irosustat and Breast-Neoplasms

Estrogen governs the regulations of various pathological and physiological actions throughout the body in both males and females. Generally, 17β-estradiol an endogenous estrogen is responsible for different health problems in pre and postmenopausal women. The major activities of endogenous estrogen are executed by nuclear estrogen receptors (ERs) ERα and ERβ while non-genomic cytoplasmic pathways also govern cell growth and apoptosis. Estrogen accomplished a fundamental role in the formation and progression of breast cancer. In this review, we have hyphenated different studies regarding ERs and a thorough and detailed study of estrogen receptors is presented. This review highlights different aspects of estrogens ranging from receptor types, their isoforms, structures, signaling pathways of ERα, ERβ and GPER along with their crystal structures, pathological roles of ER, ER ligands, and therapeutic strategies to overcome the resistance.

Topics: Breast Neoplasms; Estradiol; Estrogen Receptor alpha; Estrogen Receptor beta; Estrogens; Female; Humans; Ligands; Male; Receptors, Estrogen

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Drug Design; Enzyme Inhibitors; Female; Humans; Patents as Topic; Steryl-Sulfatase; Sulfonic Acids

Steroid sulfatase (STS) plays a momentous role in the conversion of sulfated steroids, which are biologically inactive, into biologically active un-sulfated steroid hormones, which support the development and growth of a number of hormone-dependent cancers, including breast cancer. Therefore, inhibitors of STS are supposed to be potential drugs for the treatment of breast and other steroid-dependent cancers. The present review concentrates on broad chemical classification of steroid sulfatase inhibitors. The inhibitors reviewed are classified into four main categories: Steroid sulfamate based inhibitors; Steroid non-sulfamate based inhibitors; Non-steroidal sulfamate based inhibitors; Non-steroidal non-sulfamate based inhibitors. A succinct overview of current treatment of cancer, estradiol precursors, STS enzyme and its role in breast cancer is herein described.

Topics: Breast Neoplasms; Enzyme Inhibitors; Estrogens; Female; Humans; Neoplasm Recurrence, Local; Sulfatases; Sulfonic Acids

Manipulation of the hormone oestrogen has been used for decades to treat hormone-dependent breast cancer. Currently, aromatase inhibitors (AIs) are used as first-line therapy against early and metastatic breast cancer in post-menopausal women. Despite these advances, several patients eventually experience a relapse of breast cancer and declined clinical response to treatment. As per recent findings, steroid sulfatase (STS) has emerged as a novel therapy target. This review aims at summarising the emerging field of STS inhibitor development and highlighting current findings from pre-clinical and clinical trials. The recently-developed dual-targeting compounds, such as dual aromatase-sulfatase inhibitors (DASI), have shown encouraging preclinical results and represent important new treatments for hormone-dependent breast cancer.

Topics: Aromatase Inhibitors; Azasteroids; Breast Neoplasms; Coumarins; Drug Discovery; Enzyme Inhibitors; Estrogens; Female; Humans; Steryl-Sulfatase; Sulfonamides; Sulfonic Acids

Steroid sulfatase (STS) converts sulfated hormones to free hormones of importance in hormone-dependent diseases such as breast cancer and endometriosis. Carbohydrate sulfatases degrade complex carbohydrates as part of normal cellular turnover; certain lysosomal storage disorders (LSDs) involve defective processing of sulfated glycosaminoglycans by mutant sulfatases.. Aryl sulfamates have been developed as STS inhibitors, and STX64 and PGL2001 are under evaluation in Phase I and II clinical trials for treatment of endometrial and metastatic breast and prostate cancers and endometriosis. Dual-acting compounds have emerged that are aromatase inhibitors (AIs), selective estrogen receptor antagonists, or inhibitors of microtubule polymerization. Sulfamidase inhibitors as pharmacological chaperones to assist maturation of folding-defective mutants for the treatment of Sanfilippo type A disease are under investigation. Coverage: The patent literature after the mid-1990s.. The failure of STX64 in a Phase II monotherapy clinical trial should not dissuade further investigations in multidrug regimens, particularly in combination with AIs. The recent development of dual-acting compounds may enhance the potential for success in the clinic. Further investigations into aryl sulfamates are required to clarify the molecular mechanism of action; additionally, new reversible sulfatase inhibition concepts are needed for the development of pharmacological chaperones for sulfatase LSDs.

