The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Michael J Reed - One of the best experts on this subject based on the ideXlab platform.
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The In Vitro and In Vivo Activity of the Microtubule Disruptor STX140 Is Mediated by Hif-1 Alpha and CAIX Expression.
Anticancer research, 2015Co-Authors: Chloe Stengel, Atul Purohit, Michael J Reed, Barry V L Potter, Simon P. Newman, Mathew P. Leese, Mark P. Thomas, Paul FosterAbstract:Tumor neo-angiogenesis is regulated, in part, by the hypoxia-inducible gene HIF1. Evidence suggests HIF1 associates with polymerized microtubules and traffics to the nucleus. This study investigated the role of HIF1 in mediating the antitumor activity of two steroid-based Sulfamate Ester microtubule disruptors, STX140 and STX243, in vitro and in vivo. The effects of STX140, STX243 and the parental compound 2-methoxyestradiol (STX66) on HIF1α and HIF2α protein expression were assessed in vitro in MCF-7 and MDA-MB-231 cells cultured under hypoxia. More pertinently, their effects were examined on HIF1-regulated genes in vivo in mice bearing MCF-7 or MDA-MB-231 tumors. The level of mRNA expression of vascular endothelial growth factor (VEGF), glucose transporter 1 (GLUTI), phosphoglycerate kinase (PGK), ATP-binding cassette sub-family B member 1 (ABCB1) and carbonic anhydrase IX (CAIX) was quantified by Real-time Polymerase Chain Reaction (RT-PCR). Despite inhibiting nuclear HIF1α protein accumulation under hypoxia in vitro, STX140 and STX243 did not significantly regulate the expression of four out of five HIF1α-regulated genes in vitro and in vivo. Only CAIX mRNA expression was down-regulated both in vitro and in vivo. Immunoblot analysis showed that STX140 and STX243 reduced CAIX protein expression in vitro. These compounds had no effect on HIF2α translocation. The potential for inhibition of CAIX by STX140 and STX243 was examined by docking the ligands to the active site in comparison with a known Sulfamate-based inhibitor. Microtubule disruption and antitumor activity of STX140 and STX243 is most likely HIF1-independent and may, at least in part, be mediated by inhibition of CAIX expression and activity.
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Recent developments of steroid sulfatase inhibitors as anti-cancer agents.
Anti-Cancer Agents in Medicinal Chemistry, 2008Co-Authors: Paul A. Foster, Michael J Reed, Atul PurohitAbstract:The steroid sulfatase (STS) enzyme plays a pivotal role in the formation of biologically active steroid hormones. Its involvement in the hydrolysis of estrone sulfate and dehydroepiandrosterone sulfate to estrone and dehydroepiandrosterone, respectively, is an important step in the formation of estradiol and androstenediol, both of which are estrogenic steroids that can stimulate tumor growth. Consequently, as STS is widely distributed throughout the entire body, it has a substantial influence on hormone-dependent cancer mitogenesis. It is a useful prognostic marker of disease as a significant majority of breast tumors over-express the enzyme and there are indications of STS having a role in prostate cancer. This knowledge has led to the development of potent STS inhibitors for use as anti-cancer agents. There are now several steroidal and non-steroidal STS inhibitors available. New in vivo models, using ovariectomized female nude mice, have been developed to pre-clinically test these inhibitors. These studies have demonstrated the excellent efficacy and effect of STS inhibitors on breast carcinoma development. Recently, 667 COUMATE, an irreversible type of inhibitor which utilizes a phenol Sulfamate Ester as its active pharmacophore, has completed a Phase I clinical trial in postmenopausal women with breast cancer. These studies have indicated the potential clinical benefit for the use of STS inhibitors. Most pre-clinical and clinical studies have focused on breast cancer as the target for STS inhibition. However, there are other hormone-dependent malignancies, such as endometrial and prostate cancer, that could in the future be treated with these new potent STS inhibitors.
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Dual aromatase-sulfatase inhibitors based on the anastrozole template: synthesis, in vitro SAR, molecular modelling and in vivo activity.
Organic & biomolecular chemistry, 2007Co-Authors: Toby Jackson, L W Lawrence Woo, Melanie N Trusselle, Surinder K Chander, Atul Purohit, Michael J Reed, Barry V L PotterAbstract:The synthesis and biological evaluation of a series of novel Dual Aromatase-Sulfatase Inhibitors (DASIs) are described. It is postulated that dual inhibition of the aromatase and steroid sulfatase enzymes, both responsible for the biosynthesis of oestrogens, will be beneficial in the treatment of hormone-dependent breast cancer. The compounds are based upon the Anastrozole aromatase inhibitor template which, while maintaining the haem ligating triazole moiety crucial for enzyme inhibition, was modified to include a phenol Sulfamate Ester motif, the pharmacophore for potent irreversible steroid sulfatase inhibition. Adaption of a synthetic route to Anastrozole was accomplished via selective radical bromination and substitution reactions to furnish a series of aromatase inhibitory pharmacophores. Linking these fragments to the phenol Sulfamate Ester moiety employed SN2, Heck and Mitsunobu reactions with phenolic precursors, from where the completed DASIs were achieved via sulfamoylation. In vitro, the lead compound, 11, had a high degree of potency against aromatase (IC50 3.5 nM), comparable with that of Anastrozole (IC50 1.5 nM) whereas, only moderate activity against steroid sulfatase was found. However, in vivo, 11 surprisingly exhibited potent dual inhibition. Compound 11 was modelled into the active site of a homology model of human aromatase and the X-ray crystal structure of steroid sulfatase.
