Therapy For ER-positive Breast Cancer Research Articles

Reactivation of cAMP Pathway by PDE4D Inhibition Represents a Novel Druggable Axis for Overcoming Tamoxifen Resistance in ER-positive Breast Cancer.

Purpose: Tamoxifen remains an important hormonal therapy for ER-positive breast cancer; however, development of resistance is a major obstacle in clinics. Here, we aimed to identify novel mechanisms of tamoxifen resistance and provide actionable drug targets overcoming resistance.Experimental Design: Whole-transcriptome sequencing, downstream pathway analysis, and drug repositioning approaches were used to identify novel modulators [here: phosphodiesterase 4D (PDE4D)] of tamoxifen resistance. Clinical data involving tamoxifen-treated patients with ER-positive breast cancer were used to assess the impact of PDE4D in tamoxifen resistance. Tamoxifen sensitization role of PDE4D was tested in vitro and in vivo Cytobiology, biochemistry, and functional genomics tools were used to elucidate the mechanisms of PDE4D-mediated tamoxifen resistance.Results: PDE4D, which hydrolyzes cyclic AMP (cAMP), was significantly overexpressed in both MCF-7 and T47D tamoxifen-resistant (TamR) cells. Higher PDE4D expression predicted worse survival in tamoxifen-treated patients with breast cancer (n = 469, P = 0.0036 for DMFS; n = 561, P = 0.0229 for RFS) and remained an independent prognostic factor for RFS in multivariate analysis (n = 132, P = 0.049). Inhibition of PDE4D by either siRNAs or pharmacologic inhibitors (dipyridamole and Gebr-7b) restored tamoxifen sensitivity. Sensitization to tamoxifen is achieved via cAMP-mediated induction of unfolded protein response/ER stress pathway leading to activation of p38/JNK signaling and apoptosis. Remarkably, acetylsalicylic acid (aspirin) was predicted to be a tamoxifen sensitizer using a drug repositioning approach and was shown to reverse resistance by targeting PDE4D/cAMP/ER stress axis. Finally, combining PDE4D inhibitors and tamoxifen suppressed tumor growth better than individual groups in vivoConclusions: PDE4D plays a pivotal role in acquired tamoxifen resistance via blocking cAMP/ER stress/p38-JNK signaling and apoptosis. Clin Cancer Res; 24(8); 1987-2001. ©2018 AACR.

Ultrasonically controlled estrone-modified liposomes for estrogen-positive breast cancer therapy

A new modality of drug targeting to tumors has been proposed. The ligand-mediated approach, that already increases the therapeutic index of the drug, can still be optimized by the encapsulation of the drug into sonosensitive nanoparticles. In this work, an endogenous ligand, estrone, was used to synthesize doxorubicin-encapsulating liposomes for estrogen receptor (ER)-positive breast cancer therapy with cyanuric chloride (2,4,6 trichloro-1,3,5 triazine) being used as a linking molecule to attach 3–OH group of estrone to the surface of liposomes. Then, drug release from liposomes was studied using ultrasound waves as a triggering mechanism with different frequencies and power densities. In addition, drug uptake by two cell lines ER-positive (MCF-7) and ER-negative (MDA-MB-231) was assessed, with the former cell line being examined later to study the synergetic effect of the receptor mediator targeting and ultrasound trigger. The sizes of the liposomes loaded with calcein (as a doxorubicin model drug) were determined by dynamic light scattering, and they were characterized as large unilamellar vesicles (LUVs). The release from the prepared liposomes triggered by ultrasound (US) waves at low frequency (20 kHz) and high frequency (1.07 and 3.24 MHz), at several power densities, was determined by monitoring the changes in calcein fluorescence, using a spectrofluorometer. Increasing power densities showed a significant effect on release at high frequencies and during the first two US pulses at low frequency. The echogenicity of the liposomes was proven and characterized at different power densities and frequencies. To confirm the viability of the carrier as a doxorubicin carrier, doxorubicin-encapsulating liposomes were prepared using the ammonium sulfate transmembrane gradient method. The liposomes were LUVs and were US-sensitive, exhibiting similar behavior to calcein-encapsulating liposomes. The calcein uptake by an ER + cell line (MCF-7) was compared with the uptake by an ER-cell line (MDA-MB-231). The MCF-7 uptake was significantly higher than the MDA-MB-231 uptake, which proved the targeting potential of estrone-conjugated liposomes. The exposure to low-frequency ultrasound (LFUS) revealed a statistically significant uptake of calcein compared to uptake without ultrasound. The described drug delivery (DD) system, comprising a new echogenic liposomal formulation, promises a non-immunogenic and site-specific biomedical approach to ER-positive breast cancer therapy.

