2-methoxyestradiol-3-17-o-o-bis(sulfamate) and Breast-Neoplasms

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

Despite paclitxael's clinical success, treating hormone-refractory breast cancer remains challenging. Paclitaxel has a poor pharmacological profile, characterized by a low therapeutic index (TIX) caused by severe dose limiting toxicities, such as neutropenia and peripheral neuropathy. Consequently, new drugs are urgently required. STX140, a compound previously shown to have excellent efficacy against many tumors, is here compared to paclitaxel in three translational in vivo breast cancer models, a rat model of peripheral neuropathy, and through pharmacological testing. Three different in vivo mouse models of breast cancer were used; the metastatic 4T1 orthotopic model, the C3(1)/SV40 T-Ag model, and the MDA-MB-231 xenograft model. To determine TIX and pharmacological profile of STX140, a comprehensive dosing regime was performed in mice bearing MDA-MD-231 xenografts. Finally, peripheral neuropathy was examined using a rat plantar thermal hyperalgesia model. In the 4T1 metastatic model, STX140 and paclitaxel significantly inhibited primary tumor growth and lung metastases. All C3(1)/SV40 T-Ag mice in the control and paclitaxel treated groups developed palpable mammary cancer. STX140 blocked 47% of tumors developing and significantly inhibited growth of tumors that did develop. STX140 treatment caused a significant (P<0.001) survival advantage for animals in early and late intervention groups. Conversely, in C3(1)/SV40 T-Ag mice, paclitaxel failed to inhibit tumor growth and did not increase survival time. Furthermore, paclitaxel, but not STX140, induced significant peripheral neuropathy and neutropenia. These results show that STX140 has a greater anti-cancer efficacy, TIX, and reduced neurotoxicity compared to paclitaxel in C3(1)/SV40 T-Ag mice and therefore may be of significant benefit to patients with breast cancer.

Topics: Adenocarcinoma; Animals; Antigens, Polyomavirus Transforming; Antineoplastic Agents; Breast Neoplasms; Disease Progression; Drug Administration Schedule; Drug Dosage Calculations; Estrenes; Female; Humans; Hyperalgesia; Lung Neoplasms; Mammary Glands, Animal; Mammary Neoplasms, Experimental; Mice; Mice, Transgenic; Paclitaxel; Peripheral Nervous System Diseases; Rats; Survival Analysis; Transplantation, Heterologous

A priority in recent anti-cancer drug development has been attaining better side-effect profiles for potential compounds. To produce highly specific cancer therapies it is necessary to understand both the effects of the proposed compound on cancer and on normal cells comprising the rest of the human body. Thus in vitro evaluation of these compounds against non-carcinogenic cell lines is of critical importance. One of the most recent developments in experimental anti-cancer agents is 2-methoxyestradiol-bis-sulphamate (2ME-BM), a sulphamoylated derivative of 2-methoxyestradiol. The aim of this study was to evaluate the in vitro effects of 2ME-BM on cell proliferation, morphology and mechanisms of cell death in the non-carcinogenic MCF-12A breast epithelial cell line. The study revealed changes in proliferative capacity, morphology and cell death induction in response to 2ME-BM exposure (24 h at 0.4 microM). Microscopy showed decreased cell density and cell death-associated morphology (increased apoptotic characteristics), a slight increase in acidic intracellular vesicles and insignificant ultra-structural aberrations. Mitotic indices revealed a G(2)M-phase cell cycle block. This was confirmed by flow cytometry, where an increased fraction of abnormal cells and a decrease in cyclin B1 levels were observed. These results evidently demonstrate that the non-carcinogenic MCF-12A cell line is less susceptible when compared to 2ME-BM-exposed cancer cell lines previously tested. Further in vitro research into the mechanism of this potentially useful compound is warranted.

Topics: Antineoplastic Agents; Apoptosis; Breast Neoplasms; Cell Division; Cell Line, Tumor; Cyclin B1; Estrenes; Female; Flow Cytometry; G2 Phase; Humans; Time Factors

The anti-proliferative and anti-angiogenic properties of the endogenous oestrogen metabolite, 2-methoxyoestradiol (2-MeOE2), are enhanced in a series of sulphamoylated derivatives of 2-MeOE2. To investigate possible mechanisms of resistance to these compounds, a cell line, A2780.140, eightfold less sensitive to the 3,17-O,O-bis-sulphamoylated derivative, STX140, was derived from the A2780 ovarian cancer cell line by dose escalation. Other cell lines tested did not develop STX140 resistance. RT-PCR and immunoblot analysis demonstrated that breast cancer resistance protein (BCRP) expression is dramatically increased in A2780.140 cells. The cells are cross-resistant to the most structurally similar bis-sulphamates, and to BCRP substrates, mitoxantrone and doxorubicin; but they remain sensitive to taxol, an MDR1 substrate, and to all other sulphamates tested. Sensitivity can be restored using a BCRP inhibitor, and this pattern of resistance is also seen in a BCRP-expressing MCF-7-derived cell line, MCF-7.MR. In mice bearing wild-type (wt) and BCRP-expressing tumours on either flank, both STX140 and mitoxantrone inhibited the growth of the MCF-7wt xenografts, but only STX140 inhibited growth of the MCF-7.MR tumours. In conclusion, STX140, a promising orally bioavailable anti-cancer agent in pre-clinical development, is highly efficacious in BCRP-expressing xenografts. This is despite an increase in BCRP expression in A2780 cells in vitro after chronic dosing with STX140.