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Discovery and development of sulfatase inhibitors via academia, biotech & mid-size pharma
Cancer Research, 2007Co-Authors: Barry V L Potter, Michael J ReedAbstract:SY25-01 Breast cancer remains a major cause of death in women in most WEstern countries. While estrogens have an important role in supporting the development and growth of breast tumors, the highest incidence of breast cancer occurs in postmenopausal women when ovarian production of estrogens has ceased. However, the enzymes required for estrogen synthesis (aromatase, steroid sulfatase, 17β-hydroxysteroid dehydrogenase) are present in normal and malignant breast tissues and contribute to local synthesis. Steroid sulfatase (STS) is a novel therapeutic target for hormone dependent cancer, currently in clinical validation. Aromatase inhibitors, while clinically successful, do not address the large reservoir of conjugated estrone sulfate that can be converted to estrone by steroid sulfatase and on to estradiol to stimulate tumor growth, nor formation of the androgen androstenediol that, although weaker than estradiol, can still stimulate the estrogen receptor and is produced in large quantities in the post-menopausal setting. Both of these pathways represent aromatase-inhibitor-independent pathways of tumor progression with no active agents available. Our aim was to approach this challenge in a novel fashion. While nucleoside Sulfamates, such as the antitrypanosomal antibiotic nucleocidin, have been known for many years and the derivatized carbohydrate Sulfamate topiramate is a marketed anticonvulsant, the discovery that an aryl Sulfamate Ester, as in the steroidal estrone 3-O-Sulfamate, irreversibly inhibits steroid sulfatase in a time- and concentration-dependent fashion, with concomitant protein sulfamoylation, was a major advance in validating this enzyme as a novel oncology target. This was preceded by development of reversible inhibitors based upon structural surrogates of the sulfate group and early stage work was sponsored by both 3i Research Exploitation Ltd and IMPEL, the then technology transfer arm of Imperial College London. The unique activity of the aryl Sulfamate pharmacophore facilitated the filing of major dominating intellectual property with broad structure per se coverage critical to future success. A licence to a major US company was achieved, to develop the steroidal estrone 3-O-Sulfamate as an anticancer agent, but was terminated upon acquisition of this company and the discovery that estrone 3-O-Sulfamate is highly estrogenic. Subsequent funding to develop a non-steroidal sulfatase inhibitor for breast cancer came from the UK Cancer Research Campaign (now CRUK). Fortuitously, another licence with a major European pharma company was secured for development of estradiol 3-O-Sulfamate for hormone replacement therapy and this provided the seed capital for “series A” funding and incorporation of Sterix Ltd, a spin-out company from the universities of Bath and Imperial College London in 1997, that became fully functional in 1998. Sterix had the remit to develop the potential of a non-steroidal inhibitor of steroid sulfatase in hormone-dependent breast cancer through a phase I clinical trial, to oversee the development of estradiol 3-O-Sulfamate with its partner and to further exploit the potential of the aryl Sulfamate pharmacophore. In addition, it supported projects in other oncology and endocrinology areas relating to hydroxysteroid dehydrogenases. Sterix raised £8M of venture capital funding in 2001 and functioned as a semi-virtual company with headquarters and biology/DMPK labs on the Oxford University Science Park with a small cohort of employees, but all discovery science funded through formal agreements with the two universities. This model functioned well for all parties and had a number of advantages that will be outlined. Issues relevant to moving from a functioning early stage company to a VC-funded company will be discussed. Postmenopausal women with locally advanced or metastatic ER+ breast cancer were recruited to a phase I clinical trial of our “first in class” non-steroidal steroid sulfatase inhibitor STX64funded by Sterix andunder the auspicies of CRUK during 2003-5. Patients for the phase I trial were recruited from Charing Cross Hospital, London and Belfast City Hospital. Due to limited funding available laboratory measurements of STS inhibition in peripheral blood monocytes and tumor tissues were carried out in an academic laboratory. This proved to be a considerable challenge, but with the support of an MD student, a steroid biochemist and a GLP advisor these analyses were successfully carried out to a near GLP standard. The drug was well tolerated with high oral bioavailability and importantly, in this heavily pre-treated group of women (including tamoxifen and aromatase inhibitors), 5/8 evaluable patients showed evidence of stable disease for up to 7 months. While such an approach was acceptable for a preliminary phase I trial, future phase I/II trials will require considerably more support for these analyses to be carried out to an acceptable standard. Results from this trial will be discussed and examples of next generation sulfatase inhibitors and potent dual aromatase-sulfatase inhibitors presented. Further trials on STX64 (BN83495) commenced in early 2007. The competitive landscape for sulfatase inhibition has developed during the last 15 years with a number of major companies filing patents on both irreversible and reversible sulfatase inhibitors. Most of those in the former “me-too” class have exploited the aryl Sulfamate motif and are dominated by Sterix prior art, but none has yet reached a clinical trial and the reversible inhibitors have not been demonstrated to be effective beyond moderate in vitro activity. Particularly interesting is the growth of interest in other therapeutic targets for steroid sulfatase inhibition beyond oncology, ie in dermatology, immunomodulation, and aspects of cognitive function. Sterix Ltd was acquired by Ipsen in 2004 while the STX64 trial was in progress. Ipsen is a European pharmaceutical group with over 20 products on the market and a worldwide staff of nearly 4,000. With Sterix now as a fully owned subsidiary, Ipsen has continued funding the research teams at Bath and Imperial College to maintain expertise in all major ongoing discovery and development programmes. Issues relevant to the transition from small founder-VC driven biotech to working with a mid-size major pharmaceutical company will be discussed. As part of studies designed to reduce the estrogenicity of estrone 3-O-Sulfamate we explored the chemical substitution of the A ring. This resulted in the discovery of a new class of oncology-relevant steroid Sulfamates based upon 2-methoxyestradiol 3-O-Sulfamate that were found to have profound effects on mitotic arrest, apoptosis and microtubule assembly