toremifene and droloxifene

During recent years the development of hormone therapy for the treatment breast neoplasms has seen, in addition to classic aspecific antiestrogens (AE) like tamoxifen (TAM) and to a lesser extent toremifen, a major development of new molecules divided into two groups: the first is the so-called selective estrogen receptor modulators (SERMs), the most important of which is Raloxifen, which mediate estrogen-agonist effects in some tissues and estrogen-antagonist effects in others; the second group includes the aromatase inhibitors (AI), important enzymes for peripheral estrogen conversion. Some studies compare or associate classic AE with the new SERMs and AI, both in adjuvant therapy and in treatment for advanced forms. Other trials assess the anti-osteoporotic activity of some SERMs which present concomitant inhibitory activity on the breast and endometrium.

Topics: Adult; Anastrozole; Antineoplastic Agents; Antineoplastic Agents, Hormonal; Aromatase Inhibitors; Breast Neoplasms; Clinical Trials as Topic; Clinical Trials, Phase III as Topic; Enzyme Inhibitors; Estrogen Antagonists; Female; Forecasting; Humans; Indoles; Letrozole; Middle Aged; Neoplasm Metastasis; Nitriles; Osteoporosis; Postmenopause; Raloxifene Hydrochloride; Selective Estrogen Receptor Modulators; Tamoxifen; Toremifene; Triazoles

Based on the data and clinical experience derived from tamoxifen usage, the properties of an ideal antiestrogen is described that could have applications as a breast cancer preventative agent, long-term adjuvant therdpy, or as a treatment for osteoporosis. Each of the new antiestrogens currently being tested is discussed in terms of laboratory development, toxicology, pharmacology, endocrinology, and clinical evaluation. And each new compound is assessed according to the properties of an ideal antiestrogen.. A review of all published reports was facilitated by the use of Medline computer searches.. Numerous compounds are being evaluated in clinical trials and can be categorized as triphenylethylenes or tamoxifen analogs, pure antiestrogens, and targeted antiestrogens. Several of these compounds may have fewer uterotropic properties and greater effects on maintaining bone density compared with tamoxifen; however, the clinical experience (ie, patient-years of treatment) with any of these compounds is minimal.. Although many of these compounds appear promising, further evaluation will be necessary to determine the role these compounds may serve as preventive agents, adjuvant therapies, treatments for advanced disease, or other medical indications such as osteoporosis.

Topics: Antineoplastic Agents, Hormonal; Bone Density; Drugs, Investigational; Estradiol; Estrogen Antagonists; Female; Fulvestrant; Humans; Osteoporosis, Postmenopausal; Piperidines; Raloxifene Hydrochloride; Tamoxifen; Toremifene

Tamoxifen (20-40 mg/day) has been widely used for the treatment of breast cancer and is recognized as a useful antiestrogen. A 40 mg/day dose of toremifene showed comparable efficacy, safety and usefulness to a 20 mg/day dose of tamoxifen in the double-blind comparative study with tamoxifen. Furthermore, high-dose toremifene (120 mg/day) was effective on the tamoxifen-failed breast cancer patients. Although droloxifene (3-hydroxytamoxifen) showed efficacy and safety in phase I and phase II studies, this trial has regretably been ineffective in Japan. In phase I and early phase II trials in Japan, the safety and efficacy of TAT-59 was demonstrated and a 20 mg/day dose was moderate. Tamoxifen analogues including their metabolites are expected to act effectively on tamoxifen-resistant, low estrogen receptor levels or estrogen receptor-negative tumors by mechanisms of action different from tamoxifen.

Topics: Binding, Competitive; Breast Neoplasms; Clinical Trials as Topic; Double-Blind Method; Female; Humans; Receptors, Estrogen; Tamoxifen; Toremifene