Topics: Animals; Breast Neoplasms; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Drug Design; Endometriosis; Enzyme Inhibitors; Estradiol; Female; Humans; Male; Mucopolysaccharidosis III; Patents as Topic; Prostatic Neoplasms; Steryl-Sulfatase; Sulfonic Acids

Endocrine therapy is a key modality in the management of breast cancer, with current options for postmenopausal women including tamoxifen, aromatase inhibitors and fulvestrant. Unfortunately, in spite of these advances, many women still relapse or progress on endocrine therapy. Given that resistance (de novo or acquired resistance) is a major limiting factor in the use of endocrine therapy, additional endocrine therapies with novel methods of action are required. Steroid sulfatase, which is responsible for the conversion of estrone sulfate to estrone, as well as dehydroepiandrosterone sulfate to dehydroepiandrosterone, has been implicated in endocrine resistance. In this article, we summarize the preclinical and clinical data to support the potential role of steroid sulfatase in breast cancer, as well as the current data on the first available steroid sulfatase inhibitor named irosustat (STX64; 667 Coumate; BN83495), and discuss its potential clinical development.

Topics: Antineoplastic Agents, Hormonal; Aromatase Inhibitors; Breast Neoplasms; Clinical Trials, Phase II as Topic; Dehydroepiandrosterone Sulfate; Estradiol; Estrone; Female; Fulvestrant; Humans; Neoplasms, Hormone-Dependent; Steryl-Sulfatase; Sulfonic Acids; Tamoxifen

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.

Topics: Antineoplastic Agents, Hormonal; Breast Neoplasms; Clinical Trials as Topic; Enzyme Inhibitors; Female; Humans; Neoplasms, Hormone-Dependent; Steryl-Sulfatase; Sulfonic Acids

Steroid sulfatase (STS) is responsible for the hydrolysis of aryl and alkyl steroid sulfates and therefore has a pivotal role in regulating the formation of biologically active steroids. The enzyme is widely distributed throughout the body, and its action is implicated in physiological processes and pathological conditions. The crystal structure of the enzyme has been resolved, but relatively little is known about what regulates its expression or activity. Research into the control and inhibition of this enzyme has been stimulated by its important role in supporting the growth of hormone-dependent tumors of the breast and prostate. STS is responsible for the hydrolysis of estrone sulfate and dehydroepiandrosterone sulfate to estrone and dehydroepiandrosterone, respectively, both of which can be converted to steroids with estrogenic properties (i.e., estradiol and androstenediol) that can stimulate tumor growth. STS expression is increased in breast tumors and has prognostic significance. The role of STS in supporting tumor growth prompted the development of potent STS inhibitors. Several steroidal and nonsteroidal STS inhibitors are now available, with the irreversible type of inhibitor having a phenol sulfamate ester as its active pharmacophore. One such inhibitor, 667 COUMATE, has now entered a phase I trial in postmenopausal women with breast cancer. The skin is also an important site of STS activity, and deficiency of this enzyme is associated with X-linked ichthyosis. STS may also be involved in regulating part of the immune response and some aspects of cognitive function. The development of potent STS inhibitors will allow investigation of the role of this enzyme in physiological and pathological processes.

Topics: Animals; Breast Neoplasms; Clinical Trials, Phase I as Topic; Coumarins; Enzyme Inhibitors; Estrone; Female; Humans; Models, Molecular; Neoplasms, Hormone-Dependent; Steryl-Sulfatase; Sulfonamides; Sulfonic Acids