in human breast cancer cells and where the Sulfamate group had very significant potency- and DMPK-enhancing properties, independent of steroid sulfatase inhibition. To further exploit the aryl Sulfamate pharmacophore as a non-transformable structural motif in a hormone-independent setting we have developed the steroidal bis-Sulfamate derivatives STX140 and STX243 as attractive anti-cancer agents with, in addition to STS activity, a multi-targeted mechanism of action, exhibiting potent anti-proliferative and anti-angiogenic effects and disruption of microtubules with pro-apoptotic effects; G2M cell cycle arrest, p53 induction, BCL-2 phosphorylation and activation of caspases are all observed in cancer cells treated with these compounds. A full SAR study will be presented. Steroid Sulfamate Esters have high oral bioavailability, atypical of estradiol derivatives, due to sequestration into red blood cells and binding to carbonic anhydrase II (CAII). We co-crystallized steroidal bis-Sulfamates with CAII and obtained protein X-ray crystal data, demonstrating that an A-ring 2-substituent does not impede drug binding to this carrier, although an unexpected binding mode was observed. Interaction as the mono-anion with CAII supports the idea that the good oral bioavailability and PK properties of STX140 are due to a mechanism whereby erythrocyte drug uptake and reversible interaction with CAII provide a route to avoid first pass liver metabolism and, additionally, undesirable metabolic conjugation is blocked by hydroxyl substitution. The advantages of exploring such aspects in an academic environment will be discussed. The potential of bis-sulfamoylated estradiol derivatives for clinical development is reinforced by their in vivo activities. In an MDA-MB-231 hormone independent breast cancer xenograft model in athymic female nude mice STX140 (40 mg/kg p.o.) caused regression and prolonged inhibition of tumor growth continuing after cessation of dosing (6/6 animals) and tumor disappearance (1/6 animals), with no observed toxicity. Moreover, in the androgen receptor negative PC-3 prostate cancer xenograft model in athymic male nude mice using STX140 (20mg/kg p.o.) impressive tumor growth inhibition was observed with 2/8 tumors disappearing and, for STX243 (40mg/kg p.o.), with 3/8 tumors disappearing. In the DU145 prostate cancer model at the same doses STX140 reduced tumor growth by 40% after 6 weeks treatment and STX243 by 60%. Studies are directed towards selection of a clinical candidate for proposed entry in 2008. The aryl Sulfamate pharmacophore is a versatile motif for anti-cancer drug design and one that that has withstood a complex development pathway from academic/technology transfer/charity-funded origins through an entrepreneurial phase to formal exploitation by mid-size pharma. Being first in class to originate the fundamental innovative science and developing a supporting intellectual property position of the highest quality are shown to be critical to this survival.
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Dual aromatase–sulfatase inhibitors based on the anastrozole template: synthesis, in vitro SAR, molecular modelling and in vivo activity
Organic & Biomolecular Chemistry, 2007Co-Authors: Toby Jackson, L W Lawrence Woo, Melanie N Trusselle, Surinder K Chander, Atul Purohit, Michael J Reed, Barry V L PotterAbstract:The synthesis and biological evaluation of a series of novel Dual Aromatase–Sulfatase Inhibitors (DASIs) are described. It is postulated that dual inhibition of the aromatase and steroid sulfatase enzymes, both responsible for the biosynthesis of oestrogens, will be beneficial in the treatment of hormone-dependent breast cancer. The compounds are based upon the Anastrozolearomatase inhibitor template which, while maintaining the haem ligating triazole moiety crucial for enzyme inhibition, was modified to include a phenol Sulfamate Ester motif, the pharmacophore for potent irreversible steroid sulfatase inhibition. Adaption of a synthetic route to Anastrozole was accomplished via selective radical bromination and substitution reactions to furnish a series of aromatase inhibitory pharmacophores. Linking these fragments to the phenol Sulfamate Ester moiety employed SN2, Heck and Mitsunobu reactions with phenolic precursors, from where the completed DASIs were achieved via sulfamoylation. In vitro, the lead compound, 11, had a high degree of potency against aromatase (IC50 3.5 nM), comparable with that of Anastrozole (IC50 1.5 nM) whereas, only moderate activity against steroid sulfatase was found. However, in vivo, 11 surprisingly exhibited potent dual inhibition. Compound 11 was modelled into the active site of a homology model of human aromatase and the X-ray crystal structure of steroid sulfatase.
Barry V L Potter - One of the best experts on this subject based on the ideXlab platform.
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The In Vitro and In Vivo Activity of the Microtubule Disruptor STX140 Is Mediated by Hif-1 Alpha and CAIX Expression.
Anticancer research, 2015Co-Authors: Chloe Stengel, Atul Purohit, Michael J Reed, Barry V L Potter, Simon P. Newman, Mathew P. Leese, Mark P. Thomas, Paul FosterAbstract:Tumor neo-angiogenesis is regulated, in part, by the hypoxia-inducible gene HIF1. Evidence suggests HIF1 associates with polymerized microtubules and traffics to the nucleus. This study investigated the role of HIF1 in mediating the antitumor activity of two steroid-based Sulfamate Ester microtubule disruptors, STX140 and STX243, in vitro and in vivo. The effects of STX140, STX243 and the parental compound 2-methoxyestradiol (STX66) on HIF1α and HIF2α protein expression were assessed in vitro in MCF-7 and MDA-MB-231 cells cultured under hypoxia. More pertinently, their effects were examined on HIF1-regulated genes in vivo in mice bearing MCF-7 or MDA-MB-231 tumors. The level of mRNA expression of vascular endothelial growth factor (VEGF), glucose transporter 1 (GLUTI), phosphoglycerate kinase (PGK), ATP-binding cassette sub-family B member 1 (ABCB1) and carbonic anhydrase IX (CAIX) was quantified by Real-time Polymerase Chain Reaction (RT-PCR). Despite inhibiting nuclear HIF1α protein accumulation under hypoxia in vitro, STX140 and STX243 did not significantly regulate the expression of four out of five HIF1α-regulated genes in vitro and in vivo. Only CAIX mRNA expression was down-regulated both in vitro and in vivo. Immunoblot analysis showed that STX140 and STX243 reduced CAIX protein expression in vitro. These compounds had no effect on HIF2α translocation. The potential for inhibition of CAIX by STX140 and STX243 was examined by docking the ligands to the active site in comparison with a known Sulfamate-based inhibitor. Microtubule disruption and antitumor activity of STX140 and STX243 is most likely HIF1-independent and may, at least in part, be mediated by inhibition of CAIX expression and activity.