Topics: Animals; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Base Sequence; Blotting, Western; Breast Neoplasms; Cell Cycle; Cell Line, Tumor; DNA Primers; Drug Resistance, Neoplasm; Estrenes; Female; Flow Cytometry; Humans; Mice; Neoplasm Proteins; Ovarian Neoplasms; Reverse Transcriptase Polymerase Chain Reaction

The steroidal-based drug 2-ethyloestradiol-3,17-O,O-bis-sulphamate (STX243) has been developed as a potent antiangiogenic and antitumour compound. The objective of this study was to ascertain whether STX243 is more active in vivo than the clinically relevant drug 2-methoxyoestradiol (2-MeOE2) and the structurally similar compound 2-MeOE2-3,17-O,O-bis-sulphamate (STX140). The tumour growth inhibition efficacy, antiangiogenic potential and pharmacokinetics of STX243 were examined using four in vivo models. Both STX243 and STX140 were capable of retarding the growth of MDA-MB-231 xenograft tumours (72 and 63%, respectively), whereas no inhibition was observed for animals treated with 2-MeOE2. Further tumour inhibition studies showed that STX243 was also active against MCF-7 paclitaxel-resistant tumours. Using a Matrigel plug-based model, in vivo angiogenesis was restricted with STX243 and STX140 (50 and 72%, respectively, using a 10 mg kg(-1) oral dose), thereby showing the antiangiogenic activity of both compounds. The pharmacokinetics of STX243 were examined at two different doses using adult female rats. The compound was orally bioavailable (31% after a single 10 mg kg(-1) dose) and resistant to metabolism. These results show that STX243 is a potent in vivo drug and could be clinically effective at treating a number of oncological conditions.

Topics: 2-Methoxyestradiol; Angiogenesis Inhibitors; Animals; Breast Neoplasms; Cell Line, Tumor; Estradiol; Estrenes; Female; Humans; Mice; Mice, Inbred C57BL; Rats; Rats, Wistar; Sulfonic Acids

Drug combination therapy is a key strategy to improve treatment efficacy and survival of cancer patients. In this study the effects of combining 2-methoxyoestradiol-3,17-O,O-bis-sulphamate (STX140), a microtubule disruptor, with 2-deoxy-D-glucose (2DG) were assessed in MCF-7 (breast) and LNCaP (prostate) xenograft models in vivo. In mice bearing MCF-7 xenografts, daily p.o. administration of STX140 (5 mg kg(-1)) resulted in a 46% (P<0.05) reduction of tumour volume. However, the combination of STX140 (5 mg kg(-1) p.o.) and 2DG (2 g kg(-1) i.p.) reduced tumour volume by 76% (P<0.001). 2-Methoxyoestradiol-3,17-O,O-bis-sulphamate also reduced tumour vessel density. 2-Deoxy-D-glucose alone had no significant effect on tumour volume or vessel density. A similar benefit of the combination treatment was observed in the LNCaP prostate xenograft model. In vitro the degree of inhibition of cell proliferation by STX140 was unaffected by oxygen concentrations. In contrast, the inhibition of proliferation by 2DG was enhanced under hypoxia by 20 and 25% in MCF-7 and LNCaP cells, respectively. The combination of STX140 and 2DG in LNCaP cells under normoxia or hypoxia inhibited proliferation to a greater extent than either compound alone. These results suggest that the antiangiogenic and microtubule disruption activities of STX140 may make tumours more susceptible to inhibition of glycolysis by 2DG. This is the first study to show the benefit of combining a microtubule disruptor with 2DG in the two most common solid tumours.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Breast Neoplasms; Cell Cycle; Cell Hypoxia; Cell Line, Tumor; Cell Proliferation; Deoxyglucose; Estrenes; Female; Humans; Immunohistochemistry; Male; Mice; Mice, Nude; Prostatic Neoplasms; Xenograft Model Antitumor Assays