In contrast to aromatase inhibitors, which are now in clinical use, the development of steroid sulphatase (STS) inhibitors for breast cancer therapy is still at an early stage. STS regulates the formation of oestrone from oestrone sulphate (E1S) but also controls the hydrolysis of dehydroepiandrosterone sulphate (DHEA-S). DHEA can be reduced to 5-androstenediol (Adiol), a steroid with potent oestrogenic properties. The active pharmacophore for potent STS inhibitors has now been identified, i.e. a sulphamate ester group linked to an aryl ring. This has led to the development of a number of STS inhibitors, some of which are due to enter Phase I trials in the near future. Such first generation inhibitors include the tricyclic coumarin-based 667 COUMATE. Aryl sulphamates, such as 667 COUMATE, are taken up by red blood cells (rbc), binding to carbonic anhydrase II (CA II), and transit the liver without undergoing first-pass inactivation. 667 COUMATE is also a potent inhibitor of CA II activity with an IC50 of 17 nM. Second generation STS inhibitors, such as 2-methoxyoestradiol bis-sulphamate (2-MeOE2bisMATE), in addition to inhibiting STS activity, also inhibit the growth of oestrogen receptor negative (ER-) tumours in mice and are anti-angiogenic. As the active pharmacaphores for the inhibition of aromatase and STS are now known it may be possible to develop third generation inhibitors that are capable of inhibiting the activities of both enzymes. Whilst exploring the potential of such a strategy it was discovered that 667 COUMATE possessed weak aromatase inhibitory properties with an IC50 of 300 nM in JEG-3 cells. The identification of potent STS inhibitors will allow the therapeutic potential of this new class of drug to be explored in post-menopausal women with hormone-dependent breast cancer. Second generation inhibitors, such as 2-MeOE2bisMATE, which also inhibit the growth of ER- tumours should be active against a wide range of cancers.

Topics: Animals; Aromatase Inhibitors; Breast Neoplasms; Coumarins; Enzyme Inhibitors; Erythrocytes; Estrogens; Humans; Mammary Neoplasms, Experimental; Steryl-Sulfatase; Sulfonamides; Sulfonic Acids

Steroid sulfatase (STS) is involved in oestrogen biosynthesis and irosustat is a first generation, irreversible steroid sulfatase inhibitor. A pre-surgical window-of-opportunity study with irosustat was undertaken in estrogen receptor-positive (ER+) breast cancer to assess the effect of irosustat on tumour cell proliferation as measured by 3'-deoxy-3'-[18F] fluorothymidine uptake measured by PET scanning (FLT-PET) and Ki67.. Postmenopausal women with untreated ER+ early breast cancer were recruited, and imaged with FLT-PET at baseline and after at least 2 weeks treatment with irosustat, 40 mg once daily orally. The primary endpoint was changed in FLT uptake; secondary endpoints included safety and tolerability of irosustat, changes in tumoral Ki67 and steroidogenic enzymes expression and circulating steroid hormone levels.. Thirteen women were recruited, and ten started irosustat for 2 weeks, followed by repeat FLT-PET scans in eight. Defining response as decreases of ≥20% in standardized uptake value (SUV) or ≥30% in Ki, 1 (12.5% (95% CI 2-47%, p = 0.001)) and 3 (43% (95% CI 16-75%, p = <0.001) patients, respectively, responded. 6 out of 7 patients had a Ki67 reduction (range = -19.3 to 76.4%), and median percentage difference in Ki67 was 52.3% (p = 0.028). In one patient with a low baseline STS expression, a 19.7% increase in Ki67 was recorded. STS decreases were seen in tumours with high basal STS expression, significant decreases were also noted in aromatase, and 17β-hydroxysteroid dehydrogenase type 1 and 2. Irosustat was generally well tolerated with all adverse event CTCAE Grade ≤2.. Irosustat resulted in a significant reduction in FLT uptake and Ki67, and is well tolerated. These data are the first demonstrating clinical activity of irosustat in early breast cancer. Baseline expression of STS may be a biomarker of sensitivity to irosustat.

Topics: Aged; Aged, 80 and over; Breast Neoplasms; Early Detection of Cancer; Female; Humans; Middle Aged; Positron-Emission Tomography; Postmenopause; Radiopharmaceuticals; Receptors, Estrogen; Steryl-Sulfatase; Sulfonic Acids; Treatment Outcome; Vascular Endothelial Growth Factor Receptor-1