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Dual aromatase-sulfatase inhibitors based on the anastrozole template: synthesis, in vitro SAR, molecular modelling and in vivo activity.
Organic & biomolecular chemistry, 2007Co-Authors: Toby Jackson, L W Lawrence Woo, Melanie N Trusselle, Surinder K Chander, Atul Purohit, Michael J Reed, Barry V L PotterAbstract:The synthesis and biological evaluation of a series of novel Dual Aromatase-Sulfatase Inhibitors (DASIs) are described. It is postulated that dual inhibition of the aromatase and steroid sulfatase enzymes, both responsible for the biosynthesis of oestrogens, will be beneficial in the treatment of hormone-dependent breast cancer. The compounds are based upon the Anastrozole aromatase inhibitor template which, while maintaining the haem ligating triazole moiety crucial for enzyme inhibition, was modified to include a phenol Sulfamate Ester motif, the pharmacophore for potent irreversible steroid sulfatase inhibition. Adaption of a synthetic route to Anastrozole was accomplished via selective radical bromination and substitution reactions to furnish a series of aromatase inhibitory pharmacophores. Linking these fragments to the phenol Sulfamate Ester moiety employed SN2, Heck and Mitsunobu reactions with phenolic precursors, from where the completed DASIs were achieved via sulfamoylation. In vitro, the lead compound, 11, had a high degree of potency against aromatase (IC50 3.5 nM), comparable with that of Anastrozole (IC50 1.5 nM) whereas, only moderate activity against steroid sulfatase was found. However, in vivo, 11 surprisingly exhibited potent dual inhibition. Compound 11 was modelled into the active site of a homology model of human aromatase and the X-ray crystal structure of steroid sulfatase.
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Discovery and development of sulfatase inhibitors via academia, biotech & mid-size pharma
Cancer Research, 2007Co-Authors: Barry V L Potter, Michael J ReedAbstract:SY25-01 Breast cancer remains a major cause of death in women in most WEstern countries. While estrogens have an important role in supporting the development and growth of breast tumors, the highest incidence of breast cancer occurs in postmenopausal women when ovarian production of estrogens has ceased. However, the enzymes required for estrogen synthesis (aromatase, steroid sulfatase, 17β-hydroxysteroid dehydrogenase) are present in normal and malignant breast tissues and contribute to local synthesis. Steroid sulfatase (STS) is a novel therapeutic target for hormone dependent cancer, currently in clinical validation. Aromatase inhibitors, while clinically successful, do not address the large reservoir of conjugated estrone sulfate that can be converted to estrone by steroid sulfatase and on to estradiol to stimulate tumor growth, nor formation of the androgen androstenediol that, although weaker than estradiol, can still stimulate the estrogen receptor and is produced in large quantities in the post-menopausal setting. Both of these pathways represent aromatase-inhibitor-independent pathways of tumor progression with no active agents available. Our aim was to approach this challenge in a novel fashion. While nucleoside Sulfamates, such as the antitrypanosomal antibiotic nucleocidin, have been known for many years and the derivatized carbohydrate Sulfamate topiramate is a marketed anticonvulsant, the discovery that an aryl Sulfamate Ester, as in the steroidal estrone 3-O-Sulfamate, irreversibly inhibits steroid sulfatase in a time- and concentration-dependent fashion, with concomitant protein sulfamoylation, was a major advance in validating this enzyme as a novel oncology target. This was preceded by development of reversible inhibitors based upon structural surrogates of the sulfate group and early stage work was sponsored by both 3i Research Exploitation Ltd and IMPEL, the then technology transfer arm of Imperial College London. The unique activity of the aryl Sulfamate pharmacophore facilitated the filing of major dominating intellectual property with broad structure per se coverage critical to future success. A licence to a major US company was achieved, to develop the steroidal estrone 3-O-Sulfamate as an anticancer agent, but was terminated upon acquisition of this company and the discovery that estrone 3-O-Sulfamate is highly estrogenic. Subsequent funding to develop a non-steroidal sulfatase inhibitor for breast cancer came from the UK Cancer Research Campaign (now CRUK). Fortuitously, another licence with a major European pharma company was secured for development of estradiol 3-O-Sulfamate for hormone replacement therapy and this provided the seed capital for “series A” funding and incorporation of Sterix Ltd, a spin-out company from the universities of Bath and Imperial College London in 1997, that became fully functional in 1998. Sterix had the remit to develop the potential of a non-steroidal inhibitor of steroid sulfatase in hormone-dependent breast cancer through a phase I clinical trial, to oversee the development of estradiol 3-O-Sulfamate with its partner and to further exploit the potential of the aryl Sulfamate pharmacophore. In addition, it supported projects in other oncology and endocrinology areas relating to hydroxysteroid dehydrogenases. Sterix raised £8M of venture capital funding in 2001 and functioned as a semi-virtual company with headquarters and biology/DMPK labs on the Oxford University Science Park with a small cohort of employees, but all discovery science funded through formal agreements with the two universities. This model functioned well for all parties and had a number of advantages that will be outlined. Issues relevant to moving from a functioning early stage company to a VC-funded company will be discussed. Postmenopausal women with locally advanced or metastatic ER+ breast