toremifene and Adenocarcinoma

Toremifene, a triphenylethylene antiestrogen first synthesized in 1981, binds to the estrogen receptor with an affinity about 5% that of estradiol. Its antiestrogenicity/estrogenicity ratio in animal models is about 5 times that of tamoxifen, though it requires somewhat higher doses for full effectiveness, and it is active against breast cancer in animal and cell culture models. It has a long elimination half-life and there are several metabolites, but the principal antitumor activity appears to be due to the unchanged drug. In Phase I and Phase II clinical trials, toremifene has shown good response rates in ER-positive or ER-unknown tumors, and significant responses after failure of tamoxifen or other hormonal or chemotherapeutic regimens, with rare and mild side effects.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Breast Neoplasms; Estrogen Antagonists; Female; Humans; Mammary Neoplasms, Experimental; Rats; Tamoxifen; Toremifene

Breast cancer resistance protein (BCRP/ABCG2), an ATP-binding cassette half transporter, confers multidrug resistance (MDR) to a series of antitumor agents such as mitoxantrone, daunorubicin, SN-38, and topotecan, and often limits the efficacy of chemotherapy. Recent studies have indicated that a putative estrogen response element (ERE) is located in the promoter region of the BCRP gene. However, whether and how BCRP is regulated transcriptionally by toremifene (TOR) remains unknown. In the present study, two plasmid vectors have been designed to express the wild-type full-length BCRP cDNA enforced driven by its endogenous promoter containing a functional ERE and a constitutive cytomegalovirus (CMV) promoter as control, respectively, which were transfected into estrogen-responsive MCF-7 and estrogen-independent MDA-MB-231 human breast adenocarcinoma cell lines. We showed that toremifene alone significantly downregulated BCRP mRNA and protein levels in estrogen receptor α (ERα)-positive MCF-7 cells in a dose-dependent manner, and the inhibitory effect was partially reversed by estrone (E(1)). Furthermore, gel shift assays demonstrated that specific binding of ERα to the ERE in the BCRP promoter is essential for transcriptional inhibition of BCRP by toremifene. Interestingly, toremifene alone increased the cellular accumulation of mitoxantrone in BCRP-transfected cells, suggesting that TOR indeed inhibits BCRP-mediated drug efflux and overcome drug resistance. To the best of our knowledge, this is the first report describing a direct effect of toremifene on BCRP. Our results thus indicate that toremifene by itself downregulates BCRP expression to reverse BCRP-mediated atypical multidrug resistance via a novel transcriptionally mechanism, which might be involved in TOR-ER complexes binding to the ERE of BCRP promoter to repress transcription of BCRP gene.

Topics: Adenocarcinoma; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Binding Sites; Breast Neoplasms; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Down-Regulation; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Electrophoretic Mobility Shift Assay; Estrogen Receptor alpha; Estrone; Female; Gene Expression Regulation, Neoplastic; Humans; Inhibitory Concentration 50; Mitoxantrone; Neoplasm Proteins; Promoter Regions, Genetic; RNA, Messenger; Selective Estrogen Receptor Modulators; Toremifene; Transcription, Genetic; Transfection

The chemopreventive efficacy of toremifene, an antiestrogen, was evaluated in the transgenic adenocarcinoma of mouse prostate (TRAMP) model. TRAMP mice were segregated into three groups: (a) the low-dose toremifene group (6.6 mg/kg/day); (b) the high-dose toremifene group (33 mg/kg/day); and (c) the control placebo group. Efficacy of treatment was measured by the absence of palpable tumor. To extend these studies using more sensitive techniques, TRAMP mice were then treated with placebo, flutamide (an antiandrogen; 33 mg/kg/day), or toremifene (10 mg/kg/day). Animals from each treatment group were sacrificed at 7, 10, 15, 20, 25, and 30 weeks of age, and prostate tissues and seminal vesicles were harvested. Tissues from animals (n = 5) in each group were evaluated by wholemount dissections of genitourinary tracts, histology, immunohistochemistry, and Western blot analyses. Blood was pooled per group to measure estradiol and testosterone hormonal levels. Tumors formed at week 17 in the placebo group (n = 10), at week 21 in the high-dose toremifene group (n = 12), and at week 29 in the low-dose toremifene group (n = 12). This represents an increased tumor latency of up to 12 weeks. By 33 weeks, all animals in the placebo group had tumors compared with only 35% of the animals treated with toremifene. Although both flutamide and toremifene decreased tumor incidence compared with the placebo, toremifene was more effective than flutamide. High-grade prostatic intraepithelial neoplasia was observed in animals in the placebo group, but not in animals treated with toremifene. Moreover, toremifene-treated animals had prolonged survival compared with placebo-treated animals. By 33 weeks of age, 100% of the placebo-treated animals had developed palpable tumors and died, whereas 60% of the toremifene-treated animals were tumor free. T antigen levels in the prostate of toremifene-treated animals were similar to those of placebo-treated, age-matched animals. Whereas serum estradiol levels remained unchanged, the total and free testosterone levels were elevated in the toremifene-treated group. Toremifene treatment did not affect androgen receptor levels. Because toremifene prevented prostate cancer in a milieu of elevated blood free testosterone levels with no change in prostate androgen receptor expression, the mechanism of toremifene's chemopreventive activity may be through nonandrogenic pathways, such as estrogen receptor signaling.