Irosustat is the 'first-in-class' irreversible potent steroid sulphatase inhibitor with lack of oestrogenic activity. The objective of this work was to develop a population model characterizing simultaneously the pharmacokinetic profiles of irosustat in plasma and whole blood.. This clinical study was an open label, multicentre, phase I multiple cohort dose escalation trial conducted in 35 postmenopausal women with oestrogen-receptor positive breast cancer. Patients received 1, 5, 20, 40, or 80 mg oral doses. Irosustat was administered as a single oral dose to each patient followed by an observation period of 7 days. On day 8 each patient received once daily oral administration until day 34. Concentrations of irosustat in both blood and plasma were obtained and pharmacokinetic analyses were performed with NONMEM 7.2.. Irosustat showed non-linear disposition characteristics modelled as maximum binding capacity into the red blood cells. Plasma concentration corresponding to half of the maximum capacity was 32.79 ng/mL. The value of the blood to plasma concentration ratio in linear conditions was 419, indicating very high affinity for the red blood cells. Apparent plasma and blood clearances were estimated in 1199.52 and 3.90 L/day, respectively. Pharmacokinetics of irosustat showed low-moderate inter-subject variability, and neither the demographics (e.g., age, or weight) nor the phenotypes for CYP2C9, CYP2C19, and CYP3A5 enzymes showed statistically significant effects. Relative bioavailability was decreased as the administered dose was augmented. The model predicted a 47% decrease in relative bioavailability in the 40 mg with respect to the 1 mg dose.

Topics: Administration, Oral; Aged; Aged, 80 and over; Antineoplastic Agents, Hormonal; Breast Neoplasms; Erythrocytes; Female; Humans; Middle Aged; Models, Biological; Nonlinear Dynamics; Postmenopause; Receptors, Estrogen; Sulfonic Acids

Inhibition of steroid sulfatase (STS), the enzyme responsible for the hydrolysis of steroid sulfates, represents a potential novel treatment for postmenopausal women with hormone-dependent breast cancer. Estrone and DHEA are formed by this sulfatase pathway and can be converted to steroids (estradiol and androstenediol, respectively), which have potent estrogenic properties.. STX64 (667 Coumate), a tricylic coumarin-based sulfamate that irreversibly inhibits STS activity, was selected for entry into the first phase I trial of a STS inhibitor in postmenopausal women with breast cancer. STX64 was administered orally (nine patients at 5 mg and five patients at 20 mg) as an initial dose followed 1 week later by 3 x 2 weekly cycles, with each cycle comprising daily dosing for 5 days followed by 9 days off treatment. Blood and tumor tissue samples were collected for the assessment of STS activity and serum was obtained for steroid hormone measurements before and after treatment.. The median inhibition of STS activity by STX64 was 98% in peripheral blood lymphocytes (PBL) and 99% in breast tumor tissue at the end of the 5-day dosing period. As expected, serum concentrations of estrone, estradiol, androstenediol, and DHEA all decreased significantly from pretreatment levels. Unexpectedly, androstenedione and testosterone concentrations also decreased. Four patients, all of whom had previously progressed on aromatase inhibitors, showed evidence of stable disease for 2.75 to 7 months. The drug was well tolerated with only minor drug-related adverse events recorded.. STX64 is a potent, well-tolerated STS inhibitor. It inhibits STS activity in PBLs and tumor tissues and causes significant decreases in serum concentrations of steroids with estrogenic properties.

Topics: Administration, Oral; Adult; Aged; Aged, 80 and over; Androstenediol; Breast Neoplasms; Coumarins; Dose-Response Relationship, Drug; Estradiol; Estrone; Female; Humans; Maximum Tolerated Dose; Middle Aged; Neoplasm Metastasis; Neoplasms, Hormone-Dependent; Steryl-Sulfatase; Sulfonamides; Sulfonic Acids; Testosterone

Topics: Animals; Breast Neoplasms; Enzyme Inhibitors; Female; Humans; MCF-7 Cells; Mice; Phenol; Steryl-Sulfatase; Structure-Activity Relationship

Steroid sulfatase (STS) has recently emerged as a drug target for management of hormone-dependent malignancies. In the present study, a new series of twenty-one aryl amido-linked sulfamate derivatives 1a-u was designed and synthesized, based upon a cyclohexyl lead compound. All members were evaluated as STS inhibitors in a cell-free assay. Adamantyl derivatives 1h and 1p-r were the most active with more than 90% inhibition at 10 µM concentration and, for those with the greatest inhibitory activity, IC

Topics: Antineoplastic Agents; Breast Neoplasms; Cell-Free System; Female; Humans; Inhibitory Concentration 50; Molecular Structure; Steryl-Sulfatase; Structure-Activity Relationship; Sulfonic Acids