cancer were recruited to a phase I clinical trial of our “first in class” non-steroidal steroid sulfatase inhibitor STX64funded by Sterix andunder the auspicies of CRUK during 2003-5. Patients for the phase I trial were recruited from Charing Cross Hospital, London and Belfast City Hospital. Due to limited funding available laboratory measurements of STS inhibition in peripheral blood monocytes and tumor tissues were carried out in an academic laboratory. This proved to be a considerable challenge, but with the support of an MD student, a steroid biochemist and a GLP advisor these analyses were successfully carried out to a near GLP standard. The drug was well tolerated with high oral bioavailability and importantly, in this heavily pre-treated group of women (including tamoxifen and aromatase inhibitors), 5/8 evaluable patients showed evidence of stable disease for up to 7 months. While such an approach was acceptable for a preliminary phase I trial, future phase I/II trials will require considerably more support for these analyses to be carried out to an acceptable standard. Results from this trial will be discussed and examples of next generation sulfatase inhibitors and potent dual aromatase-sulfatase inhibitors presented. Further trials on STX64 (BN83495) commenced in early 2007. The competitive landscape for sulfatase inhibition has developed during the last 15 years with a number of major companies filing patents on both irreversible and reversible sulfatase inhibitors. Most of those in the former “me-too” class have exploited the aryl Sulfamate motif and are dominated by Sterix prior art, but none has yet reached a clinical trial and the reversible inhibitors have not been demonstrated to be effective beyond moderate in vitro activity. Particularly interesting is the growth of interest in other therapeutic targets for steroid sulfatase inhibition beyond oncology, ie in dermatology, immunomodulation, and aspects of cognitive function. Sterix Ltd was acquired by Ipsen in 2004 while the STX64 trial was in progress. Ipsen is a European pharmaceutical group with over 20 products on the market and a worldwide staff of nearly 4,000. With Sterix now as a fully owned subsidiary, Ipsen has continued funding the research teams at Bath and Imperial College to maintain expertise in all major ongoing discovery and development programmes. Issues relevant to the transition from small founder-VC driven biotech to working with a mid-size major pharmaceutical company will be discussed. As part of studies designed to reduce the estrogenicity of estrone 3-O-Sulfamate we explored the chemical substitution of the A ring. This resulted in the discovery of a new class of oncology-relevant steroid Sulfamates based upon 2-methoxyestradiol 3-O-Sulfamate that were found to have profound effects on mitotic arrest, apoptosis and microtubule assembly in human breast cancer cells and where the Sulfamate group had very significant potency- and DMPK-enhancing properties, independent of steroid sulfatase inhibition. To further exploit the aryl Sulfamate pharmacophore as a non-transformable structural motif in a hormone-independent setting we have developed the steroidal bis-Sulfamate derivatives STX140 and STX243 as attractive anti-cancer agents with, in addition to STS activity, a multi-targeted mechanism of action, exhibiting potent anti-proliferative and anti-angiogenic effects and disruption of microtubules with pro-apoptotic effects; G2M cell cycle arrest, p53 induction, BCL-2 phosphorylation and activation of caspases are all observed in cancer cells treated with these compounds. A full SAR study will be presented. Steroid Sulfamate Esters have high oral bioavailability, atypical of estradiol derivatives, due to sequestration into red blood cells and binding to carbonic anhydrase II (CAII). We co-crystallized steroidal bis-Sulfamates with CAII and obtained protein X-ray crystal data, demonstrating that an A-ring 2-substituent does not impede drug binding to this carrier, although an unexpected binding mode was observed. Interaction as the mono-anion with CAII supports the idea that the good oral bioavailability and PK properties of STX140 are due to a mechanism whereby erythrocyte drug uptake and reversible interaction with CAII provide a route to avoid first pass liver metabolism and, additionally, undesirable metabolic conjugation is blocked by hydroxyl substitution. The advantages of exploring such aspects in an academic environment will be discussed. The potential of bis-sulfamoylated estradiol derivatives for clinical development is reinforced by their in vivo activities. In an MDA-MB-231 hormone independent breast cancer xenograft model in athymic female nude mice STX140 (40 mg/kg p.o.) caused regression and prolonged inhibition of tumor growth continuing after cessation of dosing (6/6 animals) and tumor disappearance (1/6 animals), with no observed toxicity. Moreover, in the androgen receptor negative PC-3 prostate cancer xenograft model in athymic male nude mice using STX140 (20mg/kg p.o.) impressive tumor growth inhibition was observed with 2/8 tumors disappearing and, for STX243 (40mg/kg p.o.), with 3/8 tumors disappearing. In the DU145 prostate cancer model at the same doses STX140 reduced tumor growth by 40% after 6 weeks treatment and STX243 by 60%. Studies are directed towards selection of a clinical candidate for proposed entry in 2008. The aryl Sulfamate pharmacophore is a versatile motif for anti-cancer drug design and one that that has withstood a complex development pathway from academic/technology transfer/charity-funded origins through an entrepreneurial phase to formal exploitation by mid-size pharma. Being first in class to originate the fundamental innovative science and developing a supporting intellectual property position of the highest quality are shown to be critical to this survival.
