Hormone-responsive Breast Cancer Research Articles

Fatty Acid Synthase Confers Tamoxifen Resistance to ER+/HER2+ Breast Cancer.

Simple SummaryOveractivation of the human epidermal growth factor receptor 2 (HER2) is one of the main drivers of tamoxifen resistance in estrogen receptor (ER)-positive breast cancer patients. Combined targeting of HER2 and ER, however, has yielded disappointing results in the clinical setting. Therefore, other potential mechanisms for tamoxifen resistance would not be overcome by solely blocking the cross-talk between ER and HER2 at the receptor(s) level. Using cell lines, animal models, and clinical data, we provide evidence to support a critical role of fatty acid synthase (FASN)—the major site for endogenous fat synthesis—in HER2-driven tamoxifen resistance. Importantly, treatment with a FASN inhibitor impeded the estrogen-like tumor-promoting effects of tamoxifen and fully restored the anti-estrogenic activity of tamoxifen in ER+/HER2-overexpressing breast cancer xenografts. We postulate FASN as a biological determinant of HER2-driven tamoxifen resistance and FASN inhibition as a novel therapeutic approach to restore tamoxifen sensitivity in endocrine-resistant breast cancer.The identification of clinically important molecular mechanisms driving endocrine resistance is a priority in estrogen receptor-positive (ER+) breast cancer. Although both genomic and non-genomic cross-talk between the ER and growth factor receptors such as human epidermal growth factor receptor 2 (HER2) has frequently been associated with both experimental and clinical endocrine therapy resistance, combined targeting of ER and HER2 has failed to improve overall survival in endocrine non-responsive disease. Herein, we questioned the role of fatty acid synthase (FASN), a lipogenic enzyme linked to HER2-driven breast cancer aggressiveness, in the development and maintenance of hormone-independent growth and resistance to anti-estrogens in ER/HER2-positive (ER+/HER2+) breast cancer. The stimulatory effects of estradiol on FASN gene promoter activity and protein expression were blunted by anti-estrogens in endocrine-responsive breast cancer cells. Conversely, an AKT/MAPK-related constitutive hyperactivation of FASN gene promoter activity was unaltered in response to estradiol in non-endocrine responsive ER+/HER2+ breast cancer cells, and could be further enhanced by tamoxifen. Pharmacological blockade with structurally and mechanistically unrelated FASN inhibitors fully impeded the strong stimulatory activity of tamoxifen on the soft-agar colony forming capacity—an in vitro metric of tumorigenicity—of ER+/HER2+ breast cancer cells. In vivo treatment with a FASN inhibitor completely prevented the agonistic tumor-promoting activity of tamoxifen and fully restored its estrogen antagonist properties against ER/HER2-positive xenograft tumors in mice. Functional cancer proteomic data from The Cancer Proteome Atlas (TCPA) revealed that the ER+/HER2+ subtype was the highest FASN protein expressor compared to basal-like, HER2-enriched, and ER+/HER2-negative breast cancer groups. FASN is a biological determinant of HER2-driven endocrine resistance in ER+ breast cancer. Next-generation, clinical-grade FASN inhibitors may be therapeutically relevant to countering resistance to tamoxifen in FASN-overexpressing ER+/HER2+ breast carcinomas.

A follow-up study of a randomized controlled study evaluating safety and efficacy of leuprorelin acetate every-3-month depot for 2 versus 3 or more years with tamoxifen for 5\xa0years as adjuvant treatment in premenopausal patients with endocrine-responsive breast cancer

BackgroundPreviously, we conducted the 5-year open-label, randomized controlled trial (RCT) of leuprorelin adjuvant therapy in post-operative premenopausal patients with endocrine-responsive breast cancer, which was a pilot study to investigate the optimal duration of leuprorelin treatment. Since, however, long-term outcomes became required for the adjuvant endocrine therapy, we performed this follow-up observation study.MethodsFollow-up observation study was performed up to 10th year after randomization, continuing RCT to evaluate the efficacy and safety of leuprorelin every 3 months for ≥ 3 versus 2 years, with daily tamoxifen for 5 years. Primary endpoints were disease-free survival (DFS) and 2-year landmark DFS.ResultsEligible patients (N = 222) were randomly assigned to receive leuprorelin for either 2 years (N = 112) or ≥ 3 years (N = 110) with tamoxifen. Leuprorelin treatment for ≥ 3 years versus 2 years provided no significant difference in DFS (HR 0.944, 95% CI 0.486–1.8392) or 2-year landmark DFS (N = 99 and 102 in 2-year and ≥ 3-year groups, HR 0.834, 0.397–1.753). In small, higher-risk subgroup (n = 17); however, 2-year landmark DFS in ≥ 3-year group was significantly longer (HR 0.095, 0.011–0.850) than that in 2-year group. The incidence of bone-related adverse events was around 5% in both groups.ConclusionsAdjuvant leuprorelin treatment for ≥ 3 years with tamoxifen only showed similar efficacy and safety profiles to those for 2 years in analyses among all patients but suggested greater benefit in higher-risk patients. No new safety signal was identified for long-term leuprorelin treatment.Trial registration numberNot applicable. This was an observational study.