EM-652 exerts pure antiestrogenic activity in the mammary gland and endometrium, while tamoxifen, the antiestrogen most widely used for the treatment of breast cancer, exerts mixed antiestrogenic-estrogenic activity in these tissues. Our objective was to compare the agonistic and antagonistic effects of EM-652 with tamoxifen and 5 other antiestrogens on the growth of ZR-75-1 human breast xenografts in ovariectomized nude mice. During the 23 weeks of treatment at a daily oral dose of 50 microg, EM-652 was the only compound that decreased tumor size relative to pretreatment values, whereas the 6 other antiestrogens only decreased to various extents the progression rate stimulated by estrone. Under estrone stimulation, all groups of animals had more than 60% of their tumors in the progression category except for the EM-652-treated group, where only 7% of the tumors progressed. In the absence of estrone stimulation, progression was seen in 60%, 33%, 21% and 12% of tumors in the tamoxifen-, idoxifene-, toremifene- and raloxifene-treated groups, respectively, while only 4% of tumors progressed in the EM-652-treated group. The agonistic and antagonistic actions of each antiestrogen were also measured on endometrial epithelial cell thickness. Our present findings indicate that EM-652, in addition to being the most potent antiestrogen on human breast tumor growth, has no agonistic effect in breast and endometrial tissues. Since previous data have shown benefits of EM-652 on bone density and lipid profile, this compound could be an ideal candidate for chemoprevention of breast and uterine cancers, while protecting against osteoporosis and cardiovascular disease.

Topics: Animals; Breast Neoplasms; Cell Division; Cell Size; Cinnamates; Endometrium; Epithelial Cells; Estrogen Antagonists; Estrone; Female; Humans; Kinetics; Mice; Mice, Nude; Neoplasm Transplantation; Ovariectomy; Piperidines; Raloxifene Hydrochloride; Stilbenes; Tamoxifen; Toremifene; Tumor Cells, Cultured

Tamoxifen remains the endocrine therapy of choice in the treatment of all stages of hormone-dependent breast cancer. However, tamoxifen has been shown to increase the risk of endometrial cancer which has stimulated research for new effective antiestrogens, such as droloxifene and toremifene. In this study, the potential for these compounds to cause cytotoxic effects was investigated. One potential cytotoxic mechanism could involve metabolism of droloxifene and toremifene to catechols, followed by oxidation to reactive o-quinones. Another cytotoxic pathway could involve the oxidation of 4-hydroxytoremifene to an electrophilic quinone methide. Comparison of the amounts of GSH conjugates formed from 4-hydroxytamoxifen, droloxifene, and 4-hydroxytoremifene suggested that 4-hydroxytoremifene is more effective at formation of a quinone methide. However, all three substrates formed similar amounts of o-quinones. Both the tamoxifen-o-quinone and toremifene-o-quinone reacted with deoxynucleosides to give corresponding adducts. However, the toremifene-o-quinone was shown to be considerably more reactive than the tamoxifen-o-quinone in terms of both kinetic data as well as the yield and type of deoxynucleoside adducts formed. Since thymidine formed the most abundant adducts with the toremifene-o-quinone, sufficient material was obtained for characterization by (1)H NMR, COSY-NMR, DEPT-NMR, and tandem mass spectrometry. Cytotoxicity studies with tamoxifen, droloxifene, 4-hydroxytamoxifen, 4-hydroxytoremifene, and their catechol metabolites were carried out in the human breast cancer cell lines S30 and MDA-MB-231. All of the metabolites tested showed cytotoxic effects that were similar to the parent antiestrogens which suggests that o-quinone formation from tamoxifen, droloxifene, and 4-hydroxytoremifene is unlikely to contribute to their cytotoxicity. However, the fact that the o-quinones formed adducts with deoxynucleosides in vitro implies that the o-quinone pathway might contribute to the genotoxicity of the antiestrogens in vivo.

Topics: Animals; Antineoplastic Agents; Benzoquinones; Breast Neoplasms; Cell Survival; Deoxyribonucleosides; DNA Adducts; Female; Glutathione; Indolequinones; Indoles; Microsomes, Liver; Quinones; Rats; Rats, Sprague-Dawley; Spectrometry, Mass, Electrospray Ionization; Tamoxifen; Toremifene; Tumor Cells, Cultured