Steroid sulfatase is detectable in most hormone-dependent breast cancers. STX64, an STS inhibitor, induced tumor reduction in animal assay. Despite success in phase І clinical trial, the results of phase II trial were not that significant. Breast Cancer epithelial cells (MCF-7 and T47D) were treated with two STS inhibitors (STX64 and EM1913). Cell proliferation, cell cycle, and the concentrations of estradiol and 5α-dihydrotestosterone were measured to determine the endocrinological mechanism of sulfatase inhibition. Comparisons were made with inhibitions of reductive 17β-hydroxysteroid dehydrogenases (17β-HSDs). Proliferation studies showed that DNA synthesis in cancer cells was modestly decreased (approximately 20%), accompanied by an up to 6.5% in cells in the G0/G1 phase and cyclin D1 expression reduction. The concentrations of estradiol and 5α-dihydrotestosterone were decreased by 26% and 3% respectively. However, supplementation of 5α-dihydrotestosterone produced a significant increase (approximately 35.6%) in the anti-proliferative effect of sulfatase inhibition. This study has clarified sex-hormone control by sulfatase in BC, suggesting that the different roles of estradiol and 5α-dihydrotestosterone can lead to a reduction in the effect of sulfatase inhibition when compared with 17β-HSD7 inhibition. This suggests that combined treatment of sulfatase inhibitors with 17β-HSD inhibitors such as the type7 inhibitor could hold promise for hormone-dependent breast cancer.

Topics: Aromatase Inhibitors; Breast Neoplasms; Cell Cycle; Cell Proliferation; Cyclin D1; Dihydrotestosterone; Drug Therapy, Combination; Estradiol; Estradiol Dehydrogenases; Female; Gene Expression Regulation, Neoplastic; Humans; Neoplasms, Hormone-Dependent; Steryl-Sulfatase; Sulfonic Acids; Tumor Cells, Cultured

STS and 17β-HSD1 are attractive targets for the treatment of estrogen-dependent diseases like endometriosis and breast cancer. The simultaneous inhibition of both enzymes appears more promising than blockage of either protein alone. We describe a designed multiple ligand approach resulting in highly potent dual inhibitors. The most interesting compound 9 showed nanomolar IC

Topics: 17-Hydroxysteroid Dehydrogenases; Breast Neoplasms; Cell Proliferation; Endometriosis; Enzyme Inhibitors; Female; Humans; Ligands; Steryl-Sulfatase

In 1994, following work from this laboratory, it was reported that estrone-3-O-sulfamate irreversibly inhibits a new potential hormone-dependent cancer target steroid sulfatase (STS). Subsequent drug discovery projects were initiated to develop the core aryl O-sulfamate pharmacophore that, over some 20 years, have led to steroidal and nonsteroidal drugs in numerous preclinical and clinical trials, with promising results in oncology and women's health, including endometriosis. Drugs have been designed to inhibit STS, e.g., Irosustat, as innovative dual-targeting aromatase-steroid sulfatase inhibitors (DASIs) and as multitargeting agents for hormone-independent tumors, such as the steroidal STX140 and nonsteroidal counterparts, acting inter alia through microtubule disruption. The aryl sulfamate pharmacophore is highly versatile, operating via three distinct mechanisms of action, and imbues attractive pharmaceutical properties. This Perspective gives a personal view of the work leading both to the therapeutic concepts and these drugs, their current status, and how they might develop in the future.

Topics: Animals; Antineoplastic Agents; Aromatase Inhibitors; Breast Neoplasms; Drug Discovery; Endometriosis; Estrone; Female; Humans; Male; Molecular Targeted Therapy; Prostatic Neoplasms; Steryl-Sulfatase; Sulfonic Acids; Tubulin Modulators

Steroid sulfatase (STS) catalyzes the desulfation of biologically inactive sulfated steroids to yield biologically active desulfated steroids and is currently being examined as a target for therapeutic intervention for the treatment of breast cancer. We previously demonstrated that 4-formyl estrone is a time- and concentration-dependent inhibitor of STS. We have prepared a series of 4-formylated estrogens and examined them as irreversible STS inhibitors. Introducing a formyl, bromo or nitro group at the 2-position of 4-formylestrone resulted in loss of concentration and time-dependent inhibition and a considerable decrease in binding affinity. An estradiol derivative bearing a formyl group at the 4-position and a benzyl group at the 17β-position yielded a potent concentration and time-dependent STS inhibitor with a K(I) of 85 nM and a k(inact) of 0.021 min(-1) (k(inact)/K(I) of 2.3 × 10(5)M(-1)min(-1)). Studies with estrone or estradiol substituted at the 4-position with groups other than a formyl group revealed that good reversible inhibitors can be obtained by introducing small electron withdrawing groups at this position. An estradiol derivative with fluorine at the 4-position and a benzyl group at the 17β-position yielded a potent, reversible inhibitor of STS with an IC(50) of 40 nM. The introduction of relatively small electron withdrawing groups at the 4-position of estrogens and their derivatives may prove to be a general approach to enhancing the potency of estrogen-derived STS inhibitors.