Randomized phase II study of anastrozole plus tegafur-uracil as neoadjuvant therapy for ER-positive breast cancer in postmenopausal Japanese women (Neo-ACET BC)

PurposeThis phase II study evaluated the efficacy and safety of anastrozole concurrent with tegafur/uracil (UFT) as neoadjuvant therapy for ER-positive postmenopausal breast cancer.MethodsPostmenopausal Japanese women with ER-positive, HER2-negative, T2,N0-1,M0 breast cancer seen at tertiary hospitals were eligible for this open-label, randomized, multicenter study. Patients were randomized 1:1 by minimization to orally receive either anastrozole (1 mg once daily) plus UFT (tegafur/uracil combination in 1:4 molar ratio; 270 mg/m2/day in two divided doses) or anastrozole (as above) alone for 24 weeks. Tumor response was assessed by investigator and central review as per RECIST v1.1. The primary endpoint was the proportion of patients with best overall response of CR or PR [clinical response rate (RR)] determined by central radiologic review.ResultsThe study was prematurely terminated due to Grade ≥ 3 liver dysfunction reported in 3 patients receiving anastrozole/UFT. Of 57 patients randomized before termination (29 anastrozole/UFT, 28 anastrozole), all were analyzed for safety and 56 (28 each group) for tumor response. Compared with anastrozole alone, anastrozole/UFT did not achieve significantly higher RR [39.3% (90% CI 23.8–56.5%) vs 14.3% (90% CI 5.0–29.8%); p = 0.0683, Fisher’s exact test], but produced significantly greater tumor shrinkage (mean tumor reduction rate 31.0 vs. 14.2%; p = 0.0181, unpaired t-test). Grade ≥ 3 adverse events were more common with anastrozole/UFT than with anastrozole (17.2 vs. 0%).ConclusionAlthough the study was terminated owing to the altered liver function, it showed that there was a trend to greater shrinkage of tumor in the combination group for ER-positive, HER2-negative postmenopausal breast cancer.

Role of RBP2-Induced ER and IGF1R-ErbB Signaling in Tamoxifen Resistance in Breast Cancer.

Despite the benefit of endocrine therapy, acquired resistance during or after treatment still remains a major challenge in estrogen receptor (ER)-positive breast cancer. We investigated the potential role of histone demethylase retinoblastoma-binding protein 2 (RBP2) in endocrine therapy resistance of breast cancer. Survival of breast cancer patients according to RBP2 expression was analyzed in three different breast cancer cohorts including METABRIC (n = 1980) and KM plotter (n = 1764). RBP2-mediated tamoxifen resistance was confirmed by invitro sulforhodamine B (SRB) colorimetric, colony-forming assays, and invivo xenograft models (n = 8 per group). RNA-seq analysis and receptor tyrosine kinase assay were performed to identify the tamoxifen resistance mechanism by RBP2. All statistical tests were two-sided. RBP2 was associated with poor prognosis to tamoxifen therapy in ER-positive breast cancer (P = .04 in HYU cohort, P = .02 in KM plotter, P = .007 in METABRIC, log-rank test). Furthermore, RBP2 expression was elevated in patients with tamoxifen-resistant breast cancer (P = .04, chi-square test). Knockdown of RBP2 conferred tamoxifen sensitivity, whereas overexpression of RBP2 induced tamoxifen resistance invitro and invivo (MCF7 xenograft: tamoxifen-treated control, mean [SD] tumor volume = 70.8 [27.9] mm3, vs tamoxifen-treated RBP2, mean [SD] tumor volume = 387.9 [85.1] mm3, P < .001). Mechanistically, RBP2 cooperated with ER co-activators and corepressors and regulated several tamoxifen resistance-associated genes, including NRIP1, CCND1, and IGFBP4 and IGFBP5. Furthermore, epigenetic silencing of IGFBP4/5 by RBP2-ER-NRIP1-HDAC1 complex led to insulin-like growth factor-1 receptor (IGF1R) activation. RBP2 also increased IGF1R-ErbB crosstalk and subsequent PI3K-AKT activation via demethylase activity-independent ErbB protein stabilization. Combinational treatment with tamoxifen and PI3K inhibitor could overcome RBP2-mediated tamoxifen resistance (RBP2-overexpressing cells: % cell viability [SD], tamoxifen = 89.0 [3.8]%, vs tamoxifen with BKM120 = 41.3 [5.6]%, P < .001). RBP2 activates ER-IGF1R-ErbB signaling cascade in multiple ways to induce tamoxifen resistance, suggesting that RBP2 is a potential therapeutic target for ER-driven cancer.