Abstract PS12-17: Baseline characteristics of women enrolled in the POSITIVE trial (pregnancy outcome and safety of interrupting therapy for women with endocrine responsIVE breast cancer)

Abstract Background: Pregnancy is a major concern for young breast cancer (BC) survivors. Conception after BC in women with hormone receptor positive (HR+) disease is affected by the standard 5-10 years of adjuvant endocrine therapy (ET) during which pregnancy is contraindicated and fertility may be waning. The POSITIVE Trial (IBCSG 48-14/BIG 8-13/Alliance A221405/NCT02308085) investigates the impact of temporary ET interruption to allow pregnancy. Methods: POSITIVE enrolled premenopausal women with stage I-III HR+ early BC, ≤42 years of age, who had received adjuvant ET (SERM alone, ovarian function suppression (OFS) plus SERM or AI) for 18 to 30 months, and wished to interrupt ET to attempt pregnancy. An interruption of ET for up to 2 years was foreseen to allow pregnancy (after a 3-month ET washout period), delivery, and breastfeeding if desired/feasible. Resumption of ET to complete 5-10 years of treatment was planned as soon as pregnancy/breastfeeding was completed or after it was ensured conception was not possible. We report baseline characteristics of participants enrolled in POSITIVE by region of enrollment. Results: From 12/2014 to 12/2019, 518 participants were enrolled at 116 centers in 20 countries across 4 continents. The table shows the baseline characteristics of the enrolled women. Several differences were seen across regions: A higher proportion of participants <35 yrs (43%) enrolled in North America than in Europe (33%) or Asia (26%). Eighty-one percent of Asian women had no children at enrollment compared to 75% and 68% of European and North American women, respectively. Consistently, a greater percent of women in Asia (56%) had used fertility preservation measures, compared to Europe (53%) and North America (43%). Stage distribution was also different across continents: a greater percent of Asian participants had stage I, grade 1 and node-negative disease (51%, 29% and 76 %, respectively) compared to European (46%, 14% and 67%) and North American (43%, 16% and 55%) women. Only 19% of Asian women had either 1-3 positive nodes and grade 3 tumors, the proportion increased to 28% and 35% in Europe and to 41% and 38% in North America, respectively. North American women were more likely to have had mastectomy (60% vs. Asian (44%) and European (41%)); European women were more likely to have had chemotherapy (69% vs. North American (56%) and Asian (42%)). ET administration prior to enrollment differed substantially by region: Most North American women had SERM (T) alone (58%), and when OFS was added to oral ET, it was combined with AI in 19% and with T in 8% of participants, respectively. In Asia most women received T + OFS (55%), followed by T alone (36%), and AI + OFS (6%). In Europe, T + OFS was the most frequent treatment (40%), followed by T alone (37%) and AI + OFS (17%). Median duration of ET before enrollment was similar across regions (22-24 months). Conclusion: Regional variation of baseline characteristics of women enrolled in the POSITIVE trial may provide important insights into different medical and sociocultural attributes and attitudes of the study participants and investigators from those regions. Affiliation: POSITIVE Investigators, International Breast Cancer Study Group, Alliance for Clinical Trials in Oncology, Breast International Group, North American Breast Cancer Group CharacteristicRegion: Europe / North America / Asia-Pacific61% / 23% / 16%Median age at enrollment, yrs (IQR)37 (33-39)Caucasian race77%No children prior to enrollment74%Prior fertility preservation measures taken51%Stage I / II46% / 45%0 / 1 positive nodes65% / 21%Grade 2 / 348% / 33%HER2-negative74%Mastectomy46%Chemotherapy61%ET: SERM alone / SERM+OFS / AI+OFS41% / 35% / 16%Median duration of prior ET, mos (IQR)23 (20-27) Citation Format: Ann H Partridge, Samuel M Niman, Monica Ruggeri, Fedro A Peccatori, Hatem A Azim, Jr, Marco Colleoni, Cristina Saura, Chikako Shimizu, Anna Barbro Sætersdal, Judith Kroep, Ellen Warner, Virginia F Borges, Andrea Gombos, Akemi Kataoka, Christine Rousset-Jablonski, Simona Borstnar, Hideko Yamauchi, Jeong Eon Lee, Janice M Walshe, Manuel Ruíz Borrego, Halle CF Moore, Christobel Saunders, Fatima Cardoso, Snezana Susnjar, Vesna Bjelic-Radisic, Karen L Smith, Martine Piccart, Larissa A Korde, Aron Goldhirsch, Richard D Gelber, Olivia Pagani. Baseline characteristics of women enrolled in the POSITIVE trial (pregnancy outcome and safety of interrupting therapy for women with endocrine responsIVE 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 PS12-17.