Topics: Breast Neoplasms; Enzyme Inhibitors; Estradiol; Estrone; Female; Humans; Kinetics; Placenta; Pregnancy; Steryl-Sulfatase

Thiosemicarbazones of the microbial metabolite madurahydroxylactone, a polysubstituted benzo[a]naphthacenequinone, have been previously reported by us as potent nonsteroidal inhibitors of the enzyme estrone sulfatase (cyclohexylthiosemicarbazone 1, IC50 0.46 microM). The active pharmacophore of 1 has now been identified to be 2-formyl-6-hydroxybenzoic acid cyclohexylthiosemicarbazone (25, IC50 4.2 microM). The active partial structure was derivatized in the search for novel agents against hormone-dependent breast cancer. Further substantial increases in activity were achieved by reversal of functional groups leading to the cyclohexylthiosemicarbazones of 5-formylsalicylic acid (35, IC50 0.05 microM) and 3-formylsalicylic acid (34, IC50 0.15 microM) as the most potent analogues identified to date. Both compounds were shown to be noncompetitive inhibitors of estrone sulfatase with Ki values of 0.13 microM and 0.12 microM, respectively. The compounds showed low acute toxicity in the hen's fertile egg screening test.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Chickens; Female; Humans; In Vitro Techniques; Microsomes; Neoplasms, Hormone-Dependent; Placenta; Salicylates; Structure-Activity Relationship; Sulfatases; Thiosemicarbazones; Toxicity Tests, Acute

In the present study, we found that two hormone receptor-positive human breast cancer cell lines, ZR-75-1 and BT-474, naturally expressed steroid sulfatase (STS) protein and had catalytic activity to produce estrone from estrone sulfate (E1S) with a comparable level to those in human breast cancer tissues. E1S at physiological concentrations stimulated the growth of those cells. A novel steroidal STS inhibitor, KW-2581 inhibited the STS activity of ZR-75-1 cells with an IC(50) of 13 nM, a potency equal to or higher than that of the non-steroidal STS inhibitor, 667 COUMATE. The inhibitory effect of KW-2581 was enhanced by pre-incubation with STS enzyme, suggests being irreversible inhibition. KW-2581 inhibited the E1S-stimulated growth of ZR-75-1 cells with an IC(50) of 0.18 nM, but failed to inhibit the growth stimulated by 17beta-estradiol. Expression of E1S-induced progesterone receptors in ZR-75-1 cells was reduced by treatment of KW-2581 at concentrations as low as 0.1 nM. Oral administration of KW-2581 for 4 weeks caused tumor shrinkage in a mouse xenograft model. Tumor STS activity had been completely (>95%) eliminated by 24 hours after the last administration. These findings suggest that KW-2581 has considerable potential for therapeutic development as a novel anti-hormonal drug for treatment of breast cancer.

Topics: Animals; Breast Neoplasms; Cell Proliferation; Coumarins; Enzyme Inhibitors; Estradiol; Female; Gene Expression Regulation, Enzymologic; Humans; In Vitro Techniques; Mice; Mice, Inbred BALB C; Mice, Nude; Molecular Structure; Receptors, Progesterone; Signal Transduction; Steryl-Sulfatase; Sulfonamides; Sulfonic Acids; Tumor Cells, Cultured