FC1271a is a novel triphenylethylene compound with a tissue-selective profile of estrogen agonistic and weak antagonistic effects. It specifically binds to the estrogen receptor alpha and beta with affinity closely similar to that of toremifene and tamoxifen. To study the in vivo effects of the compound, 4-month-old rats were sham operated (sham) or ovariectomized (OVX) and treated daily for 4 weeks with various doses of FC1271a or vehicle (orally). FC1271a was able to oppose OVX-induced bone loss by maintaining the trabecular bone volume of the distal femur. Accordingly, the OVX-induced loss of bone strength was prevented at doses of 1 and 10 mg/kg. FC1271a also prevented the OVX-induced increase in serum cholesterol in a dose-dependent manner. No significant changes in uterine wet weight or morphology were observed in the OVX-rats treated with 0.1 or 1 mg/kg FC1271a, but at a dose of 10 mg/kg it had a slightly estrogenic effect. In immature rats the effect of FC1271a on uterine wet weight was less stimulatory than that of toremifene or tamoxifen, but more stimulatory than that of raloxifene or droloxifene. The appearance of the dimethylbenzanthracene (DMBA)-induced mammary tumors was inhibited by treatment of DMBA-treated rats with FC1271a in a dose-dependent manner. In human MCF-7 breast cancer cell tumors raised in nude mice in the presence of estrogen, the growth and expression of pS2 marker gene could not be maintained after estrogen withdrawal by treatment with FC1271a. No formation of DNA adducts was observed in the liver of the FC1271a-treated rats. In conclusion, the bone-sparing, antitumor, and cholesterol-lowering effects of FC1271a combined with a low uterotropic activity and lack of liver toxicity indicate that FC1271a could be an important alternative in planning antiosteoporosis therapy for estrogen deficiency.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Bone and Bones; Breast Neoplasms; Cholesterol; Estrogen Antagonists; Female; Humans; Mammary Neoplasms, Experimental; Mice; Mice, Nude; Organ Size; Osteoporosis; Ovariectomy; Raloxifene Hydrochloride; Rats; Rats, Sprague-Dawley; Reference Values; Tamoxifen; Toremifene; Transplantation, Heterologous; Tumor Cells, Cultured; Uterus

Tamoxifen and its analogues 4-hydroxytamoxifen, toremifene, 4-hydroxytoremifene, clomifene and droloxifene were tested for clastogenic effects in a human lymphoblastoid cell line (MCL-5) expressing elevated native CYP1A1 and containing transfected CYP1A2, CYP2A6, CYP2E1 and CYP3A4 and epoxide hydrolase and in a cell line containing only the viral vector (Ho1). MCL-5 or Ho1 cells were incubated with 4-hydroxytamoxifen, 4-hydroxytoremifene, clomifene or droloxifene and the incidence of micronuclei estimated. With MCL-5 cells there was an increase in micronuclei with 4-hydroxytamoxifen, 4-hydroxytoremifene and clomifene but not with droloxifene. With Ho1 cells only 4-hydroxytamoxifen and 4-hydroxytoremifene caused an increase in micronuclei. MCL-5 cells were incubated with tamoxifen, 4-hydroxytamoxifen, toremifene, droloxifene, clomifene or diethylstilbestrol (0.25-10 microg/ml) for 48 h and subjected to 3 h treatment with vinblastine (0.25 microg/ml) to arrest cells in metaphase. The incidence of cells with chromosomal numerical aberrations (aneuploidy) was increased in cells treated with tamoxifen, 4-hydroxytamoxifen, toremifene, clomifene and diethylstilbestrol but not droloxifene. The frequency of cells with structural abnormalities (excluding gaps) was increased in cells treated with tamoxifen and toremifene but not 4-hydroxytamoxifen, clomifene, droloxifene or diethylstilbestrol. The clastogenic activities of tamoxifen (35 mg/kg), toremifene (36.3 mg/kg), droloxifene (35.2 mg/kg) and diethylstilbestrol (25 mg/kg) were compared in groups of four female Wistar rats. Each chemical was dissolved in glycerol formal, administered as a single dose by gavage and hepatocytes isolated by collagenase perfusion 24 h later. The cells were cultured in the presence of epidermal growth factor (40 ng/ml) for 48 h, colchicine (10 microg/ml) being added for the final 3 h of incubation. At least 100 chromosomal spreads were examined from each animal for the presence of numerical and structural abnormalities. The incidences of aneuploidy following treatment were: tamoxifen 81%, toremifene 46%, droloxifene 9.6%, diethylstilbestrol 45.7%, vehicle control 5.3%. The incidences of chromosomal structural abnormalities excluding gaps were: tamoxifen 4.3%, toremifene 0.8%, droloxifene 0.5%, diethylstilbestrol 0.8%, control 0.5%. The incidence of chromosomal structural aberrations excluding gaps in the treated animals was not statistically significantly different from controls exce