-
Dual aromatase–sulfatase inhibitors based on the anastrozole template: synthesis, in vitro SAR, molecular modelling and in vivo activity
Organic & Biomolecular Chemistry, 2007Co-Authors: Toby Jackson, L W Lawrence Woo, Melanie N Trusselle, Surinder K Chander, Atul Purohit, Michael J Reed, Barry V L PotterAbstract:The synthesis and biological evaluation of a series of novel Dual Aromatase–Sulfatase Inhibitors (DASIs) are described. It is postulated that dual inhibition of the aromatase and steroid sulfatase enzymes, both responsible for the biosynthesis of oestrogens, will be beneficial in the treatment of hormone-dependent breast cancer. The compounds are based upon the Anastrozolearomatase inhibitor template which, while maintaining the haem ligating triazole moiety crucial for enzyme inhibition, was modified to include a phenol Sulfamate Ester motif, the pharmacophore for potent irreversible steroid sulfatase inhibition. Adaption of a synthetic route to Anastrozole was accomplished via selective radical bromination and substitution reactions to furnish a series of aromatase inhibitory pharmacophores. Linking these fragments to the phenol Sulfamate Ester moiety employed SN2, Heck and Mitsunobu reactions with phenolic precursors, from where the completed DASIs were achieved via sulfamoylation. In vitro, the lead compound, 11, had a high degree of potency against aromatase (IC50 3.5 nM), comparable with that of Anastrozole (IC50 1.5 nM) whereas, only moderate activity against steroid sulfatase was found. However, in vivo, 11 surprisingly exhibited potent dual inhibition. Compound 11 was modelled into the active site of a homology model of human aromatase and the X-ray crystal structure of steroid sulfatase.
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Steroid Sulfatase: A New Target for the Endocrine Therapy of Breast Cancer
The Oncologist, 2007Co-Authors: Susannah J. Stanway, L W Lawrence Woo, Atul Purohit, Barry V L Potter, Patrick Delavault, Christophe Thurieau, Michael J ReedAbstract:Inhibitors of steroid sulfatase are being developed as a novel therapy for hormone-dependent breast cancer in postmenopausal women. Data suggest that steroid sulfatase (STS) activity is much higher than aromatase activity in breast tumors and high levels of STS mRNA expression in tumors are associated with a poor prognosis. STS hydrolyzes steroid sulfates, such as estrone sulfate and dehydroepiandrosterone sulfate (DHEAS), to estrone and DHEA, which can be converted to steroids with potent estrogenic properties, that is, estradiol and androstenediol, respectively. Several potent irreversible STS inhibitors have now been identified, including STX64 (BN83495), a tricyclic Sulfamate Ester. This drug recently completed the first-ever trial of this new type of therapy in postmenopausal women with estrogen receptor-positive metastatic breast cancer. STX64, tested at 5-mg and 20-mg doses, was able to almost completely block STS activity in peripheral blood lymphocytes and tumor tissues. Inhibition of STS activity was associated with significant reductions in serum concentrations of androstenediol and estrogens. Unexpectedly, serum androstenedione concentrations also decreased by up to 86%, showing that this steroid, which is the main substrate for the aromatase in postmenopausal women, is derived mainly from the peripheral conversion of DHEAS. Of eight patients who completed therapy, five showed evidence of stable disease for up to 7.0 months. This new endocrine therapy offers considerable potential for the treatment of hormone-dependent breast cancer in postmenopausal women.
Atul Purohit - One of the best experts on this subject based on the ideXlab platform.
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The In Vitro and In Vivo Activity of the Microtubule Disruptor STX140 Is Mediated by Hif-1 Alpha and CAIX Expression.
Anticancer research, 2015Co-Authors: Chloe Stengel, Atul Purohit, Michael J Reed, Barry V L Potter, Simon P. Newman, Mathew P. Leese, Mark P. Thomas, Paul FosterAbstract:Tumor neo-angiogenesis is regulated, in part, by the hypoxia-inducible gene HIF1. Evidence suggests HIF1 associates with polymerized microtubules and traffics to the nucleus. This study investigated the role of HIF1 in mediating the antitumor activity of two steroid-based Sulfamate Ester microtubule disruptors, STX140 and STX243, in vitro and in vivo. The effects of STX140, STX243 and the parental compound 2-methoxyestradiol (STX66) on HIF1α and HIF2α protein expression were assessed in vitro in MCF-7 and MDA-MB-231 cells cultured under hypoxia. More pertinently, their effects were examined on HIF1-regulated genes in vivo in mice bearing MCF-7 or MDA-MB-231 tumors. The level of mRNA expression of vascular endothelial growth factor (VEGF), glucose transporter 1 (GLUTI), phosphoglycerate kinase (PGK), ATP-binding cassette sub-family B member 1 (ABCB1) and carbonic anhydrase IX (CAIX) was quantified by Real-time Polymerase Chain Reaction (RT-PCR). Despite inhibiting nuclear HIF1α protein accumulation under hypoxia in vitro, STX140 and STX243 did not significantly regulate the expression of four out of five HIF1α-regulated genes in vitro and in vivo. Only CAIX mRNA expression was down-regulated both in vitro and in vivo. Immunoblot analysis showed that STX140 and STX243 reduced CAIX protein expression in vitro. These compounds had no effect on HIF2α translocation. The potential for inhibition of CAIX by STX140 and STX243 was examined by docking the ligands to the active site in comparison with a known Sulfamate-based inhibitor. Microtubule disruption and antitumor activity of STX140 and STX243 is most likely HIF1-independent and may, at least in part, be mediated by inhibition of CAIX expression and activity.
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Recent developments of steroid sulfatase inhibitors as anti-cancer agents.