We screened a series of 17beta-(N-alkylcarbamoyl)-estra-1,3,5(10)trine-3-O-sulfamate derivatives, and describe here a potent and selective steroid sulfatase (STS) inhibitor with antitumor effects in breast cancer models in vitro and in vivo. In biochemical assays using crude enzymes isolated from recombinant Chinese hamster ovary cells expressing human arylsulfatses (ARSs), one of the best compounds, KW-2581, inhibited STS activity with an IC(50) of 4.0 nM, while > 1000-fold higher concentrations were required to inhibit the other ARSs. The failure to stimulate the growth of MCF-7 human breast cancer cells as well as in uteri in ovariectomized rats indicated the lack of estrogenicity of this compound. In MCF-7 cells transfected with the STS gene, termed MCS-2 cells, KW-2581 inhibited the growth of cells stimulated by estrone sulfate (E1S) but also 5-androstene-3beta, 17beta-diol 3-sulfate (ADIOLS) and dehydroepiandrostenedione 3-sulfate. We found that oral administration of KW-2581 inhibited both E1S- and ADIOLS-stimulated growth of MCS-2 cells in a mouse hollow fiber model. In a nitrosomethylurea-induced rat mammary tumor model, KW-2581 induced regression of E1S-stimulated tumor growth as effectively as tamoxifen or another STS inhibitor, 667 Coumate. Dose-response studies in the same rat model demonstrated that more than 90% inhibition of STS activity in tumors was necessary to induce tumor shrinkage. STS activity in tumors has well correlated with that in leukocytes, suggesting that STS activity in leukocytes could be used as an easily detectable pharmacodynamic marker. These findings demonstrate that KW-2581 is a candidate for development as a therapeutic agent for the treatment of hormone receptors-positive breast cancer.

Topics: Administration, Oral; Animals; Breast Neoplasms; Cell Proliferation; Coumarins; Cricetinae; Disease Models, Animal; Enzyme Inhibitors; Estradiol; Estrogen Antagonists; Estrone; Female; Gene Expression Regulation, Enzymologic; Humans; Leukocytes; Methylnitrosourea; Molecular Structure; Rats; Rats, Sprague-Dawley; Receptors, Progesterone; Signal Transduction; Steryl-Sulfatase; Sulfonamides; Sulfonic Acids; Tamoxifen; Tumor Cells, Cultured

Topics: Antineoplastic Agents, Hormonal; Aromatase Inhibitors; Breast Neoplasms; Coumarins; Female; Humans; Sulfonamides; Sulfonic Acids; Tamoxifen; Treatment Outcome

Breast cancer is a major cause of mortality in Western countries and there is an urgent requirement for novel treatment strategies. The nonsteroidal sulphatase inhibitor 667 COUMATE inhibits hepatic steroid sulphatase and growth of oestrone sulphate stimulated tumours in the nitrosomethylurea-induced rat mammary model. Other compounds that contain an aryl sulphamate moiety, for example, oestrone-3-O-sulphamate, are sequestered into red blood cells (RBCs). The aims of this study were to determine the pharmacokinetics of 667 COUMATE and to investigate its sequestration into RBCs. We administered a single p.o. or i.v. dose (10 mg kg(-1)) of 667 COUMATE to rats and used a high-performance liquid chromatography method to measure the levels of the agent and its putative metabolites in plasma. 667 COUMATE had a bioavailability of 95% and could be detected in plasma for up to 8 h. Using two independent analytical methods, we demonstrated that 667 COUMATE is sequestered by RBCs both ex vivo and in vivo. Previous investigations have revealed that 667 COUMATE is rapidly degraded in plasma ex vivo. In this study, we demonstrate that 667 COUMATE is stabilised due to its sequestration into RBCs. In conclusion, the pharmacological efficacy and high oral bioavailability of 667 COUMATE may be partly a consequence of the ability of RBCs to both protect the agent from metabolic degradation and facilitate its transport to tissues. These data support the further clinical evaluation of this novel endocrine therapeutic agent.

Topics: Administration, Oral; Animals; Breast Neoplasms; Chromatography, High Pressure Liquid; Coumarins; Erythrocytes; Female; Infusions, Intravenous; Rats; Rats, Wistar; Sulfonamides; Sulfonic Acids

