < 2) of ILC. PV frequencies in these genes in ILC and IDC were similar except for PV frequencies in BRCA1 and CDH1. Conclusions: The study establishes that PVs in ATM, BRCA2, CDH1, CHEK2 and PALB2 are associated with an increased risk of ILC, whereas BRCA1 PVs are not. The similar overall PV frequencies for ILC and IDC suggest that cancer histology should not influence the decision to proceed with genetic testing. While, multigene panel testing may be appropriate for women with ILC, CDH1 should be specifically discussed in the context of low prevalence and attendant gastric cancer risk.

De-escalation of five years adjuvant endocrine therapy duration in patients with ER-low positive (immunohistochemical 1% to 10%) early-stage breast cancer: A propensity-matched analysis from the prospectively maintained database.

538 Background: There are limited data on endocrine therapy benefits for patients with estrogen receptor (ER)-low positive breast cancer (staining 1% to 10% of tumor nuclei by immunohistology). We aimed to compare the effect of short-term 2-3 years versus standard 5 years of adjuvant endocrine therapy on survival outcomes in patients with ER-low positive early breast cancer. Methods: We used data from the prospectively maintained Breast Surgery Database of Fudan University Shanghai Cancer Center for this propensity-matched analysis. Women with ER-low positive, operable, and unilateral early-stage invasive ductal breast cancer were enrolled in this study. Patients with advanced disease, having received neoadjuvant chemotherapy or ovarian function suppression, or with unknown duration or longer than 5 years of adjuvant endocrine therapy were excluded. Enrolled patients were divided into three groups: received no endocrine therapy; received 2-3 years of endocrine therapy; and received approximately 5 years of endocrine therapy. The primary endpoint was disease-free survival (DFS). Multivariate Cox regression analysis and propensity score matching were performed to minimize bias. Hazard ratios (HR) with 95% CIs were calculated. Results: From 2012 to 2017, 634 patients with ER-low positive breast cancer in the database met the inclusion criteria. At a median follow-up of 60 months (interquartile range, 46-74), the 5-year DFS of the whole cohort was 84.9%, with 77.6% for patients who received no endocrine therapy (N = 89), 83.7% for patients who received 2-3 years endocrine treatment (N = 185), and 87.5% for patients who received 5 years endocrine therapy (N = 360). When compared with those receiving no endocrine therapy, patients receiving 5 years treatment was associated with a significantly improved DFS (HR, 0.55; 95% CI 0.32-0.95; P = 0.03); however, there was no significant difference in DFS between patients receiving 2-3 years and 5 years endocrine therapy (HR, 0.79; 95% CI, 0.48-1.28; P = 0.33). In the multivariate Cox regression analysis of the propensity score-matched samples of 360 patients, the DFS was not significantly better for patients who received 5 years of endocrine therapy than 2-3 years treatment (HR, 0.74; 95% CI 0.41-1.34; P = 0.32). An exploratory analysis of re-biopsy of the recurrence lesions indicated more than half of relapsed disease displayed ER-negative, and less than 5% lesions were proved to be ER ≥10% positive. Conclusions: Our data did not support the necessity of 5 years duration of endocrine therapy for patients with ER-low positive breast cancer. Short-term 2-3 years duration might be an alternative option. Further translational research on identifying endocrine-sensitive cases within ER-low positive patients is needed.

Towards reducing cancer burden within the Medicaid program: Impact of Medicaid expansion on cancer stage at diagnosis.