Anti-Cancer Agents in Medicinal Chemistry, 2008Co-Authors: Paul A. Foster, Michael J Reed, Atul PurohitAbstract:The steroid sulfatase (STS) enzyme plays a pivotal role in the formation of biologically active steroid hormones. Its involvement in the hydrolysis of estrone sulfate and dehydroepiandrosterone sulfate to estrone and dehydroepiandrosterone, respectively, is an important step in the formation of estradiol and androstenediol, both of which are estrogenic steroids that can stimulate tumor growth. Consequently, as STS is widely distributed throughout the entire body, it has a substantial influence on hormone-dependent cancer mitogenesis. It is a useful prognostic marker of disease as a significant majority of breast tumors over-express the enzyme and there are indications of STS having a role in prostate cancer. This knowledge has led to the development of potent STS inhibitors for use as anti-cancer agents. There are now several steroidal and non-steroidal STS inhibitors available. New in vivo models, using ovariectomized female nude mice, have been developed to pre-clinically test these inhibitors. These studies have demonstrated the excellent efficacy and effect of STS inhibitors on breast carcinoma development. Recently, 667 COUMATE, an irreversible type of inhibitor which utilizes a phenol Sulfamate Ester as its active pharmacophore, has completed a Phase I clinical trial in postmenopausal women with breast cancer. These studies have indicated the potential clinical benefit for the use of STS inhibitors. Most pre-clinical and clinical studies have focused on breast cancer as the target for STS inhibition. However, there are other hormone-dependent malignancies, such as endometrial and prostate cancer, that could in the future be treated with these new potent STS inhibitors.
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Dual aromatase-sulfatase inhibitors based on the anastrozole template: synthesis, in vitro SAR, molecular modelling and in vivo activity.
Organic & biomolecular chemistry, 2007Co-Authors: Toby Jackson, L W Lawrence Woo, Melanie N Trusselle, Surinder K Chander, Atul Purohit, Michael J Reed, Barry V L PotterAbstract:The synthesis and biological evaluation of a series of novel Dual Aromatase-Sulfatase Inhibitors (DASIs) are described. It is postulated that dual inhibition of the aromatase and steroid sulfatase enzymes, both responsible for the biosynthesis of oestrogens, will be beneficial in the treatment of hormone-dependent breast cancer. The compounds are based upon the Anastrozole aromatase inhibitor template which, while maintaining the haem ligating triazole moiety crucial for enzyme inhibition, was modified to include a phenol Sulfamate Ester motif, the pharmacophore for potent irreversible steroid sulfatase inhibition. Adaption of a synthetic route to Anastrozole was accomplished via selective radical bromination and substitution reactions to furnish a series of aromatase inhibitory pharmacophores. Linking these fragments to the phenol Sulfamate Ester moiety employed SN2, Heck and Mitsunobu reactions with phenolic precursors, from where the completed DASIs were achieved via sulfamoylation. In vitro, the lead compound, 11, had a high degree of potency against aromatase (IC50 3.5 nM), comparable with that of Anastrozole (IC50 1.5 nM) whereas, only moderate activity against steroid sulfatase was found. However, in vivo, 11 surprisingly exhibited potent dual inhibition. Compound 11 was modelled into the active site of a homology model of human aromatase and the X-ray crystal structure of steroid sulfatase.
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Dual aromatase–sulfatase inhibitors based on the anastrozole template: synthesis, in vitro SAR, molecular modelling and in vivo activity
Organic & Biomolecular Chemistry, 2007Co-Authors: Toby Jackson, L W Lawrence Woo, Melanie N Trusselle, Surinder K Chander, Atul Purohit, Michael J Reed, Barry V L PotterAbstract:The synthesis and biological evaluation of a series of novel Dual Aromatase–Sulfatase Inhibitors (DASIs) are described. It is postulated that dual inhibition of the aromatase and steroid sulfatase enzymes, both responsible for the biosynthesis of oestrogens, will be beneficial in the treatment of hormone-dependent breast cancer. The compounds are based upon the Anastrozolearomatase inhibitor template which, while maintaining the haem ligating triazole moiety crucial for enzyme inhibition, was modified to include a phenol Sulfamate Ester motif, the pharmacophore for potent irreversible steroid sulfatase inhibition. Adaption of a synthetic route to Anastrozole was accomplished via selective radical bromination and substitution reactions to furnish a series of aromatase inhibitory pharmacophores. Linking these fragments to the phenol Sulfamate Ester moiety employed SN2, Heck and Mitsunobu reactions with phenolic precursors, from where the completed DASIs were achieved via sulfamoylation. In vitro, the lead compound, 11, had a high degree of potency against aromatase (IC50 3.5 nM), comparable with that of Anastrozole (IC50 1.5 nM) whereas, only moderate activity against steroid sulfatase was found. However, in vivo, 11 surprisingly exhibited potent dual inhibition. Compound 11 was modelled into the active site of a homology model of human aromatase and the X-ray crystal structure of steroid sulfatase.
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Steroid Sulfatase: A New Target for the Endocrine Therapy of Breast Cancer
The Oncologist, 2007Co-Authors: Susannah J. Stanway, L W Lawrence Woo, Atul Purohit, Barry V L Potter, Patrick Delavault, Christophe Thurieau, Michael J ReedAbstract:Inhibitors of steroid sulfatase are being developed as a novel therapy for hormone-dependent breast cancer in postmenopausal women. Data suggest that steroid sulfatase (STS) activity is much higher than aromatase activity in breast tumors and high levels of STS mRNA expression in tumors are associated with a poor prognosis. STS hydrolyzes steroid sulfates, such as estrone sulfate and dehydroepiandrosterone sulfate (DHEAS), to estrone and DHEA, which can be converted to steroids with potent estrogenic properties, that is, estradiol and androstenediol, respectively. Several potent irreversible STS inhibitors have now been identified, including STX64 (BN83495), a tricyclic Sulfamate Ester. This drug recently completed the first-ever trial of this new type of therapy in postmenopausal women with estrogen receptor-positive metastatic breast cancer. STX64, tested at 5-mg and 20-mg doses, was able to almost completely block STS activity in peripheral blood lymphocytes and tumor tissues. Inhibition of STS activity was associated with significant reductions in serum concentrations of androstenediol and estrogens. Unexpectedly, serum androstenedione concentrations also decreased by up to 86%, showing that this steroid, which is the main substrate for the aromatase in postmenopausal women, is derived mainly from the peripheral conversion of DHEAS. Of eight patients who completed therapy, five showed evidence of stable disease for up to 7.0 months. This new endocrine therapy offers considerable potential for the treatment of hormone-dependent breast cancer in postmenopausal women.
