scholarly journals Evaluation of the pharmacological activities of RAD1901, a selective estrogen receptor degrader

2015 ◽  
Vol 22 (5) ◽  
pp. 713-724 ◽  
Author(s):  
Suzanne E Wardell ◽  
Erik R Nelson ◽  
Christina A Chao ◽  
Holly M Alley ◽  
Donald P McDonnell
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Tumor Growth ◽  
Endocrine Therapy ◽  
Cancer Metastasis ◽  
Xenograft Tumor ◽  
Metastatic Setting ◽  
Dose Dependent ◽  
The Brain ◽  
Xenograft Tumor Growth

Endocrine therapy, using tamoxifen or an aromatase inhibitor, remains a first-line treatment for estrogen receptor 1 (ESR1) positive breast cancer. However, tumor resistance limits the duration of response. The clinical efficacy of fulvestrant, a selective ER degrader (SERD) that triggers receptor degradation, has confirmed that ESR1 often remains engaged in endocrine therapy resistant cancers. Recently developed, selective ER modulators (SERMs)/SERD hybrids (SSHs) that facilitate ESR1 degradation in breast cancer cells and reproductive tissues have been advanced as an alternative treatment for advanced breast cancer, particularly in the metastatic setting. RAD1901 is one SSH currently being evaluated clinically that is unique among ESR1 modulators in that it readily enters the brain, a common site of breast cancer metastasis. In this study, RAD1901 inhibited estrogen activation of ESR1in vitroandin vivo, inhibited estrogen-dependent breast cancer cell proliferation and xenograft tumor growth, and mediated dose-dependent downregulation of ESR1 protein. However, doses of RAD1901 insufficient to induce ESR1 degradation were shown to result in the activation of ESR1 target genes and in the stimulation of xenograft tumor growth. RAD1901 is an SSH that exhibits complex pharmacology in breast cancer models, having dose-dependent agonist/antagonist activity displayed in a tissue-selective manner. It remains unclear how this unique pharmacology will impact the utility of RAD1901 for breast cancer treatment. However, being the only SERD currently known to access the brain, RAD1901 merits evaluation as a targeted therapy for the treatment of breast cancer brain metastases.

scholarly journals Obesity-Altered Adipose Stem Cells Promote ER+ Breast Cancer Metastasis through Estrogen Independent Pathways

2019 ◽  
Vol 20 (6) ◽  
pp. 1419 ◽  
Author(s):  
Rachel A. Sabol ◽  
Adam Beighley ◽  
Paulina Giacomelli ◽  
Rachel M. Wise ◽  
Mark A. A. Harrison ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Stem Cells ◽  
Estrogen Receptor ◽  
Tumor Growth ◽  
Estrogen Receptor Alpha ◽  
Cancer Metastasis ◽  
Breast Cancer Metastasis ◽  
Adipose Stem Cells ◽  
Estrogen Signaling ◽  
Promote Tumor Growth

Adipose stem cells (ASCs) play an essential role in tumor microenvironments. These cells are altered by obesity (obASCs) and previous studies have shown that obASCs secrete higher levels of leptin. Increased leptin, which upregulates estrogen receptor alpha (ERα) and aromatase, enhances estrogen bioavailability and signaling in estrogen receptor positive (ER+) breast cancer (BC) tumor growth and metastasis. In this study, we evaluate the effect of obASCs on ER+BC outside of the ERα signaling axis using breast cancer models with constitutively active ERα resulting from clinically relevant mutations (Y537S and D538G). We found that while obASCs promote tumor growth and proliferation, it occurs mostly through abrogated estrogen signaling when BC has constitutive ER activity. However, obASCs have a similar promotion of metastasis irrespective of ER status, demonstrating that obASC promotion of metastasis may not be completely estrogen dependent. We found that obASCs upregulate two genes in both ER wild type (WT) and ER mutant (MUT) BC: SERPINE1 and ABCB1. This study demonstrates that obASCs promote metastasis in ER WT and MUT xenografts and an ER MUT patient derived xenograft (PDX) model. However, obASCs promote tumor growth only in ER WT xenografts.

Targeting Monoacylglycerol Lipase in Triple Negative Breast Cancer Reduced Tumor-Associated Inflammation, Tumor Growth and Tumor Colonization in the Brain

2021 ◽  
Author(s):  
Othman Benchama ◽  
Sergiy Tyukhtenko ◽  
Michael S. Malamas ◽  
Mark K. Williams ◽  
Alexandros Makriyannis ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Tumor Growth ◽  
Cancer Metastasis ◽  
Triple Negative ◽  
Breast Cancer Metastasis ◽  
Monoacylglycerol Lipase ◽  
Breast Cancers ◽  
Novel Treatments ◽  
The Brain

Abstract While the prevalence of breast cancer metastasis in the brain is significantly higher in triple negative breast cancers (TNBCs), there is a lack of novel and/or improved therapies for these patients. Monoacylglycerol lipase (MAGL) is a hydrolase involved in lipid metabolism that catalyzes the degradation of 2-arachidonoylglycerol (2-AG) linked to generation of pro- and anti-inflammatory molecules. Here, we targeted MAGL in TNBCs, using the selective MAGL inhibitor AM9928 (hMAGL IC50 = 9nM, with prolonged pharmacodynamic effects of 46 hours residence time). AM9928 blocked TNBC cell adhesion and transmigration across human brain microvascular endothelial cells (HBMECs) in 3D co-cultures. In addition, AM9928 inhibited the secretion of IL-6, IL-8, and VEGF-A from TNBC cells. TNBC-derived exosomes activated HBMECs resulting in secretion of elevated levels of IL-8 and VEGF, which were inhibited by AM9928. Knockdown of MAGL by siRNA or treatment with AM9928 increased the expression of the adherent junction E-cadherin, known to be regulated by MAGL. Using in vivo studies of syngeneic GFP-4T1-BrM5 mammary tumor cells, AM9928 inhibited tumor growth in the mammary fat pads and attenuated blood brain barrier (BBB) permeability changes, resulting in reduced TNBC colonization in brain. Together, these results support the potential clinical application of MAGL inhibitors as novel treatments for TNBC.