1572 Background: Studies to date have shown post-Medicaid expansion (M-exp) decreases in the percentage of cancer patients who are uninsured and improvements in cancer stage at diagnosis in states that expanded Medicaid as part of the Affordable Care Act. However, most studies have examined impact of M-exp on stage outcomes at the population level, or among Medicaid and uninsured, rather than solely in the Medicaid population. Using cancer registry data from a non M-exp state (Georgia (GA)) and two M-exp states (Ohio (OH) and New Jersey (NJ)), we compared changes in cancer stage in patients on Medicaid, accounting for individual- and contextual-level characteristics at the Zip Code Tabulation Area (ZCTA) level. Methods: We used GA, OH, and NJ cancer registry data for individuals 20-64 years of age and diagnosed with incident invasive female breast (BC), cervical (CC), and colorectal cancer (CRC). Data spanned from 2010-2017 for GA and OH, and from 2011-2016 for NJ (for BC and CRC only), with 2014 marking the year in which Medicaid was expanded in OH and NJ. We retrieved demographic data (age, race/ethnicity, sex for CRC, insurance status, and cancer stage from the cancer registries), and obtained ZCTA-level data from the American Community Survey (e.g., income, education, and female-headed households). We defined late-stage diagnosis as regional- or distant- stage. We conducted multivariable logistic regression models by state and cancer site to examine changes in late-stage cancer diagnosis pre- and post-M-exp, accounting for individual- and ZCTA-level covariates. Results: The number of patients with incident cancer who were on Medicaid increased by 41.7% (n = 1757 to 2490), 59.6% (327 to 522), and 76.4% (953 to 1681) for BC, CC, and CRC cancers, respectively, in Ohio; by 92.4% (433 to 833) for BC and by over 100% for CRC (232 to 496) in NJ; but by 12.7% (662 to 746) among CRC patients in GA, where the number of BC and CC patients on Medicaid remained relatively stable. Adjusting for individual and contextual-level factors, the adjusted risk ratio (ARR and (95% Confidence Interval)) for late-stage disease was lowest for BC patients in OH (0.93 (0.87, 0.99)) and for CRC patients in GA (0.94 (0.89, 0.99)). The ARR for BC and CRC in NJ were not statistically significant, though they trended towards improvement. Similarly, changes in late-stage for CC were not statistically significant in OH or in GA. Conclusions: The increased number of cancer patients in Medicaid and the reductions in late-stage diagnosis observed may potentially translate into reduced, or at least stabilized, cancer-related morbidity and mortality burden among Medicaid beneficiaries over time. However, reductions in late-stage diagnosis were not consistent across cancer sites or states, possibly due to differences in population demographics, health behaviors, healthcare seeking patterns, and state-level cancer prevention efforts.

Targeted breast surgery: Non-direct approach.

e12602 Background: Breast conserving surgery is the standard in T1-T3 primary breast cancer. The cosmetic result is very much depending upon the surgeon ́s experience, the tumor-size/breast ratio and the technique applied. We have proposed a nomogram earlier (1) which has been cited earlier by the American Society of Breast Surgeons Consensus Conference as a concept for avoidance of re-excisions and achievement of a favorable aesthetic result. Our nomogram proposed 5 simple oncoplastic techniques to handle the vast majority of breast cancer cases, with high rates of free margins. However, these techniques all used direct access to the mammary gland through the skin above the tumor, leaving permanent scars in the visible skin of the breast. To avoid this, we now have chosen a more natural access to the mammary gland along natural transitions and Langerhans´s skin lines in this prospective open-label study. Methods: We conducted a prospective open-arm study including all primary invasive and non-invasive breast cancer cases of tumor stages AJCC 0-III A (Version 8.0). Non-palbable tumors and those undergoing neoadjuvant chemotherapy had to be marked by a wire and clipped before. Intraoperative ultrasound was applied before skin incision and after removal of the tumor including ultrasound of the specimen to confirm clear margins). Resection was performed as a segmentectomy and SLN biopsy and axillary clearance was done according to national guidelines. Access to the tumor was chosen in a non-direct approach according to the proximity of the tumor to one of the following natural transitions: 1. areola 2. axillary line 3. inframammary fold. Results: 84 patients with breast conserving targeted breast surgery with a "non-direct to the tumor approach" have been enrolled so far. 76 patients had primary surgery with stage distribution as follows: Tis (1), T1a (3), T1b (8), T1c (30), T2 (30), T3 (4) and T4b(1). 8 patients had neoadjuvant chemotherapy with stage distribution as follows: ypT0 (3), ypT1a (2), ypT1c (1) and ypT2 (2). Histopathology was predominantly invasive-ductal breast cancer (70), followed by invasive-lobular (6), ductulo-lobular (5), invasive- ductal and pure DCIS (1), invasive-ductal and mucinous (1) and mucinous only (1). After first surgery according to our nomogram 77 patients had a tumor resection with free margins and 7 with involved margins, thus 91,6 % tumors were resected with free margins at first surgery. The remaining 8,4 % of cases were margin-free after second surgery. Conclusions: Scars were not visible on the surface of the breast outside of natural transitions and rate of free margins was high with targeted breast surgery at a rate of 91,6 % without any cosmetic impairment due to the remote natural access to the mammary gland. Patient-reported outcome in detail has been evaluated by validated questionnaires and demonstrated a high satisfaction with scar pattern, volume and symmetry.