Abstract PS18-48: Comprehensive analysis of solute carriers to characterise differential expression in breast cancer cell lines and human tissue

Abstract Essential nutrient uptake required for cell growth and survival is mediated by Solute Carrier (SLC) transporters both physiologically and in cancers. The SLC super-family encompasses sub-families of transport proteins including organic anion transporters (OAT), organic cation transporters (OCT) and organic anion transporting polypeptides (OATP). SLCs transport a vast array of endogenous and exogenous substances, including estrogen, its conjugates, and clinically relevant anti-cancer drugs. Accumulating evidence suggests that SLC transporters are differentially expressed in hormone-responsive and hormone non-responsive breast cancers, which could influence breast cancer pathogenesis, both in disease progression and treatment resistance. We investigated whether SLC transporters are differentially expressed in different breast cancer cell lines and in human breast cancer tissue. First, bulk cells from the breast cancer cell lines MCF-7 (hormone responsive) and MDA-MB-231 (hormone non-responsive) were analysed for differential expression of SLCs using sq-PCR and RT-PCR. 8 of 11 SLCO and 10 of 14 SLC22 transporters were expressed in at least one cell line. Transporter expression was either similar or lower in MCF-7 cells compared to MDA-MB-231 cells, with the exception of SLCO2A1, SLCO4C1, SLCO5A1 and SLC22A5 which were higher in MCF-7 cells. mRNA expression of SLCs was then compared between both cell lines and human breast cancer tissue. The latter showed an expression pattern largely reminiscent of the MCF-7 cells. Because these techniques measure the average level of expression shown by a pooled cell population, there is the potential disadvantage that cell heterogeneity is masked. To help address this, Single Cell RNA Sequencing (scRNA-Seq) was performed using the 10x Genomics Chromium Single Cell 3’ platform and NovaSeq Technologies to compare SLC transporter expression between the cell lines. Together these results provide evidence for differences in SLC transporter expression between cell lines and cancer tissues that may contribute to cancer progression. Citation Format: Rachel Jane Sutherland, Annette Meeson, Simon Lowes. Comprehensive analysis of solute carriers to characterise differential expression in breast cancer cell lines and human tissue [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 PS18-48.

Managing Menopausal Symptoms in Young Women With Breast Cancer: When Medicine Is Not All. The Take Care Project

In the last decade, endocrine therapy strategies in perimenopausal women with hormone-responsive early breast cancer (BC) have changed and now ovarian function suppression (OFS) is recommended for the majority of patients. Side effects of OFS mimic menopausal symptoms, including hot flushes, sweats, weight gain, and sexual dysfunction, which may negatively impact quality of life (QoL). Aims of the Take Care Project are the education of physicians and patients to have all the information (medical and nonmedical) they need to manage menopausal symptoms by distributing educational materials useful to face menopause. Four different areas have been identified by surveys conducted among physicians and young patients: for each area, interventions and tools have been elaborated by a doctor and nonphysician professionals of these identified areas, to offer the widest information available. Clinical and practical suggestions have been provided. Based on the evidence given, we strongly suggest setting up a multidisciplinary team for the treatment planning of young patients with BC, which could help patients to face and manage their new menopause condition. The reduction of side effects and the improvement in QoL should be the best ally to treat young patients with BC.

Experimental models of endocrine responsive breast cancer: strengths, limitations, and use.

Breast cancers characterized by expression of estrogen receptor-alpha (ER; ESR1) represent approximately 70% of all new cases and comprise the largest molecular subtype of this disease. Despite this high prevalence, the number of adequate experimental models of ER+ breast cancer is relatively limited. Nonetheless, these models have proved very useful in advancing understanding of how cells respond to and resist endocrine therapies, and how the ER acts as a transcription factor to regulate cell fate signaling. We discuss the primary experimental models of ER+ breast cancer including 2D and 3D cultures of established cell lines, cell line- and patient-derived xenografts, and chemically induced rodent models, with a consideration of their respective general strengths and limitations. What can and cannot be learned easily from these models is also discussed, and some observations on how these models may be used more effectively are provided. Overall, despite their limitations, the panel of models currently available has enabled major advances in the field, and these models remain central to the ability to study mechanisms of therapy action and resistance and for hypothesis testing that would otherwise be intractable or unethical in human subjects.