PI3K pathway regulates ER-dependent transcription in breast cancer through the epigenetic regulator KMT2D.

Activating mutations in PIK3CA, the gene encoding phosphoinositide-(3)-kinase α (PI3Kα), are frequently found in estrogen receptor (ER)-positive breast cancer. PI3Kα inhibitors, now in late-stage clinical development, elicit a robust compensatory increase in ER-dependent transcription that limits therapeutic efficacy. We investigated the chromatin-based mechanisms leading to the activation of ER upon PI3Kα inhibition. We found that PI3Kα inhibition mediates an open chromatin state at the ER target loci in breast cancer models and clinical samples. KMT2D, a histone H3 lysine 4 methyltransferase, is required for FOXA1, PBX1, and ER recruitment and activation. AKT binds and phosphorylates KMT2D, attenuating methyltransferase activity and ER function, whereas PI3Kα inhibition enhances KMT2D activity. These findings uncover a mechanism that controls the activation of ER by the posttranslational modification of epigenetic regulators, providing a rationale for epigenetic therapy in ER-positive breast cancer.

Inhibition of CDK8 mediator kinase suppresses estrogen dependent transcription and the growth of estrogen receptor positive breast cancer.

Hormone therapy targeting estrogen receptor (ER) is the principal treatment for ER-positive breast cancers. However, many cancers develop resistance to hormone therapy while retaining ER expression. Identifying new druggable mediators of ER function can help to increase the efficacy of ER-targeting drugs. Cyclin-dependent kinase 8 (CDK8) is a Mediator complex-associated transcriptional regulator with oncogenic activities. Expression of CDK8, its paralog CDK19 and their binding partner Cyclin C are negative prognostic markers in breast cancer. Meta-analysis of transcriptome databases revealed an inverse correlation between CDK8 and ERα expression, suggesting that CDK8 could be functionally associated with ER. We have found that CDK8 inhibition by CDK8/19-selective small-molecule kinase inhibitors, by shRNA knockdown or by CRISPR/CAS9 knockout suppresses estrogen-induced transcription in ER-positive breast cancer cells; this effect was exerted downstream of ER. Estrogen addition stimulated the binding of CDK8 to the ER-responsive GREB1 gene promoter and CDK8/19 inhibition reduced estrogen-stimulated association of an elongation-competent phosphorylated form of RNA Polymerase II with GREB1. CDK8/19 inhibitors abrogated the mitogenic effect of estrogen on ER-positive cells and potentiated the growth-inhibitory effects of ER antagonist fulvestrant. Treatment of estrogen-deprived ER-positive breast cancer cells with CDK8/19 inhibitors strongly impeded the development of estrogen independence. In vivo treatment with a CDK8/19 inhibitor Senexin B suppressed tumor growth and augmented the effects of fulvestrant in ER-positive breast cancer xenografts. These results identify CDK8 as a novel downstream mediator of ER and suggest the utility of CDK8 inhibitors for ER-positive breast cancer therapy.