Loss of Mammographic Tissue Homeostasis in Invasive Lobular and Ductal Breast Carcinomas vs. Benign Lesions.

The 2D wavelet transform modulus maxima (WTMM) method is used to perform a comparison of the spatial fluctuations of mammographic breast tissue from patients with invasive lobular carcinoma, those with invasive ductal carcinoma, and those with benign lesions. We follow a procedure developed and validated in a previous study, in which a sliding window protocol is used to analyze thousands of small subregions in a given mammogram. These subregions are categorized according to their Hurst exponent values (H): fatty tissue (H ≤ 0.45), dense tissue (H ≥ 0.55), and disrupted tissue potentially linked with tumor-associated loss of homeostasis (0.45 < H < 0.55). Following this categorization scheme, we compare the mammographic tissue composition of the breasts. First, we show that cancerous breasts are significantly different than breasts with a benign lesion (p-value ∼ 0.002). Second, the asymmetry between a patient’s cancerous breast and its contralateral counterpart, when compared to the asymmetry from patients with benign lesions, is also statistically significant (p-value ∼ 0.006). And finally, we show that lobular and ductal cancerous breasts show similar levels of disruption and similar levels of asymmetry. This study demonstrates reproducibility of the WTMM sliding-window approach to help detect and characterize tumor-associated breast tissue disruption from standard mammography. It also shows promise to help with the detection lobular lesions that typically go undetected via standard screening mammography at a much higher rate than ductal lesions. Here both types are assessed similarly.

AB009. SOH21AS214. Invasive lobular breast cancer—patterns of metastatic disease and survival

AB009. SOH21AS214. Invasive lobular breast cancer—patterns of metastatic disease and survival

Cytoplasmic ADP-ribosylation levels correlate with markers of patient outcome in distinct human cancers

ADP-ribosylation (ADPR) is a posttranslational modification whose importance in oncology keeps increasing due to frequent use of PARP inhibitors (PARPi) to treat different tumor types. Due to the lack of suitable tools to analyze cellular ADPR levels, ADPR’s significance for cancer progression and patient outcome is unclear. In this study, we assessed ADPR levels by immunohistochemistry using a newly developed anti-ADP-ribose (ADPr) antibody, which is able to detect both mono- and poly-ADPR. Tissue microarrays containing brain (n = 103), breast (n = 1108), colon (n = 236), lung (n = 138), ovarian (n = 142), and prostate (n = 328) cancers were used to correlate ADPR staining intensities to clinico-pathological data, including patient overall survival (OS), tumor grade, tumor stage (pT), lymph node status (pN), and the presence of distant metastasis (pM). While nuclear ADPR was detected only in a minority of the samples, cytoplasmic ADPR (cyADPR) staining was observed in most tumor types. Strong cyADPR intensities were significantly associated with better overall survival in invasive ductal breast cancer (p < 0.0001), invasive lobular breast cancer (p < 0.005), and high grade serous ovarian cancer patients (p < 0.01). Furthermore, stronger cytoplasmic ADPR levels significantly correlated with early tumor stage in colorectal and in invasive ductal breast adenocarcinoma (p < 0.0001 and p < 0.01, respectively) and with the absence of regional lymph node metastasis in colorectal adenocarcinoma (p < 0.05). No correlation to cyADPR was found for prostate and lung cancer or brain tumors. In conclusion, our new anti-ADP-ribose antibody revealed heterogeneous ADPR staining patterns with predominant cytoplasmic ADPR staining in most tumor types. Different cyADPR staining patterns could help to better understand variable response rates to PARP inhibitors in the future.