Topics: Aneuploidy; Animals; Anticarcinogenic Agents; Cell Line; Cell Nucleus; Clomiphene; Female; Humans; Liver; Lymphocytes; Micronucleus Tests; Rats; Rats, Wistar; Tamoxifen; Toremifene; Transfection

Although temporary benefits of tamoxifen therapy are observed in up to 40% of women with breast cancer, this compound, which is known to possess mixed estrogenic and antiestrogenic activities, has been associated with increased risk of endometrial carcinoma. This study compares the effects of the novel nonsteroidal pure antiestrogen EM-800 and related compounds with those of a series of antiestrogens on the estrogen-sensitive alkaline phosphatase (AP) activity in human endometrial adenocarcinoma Ishikawa cells. Exposure to increasing concentrations of up to 1000 nM EM-800 or its active metabolite EM-652 alone failed to affect basal AP activity. In contrast, incubation with 10 nM (Z)-4-OH-tamoxifen, (Z)-4-OH-toremifene, droloxifene, or raloxifene increased the value of this estrogen-sensitive parameter by 3.3-, 3.5-, 2.2-, and 1.6-fold, respectively, a stimulatory effect that was completely reversed by simultaneous exposure to 30 nM EM-800. Moreover, the stimulation of AP activity induced by 1 nM 17beta-estradiol was completely reversed by EM-800, EM-652, or ICI-182780, at the IC50 value of 1.98 +/- 0.23, 1.01 +/- 0.16, and 5.64 +/- 0.59 nM, respectively, whereas the partial blockade exerted by (Z)-4-OH-tamoxifen, (Z)-4-OH-toremifene, or raloxifene was observed at IC50 values of 13.5 +/- 3.80, 41.0 +/- 7.2, and 3.74 +/- 0.43 nM, respectively. Thus, as assessed by their activity in the human Ishikawa endometrial carcinoma cells, EM-800 and EM-652 are the most potent known antiestrogens in Ishikawa cells, and, most importantly, they are devoid of the estrogenic activity observed in these human endometrial cancer cells with (Z)-4-OH-tamoxifen, (Z)-4-OH-toremifene, droloxifene, and raloxifene.

Topics: Adenocarcinoma; Alkaline Phosphatase; Benzopyrans; Endometrial Neoplasms; Estradiol; Estrogen Antagonists; Female; Fulvestrant; Humans; Neoplasm Proteins; Piperidines; Propionates; Raloxifene Hydrochloride; Tamoxifen; Toremifene; Tumor Cells, Cultured

Toremifene, a compound which differs from tamoxifen by the substitution of a chlorine atom for a hydrogen atom in the ethyl group, is significantly less potent than tamoxifen in causing DNA adduct formation in rats. To examine the relationship of the DNA adduct-forming ability of these compounds with their physicochemical properties such as stable conformation and chemical reactivity, we carried out molecular mechanics, molecular dynamics, and quantum mechanics calculations for the two compounds. For tamoxifen, six stable conformers were identified by conformational search with CFF91 force field. Molecular dynamics simulations showed that these were often interconverted within 1.0 ns. On the other hand, although the conformation of stable conformers and dynamical behavior of toremifene were almost the same as those of tamoxifen, a few conformations were slightly different from those of tamoxifen owing to the effect of the chlorine atom at chloroethyl group. In addition, the stability of the allylic carbocation, which had been proposed as the reactive intermediate leading to DNA adduct formation, was calculated with both semiempirical and density functional methods. Results showed that the carbocation intermediate of toremifene was less stable than that of tamoxifen by 4-5 kcal/mol, suggesting that toremifene was less frequently activated to the intermediate than tamoxifen. Furthermore, the carbocation intermediates of two other tamoxifen derivatives, 4-iodotamoxifen and droxifene, which show no DNA adduct-forming ability, were also less stable compared with that of tamoxifen. These calculated results suggest a close relation between the stability of the proposed carbocation intermediate and DNA adduct-forming ability.