Passive Diffusion vs Active pH-Dependent Encapsulation of Tyrosine Kinase Inhibitors Vandetanib and Lenvatinib into Folate-Targeted Ferritin Delivery System

IntroductionThe present study reports on examination of the effects of encapsulating the tyrosine kinase inhibitors (TKIs) vandetanib and lenvatinib into a biomacromolecular ferritin-based delivery system.MethodsThe encapsulation of TKIs was performed via two strategies: i) using an active reversible pH-dependent reassembly of ferritin´s quaternary structure and ii) passive loading of hydrophobic TKIs through the hydrophobic channels at the junctions of ferritin subunits. After encapsulation, ferritins were surface-functionalized with folic acid promoting active-targeting capabilities.ResultsThe physico-chemical and nanomechanical analyses revealed that despite the comparable encapsulation efficiencies of both protocols, the active loading affects stability and rigidity of ferritins, plausibly due to their imperfect reassembly. Biological experiments with hormone-responsive breast cancer cells (T47-D and MCF-7) confirmed the cytotoxicity of encapsulated and folate-targeted TKIs to folate-receptor positive cancer cells, but only limited cytotoxic effects to healthy breast epithelium. Importantly, the long-term cytotoxic experiments revealed that compared to the pH-dependent encapsulation, the passively-loaded TKIs exert markedly higher anticancer activity, most likely due to undesired influence of harsh acidic environment used for the pH-dependent encapsulation on the TKIs’ structural and functional properties.ConclusionSince the passive loading does not require a reassembly step for which acids are needed, the presented investigation serves as a solid basis for future studies focused on encapsulation of small hydrophobic molecules.

The VES-13 and G-8 tools as predictors of toxicity associated with aromatase inhibitors in the adjuvant treatment of breast cancer in elderly patients: A single-center study.

Adjuvant hormone treatment of postmenopausal breast cancer is mainly based on aromatase inhibitors. Adverse events associated with such class of drugs are particularly severe in elderly patients. Therefore, we investigated the possibility of ab initio predict which elderly patients could encounter toxicity. In light of national and international oncological guidelines recommending the use of screening tests for multidimensional geriatric assessment in elderly patients aged ≥70 years and eligible for active cancer treatment, we assessed whether the Vulnerable Elder Survey (VES)-13 and the Geriatric (G)-8 could be predictors of toxicity associated with aromatase inhibitors. Seventy-seven consecutive patients aged ≥70 diagnosed with non-metastatic hormone-responsive breast cancer and therefore eligible for adjuvant hormone therapy with aromatase inhibitors, were screened with the VES-13 and the G-8, and underwent a six-monthly clinical and instrumental follow-up in our medical oncology unit, from September 2016 to March 2019 (30 months). Said patients were identified as vulnerable (VES-13 score ≥3 or G-8 score ≤14) and fit (VES-13 score <3 or G-8 score >14). The likelihood of experiencing toxicity is greater among vulnerable patients. The correlation between the VES-13 or the G-8 tools and the presence of adverse events is equal to 85.7% (p = 0.03). The VES-13 demonstrated 76.9% sensitivity, 90.2% specificity, 80.0% positive predictive value, 88.5% negative predictive value. The G-8 demonstrated 79.2% sensitivity, 88.7% specificity, 76% positive predictive value, 90.4% negative predictive value. The VES-13 and the G-8 tools could be valuable predictors of the onset of toxicity associated with aromatase inhibitors in the adjuvant treatment of breast cancer in elderly patients aged ≥70.

Fertility preservation in endocrine responsive breast cancer: data and prejudices.

Even if current guidelines suggest an early referral of young breast cancer (BC) patients to fertility preservation counselling, physicians still lack knowledge about the different available strategies. Hormonal stimulation to harvest mature oocytes is considered unsafe by many oncologists and experts in reproductive medicine, particularly in the setting of oestrogen receptor-positive BC. The aim of this mini-review is to provide an overview on the available data about this topic in order to clarify potential misunderstandings and to highlight the new trends in the oncofertility field with their pros and limitations.

Amphiregulin retains ERα expression in acquired aromatase inhibitor resistant breast cancer cells.

Acquired resistance to aromatase inhibitors (AIs) is a significant clinical issue in endocrine therapy for estrogen receptor (ER) positive breast cancer which accounts for the majority of breast cancer. Despite estrogen production being suppressed, ERα signaling remains active and plays a key role in most AI-resistant breast tumors. Here, we found that amphiregulin (AREG), an ERα transcriptional target and EGF receptor (EGFR) ligand, is crucial for maintaining ERα expression and signaling in acquired AI-resistant breast cancer cells. AREG was deregulated and critical for cell viability in ER+ AI-resistant breast cancer cells, and ectopic expression of AREG in hormone responsive breast cancer cells promoted endocrine resistance. RNA-sequencing and reverse phase protein array analyses revealed that AREG maintains ERα expression and signaling by activation of PI3K/Akt/mTOR signaling and upregulation of forkhead box M1 (FOXM1) and serum- and glucocorticoid-inducible kinase 3 (SGK3) expression. Our study uncovers a previously unappreciated role of AREG in maintaining ERα expression and signaling, and establishes the AREG-ERα crosstalk as a driver of acquired AI resistance in breast cancer.

Identification of Antiestrogen-Bound Estrogen Receptor α Interactomes in Hormone-Responsive Human Breast Cancer Cell Nuclei.