Abstract P4-09-17: Wnt5a expression is associated with high-grade malignancy in ER-positive breast cancer

Abstract Background: Wnt5a is a representative ligand that activates the β-catenin-independent pathways. The purpose of our study is to elucidate the implication of Wnt5a expression in breast cancer. Materials and methods: One hundred seventy eight breast cancer patients (mean age ± SD: 59.6 ± 13.2 years) with clinical Stage I∼III between January 2011 and February 2014, were prospectively evaluated. Patients who underwent operation without neoadjuvant therapy were enrolled to this study. The immunohistochemical analyses of Wnt5a protein was performed to evaluate relationships between Wnt5a expression and clinicopathological factors. MCF7 cells that stably express Wnt5a were generated and used for cDNA microarray analyses to investigate Wnt5a-dependent gene expression. Results: Wnt5a expression was significantly more frequent when estrogen receptor (ER) was present, 68/153 (44%) than when ER was absent, 1/25 (4%) (p&amp;lt;0.001). Wnt5a expression was also related with progesterone receptor (PgR) (P&amp;lt;0.001), but not with HER2 status (P=0.496). In ER-positive breast cancer, a significant interaction between expression of Wnt5a with lymph node metastasis (P&amp;lt;0.001), nuclear grade (P=0.004), lymphatic invasion (P=0.002), vessel invasion (P=0.050), and pStage (P&amp;lt;0.001). Microarray analyses identified several genes induced by Wnt5a (&amp;gt;3.0 fold), involving activated leukocyte cell adhesion molecule (ALCAM). ALCAM is known to be related with apoptosis, invasion and prognosis of breast cancer. Wnt5a expression levels correlated with those of ALCAM in ER-positive tumor samples from patients by immunohistochemical analyses (P&amp;lt;0.001). Relationship between Wnt5a expression and clinicopathological featureClinicopathological featuretotalWnt5a expressionP value (n=153)Negative (n=85)Positive (n=68) Age (median, range) 63, 35-8657.5, 34-870.065Age, n (%) ≤4528 (18)13 (46)15 (54) &amp;gt;45125 (82)72 (58)53 (42)0.282Menopausal status, n (%) Premenopausal58 (38)27 (47)31 (53) Postmenopausal95 (62)58 (61)37 (39)0.080Tumor size, n (%) pT1 ≤20mm104 (44)63 (61)41 (39) pT2/pT3 &amp;gt;20mm49 (56)22 (45)27 (55)0.069lymph node metastasis, n (%) Negative103 (67)72 (70)31 (30) Positive50 (33)13 (26)37 (74)&amp;lt;0.001Nuclear grade, n (%) 1/285 (56)56 (66)29 (34) 368 (44)29 (43)39 (57)0.004Lymphatic invasion, n (%) Negative101 (66)65 (64)36 (36) Positive52 (34)20 (38)32 (62)0.002Vessel invasion, n (%) Negative142 (93)82 (58)60 (42) Positive11 (7)3 (27)8 (73)0.050Ki-67, n (%) 0-2067 (44)43 (64)24 (36) 21-10086 (56)42 (49)44 (51)0.058pStage, n (%) pStage I80 (52)58 (73)22 (28) pStage II64 (42)27 (42)37 (58) pStage III9 (6)0 (0)9 (100)&amp;lt;0.001ALCAM, n (%) Negative85 (56)64 (75)21 (25) Positive68 (44)21 (31)47 (69)&amp;lt;0.001 Conclusions: Wnt5a express in ER-positive breast cancer and are associated with high-grade malignancy. Wnt5a could be a prognostic factor of ER-positive breast cancer. These results have implications that Wnt5a may become a preoperative and postoperative assessment tool for tumor malignancy grade and a potential therapeutic target except endocrine therapy in ER-positive breast cancer. In future studies, further research on Wnt5a are required to develop a novel treatment for more improved outcomes in a great variety of breast cancer. Citation Format: Kobayashi Y, Kadoya T, Gouda N, Kajitani K, Emi A, Shigematsu H, Masumoto N, Okada M. Wnt5a expression is associated with high-grade malignancy in ER-positive breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-09-17.