scholarly journals Lasofoxifene as a potential treatment for therapy-resistant ER-positive metastatic breast cancer

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Muriel Lainé ◽  
Sean W. Fanning ◽  
Ya-Fang Chang ◽  
Bradley Green ◽  
Marianne E. Greene ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Tumor Growth ◽  
Ligand Binding ◽  
Endocrine Therapy ◽  
Breast Cancers ◽  
Primary Tumor Growth ◽  
Wild Type ◽  
Tumor Growth And Metastasis ◽  
Anti Tumor Activity

Abstract Background Endocrine therapy remains the mainstay of treatment for estrogen receptor-positive (ER+) breast cancer. Constitutively active mutations in the ligand binding domain of ERα render tumors resistant to endocrine agents. Breast cancers with the two most common ERα mutations, Y537S and D538G, have low sensitivity to fulvestrant inhibition, a typical second-line endocrine therapy. Lasofoxifene is a selective estrogen receptor modulator with benefits on bone health and breast cancer prevention potential. This study investigated the anti-tumor activity of lasofoxifene in breast cancer xenografts expressing Y537S and D538G ERα mutants. The combination of lasofoxifene with palbociclib, a CDK4/6 inhibitor, was also evaluated. Methods Luciferase-GFP tagged MCF7 cells bearing wild-type, Y537S, or D538G ERα were injected into the mammary ducts of NSG mice (MIND model), which were subsequently treated with lasofoxifene or fulvestrant as single agents or in combination with palbociclib. Tumor growth and metastasis were monitored with in vivo and ex vivo luminescence imaging, terminal tumor weight measurements, and histological analysis. Results As a monotherapy, lasofoxifene was more effective than fulvestrant at inhibiting primary tumor growth and reducing metastases. Adding palbociclib improved the effectiveness of both lasofoxifene and fulvestrant for tumor suppression and metastasis prevention at four distal sites (lung, liver, bone, and brain), with the combination of lasofoxifene/palbociclib being generally more potent than that of fulvestrant/palbociclib. X-ray crystallography of the ERα ligand binding domain (LBD) shows that lasofoxifene stabilizes an antagonist conformation of both wild-type and Y537S LBD. The ability of lasofoxifene to promote an antagonist conformation of Y537S, combined with its long half-life and bioavailability, likely contributes to the observed potent inhibition of primary tumor growth and metastasis of MCF7 Y537S cells. Conclusions We report for the first time the anti-tumor activity of lasofoxifene in mouse models of endocrine therapy-resistant breast cancer. The results demonstrate the potential of using lasofoxifene as an effective therapy for women with advanced or metastatic ER+ breast cancers expressing the most common constitutively active ERα mutations.

Endocrine Treatment of Breast Cancer: Current Perspectives, Future Directions

2017 ◽  
Vol 8 (03) ◽  
Author(s):  
Tazia Irfan ◽  
Mainul Haque ◽  
Sayeeda Rahman ◽  
Russell Kabir ◽  
Nuzhat Rahman ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Endocrine Therapy ◽  
Ovarian Function ◽  
Premenopausal Women ◽  
New Drugs ◽  
Effective Control ◽  
Endocrine Treatment ◽  
Estrogen Production ◽  
Hormone Sensitive

Breast cancer remains one of the major causes of death in women, and endocrine treatment is currently one of the mainstay of treatment in patients with estrogen receptor positive breast cancer. Endocrine therapy either slows down or stops the growth of hormone-sensitive tumors by blocking the body’s capability to yield hormones or by interfering with hormone action. In this paper, we intended to review various approaches of endocrine treatments for breast cancer highlighting successes and limitations. There are three settings where endocrine treatment of breast cancer can be used: neoadjuvant, adjuvant, or metastatic. Several strategies have also been developed to treat hormone-sensitive breast cancer which include ovarian ablation, blocking estrogen production, and stopping estrogen effects. Selective estrogen-receptor modulators (SERMs) (e.g. tamoxifen and raloxifene), aromatase inhibitors (AIs) (e.g. anastrozole, letrozole and exemestane), gonadotropin-releasing hormone agonists (GnRH) (e.g. goserelin), and selective estrogen receptor downregulators (SERDs) (e.g. fulvestrant) are currently used drugs to treat breast cancer. Tamoxifen is probably the first targeted therapy widely used in breast cancer treatment which is considered to be very effective as first line endocrine treatment in previously untreated patients and also can be used after other endocrine therapy and chemotherapy. AIs inhibit the action of enzyme aromatase which ultimately decrease the production of estrogen to stimulate the growth of ER+ breast cancer cells. GnRH agonists suppress ovarian function, inducing artificial menopause in premenopausal women. Endocrine treatments are cheap, well-tolerated and have a fixed single daily dose for all ages, heights and weights of patients. Endocrine treatments are not nearly as toxic as chemotherapy and frequent hospitalization can be avoided. New drugs in preliminary trials demonstrated the potential for improvement of the efficacy of endocrine therapy including overcoming resistance. However, the overall goals for breast cancer including endocrine therapy should focus on effective control of cancer, design personalized medical therapeutic approach, increase survival time and quality of life, and improve supportive and palliative care for end-stage disease.

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