Estrogen receptor alpha (ERα) is a ligand-inducible transcription factor which mediates estrogen actions in hormone-responsive tumors and is targeted by effective anticancer therapies based on the ERα antagonist ligands, selective estrogen receptor modulators (such as Tamoxifen/TAM) or disruptors (such as Fulvestrant/ICI). Despite its importance for cancer therapy, including acquired resistance to endocrine therapy, the molecular basis of ERα response to different ligands is not fully known to date. Interaction proteomics shows great potential to identify and characterize molecular mechanisms of disease based on physical and functional protein-protein interaction networks. Tandem affinity purification coupled to mass spectrometry is applied here for mapping in hormone-responsive breast cancer cells nuclei, the ERα interactomes, induced by each of the two classes of antiestrogens. The results provide new insights on the molecular bases for antiestrogen-mediated control of ERα function and reveal new potential ways to overcome endocrine therapy resistance in cancer.

Abstract 5675: Metastatic organ-specific changes in ERα and XPO1 signaling and metabolic adaptations dictate the therapy responses in endocrine resistant breast cancers

Abstract Introduction: Approximately 70% of human breast cancers express estrogen receptor alpha (ERα), providing a potential for targeted endocrine therapy for patients. Unfortunately, 30-40% of ER+ patients still experience recurrence and metastasis with a 5-year relative overall survival rate of just 24%. The tumor microenvironment (TME) plays a key role in the behavior of cancer cells and their response to endocrine therapies. However, there is a critical need for relevant 3D models of different metastatic sites to use for studying the molecular mechanisms driving resistance in these tumor phenotypes. Methods: We established 3D cell culture systems in novel hydrogels derived from decellularized bone, lung and liver tissues - the major sites of metastasis of ER+ tumors, and compared with standard Matrigel culture. Endocrine responsive (MCF7 and T47D) and resistant (MCF7 and T47D cells with ESR1 Y537S or D538G mutations) breast cancer cell lines were treated with fulvestrant (FUL), tamoxifen (TAM) and palbociclib (PAL). Tumorigenicity was assessed using in vitro cell viability and colony formation assays and in vivo breast cancer cell line xenografts in athymic mice. ERα cistromes and transcriptomes were assessed using ChIP-Seq and RNA-Seq analysis. Metabolic changes were assessed using whole metabolite profiling by GC-MS, a Seahorse XF analyzer, and flux analysis with labeled glucose and glutamine. Results: We observed metastatic site-specific responses to each drug. For example, TAM blocked colony formation in Matrigel and lung hydrogel but increased colony formation in bone and liver hydrogels. FUL acted as an agonist and increased colony number and size in all three-tissue matrices, but not in Matrigel. PAL increased colony size and number in Matrigel and liver hydrogel but not in bone or lung hydrogel. Genome-wide ERα recruitment to chromatin was reduced in liver hydrogels, consistent with decreased clinical response to endocrine agents in patients with liver metastasis. We found that treatment with individual drugs activated novel metabolic pathways to increase survival in different metastatic sites. Using RNA-Seq analysis, we identified increased expression of nuclear export pathway components (XPO1, KPNA2, etc.) in various metastatic sites. Combining an FDA-approved XPO1 small molecule inhibitor, Selinexor (SEL) with the current therapies used for advanced breast cancers (FUL, TAM or PAL) decreased metabolic adaptations in response to individual drug treatments and prevented colony formation in hydrogels and tumor growth in xenograft models. Conclusions: Further developing and characterizing 3D metastatic site models will enable us to elucidate the underlying mechanisms of metastasis and resistance, and target these mechanisms with novel drug combinations in already metastasized patients. Targeting metastatic-site specific adaptations to regenerate new vulnerabilities in endocrine-resistant breast tumors is novel. Given the need for better strategies for improving therapy response of metastatic ER+ tumors, our findings show uncovering the role ERα-XPO1 crosstalk plays in metastatic breast cancer could lead to new combined therapies that reduce mortality. Citation Format: Qianying Zuo, Eylem Kulkoyluoglu Cotul, Ashlie Santaliz-Casiano, Ozan Berk Imir, Elif Tunc, Chengjian Mao, David J. Shapiro, Ben Ho Park, Yosef Landesman, Zeynep Madak-Erdogan. Metastatic organ-specific changes in ERα and XPO1 signaling and metabolic adaptations dictate the therapy responses in endocrine resistant breast cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5675.