State-of-the-Art of the Major Nanopharmaceuticals Treatments in Breast Cancer: A Systematic Review

Introduction: Breast cancer is the most frequently detected cancer in women worldwide, its metastasis is responsible for 90% of deaths. Breast carcinoma is the most common cancer in women worldwide and the most common cause of deaths associated with malignancies. Hyaluronic acid (HA) is the main molecule binding to CD44 and has proved to be a significant ally in the development of nanotransporters that demonstrate preferential accumulation of tumors and increased cellular uptake. Objective: Carry out a systematic review of the main treatments to reduce or prevent the proliferation of breast cancer. Methods: A total of 59 articles have found and after the selection process 20 articles have included and discussed in this study. PUBMED, EMBASE, OVID, AND COCHRANE LIBRARY databases were searched. Results: cationic liposomes containing the conjugate hyaluronic acid-dioleoylphosphatidylethanolamine (HA-DOPE) mediated good transfection in cell lines that express CD44 in culture. Still, other results suggested that the formulation of lapatinib (LPT) coated with HA increases the activity of LPT against triple-negative breast cancer. In addition, compared to free doxorubicin (DOX), superior in vivo antitumor efficacy of modified carbon spots (HA HA-CD) and (p-CBA-DOX) was observed in heterotopic and orthotopic 4T1 cell tumor models. In addition, hematological and biochemical analysis of blood showed that HA-CD and p-CBA-DOX did not induce noticeable toxicity, which further confirmed the good biocompatibility of HA-CD and p-CBA-DOX. Also, it was found that CD44v expression can negatively influence HA uptake and, instead, when cells expressed mainly CD44s, a positive correlation between expression and uptake was observed. Other findings point to the potential clinical utility of recombinant human proteoglycan 4 (rhPRG4) as a therapeutic treatment for invasive and metastatic breast cancer. Conclusion: The development of nanopharmaceuticals delivery systems are able to control the development of tumors and represent a promising strategy to overcome issues related to the non-specific effects of conventional anticancer therapies.

Molecular Subtype May Be More Associated With Prognosis and Chemotherapy Benefit Than Tumor Size in T1N0 Breast Cancer Patients: An Analysis of 2,168 Patients for Possible De-Escalation Treatment

PurposeBreast cancer (BC) patients with T1N0 tumors have relatively favorable clinical outcomes. However, it remains unclear whether molecular subtypes can aide in prognostic prediction for such small, nodal-negative BC cases and guide decision-making about escalating or de-escalating treatments.Patients and MethodsT1N0 BC patients diagnosed between 2009 and 2017 were included and classified into three subgroups according to receptor status: 1) hormonal receptor (HR)+/human epidermal growth factor receptor-2 (HER2)−; 2) HER2+; and 3) triple negative (TN) (HR−/HER2−). Patients’ characteristics and relapse events were reviewed. Kaplan–Meier analysis and Cox regression were used to assess the iDFS and BCSS. The effects of risk factors and adjuvant treatment benefits were evaluated by calculating hazard ratios (HRs) for invasive disease-free survival (iDFS) and breast cancer-specific survival (BCSS) with Cox proportional hazards models.ResultsIn total, 2,168 patients (1,435 HR+/HER2−, 427 HER2+, 306 TN) were enrolled. The 5-year iDFS rates were 93.6, 92.7, and 90.6% for HR+/HER2−, HER2+, and TN patients, respectively (P = 0.039). Multivariate analysis demonstrated that molecular subtype (P = 0.043), but not tumor size (P = 0.805), was independently associated with iDFS in T1N0 BC. TN patients [HRs = 1.77, 95% confidence interval (CI) = 1.11–2.84, P = 0.018] had a higher recurrence risk than HR+/HER2− patients. Adjuvant chemotherapy benefit was not demonstrated in all T1N0 patients but interacted with molecular subtype status. TN (adjusted HRs = 2.31, 95% CI = 0.68–7.54) and HER2+ (adjusted HRs = 2.26, 95% CI = 0.95–5.63) patients receiving chemotherapy had superior iDFS rates. Regarding BCSS, molecular subtype tended to be related to outcome (P = 0.053) and associated with chemotherapy benefit (P = 0.005).ConclusionMolecular subtype was more associated with disease outcome and chemotherapy benefit than tumor size in T1N0 BC patients, indicating that it may guide possible clinical de-escalating therapy in T1N0 BC.