The aim of these studies was to characterize the action of STX140 in a P-glycoprotein-overexpressing tumor cell line both in vitro and in vivo. In addition, its efficacy was determined against xenografts derived from patients who failed docetaxel therapy.. The effects of STX140, Taxol, and 2-methoxyestradiol (2-MeOE2) on cell proliferation, cell cycle, and apoptosis were assessed in vitro in drug-resistant cells (MCF-7(DOX)) and the parental cell line (MCF-7(WT)). Mice bearing an MCF-7(DOX) tumor on one flank and an MCF-7(WT) tumor on the other flank were used to assess the in vivo efficacy. Furthermore, the responses to STX140 of three xenografts, derived from drug-resistant patients, were assessed.. In this study, STX140 caused cell cycle arrest, cyclin B1 induction, and subsequent apoptosis of both MCF-7(DOX) and MCF-7(WT) cells. Taxol and 2-MeOE2 were only active in the MCF-7(WT) parental cell line. Although both STX140 and Taxol inhibited the growth of xenografts derived from MCF-7(WT) cells, only STX140 inhibited the growth of tumors derived from MCF-7(DOX) cells. 2-MeOE2 was ineffective at the dose tested against both tumor types. Two out of the three newly derived docetaxel-resistant xenografts, including a metastatic triple-negative tumor, responded to STX140 but not to docetaxel treatment.. STX140 shows excellent efficacy in both MCF-7(WT) and MCF-7(DOX) breast cancer xenograft models, in contrast to Taxol and 2-MeOE2. The clinical potential of STX140 was further highlighted by the efficacy seen in xenografts recently derived from patients who had failed on taxane therapy.

Topics: 2-Methoxyestradiol; Animals; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Apoptosis; ATP Binding Cassette Transporter, Subfamily B, Member 1; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Drug Resistance, Neoplasm; Estradiol; Estrenes; Humans; Mice; Mice, Nude; Paclitaxel; Tubulin Modulators; Xenograft Model Antitumor Assays

Therapies for hormone-independent prostate and breast cancer are limited, with the effectiveness of the taxanes compromised by toxicity, lack of oral bioavailability and drug resistance. This study aims to identify and characterise new microtubule disruptors, which may have improved efficacy relative to the taxanes in hormone-independent cancer. 2-Methoxy-3-O-sulphamoyl-17beta-cyanomethyl-oestra-1,3,5(10)-triene (STX641), 2-methoxy-3-hydroxy-17beta-cyanomethyl-oestra-1,3,5(10)-triene (STX640) and 2-methoxyoestradiol-3,17-O,O-bis-sulphamate (STX140) were all potent inhibitors of cell proliferation in a panel of prostate and breast cancer cell lines. STX641 and STX640 significantly inhibited tumour growth in the MDA-MB-231 xenograft model. STX641 inhibited both in vitro and in vivo angiogenesis. Despite good in vivo activity, STX641 was not as potent in vivo as STX140. Therefore, STX140 was evaluated in the prostate hormone-independent PC-3 xenograft model. STX140 had superior efficacy to docetaxel, 2-MeOE2 and bevacizumab. In contrast to vinorelbine, no significant toxicity was observed. Furthermore, STX140 could be dosed daily over a 60-day period leading to tumour regression and complete responses, which were maintained after the cessation of dosing. This study demonstrates that STX641 and STX140 have considerable potential for the treatment of hormone-independent breast and prostate cancer. In contrast to the taxanes, STX140 can be dosed orally, with no toxicity being observed even after prolonged daily dosing.

Topics: Angiogenesis Inhibitors; Animals; Apoptosis; Breast Neoplasms; Cell Cycle; Cell Proliferation; Cells, Cultured; Drug Resistance, Neoplasm; Endothelial Cells; Estrenes; Female; Humans; Male; Mice; Mice, Nude; Neoplasms, Hormone-Dependent; Prostatic Neoplasms; Tubulin Modulators

The anticancer activities and SARs of estradiol-17-O-sulfamates and estradiol 3,17-O,O-bis-sulfamates (E2bisMATEs) as steroid sulfatase (STS) inhibitors and antiproliferative agents are discussed. Estradiol 3,17-O,O-bis-sulfamates 20 and 21, in contrast to the 17-O-monosulfamate 11, proved to be excellent STS inhibitors. 2-Substituted E2bisMATEs 21 and 23 additionally exhibited potent antiproliferative activity with mean graph midpoint values of 18-87 nM in the NCI 60-cell-line panel. 21 Exhibited antiangiogenic in vitro and in vivo activity in an early-stage Lewis lung model, and 23 dosed p.o. caused marked growth inhibition in a nude mouse xenograft tumor model. Modeling studies suggest that the E2bisMATEs and 2-MeOE2 share a common mode of binding to tubulin, though COMPARE analysis of activity profiles was negative. 21 was cocrystallized with carbonic anhydrase II, and X-ray crystallography revealed unexpected coordination of the 17-O-sulfamate of 21 to the active site zinc and a probable additional lower affinity binding site. 2-Substituted E2bisMATEs are attractive candidates for further development as multitargeted anticancer agents.

Topics: Animals; Antineoplastic Agents; Binding Sites; Breast Neoplasms; Carbonic Anhydrase II; Carcinoma, Lewis Lung; Cell Proliferation; Crystallography, X-Ray; Estradiol; Female; Humans; Mice; Mice, Nude; Models, Molecular; Neovascularization, Pathologic; Steryl-Sulfatase; Structure-Activity Relationship; Sulfonic Acids; Survival Rate; Tumor Cells, Cultured; Xenograft Model Antitumor Assays; Zinc