Abstract 1231: Targeting JNK1/2 induces a potent cytostatic response in estrogen receptor expressing breast cancer cells, with induction of autophagy and senescence as measurable outcomes

Abstract The c-Jun N-terminal kinases, JNK1/2 are members of the mitogen activated protein kinase (MAPK) family that can mediate inflammatory responses, cell differentiation, cell proliferation, and/or cell death. In breast cancer, JNK signaling has been associated with increased proliferation, angiogenesis, and tumor metastasis. Also, inhibition of JNK has been shown to promote tumor cytostasis, but this inhibition also attenuates the cytotoxic effects of certain chemotherapeutics, calling into question the therapeutic potential of JNK inhibitors. In this study, we hypothesized that JNK1/2 inhibition induced autophagy, as a mechanism of protection against chemotherapy- and endocrine-induced apoptosis. Autophagy is a normal physiologic process required for the elimination of damaged mitochondria and misfolded proteins that can be induced in cancer cells under certain stresses such as hypoxia and drug insult to provide protection from death. To characterize the role of JNK1/2 in autophagy, we utilized two ERα expressing human breast cancer cell lines, T47-D and MCF-7. Autophagy flux experiments were performed in which the steady state levels of the autophagy protein LC3 II were analyzed in control cells versus cells undergoing JNK1/2 inhibition with the non-reversible JNK-IN8 inhibitor. JNK-IN8 was used as a single agent or in combination with estradiol and/or antiestrogen treatment. These studies reproducibly identified JNK1/2 inhibition as a mechanism of autophagy activation. The induction of autophagy correlated with sustained inhibition of proliferation as determined by cell counts, MTT, and clonogenic assays, and induction of senescence (in T47-D cells) as determined by the expression of β-galactosidase. In contrast, induction of apoptosis was not a major outcome of JNK1/2 inhibition. These pre-clinical studies provide strong evidence that JNK1/2 is an attractive molecular target to improve the treatment of endocrine responsive breast cancer, but they also emphasize that cells are surviving by autophagy and/or senescence. Because cell survival by autophagy and/or senescence could ultimately lead to breast cancer relapse, ongoing studies are addressing approaches to effectively kill these surviving cell populations. Citation Format: Kyler Herrington, Carol Joseph, Samar Abdulmoneim, Allison Lewis, Jingwen Cai, Hannah Youngblood, Yutao Liu, Patricia Schoenlein. Targeting JNK1/2 induces a potent cytostatic response in estrogen receptor expressing breast cancer cells, with induction of autophagy and senescence as measurable outcomes [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1231.

Global View of Candidate Therapeutic Target Genes in Hormone-Responsive Breast Cancer.

Breast cancer (BC) is a heterogeneous disease characterized by different biopathological features, differential response to therapy and substantial variability in long-term-survival. BC heterogeneity recapitulates genetic and epigenetic alterations affecting transformed cell behavior. The estrogen receptor alpha positive (ERα+) is the most common BC subtype, generally associated with a better prognosis and improved long-term survival, when compared to ERα-tumors. This is mainly due to the efficacy of endocrine therapy, that interfering with estrogen biosynthesis and actions blocks ER-mediated cell proliferation and tumor spread. Acquired resistance to endocrine therapy, however, represents a great challenge in the clinical management of ERα+ BC, causing tumor growth and recurrence irrespective of estrogen blockade. Improving overall survival in such cases requires new and effective anticancer drugs, allowing adjuvant treatments able to overcome resistance to first-line endocrine therapy. To date, several studies focus on the application of loss-of-function genome-wide screenings to identify key (hub) “fitness” genes essential for BC progression and representing candidate drug targets to overcome lack of response, or acquired resistance, to current therapies. Here, we review the biological significance of essential genes and relative functional pathways affected in ERα+ BC, most of which are strictly interconnected with each other and represent potential effective targets for novel molecular therapies.

Efficacy of neoadjuvant endocrine therapy compared with neoadjuvant chemotherapy in pre-menopausal patients with oestrogen receptor-positive and HER2-negative, lymph node-positive breast cancer

IntroductionNeoadjuvant endocrine therapy (NET) has demonstrated efficacy in post-menopausal patients with hormone-responsive breast cancer. This trial was designed to compare the efficacy of neoadjuvant chemotherapy (NCT) with NET in pre-menopausal breast cancer.Patients and methodsIn this prospective, randomised, phase III study, oestrogen receptor (ER)-positive, HER2-negative, and lymph node-positive pre-menopausal breast cancer patients were recruited from 7 hospitals in South Korea. Enrolled patients were randomly assigned (1:1) to receive 24 weeks of either NCT or NET with goserelin and tamoxifen. The primary purpose was to evaluate the non-inferiority of NET compared to NCT using clinical response, assessed by MRI. Besides, pathological complete response rate (pCR), changes in Ki-67 expression, breast conservation surgery (BCS) rate, and quality of life were included as secondary endpoints.ResultsA total of 187 patients were assigned to receive NCT (n = 95) or NET (n = 92), and 87 patients in each group completed treatments. More NCT patients had complete response or partial response than NET patients using MRI (NCT 83.7% vs. NET 52.9%, 95% CI 17.6–44.0, p < 0.001) and callipers (NCT 83.9% vs. NET 71.3%, 95% CI 0.4–24.9, p = 0.046). Three NCT patients (3.4%) and one NET patient (1.2%) showed pCR (p < 0.005). No difference existed in the conversion rate of BCS (13.8% for NCT vs. 11.5% for NET, p = 0.531) and Ki-67 change (p = 0.114) between the two groups. Nineteen NCT patients had treatment-related grade 3 or worse events compared with none in the NET group.ConclusionsBetter clinical responses were observed in pre-menopausal patients after 24 weeks of NCT compared to those observed after NET.Trial registrationClinicaltrials.gov, NCT01622361. Registration June 19, 2012.