Abstract SP068: The unique epigenetic state of invasive lobular breast cancers

Abstract Although the majority of invasive lobular breast cancers (ILC) are strongly hormone receptor positive and are rarely high-grade, they present a number of unique clinical problems compared with invasive ductal cancer (IDC). These include challenges for early detection, decreased response to chemotherapy and evidence of relative resistance specifically to adjuvant tamoxifen treatment. In addition to uniform loss of e-cadherin, ILCs possess genetic alterations that are suggestive of a unique estrogen receptor axis, including an increase in the frequency of FOXA1 mutations and decrease in GATA3 mutations. In this study we performed a comprehensive analysis of the estrogen receptor axis in pre-clinical models and clinical samples of ILC and IDC. We found that ILC has a unique chromatin state that stems from gained FOXA1 chromatin binding and leads the remodeling of ER chromatin binding. We demonstrated that FOXA1 recruitment can classify primary hormone receptor positive breast cancers to ILC and IDC histological subtypes. Moreover, we show that gained FOXA1 recruitment leads to the transcription of a gene signature associated with resistance to adjuvant tamoxifen in estrogen receptor positive breast cancers and is a mechanism for the divergent pattern of response to specific endocrine treatments in ILC. Collectively, these studies unveil key insights to the fundamental biology unique to ILC, set the stage for precision endocrine treatment in estrogen receptor positive breast cancer, and offer potential treatment targets to improve outcomes for patients with ILC. Citation Format: R Jeselsohn. The unique epigenetic state of invasive lobular breast cancers [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 SP068.

Abstract PS11-02: Comprehensive comparative analysis of invasive ductal and lobular breast cancer cases in great lakes breast cancer consortium

Abstract Background: Invasive lobular breast cancer (ILC) is the second most common histologic subtype of breast cancer following invasive ductal cancer (IDC). ILC accounts for ~10-15% of all breast cancers (~26-40,000 cases annually in the US) and ranks as the 6th most common cancer in women in the US. While there is increasing recognition that ILC has distinct clinical, histologic, molecular, and biological characteristics compared to IDC, it remains understudied. There are very few large cohort analyses comparing clinic-pathological features of ILC, and therefore we performed a large multi-institutional retrospective cohort study. Methods: Investigators from UPMC Hillman Cancer Center, James Cancer Hospital/OSU, and Cleveland Clinic Taussig Cancer Institute/CWRU formed the Great Lakes Breast Cancer consortium, and worked with their respective cancer registries to collect comprehensive data on patients with IDC and ILC seen at their institutions between 1990 and 2017. Descriptive statistics were performed to compare clinic-pathological features, treatments, metastases sites, and co-morbidities. Survival rates were analyzed using the Kaplan-Meier (KM) method and compared using the Cox proportional hazards model. A total of N=38,175 records (N=15,792 for UPMC, N=13,040 for CCF, and N=9,343 for OSU) were included in the study. Results Among the N=38,175 records, we identified N=30,100 unique IDC (not otherwise specific, NOS) (89.3%) and N=3,618 unique ILC cases (10.7%). There were no significant differences between IDC and ILC with respect to laterality of the cancer (IDC: Left 51%, Right 49%; 0.2% Other vs ILC: Left 51%, Right 48%, Other 0.5%) and body mass index (IDC: 28.4 vs ILC: 28.2). In contrast, we observed significant difference with respect to age - patients with ILC were significantly older (61.2 vs 57.5 years; p&amp;lt;0.0001), and there were significant differences in race (7.6% vs 9.2% African American patients in ILC vs IDC, respectively; p=0.004). Among ILC cases, there were fewer grade III tumors (11.4% vs 40.3% in IDC; p&amp;lt;0.0001). ILCs were more frequently stage III (16.6% vs 8.0% in IDC) and stage IV (3.7% vs 2.4% in IDC) (p&amp;lt;0.0001), and ILC were significantly larger than IDC (13.7% T3 vs 2.8% in IDC, p&amp;lt;0.0001). There was also significantly more lymph node involvement in patients with ILC (N2: 5.3% vs 4.0%; N3: 4.6% vs 1.5%) (p&amp;lt;0.0001). The ILC cohort had significantly fewer HER2+ cases (5.5% vs 18.1% in IDC) (p&amp;lt;0.0001), and the proportion of patients with a high recurrence score as determined by 21 gene recurrence score was significantly lower in ILC compared to IDC (1.7% vs 10.4% in IDC; p&amp;lt;0.0001). As expected, there was a significant enrichment of ER+ tumors in ILC (96.1% compared to IDC (76.6%) (p&amp;lt;0.0001). Age, stage, grade, ER, Her2, and lymph node involvement remained significantly associated with histology in a logistic regression analysis. KM analysis showed significantly shortened disease-free (p=0.041) and overall survival (p&amp;lt;0.0001) for patients with ER+ ILC (N=2,565) compared to ER+ IDC N=17,278). The estimated 5yr and 10yr DFS rates for patients with IDC are 0.94 and 0.89, and for ILC 0.94 and 0.86, confirming prior data of late recurrences in patients with ILC. Conclusions: In the largest cohort of patients with ILC made possible by multi-center collaborations we show that lobular histology carries distinct prognostic implications and that outcomes are significantly worse. This highlights the need for more ILC research and clinical trials for patients with ILC. Citation Format: Steffi Oesterreich, Azadeh Nasrazadani, Jian Zou, Tiffany Onger, Matthew Wright, George Tseng, Bhuvana Ramaswamy, Adrian V Lee, Nicole Williams, Megan Kruse. Comprehensive comparative analysis of invasive ductal and lobular breast cancer cases in great lakes breast cancer consortium [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 PS11-02.