The development of inhibitors to block the formation of estrone and 5-androstenediol from sulfated precursors is an important new strategy for the treatment of breast cancer. In this study a series of tricyclic coumarin sulfamates (665-668 COUMATE) and a tricyclic oxepin sulfamate have been synthesised and tested for their ability to inhibit estrone sulfatase activity (E1-STS). In addition the effect of the steroid-based E1-STS inhibitor, 2-methoxyestrone-3-O-sulfamate (2-MeOEMATE) on the morphology of MDA-MB-231 cells and breast tumour-derived fibroblasts was also examined. The tricyclic coumarin sulfamates and oxepin sulfamate were potent inhibitors of E1-STS activity with IC(50)s ranging from 8 to 250 nM. Of this series 667 COUMATE was the most potent inhibitor (IC(50)=8 nM) and was three-times more potent than estrone-3-O-sulfamate (EMATE, IC(50)=25 nM). 667 COUMATE did not stimulate the growth of MCF-7 breast cancer cells and is therefore devoid of estrogenicity. In vivo, 667 COUMATE inhibited E1-STS activity in rat liver tissue to a similar extent to that of EMATE. 2-MeOEMATE had a marked effect on the morphology of MDA-MB-231 cells and breast tumour-derived fibroblasts causing a significant increase in the number of rounded cells. 667 COUMATE and 2-MeOEMATE therefore offer considerable potential for development for cancer therapy.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Coumarins; Enzyme Inhibitors; Estrogens; Estrone; Female; Humans; Kinetics; Oxepins; Rats; Rats, Wistar; Sulfatases; Sulfonamides; Sulfonic Acids; Tumor Cells, Cultured

There is now abundant evidence that inhibition of steroid sulphatase alone or in conjunction with inhibition of aromatase may enhance the response of postmenopausal patients with hormone-dependent breast cancer to this type of endocrine therapy. Additionally, sulphatase inhibition has been proposed to be of potential therapeutic benefit in the immune system and for neuro-degenerative diseases. After the finding that our first highly potent active site-directed steroid sulphatase inhibitor, oestrone-3-O-sulphamate (EMATE), was highly oestrogenic, we proposed non-steroidal coumarin sulphamates such as 4-methylcoumarin-7-O-sulphamate (COUMATE) as alternative non-steroidal steroid sulphatase inhibitors. In this work, we describe how tricyclic coumarin-based sulphamates have been developed which are even more potent than COUMATE, are non-oestrogenic and orally active. We also discuss potential mechanisms of action.. 4-Ethyl- (4), 4-(n-propyl)- (6), 3-ethyl-4-methyl- (8), 4-methyl-3-(n-propyl)coumarin-7-O-sulphamate (11); the tricyclic derivatives 665COUMATE (13), 666COUMATE (15), 667COUMATE (17), 668COUMATE (20) and the tricyclic oxepin sulphamate (22) were synthesised. In a placental microsome preparation, all of these analogues were found to be more active than COUMATE in the inhibition of oestrone sulphatase, with the most potent inhibitor being 667COUMATE which has an IC(50) of 8 nM, some 3-fold lower than that for EMATE (25 nM). In addition, 667COUMATE was also found to inhibit DHEA-sulphatase some 25-fold more potently than EMATE in a placental microsome preparation. Like EMATE, 667COUMATE acts in a time- and concentration-dependent manner, suggesting that it is an active site-directed inhibitor. However, in contrast to EMATE, 667COUMATE has the important advantage of not being oestrogenic. In addition, we propose several diverse mechanisms of action for this active site-directed steroid sulphatase inhibitor in the light of recent publications on the crystal structures of human arylsulphatases A and B and the catalytic site topology for the hydrolysis of a sulphate ester.. A highly potent non-steroidal, non-oestrogenic and irreversible steroid sulphatase inhibitor has been developed. Several mechanisms of action for an active site-directed steroid sulphatase inhibitor are proposed. With 667COUMATE now in pre-clinical development for clinical trial, this should allow the biological and/or clinical significance of steroid sulphatase inhibitors in the treatment of postmenopausal women with hormone-dependent breast cancer and other therapeutic indications to be fully evaluated.

Topics: Alanine; Antineoplastic Agents; Arylsulfatases; Binding Sites; Breast Neoplasms; Coumarins; Dehydroepiandrosterone Sulfate; Dose-Response Relationship, Drug; Estrone; Female; Glycine; Heterocyclic Compounds, 3-Ring; Humans; Hydrogen Bonding; Kinetics; Microsomes; Models, Molecular; Placenta; Postmenopause; Steryl-Sulfatase; Structure-Activity Relationship; Sulfatases; Sulfonamides; Sulfonic Acids