DGM-CM6: A New Model to Predict Distant Recurrence Risk in Operable Endocrine-Responsive Breast Cancer.

To investigate the prognostic value of DGM-CM6 (Distant Genetic Model-Clinical variable Model 6) for endocrine-responsive breast cancer (ERBC) patients, we analyzed 752 operable breast cancer patients treated in a Taiwan cancer center from 2005 to 2014. Among them, 490 ERBC patients (identified by the PAM50 or immunohistochemistry method) were classified by DGM-CM6 into low- and high-risk groups (cutoff <33 and ≥33, respectively). Significant differences were observed between the DGM-CM6 low- and high-risk groups for 10-year distant recurrence-free survival (DRFS) in both lymph node (LN)- (P < 0.05) and LN+ patients (P < 0.05). Multivariate analysis confirmed the independent strength of DGM-CM6 for the prediction of high- vs. low- risk groups for DRFS (P < 0.0001, HR: 6.76, 95% CI, 1.8–25.42) and overall survival (P = 0.01, HR: 6.06, 95% CI:1.55–23.47), respectively. In summary, DGM-CM6 may be used to classify low- and high-risk groups for 10-year distant recurrence in both LN- and LN+ ERBC patients in the Asian population. A large scale clinical trial is warranted.

Similar negative emotional impact on hair loss in neoadjuvant endocrine therapy compared to neoadjuvant chemotherapy in young women with breast cancer from patient reported outcomes.

e19242 Background: We aimed to evaluate patient-reported outcomes (PROs) in the NEST phase III trial, in which neoadjuvant endocrine therapy (NET) compared to conventional neoadjuvant chemotherapy (NCT) for hormone-responsive lymph node-positive premenopausal breast cancer. Methods: Premenopausal women with estrogen receptor (ER)-positive, HER2-negative, and lymph node-positive premenopausal breast cancer patients were enrolled. Patients were randomized to either 24 weeks of neoadjuvant chemotherapy with doxorubicin plus cyclophosphamide followed by taxane (T) or neoadjuvant endocrine therapy with goserelin and tamoxifen. PROs were assessed at day 1 (baseline) and at the end of treatment, using the breast cancer module of European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 23 (EORTC QLQ BR23). ClinicalTrials.gov: NCT01622361. Results: 187 patients were randomly assigned to chemotherapy (n=95) or endocrine therapy (n=92), and 174 patients completed the 24 weeks of neoadjuvant treatment period (n=87, both). Baseline scores were similar between arms. No statistically significant between-treatment differences were observed for the function scales including body image, sexual functioning, and sexual enjoyment although endocrine treatment showed significant improvement in future perspective (HR=8.3, 95% CI:1.72-18.38; P=0.021). Even though no alopecia was reported in NET group, no statistically significant difference between both arms in the “upset by hair loss” was observed, in which NET group showed even worse score. Conclusions: Patients who received NET had significant improvement in a future perspective, however, a similar emotional negative impact on hair loss was observed compared with NCT despite no reported alopecia. Key words: breast cancer, patient-reported outcomes, quality of life, hair loss, EORTC QLQ-BR 23. Clinical trial information: NCT01622361 .

Neoadjuvant endocrine therapy versus neoadjuvant chemotherapy in young women with breast cancer: Prognosis and axillary node surgery.

e12626 Background: We aimed to evaluate patient-reported outcomes (PROs) in the NEST phase III trial, in which neoadjuvant endocrine therapy (NET) compared to conventional neoadjuvant chemotherapy (NCT) for hormone-responsive lymph node-positive premenopausal breast cancer. Methods: Premenopausal women with estrogen receptor (ER)-positive, HER2-negative, and lymph node-positive premenopausal breast cancer patients were enrolled. Patients were randomized to either 24 weeks of neoadjuvant chemotherapy with adriamycin plus cyclophosphamide (AC) followed by taxane (T) or neoadjuvant endocrine therapy with zoladex and tamoxifen. PROs were assessed at day 1 (baseline) and at the end of treatment, using the breast cancer module of European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 23 (EORTC QLQ BR23). ClinicalTrials.gov: NCT01622361. Results: 187 patients were randomly assigned to chemotherapy (n = 95) or endocrine therapy (n = 92), and 174 patients completed the 24 weeks of neoadjuvant treatment period (n = 87, both). Baseline scores were similar between arms. No statistically significant between-treatment differences were observed for the function scales including body image, sexual functioning, and sexual enjoyment although endocrine treatment showed significant improvement in future perspective (HR = 8.3, 95% CI:1.72-18.38; P= 0.021). Even though no alopecia was reported in NET group, no statistically significant difference between both arms in the “upset by hair loss” was observed, in which NET group showed even worse score. Conclusions: Patients who received NET had significant improvement in a future perspective, however, a similar emotional negative impact on hair loss was observed compared with NCT despite no reported alopecia. Key words: breast cancer, patient-reported outcomes, quality of life, hair loss, EORTC QLQ-BR 23. Clinical trial information: NCT01622361.