Abstract PS4-23: An analysis of the clinical and economic impact of the 21-gene recurrence score (RS) in invasive lobular early-stage breast cancer (ESBC) in Ireland

Abstract Background: The use of the 21-gene recurrence score assay (RS) has reduced chemotherapy (CT) administration in patients with hormone receptor (HR)-positive, HER-2 negative, lymph-node negative, early stage breast cancer (ESBC). Invasive lobular carcinoma (ILC) accounts for up to 15% of all breast cancers. This study uses real world data to assess (1) the effect of RS testing on treatment decision making in patients with ILC and (2) the economic benefit of testing in this subgroup. Methods: From October 2011 to February 2019, a retrospective, cross-sectional, observational study was conducted on HR+, HER-2 negative, lymph-node negative, ESBC patients with ILC who had RS testing in Ireland. For the decision impact analysis, a survey of Irish breast medical oncologists presumed that, without RS testing, CT would be recommended to patients with histological grade (G) 2 and 3 tumours and not for G1 tumours. In accordance with TAILOR-x results, patients were classified overall as low risk (RS≤25) and high risk (RS&amp;gt;25) and patients ≤50 years old were low risk (RS 0-15), intermediate risk (RS 16-25), and high risk (RS&amp;gt;25). Data were collected from electronic patient records. Descriptive statistics were used. Cost data were obtained from the National Healthcare Pricing Regulatory Authority. The economic analysis was adjusted for changing treatment and assay costs over the study period. Results: 166 patients with ILC were identified. Mean age was 59 years. Mean tumour size was 2.3cm (range 0.7-5.8). The majority had G2 tumors (n=152, 92%) with a small number of G3 (n=7, 4%) and G1 (n=7,4%). Overall, 153 patients (92.2%) had a low RS (≤25), 12 (7.2%) had high RS (&amp;gt;25), and 1(0.6%) was unknown. All 12 patients with RS&amp;gt;25 had G2 tumours, 6/12 (50%) had tumour size &amp;gt;3cm, 4(33.3%) were PR+ and 8(66.7%) were PR negative. In 29/166 (17.5%) patients, aged ≤50 at diagnosis, RS was ≤15 in 16(55%), 16-20 in 6(21%), 21-25 in 5(17%), &amp;gt;25 in 1(3.5%) and unknown in 1(3.5%). The majority of these patients (27, 93%) had G2 tumours, 1 had G1 and 1 had G3. Post RS testing 124 patients (74.5%) had a change in CT recommendation; all from CT to hormone therapy. In total, only 35 patients (21%) received CT. In this group, RS was 0-15 in 3(9%), RS 16-25 in 19(54%), RS &amp;gt;25 in 12 (34%) and unknown in 1(3%). Eight of 35 patients (23%) were aged ≤50. The most common CT regimen administered was docetaxel plus cyclophosphamide (TC). RS testing achieved a 78% reduction in chemotherapy use. This resulted in savings of €900,000 in treatment costs. With the incorporation of the assay cost, the net savings totalled approximately €400,000. Conclusions: Ireland was the first public health care system to reimburse the 21-gene recurrence score assay in Europe. There is limited evidence demonstrating the benefits of RS in ILC. In our study, the use of the test has resulted in a 78% reduction in chemotherapy use in an Irish ILC patient population and a substantial cost saving (greater than €400,000) to the Irish Healthcare System. Citation Format: Mehala Tharmabala, Lynda McSorley, Fathiya Al Rahbi, Evoy Denis, James G Geraghty, Rothwell Jane, Damian McCartan, Enda McDermott, Maccon M Keane, John Kennedy, Seamus O'Reilly, Steve Millen, John Crown, Lilian Mary Smyth, Catherine Margaret Kelly, Prichard Ruth, Cecily Quinn, Janice M Walshe. An analysis of the clinical and economic impact of the 21-gene recurrence score (RS) in invasive lobular early-stage breast cancer (ESBC) in Ireland [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 PS4-23.