PI3K inhibition results in enhanced estrogen receptor function and dependence in hormone receptor-positive breast cancer.

Activating mutations of PIK3CA are the most frequent genomic alterations in estrogen receptor (ER)-positive breast tumors, and selective phosphatidylinositol 3-kinase α (PI3Kα) inhibitors are in clinical development. The activity of these agents, however, is not homogeneous, and only a fraction of patients bearing PIK3CA-mutant ER-positive tumors benefit from single-agent administration. Searching for mechanisms of resistance, we observed that suppression of PI3K signaling results in induction of ER-dependent transcriptional activity, as demonstrated by changes in expression of genes containing ER-binding sites and increased occupancy by the ER of promoter regions of up-regulated genes. Furthermore, expression of ESR1 mRNA and ER protein were also increased upon PI3K inhibition. These changes in gene expression were confirmed in vivo in xenografts and patient-derived models and in tumors from patients undergoing treatment with the PI3Kα inhibitor BYL719. The observed effects on transcription were enhanced by the addition of estradiol and suppressed by the anti-ER therapies fulvestrant and tamoxifen. Fulvestrant markedly sensitized ER-positive tumors to PI3Kα inhibition, resulting in major tumor regressions in vivo. We propose that increased ER transcriptional activity may be a reactive mechanism that limits the activity of PI3K inhibitors and that combined PI3K and ER inhibition is a rational approach to target these tumors.

17β-estradiol-containing liposomes as a novel delivery system for the antisense therapy of ER-positive breast cancer: An in vitro study on the MCF-7 cell line.

The present study suggests and describes the application of a delivery system for antisense oligonucleotides against mRNA encoding estrogen receptor proteins α and β. The delivery system is composed of a cationic liposome envelope containing 17β-estradiol (E2) in its structure. Cationic liposomes protect cargo against the extracellular matrix, and E2 can increase its shuttling efficiency into cells. Using MCF-7 cells derived from estrogen receptor-positive ductal carcinoma, treatment with liposomes against ERα was found to decrease MCF-7 proliferation, and importantly the application of both the antisense against ERα and β exhibited an antiproliferative effect expressed as cell viability. Using qRT-PCR, it was shown that MT1A, NF-κB1 and K-ras genes, but not TFF1, were downregulated using E2-based liposomes (evaluated at P=0.05). Further indicators of oxidative stress were employed to assess the effect on treatment efficiency. Glutathione (GSH/GSSG redox ratio), metallothionein (MT) and malondialdehyde (MDA) confirmed a positive effect of antisense therapy resulting in their decreased levels in the MCF-7 cells. Based on these data, we suggest that E2-based liposomes offer sufficient transfer efficiency and moreover, due to the effect on NF-κB1, MT and GSH, tumor cells can be chemosensitized to increase treatment effectiveness.

Diffusion Weighted Imaging Evaluated the Early Therapy Effect of Tamoxifen in an MNU-Induced Mammary Cancer Rat Model

PurposeTo assess the optimal time point of diffusion-weighted imaging (DWI) for early prognosis of breast cancer following tamoxifen therapy using a methylnitrosourea (MNU)-induced ER-positive breast-cancer model.MethodsTwo groups of Sprague-Dawley rats (n = 15 for group 1; n = 10 for group 2) were used. All animals (50 days old) were intravenously injected with MNU (50 mg/kg body weight) to induce ER-positive mammary tumors. When tumors were approximately 2 cm in diameter, DWI was performed on days 0, 3, and 7, and intratumoral apparent diffusion coefficient (ADC) values were measured. Therapy started on day 0 with tamoxifen (10 mg/kg diet) and continued for 4 weeks for group 1, but only 1 week for group 2, while tumor volume was measured by caliper twice weekly. All animals of group 2 were euthanized on day 7 after imaging, and Ki-67, TUNEL, ERα, and ERβ staining were performed on tumor tissue.ResultsDW images of MNU-induced mammary tumors were successfully obtained with minimal motion artifact. For group 1, ADC change for 3 days after therapy initiation (ADC3D) was significantly correlated with tumor-volume change until day 11, but the significant correlation between ADC change for 7 days (ADC7D) and the tumor-volume change was observed until day 18. Similarly, for group 2, either ADC7D or ADC3D was significantly correlated with the tumor-volume change, but the higher significance was observed for ADC7D. Furthermore, ADC7D was significantly correlated with apoptotic (TUNEL stained), proliferative (Ki-67 stained), and ERβ-positive cell densities, but ADC3D was not significantly correlated with any of those.ConclusionsADC7D might be a more reliable surrogate imaging biomarker than ADC3D to assess effectiveness of tamoxifen therapy for ER-positive breast cancer, which may enable personalized treatment. The significant correlation between ADC7D and ERβ-positive cell density suggests that ERβ may play an important role as a therapeutic indicator of tamoxifen.