Jennifer L. Roizen - One of the best experts on this subject based on the ideXlab platform.
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Photochemically-Mediated, Nickel-Catalyzed Synthesis of N-(Hetero)aryl Sulfamate Esters.
Organic Letters, 2019Co-Authors: J. Miles Blackburn, Anastasia L. Gant Kanegusuku, Georgia E. Scott, Jennifer L. RoizenAbstract:A general method is described for the coupling of (hetero)aryl bromides with O-alkyl Sulfamate Esters. The protocol relies on catalytic amounts of nickel and photoexcitable iridium complexes and proceeds under visible light irradiation at ambient temperature. This technology engages a broad range of simple and complex O-alkyl Sulfamate Ester substrates under mild conditions. Furthermore, it is possible to avoid undesirable N-alkylation, which was found to plague palladium-based protocols for N-arylation of O-alkyl Sulfamate Esters. These investigations represent the first use of Sulfamate Esters as nucleophiles in transition metal-catalyzed C–N coupling processes.
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Sulfamate Esters Guide C(3)-Selective Xanthylation of Alkanes.
The Journal of Organic Chemistry, 2019Co-Authors: Suraj K. Ayer, Jennifer L. RoizenAbstract:Owing to the pervasiveness of hydroxyl groups in natural isolates, alcohol derivatives are alluring directing groups. Herein, an alcohol-derived Sulfamate Ester guides the light-initiated xanthylation of primary, secondary, or tertiary centers. This process enables formal directed deuteration, azidation, thiolation, and vinylation reactions.
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Sulfamate Esters Guide Selective Radical-Mediated Chlorination of Aliphatic C-H Bonds.
Angewandte Chemie International Edition, 2017Co-Authors: Melanie A. Short, J. Miles Blackburn, Jennifer L. RoizenAbstract:Masked alcohols are particularly appealing as directing groups because of the ubiquity of hydroxy groups in organic small molecules. Herein, we disclose a general strategy for aliphatic γ-C(sp3 )-H functionalization guided by a masked alcohol. Specifically, we determine that Sulfamate Ester derived nitrogen-centered radicals mediate 1,6-hydrogen-atom transfer (HAT) processes to guide γ-C(sp3 )-H chlorination. This reaction proceeds through a light-initiated radical chain-propagation process and is capable of installing chlorine atoms at primary, secondary, and tertiary centers.
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Analyzing Site Selectivity in Rh2(esp)2‑Catalyzed Intermolecular C–H Amination Reactions
2015Co-Authors: Elizabeth N. Bess, Ryan J. Deluca, Daniel J. Tindall, Martins S. Oderinde, Jennifer L. Roizen, J. Du Bois, Matthew S. SigmanAbstract:Predicting site selectivity in C–H bond oxidation reactions involving heteroatom transfer is challenged by the small energetic differences between disparate bond types and the subtle interplay of steric and electronic effects that influence reactivity. Herein, the factors governing selective Rh2(esp)2-catalyzed C–H amination of isoamylbenzene derivatives are investigated, where modification to both the nitrogen source, a Sulfamate Ester, and substrate are shown to impact isomeric product ratios. Linear regression mathematical modeling is used to define a relationship that equates both IR stretching parameters and Hammett σ+ values to the differential free energy of benzylic versus tertiary C–H amination. This model has informed the development of a novel Sulfamate Ester, which affords the highest benzylic-to-tertiary site selectivity (9.5:1) observed for this system
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Analyzing Site Selectivity in Rh2(esp)2-Catalyzed Intermolecular C–H Amination Reactions
Journal of the American Chemical Society, 2014Co-Authors: Elizabeth N. Bess, Ryan J. Deluca, Daniel J. Tindall, Martins S. Oderinde, Jennifer L. Roizen, J. Du Bois, Matthew S. SigmanAbstract:Predicting site selectivity in C–H bond oxidation reactions involving heteroatom transfer is challenged by the small energetic differences between disparate bond types and the subtle interplay of steric and electronic effects that influence reactivity. Herein, the factors governing selective Rh2(esp)2-catalyzed C–H amination of isoamylbenzene derivatives are investigated, where modification to both the nitrogen source, a Sulfamate Ester, and substrate are shown to impact isomeric product ratios. Linear regression mathematical modeling is used to define a relationship that equates both IR stretching parameters and Hammett σ+ values to the differential free energy of benzylic versus tertiary C–H amination. This model has informed the development of a novel Sulfamate Ester, which affords the highest benzylic-to-tertiary site selectivity (9.5:1) observed for this system.
Nobuhiro Fusetani - One of the best experts on this subject based on the ideXlab platform.
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Isolation and structure elucidation of two phosphorylated sterol sulfates, MT1-MMP inhibitors from a marine sponge Cribrochalina sp.: revision of the structures of haplosamates A and B
Tetrahedron, 2001Co-Authors: Masaki Fujita, Youichi Nakao, Shigeki Matsunaga, Motoharu Seiki, Yoshifumi Itoh, Rob W. M. Van Soest, Markus Heubes, D. John Faulkner, Nobuhiro FusetaniAbstract:Abstract Two inhibitors of membrane-type matrix metalloproteinase (MT1-MMP) were isolated from a marine sponge Cribrochalina sp. Their structures were elucidated as unusual phosphorylated sterol sulfates by spectroscopic and chemical methods. One of the sterol sulfates was found to be identical to haplosamate A, whose structure was previously proposed to be a steroidal Sulfamate Ester, which led to structure revisions of both haplosamates A and B. The absolute stereochemistry of haplosamate A was determined by chemical transformation and the modified Mosher's method. The sterol sulfates inhibited MT1-MMP with IC50 values of 150 and 160 μg/mL, respectively.