Abstract PD10-06: Clinical behavior and outcomes of BRCA-mutated breast cancer in young patients according to type of BRCA mutation and hormone receptor status: Results from an international cohort study

Abstract Background: Young breast cancer patients (pts) carrying a germline BRCA mutation (mBRCA) have similar outcomes as non-carriers. However, there is currently lack of evidence regarding the impact of mBRCA type and hormone receptor status on clinical behavior and outcomes of mBRCA breast cancer. We aim to address these questions in the largest dataset to date of young mBRCA breast cancer pts. Methods: This was an international, multicenter, hospital-based, retrospective cohort study. Women harboring deleterious germline mBRCA1 or mBRCA2 that received a diagnosis of stage I-III invasive early breast cancer at age ≤40 years between January 2000 and December 2012 were included. Baseline pts, tumor, and treatment characteristics, pattern and risk over time of disease-free survival (DFS) events, and survival outcomes (DFS, distant recurrence-free interval [DRFI] and overall survival [OS]) were compared between mBRCA1 and mBRCA2 pts overall and by hormone receptor status. Multivariate Cox proportional hazard models were used to compare hazard rates (HRs). Results: 1,236 young mBRCA breast cancer pts were included. Among 808 and 428 pts with mBRCA1 or mBRCA2, respectively, 191 (23.6%) and 356 (83.2%) had hormone receptor-positive tumors while 617 (76.4%) and 72 (16.8%) hormone receptor-negative disease (p&amp;lt;0.001). Compared to mBRCA2 breast cancer pts, those with mBRCA1 were younger, more likely to have reported Jewish ancestry, had more grade 3 tumors, less nodal involvement, lobular histology and HER2 positivity, and received more frequently chemotherapy (all p&amp;lt;0.001). More mBRCA1 pts with hormone receptor-positive tumors did not receive adjuvant endocrine therapy (14.7% vs. 4.2%, p&amp;lt;0.001). No difference between mBRCA1 and mBRCA2 pts was observed in risk-reducing mastectomy (43.9% vs. 46.0%; p=0.371) or salpingo-oophorectomy (48.3% vs. 48.8%; p=1.0). Median follow-up was 7.9 years (range 5.6-10.6 years). Second primary breast cancers (17.0% vs. 12.2%, p=0.025) and non-breast primary malignancies (4.3% vs. 1.9%, p=0.033) were more frequent among mBRCA1 pts compared to mBRCA2 pts, while distant recurrences were less frequent (10.4% vs. 15.4%, p=0.013). 8-year DFS was 62.8% and 65.9% for mBRCA1 and mBRCA2 pts, respectively (adjusted HR 0.76; 95% CI 0.60-0.96). The worse DFS in mBRCA1 was observed regardless of hormone receptor status (pinteraction=0.848): hormone receptor-positive (adjusted HR 0.77; 95% CI 0.58-1.03) and hormone receptor-negative (adjusted HR 0.73; 95% CI 0.48-1.13). No differences in DRFI and OS were observed between mBRCA1 and mBRCA2 pts. Compared to pts with hormone receptor-negative disease, those with hormone receptor-positive breast cancer had higher chances of developing distant (± loco-regional) recurrences (16.1% vs. 9.0%; p&amp;lt;0.001) and less frequent second primary malignancies (BC: 12.1% vs. 17.9%, p=0.005; non-BC: 2.8% vs. 4.0%, p=0.216). No differences in DFS and OS were observed between pts with hormone receptor-positive or negative breast cancer. However, there was a trend towards worse DRFI in women with hormone receptor-positive breast cancer as compared to those with hormone receptor-negative disease (8-year DRFI: 83.4% vs. 90.1%; adjusted HR 1.39; 95% CI 0.94-2.05). Conclusions: In this large unique dataset, young mBRCA1 breast cancer pts had worse DFS than those with mBRCA2 mostly due to higher rates of second primary malignancies. Hormone receptor positivity had no positive prognostic value in young mBRCA breast cancer pts with a trend towards worse DRFI in those with hormone receptor-negative disease. These results provide important information for counseling young mBRCA breast cancer pts regarding treatment, prevention and follow-up care strategies. Citation Format: Matteo Lambertini, Marcello Ceppi, Anne-Sophie Hamy, Olivier Caron, Philip D. Poorvu, Estela Carrasco, Albert Grinshpun, Kevin Punie, Christine Rousset-Jablonski, Alberta Ferrari, Shani Paluch-Shimon, Angela Toss, Claire Senechal, Fabio Puglisi, Katarzyna Pogoda, Jose Alejandro Pérez-Fidalgo, Laura De Marchis, Riccardo Ponzone, Luca Livraghi, Maria Del Pilar Estevez-Diz, Cynthia Villarreal-Garza, Maria Vittoria Dieci, Florian Clatot, Francois P. Duhoux, Rossella Graffeo, Luis Teixeira, Octavi Córdoba, Amir Sonnenblick, Arlindo R. Ferreira, Ann H. Partridge, Antonio Di Meglio, Claire Saule, Fedro A. Peccatori, Marco Bruzzone, Lucia Del Mastro, Lieveke Ameye, Judith Balmaña, Hatem A. Azim, Jr. Clinical behavior and outcomes of BRCA-mutated breast cancer in young patients according to type of BRCA mutation and hormone receptor status: Results from an international cohort study [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 PD10-06.