18F-Fluoromisonidazole PET/CT: A Potential Tool for Predicting Primary Endocrine Therapy Resistance in Breast Cancer

Although endocrine therapy is an effective method to treat estrogen receptor (ER)-positive breast cancer, approximately 30%-40% of all hormone receptor-positive tumors display de novo resistance. The aim of our current study was to analyze whether (18)F-labeled fluoromisonidazole (1-(2-nitro-1-imidazolyl)-2-hydroxy-3-fluoropropane [(18)F-FMISO]) PET/CT could predict primary resistance to hormonal therapy in ER-positive breast cancer. Postmenopausal women who had ER-α-positive breast cancer, stages II-IV, and had never received prior endocrine therapy were prospectively enrolled in this study. Patients underwent both (18)F-FDG and (18)F-FMISO PET/CT scans before and after treatment. The hottest (18)F-FDG standardized uptake value (SUV) in the tumor foci, the SUVs at 2 and 4 h, and the TBR2 h and TBR4 h for the target lesions were calculated (TBR2 h = SUV2 hT/SUV2 hB and TBR4 h = SUV4 hT/SUV4 hB [TBR is the tumor-to-background ratio]). Clinical outcomes of primary endocrine therapy with letrozole were evaluated according to the criteria of the World Health Organization after at least 3 mo of treatment. Immunohistochemistry for markers of proliferation (Ki67) and hypoxia-induced factor 1α was performed on a subset of tumors that had undergone biopsy or surgery. Pearson and Spearman analysis was used to determine the correlation between the parameters of (18)F-FDG and (18)F-FMISO uptake and clinical or immunohistochemistry outcomes with a 0.01 threshold for statistical significance. A total of 45 lesions (13 primary, 32 metastatic) from 20 patients met the inclusion criteria in this study. Baseline (18)F-FDG and (18)F-FMISO PET/CT scans were obtained for 33 lesions from 16 patients. The correlation between baseline (18)F-FDG uptake and clinical outcome was weak and did not reach statistical significance (r = 0.37, P = 0.031). However, there was a significantly positive correlation between baseline (18)F-FMISO uptake (SUV2 hT, TBR2 h, SUV4 hT, and TBR4 h) and clinical outcomes after ≥3 mo of primary endocrine therapy with letrozole (r = 0.77, 0.76, 0.71, and 0.78, respectively; P < 0.0001). The application of a TBR4 h cutoff of ≥1.2 allowed the prediction of 88% of the cases of progressive disease (15/17). Despite poor correlation between (18)F-FMISO uptake and hypoxia-induced factor 1α expression, a marginal positive correlation between TBR4 h and Ki67 expression was measured (r = 0.51, P = 0.011) in a subset of malignant lesions acquired by biopsy or surgery. (18)F-FMISO PET/CT can be used to predict primary endocrine resistance in ER-positive breast cancer.

Doubling up?

A study reports the benefits of 10 years of adjuvant tamoxifen therapy for ER-positive breast cancer.

A nonrandomized observational trial of short-term preoperative endocrine therapy in ER-positive breast cancer to investigate change in genomic expression using the 21-gene breast cancer assay.