Patients over 65 with early breast cancer and preference for intraoperative radiation despite no survival benefit.

e12612 Background: Patients over 65 years of age with early-stage hormone receptor (HR)-positive breast cancer have many radiation treatment options based on the PRIME II and CALGB 9343. Our study aims to evaluate treatment preference of patients over 65 years of age when intraoperative radiation therapy (IORT) is offered. Methods: A retrospective chart review was conducted among patients over 65 years old diagnosed with early-stage HR-positive breast cancer during 2016-2019 in a single breast program in a large integrated healthcare system. At our institution, every breast cancer patient is reviewed at a weekly multi-disciplinary breast conference for IORT eligibility and tracked prospectively. All patients in this study met with breast surgeons and radiation oncologists prior to their locoregional treatment decisions. We identified patients who were offered IORT as an option. The tumor board discussion, treatment team recommendation, and the final patient decision for radiation were obtained from the chart review. Demographics including age, race, hormone therapy, and co-morbidities (Charlson Comorbidity Index) were collected. Logistic regression analysis was used to evaluate if any factors were associated with patients’ radiation treatment choice. Results: Among 225 patients who were over 65 with early endocrine responsive breast cancer, 63 patients met the IORT guideline (28%). Their ages ranged from 65-86 with a mean of 70.4 years. 74.6% of patients chose IORT compared with 14.3% who opted for whole breast radiation. Only 4.8% of patients chose to omit radiation after breast-conserving surgery, and 6.3% chose mastectomy. Patients who chose IORT was also more likely to take endocrine treatment (OR 4.76 CI 1.42-16.0, p = 0.01). Age, race, and co-morbidities were not associated with preference for IORT (OR 0.95 p = 0.34, OR 1.09 p 0.92, and OR 1.15 p = 0.53, respectively). Conclusions: Early-stage breast cancer patients over age 65 with HR-positive disease overwhelmingly desired radiation treatment even after being counseled that it does not confer an overall survival benefit. IORT was strongly preferred over whole breast radiation. This finding indicates that these women choose to maximize their local cancer control, regardless of its impact on overall survival, and prefer the convenience of single fraction, integrated radiation delivery. Further studies need to be completed on patient reported outcomes in this study population.

Delay discounting as a predictor of adjuvant endocrine therapy adherence among breast cancer survivors.

e24172 Background: Despite the demonstrated mortality benefit, 30-70% of hormone-responsive breast cancer (BC) survivors struggle to adhere to adjuvant endocrine therapy (ET). Little is known about patient-specific behavioral traits and their role in ET non-adherence. To gain a survival benefit, patients must adhere to ET for years. In contrast, the benefits of discontinuing ET (i.e., avoiding toxicity) are immediate. Thus, adherence requires one’s behavior to be guided by future outcomes, rather than immediate gratification. We therefore hypothesized that ET adherence may be related to the behavioral economic process of delay discounting (DD; i.e. devaluation of delayed outcomes), which provides a measure of how individuals value the future. Methods: BC survivors (age 18-80) prescribed adjuvant ET within the last 5 years were recruited. ET adherence was measured by pill count and self-report. DD was measured using two methods: monetary DD was measured using a validated task in which participants made repeated, hypothetical choices between a larger amount ($100 or $1000) available after a time delay or half of this amount ($50 or $500) available now. Across trials, the delay to the larger amount is titrated based on previous choices until reaching a delay at which the participant becomes indifferent to waiting for the larger reward. Cancer DD was measured using an investigational task adapted from the adjusting-delay task described above. This task presented repeated, hypothetical choices between preventing BC recurrence after varying time delays and avoiding ET side effects immediately. Results: Eighty nine BC survivors participated. Average pill count adherence was near 50%, but self-reported adherence was near 100%. Monetary DD was significantly associated with pill counts; adherence improved with increasing log indifference delays (standardized b 0.328, p = 0.005). Self-report adherence (categorized as discontinued/never started, suboptimal, and perfect) was significantly associated with Cancer DD and income (OR 3.764, p &lt; 0.001 and OR 1.01, p = 0.04, respectively) but not monetary DD (OR 0.978, p = 0.951). No association was found between ET non-adherence and medication type, side effect severity, menopausal status, age, education or minority status. Conclusions: DD may promote ET non-adherence among BC survivors. Behavioral therapies which reduce DD may provide a targeted strategy to improve adherence. More research is needed to develop tools that reliably assess ET adherence and that tailor DD assessments to the cancer survivor population.