Topics: Antineoplastic Agents, Hormonal; Chemical Phenomena; Chemistry, Physical; Computer Simulation; Crystallography, X-Ray; DNA Adducts; Drug Stability; Electrochemistry; Estrogen Antagonists; Hydroxylation; Models, Molecular; Molecular Conformation; Molecular Structure; Tamoxifen; Thermodynamics; Toremifene

Topics: Antineoplastic Agents, Hormonal; Breast Neoplasms; Clinical Trials as Topic; Drugs, Investigational; Estrogen Antagonists; Female; Humans; Lavandula; Male; Neoplasms; Oils, Volatile; Ovarian Neoplasms; Piperidines; Plant Oils; Plants, Medicinal; Prostatic Neoplasms; Raloxifene Hydrochloride; Retinoids; Tamoxifen; Toremifene

The author established three variant cell lines which were proliferative in the serum-free medium. These three cell lines were derived from MCF-7, a human breast cancer cell line. These 3 variants (MCF-S1, MCF-S2 and MCF-S3) proliferate estrogen (E2)-dependently, but the amounts of E2 receptor and progesterone receptor in the cells are different from each other among the variants. The author compared the effects of hormonal therapeutic agents, tamoxifen (TAM), 3-hydroxytamoxifen (3-OH-TAM), toremifene (TORE), and medroxyprogesterone acetate (MPA) on MCF-7 and the established variant cells. Although TAM showed little effect on the growth of any cell lines in the absence of E2, it considerably inhibited the growth of MCF-S2 cells and MCF-7 cells in the presence of 10(-10)M E2. TORE also provided no inhibitory effect at less than 10(-7)M concentration on any cells in the absence of E2, but it dose-dependently inhibited DNA synthesis of MCF-S2 cells in the presence of E2. On the other hand, although 3-OH-TAM markedly inhibited the growth of any cell lines at a concentration of less than 10(-6)M in the presence of E2, it dose-dependently inhibited the DNA synthesis of any cell lines in the absence of E2, and the effect was remarkable in the case of MCF-S2 or MCF-S3. MPA showed a tendency to increase the proliferation of any cells in the absence of E2, conversely in the presence of E2, and it slightly inhibited DNA synthesis at concentrations of over 10(-8)M. These results suggest that the effect of hormonal agents on breast cancer cells may depend on either hormonal levels or the characteristics of the cancer cells. The effect of the hormonal agents are diverse, and a hormonal agent which does not work well on one cancer cell population may work well on another population.

Topics: Breast Neoplasms; Cell Division; Female; Humans; Medroxyprogesterone Acetate; Mutation; Receptors, Estrogen; Receptors, Progesterone; Tamoxifen; Toremifene; Tumor Cells, Cultured

We have previously shown that transforming growth factor beta (TGF beta) is a hormonally regulated negative growth factor in estrogen responsive MCF-7 human breast cancer cells. We have now compared the antiestrogens tamoxifen, droloxifene (3-hydroxytamoxifen), and toremifene in their ability to induce the secretion of autoinhibitory TGF beta by MCF-7 cells. The main results are as follows: induction of TGF beta secretion by droloxifene is about two to three times higher than by identical concentrations of tamoxifen or toremifene. A 5-10 times higher concentration of tamoxifen or toremifene than droloxifene is necessary to reach a similar induction of TGF beta secretion. In contrast to tamoxifen, intermittent application of droloxifene is as effective as continuous treatment in inducing TGF beta secretion. We conclude from these data that TGF beta proteins represent markers of antiestrogen action and might also play a pivotal role in their mechanism of action. Droloxifene is a more effective inducer of TGF beta and a more potent growth inhibitor for estrogen responsive human breast cancer cells than tamoxifen and toremifene in vitro. Therefore, droloxifene might also possess a higher antiestrogenic potential in treatment of human breast cancer.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Division; Estrogen Antagonists; Female; Humans; Tamoxifen; Toremifene; Transforming Growth Factor beta; Tumor Cells, Cultured

Topics: Breast Neoplasms; DNA, Neoplasm; Estrogen Antagonists; Humans; Receptors, Estrogen; Receptors, Progesterone; Tamoxifen; Toremifene; Tumor Cells, Cultured