221 Background: Preoperative systemic treatment is commonly employed for women with locally advanced breast cancer. Women with early-stage breast cancer, whose resections may be delayed for 30 to 60 days while they undergo preoperative evaluation, may benefit from receiving preoperative endocrine therapy while awaiting surgery. One rationale for not initiating such treatment is that the cancer may be rendered less chemosensitive. The 21-gene assay is a proven predictor of chemotherapy responsiveness. The objective of this study is to examine the association between recurrence score (RS) and ER, PR, and HER2 RT-PCR values in core biopsy and surgical specimens from patients treated with short term pre-operative endocrine therapy. Methods: Pre- and postmenopausal women with clinical T1-N0-M0, sonographically visible, ER-positive, HER2-negative breast cancer were eligible. Patients were treated with 4-8 weeks of preoperative endocrine therapy; letrozole if postmenopausal or tamoxifen if premenopausal. Clinical breast examination and ultrasound were conducted every two weeks, with the final ultrasound immediately prior to surgery. Tumor blocks from the core biopsy and surgical excision were submitted to Genomic Health, Inc., where RS, ER, PR, and HER2 results were obtained from each of the paired specimens. Results: Nineteen matching core biopsy and surgical specimens were available for analysis. Pearson correlation coefficients between core biopsy and excisional sample results were 0.89 for RS, 0.87 for ER, 0.72 for PR, and 0.77 for HER2. On average, small but statistically significant increases in RS and decreases in ER and PR were observed (all p &lt; 0.005 from paired t-test). No obvious associations between these markers and clinical response were observed. Conclusions: In this small, hypothesis-generating study, paired RS and RT-PCR for ER/PR/HER2 remained correlated after short-term preoperative endocrine therapy. This study provides no suggestion of decreasing chemosensitivity during preoperative endocrine therapy, but additional research is warranted to explore these findings further.

Anti-tumor effects of a novel retinoic acid metabolism blocking agent VN/14-1 in the N-methyl-N-nitrosourea-induced rat mammary carcinoma model and its effects on the uterus

VN/14-1 [4-(±)-(1H-Imidazol-1-yl)-(E)-retinoic acid], a novel retinoic acid metabolism blocking agent (RAMBA), works by inhibiting the breakdown of all-trans-retinoic acid. The purpose of this study was to evaluate the anti-tumor effects of VN/14-1 on the N-methyl-N-nitrosourea (MNU)-induced rat mammary carcinoma model, and peripheral organ effects on the uteri of immature ovariectomized (OVX) rats. In tumor burden experiments, after 56 days of administration of VN/14-1 5, 10, and 20 mg/kg/day, significant tumor reductions in mean tumor weight of 19.1, 34.4, and 44.3%, compared to tumors in control animals occurred. Cumulative tumor growth was also significantly slower in a dose-dependent manner in groups receiving 5, 10, and 20 mg/kg/day of VN/14-1 compared to growth rates in the control group. Tumor apoptosis was significant increases in animals treated with 5, 10, and 20 mg/kg/day of VN/14-1. In uterotrophic experiments, immature OVX rats given VN/14-1 significantly reduced uterine weight and blocked endometrial stimulation induced by unopposed β-estradiol (E2). In both rat models, adverse toxicities included weakness, anorexia, and reduction in body weight in the groups given the highest dose of 20 mg/kg/day. In summary, VN/14-1 inhibited tumor growth in the MNU-induced estrogen receptor (ER)-positive rat mammary tumor model, and antagonized the stimulatory effect of estrogens on the uterus. The studies suggest that VN/14-1 may be a useful novel therapy for ER-positive breast cancer.

Akt2 Inhibition Enables the Forkhead Transcription Factor FoxO3a To Have a Repressive Role in Estrogen Receptor α Transcriptional Activity in Breast Cancer Cells