Abstract OT-08-01: The PREDICT registry: A prospective registry to evaluate the effect of a predictive assay on treatment decisions in patients with DCIS following breast conserving therapy

Abstract Background. The benefits of adjuvant radiation therapy (RT) in patients with ductal carcinoma in situ (DCIS) treated with breast conserving surgery (BCS) remains controversial. Although there is level-I evidence supporting the role of RT in reducing the risk of local recurrence, the absolute benefit is variable. Current guidelines generally recommend RT for all patients having BCS, but it is important to develop prognostic and predictive tools to better assess risk and understand the impact such a tool would have on treatment decisions. The DCISionRT Test (PreludeDx, Laguna Hills, CA) is a biologic signature that provides a validated score for assessing 10-year risk of recurrence and RT benefit using individual tumor biology as assessed by clinical and pathologic biomarkers.Methods. This is a prospective cohort study for patients diagnosed with DCIS of the breast. Treating physicians complete a treatment recommendation survey before and after receiving DCISionRT test results. Test results, treatment recommendations, patient preferences and clinico-pathologic features are stored in a de-identified registry for participating institutions from a variety of geographic regions across the US. The study will also collect 5- and 10-year recurrence and survival data. The study includes females over age 25 who are candidates for BCS and eligible for RT and/or systemic treatment with sufficient tissue to generate test results. Subjects must not have been previously treated for DCIS or have previous or current invasive or micro-invasive breast cancer. The primary endpoints are changes in treatment recommendations for surgical, radiation and hormonal therapy. Secondary endpoints are identification of key drivers for treatment recommendations, including age, size, grade, necrosis, hormone receptor status and other clinico-pathologic factors. Changes in treatment recommendations will be assessed using McNemar's test with an alpha level of 0.05. Differences in recurrence-free and overall survival will be evaluated by Kaplan-Meier survival analysis using the log-rank test and/or the Cox Proportional Hazards model. A planned early interim analysis based on the first 200 patients has been recently completed and reported. Results. As of July 6, 2020, 1,000 patients have been accrued from 49 institutions. Twenty additional institutions are currently in the process of joining the study. We are planning to enroll up to 2,500 patients from up to 100 institutions. Citation Format: Steve C Shivers, Pat W Whitworth, Rakesh Patel, Troy Bremer, Charles E Cox. The PREDICT registry: A prospective registry to evaluate the effect of a predictive assay on treatment decisions in patients with DCIS following breast conserving therapy [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 OT-08-01.