Topics: Adenocarcinoma; Animals; Antigens, Polyomavirus Transforming; Antineoplastic Agents, Hormonal; Estradiol; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Prostatic Neoplasms; Receptors, Androgen; Selective Estrogen Receptor Modulators; Testosterone; Toremifene

The purpose of the present study was to evaluate the tissue distribution of toremifene (TOR) in baboons following intra-tissue injections and to examine the effectiveness of intratumoral TOR therapy of baboons with various spontaneous neoplasms. Five healthy baboons (Papio sp.) were used to examine the distribution of TOR following intra-tissue injections. Twenty-three different tissue specimens were collected for HPLC analysis. In addition, four baboons with various spontaneous neoplasms (myxoma, squamous cell carcinoma, lymphosarcoma and adenocarcinoma) were treated with intratumoral TOR and their responses were evaluated. Tissue TOR distribution was also examined in these animals. In the tissue distribution study, target tissue/serum TOR concentration ratios ranged from 138 to 8873 and the target tissue/other tissue ratios ranged from 1.2 to 2428. The distribution of TOR was very favorable, with the highest concentrations outside the injection sites noted in adjacent organs. A marked response was observed in the myxoma and partial responses were observed in the other three cases. Drug level analysis data from these four animals revealed tissue concentrations similar to those seen in the TOR tissue distribution study. Intratumoral administration of TOR can achieve effective local tumor and tissue concentrations, while systemic distribution via circulation to other organs is limited.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents, Hormonal; Carcinoma, Squamous Cell; Chromatography, High Pressure Liquid; Female; Injections, Intralesional; Liver Neoplasms, Experimental; Lymphoma, Non-Hodgkin; Male; Myxoma; Neoplasms, Experimental; Papio; Parotid Neoplasms; Toremifene

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

Two cases of recurrent breast cancer, for which combined therapy using toremifene and oral chemotherapeutic agents were effective, are reported. In case 1, high-dose toremifene (120 mg/day) and 5'-DFUR were administered to a forty-seven-year-old woman with lung metastasis of estrogen-receptor positive breast cancer, who had been previously treated with polychemotherapy and tamoxifen. A complete response was obtained after six months of treatment and this condition has remained for longer than one year. In case 2, a fifty-year-old woman developed liver and lung matastasis of breast cancer with increased tumor marker levels. Forty mg/day of toremifene and oral cyclophosphamide was started and transarterial embolization of the hepatic artery using lipiodol, adriamycin and mitomycin C was performed. Both hepatic and pulmonary metastasis disappeared, and the tumor maker level was normalized one month later. No regrowth of the tumors has been observed for more than six months. The chemosensitizing effect of toremifene might be responsible for the favorable effects on these matastases of breast cancer.

Topics: Adenocarcinoma; Antineoplastic Combined Chemotherapy Protocols; Breast Neoplasms; Cyclophosphamide; Female; Floxuridine; Humans; Lung Neoplasms; Middle Aged; Mitomycin; Remission Induction; Tamoxifen; Toremifene

A phase II study of toremifene was started in patients suffering from advanced carcinoma corporis uteri. Minimum duration of treatment was 3 months but with stabilized disease (SD) and remission the treatment is to be continued as long as the treatment response lasts. At present four patients with recurrent carcinoma corpus uteri have been included. Dose level of toremifene is 200 mg per day. At 12 weeks one of the patients has partial remission (PR), two have SD and one progressive disease (PD). There have been no unacceptable side effects.

Topics: Adenocarcinoma; Aged; Aged, 80 and over; Drug Evaluation; Estrogen Antagonists; Female; Humans; Middle Aged; Tamoxifen; Toremifene; Uterine Neoplasms

MFC-7 cells were exposed to toremifene, human alpha and gamma interferons and combinations of them in vitro. Growth of the cells was followed by ATP bioluminescence method. Rats bearing DMBA-induced tumors were treated with toremifene, rat gamma interferon and their combination daily for five weeks. The growth of the tumors was followed by palpation weekly. Toremifene and interferons inhibited the growth of MCF-7 cells. Interferons alpha and gamma were additive; toremifene and interferons were additive or at the best synergistic. Toremifene inhibited the growth of DMBA-induced tumors. Rat gamma interferon alone had no clear effect on the tumor growth. Combination of toremifene and gamma interferone was the most effective treatment and did not show any detectable toxicity. Toremifene and interferons have interesting interactions. Clinical studies using the combination might be warranted.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Adenocarcinoma; Animals; Antineoplastic Combined Chemotherapy Protocols; Body Weight; Breast Neoplasms; Drug Interactions; Drug Synergism; Estrogen Antagonists; Female; Humans; Interferon Type I; Interferon-gamma; Mammary Neoplasms, Animal; Rats; Tamoxifen; Time Factors; Toremifene; Tumor Cells, Cultured