ABSTRACT Estrogen receptor alpha (ER) and the insulin-like growth factor I receptor (IGF-IR) pathways are engaged in a functional cross talk in breast cancer, promoting tumor progression and increased resistance to anticancer treatments and radiotherapy. Here, we introduce new mechanisms through which proteins of the IGF-I/IGF-IR signaling pathway may regulate ER function in the absence of ligand. Our results indicate that in ER-positive breast cancer cells, Akt2 modulates ER transcriptional activity at multiple levels, including (i) the regulation of ER expression and its nuclear retention and (ii) the activation of one of its downstream targets, the Forkhead transcription factor FoxO3a. FoxO3a colocalizes and coprecipitates with ER in the nucleus, where it binds to Forkhead-responsive sequences on the ER target pS2/ TFF-1 promoter; in addition, FoxO3a silencing leads to an increase of ER transcriptional activity, suggesting a repressive role of the Forkhead transcription factor in ER function. Moreover, 17β-estradiol upregulates FoxO3a levels, which could represent the basis for an ER-mediated homeostatic mechanism. These findings provide further evidence of the importance of mediators of the growth factor signaling in ER regulation, introducing the Akt2/FoxO3a axis as a pursuable target in therapy for ER-positive breast cancer.

Multi-gene assays: are they to become standard adjuvant therapy for ER-positive breast cancer?

Multi-gene assays: are they to become standard adjuvant therapy for ER-positive breast cancer?

Kathy Albain: Multi-Gene Assays Can Now Be Considered Standard for Planning Adjuvant Therapy for ER-Positive Breast Cancer

Kathy Albain: Multi-Gene Assays Can Now Be Considered Standard for Planning Adjuvant Therapy for ER-Positive Breast Cancer

First report of the European Cooperative Trial in Operable Breast Cancer II (ECTO II): Effects of primary chemo-endocrine therapy on local-regional disease in ER-positive breast cancer

588 Background: To improve the pathologic complete remission rate documented in the ECTO trial (ASCO 2002), in June 2005 we activated a randomized phase II two stage-type protocol with concomitant chemo-endocrine therapy in ER-positive breast cancer > 2 cm at diagnosis. Methods: 182 patients were enrolled by end of June 2007. Patients were randomly allocated to 3 chemotherapy regimens: A (AT, doxo 60 mg/m2 + paclitaxel 200 mg/m2, q 3 w x 4 followed by CMF d1+8 q 4 w x 4); B (AT as above followed by CM d1+8 + capecitabine 1,850 mg/m2 for 14 days q 4 w x 4); C (AC, doxo 60 mg/m2 + cyclophosphamide 600 mg/m2 q 3 w x 4 followed by paclitaxel 100 mg/m2 d1+8 + capecitabine as above q 3 w x 4). Exemestane (25 mg/day) was given from the start of chemotherapy till surgery in all 3 regimens, along with LH-RH analogues in all premenopausal women. Results: At the cut-off date of August 31, 2007, 102 patients were assessed for the first step of the analysis plan. Baseline characteristics (age, menopause, PgR and HER2) were well balanced and left ventricular ejection fraction (LVEF) was similar in all 3 groups. Treatment was fairly well tolerated, but more frequently delayed in arms B and C. Median delivered doses of all drugs were similar in all 3 regimens. Grade 3 neutropenia was more frequently observed during AC (7%) than during AT (3%), while no episodes of thrombocytopenia were documented. CTC 3 LVEF modification was documented in one patient in arm C. Rates of complete pathologic absence of invasive cancer in the breast (pCR) and in the breast and axilla (tnpCR) are reported in the Table. Conclusions: Exemestane did not appear to add on the expected pCR rate by chemotherapy in ER-positive cases. The capecitabine-containing regimens were more active than the non-capecitabine one. Regimen A Regimen B Regimen C Patients (n°) 35 32 35 % pCR 5.7 (0.7 - 19.2) 15.6 (5.3 - 32.8) 8.6 (1.8 -23.1) % tnpCR 2.9 (0.1 - 14.9) 12.5 (3.6 - 29.0) 8.6 (1.8 -23.1) 95% confidence limits Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Roche Roche

Adjuvant Therapy for ER-Positive Breast Cancer: Shaping the Role of Aromatase Inhibitors

The benefits of incorporating an aromatase inhibitor (AI) into adjuvant therapy for estrogen-receptor (ER)–positive early-stage breast cancer are no

E21. What is the best therapy for ER-positive breast cancer?

E21. What is the best therapy for ER-positive breast cancer?