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Endometrial K-ras mutations in postmenopausal breast cancer patients treated with adjuvant tamoxifen or toremifene.

PURPOSE: Long-term use of tamoxifen is associated with a two- to threefold increased risk of endometrial cancer in postmenopausal women. Toremifene is another triphenylethylene antiestrogen, which is as effective as tamoxifen in postmenopausal breast cancer. Thus far, its use has not been associated with an increased risk of endometrial cancer. K-ras codon 12 mutations seem to be important in endometrial carcinogenesis, and these mutations have been found in endometrial samples of patients on tamoxifen. The present study was undertaken to investigate if there is any difference in the frequency of endometrial K-ras mutations among patients treated with tamoxifen or toremifene. METHODS: Endometrial samples were taken from 23 postmenopausal breast cancer patients (tamoxifen, n = 11; toremifene, n = 12) before and after 36 months of treatment. DNA was isolated from formalin-fixed paraffin-embedded samples using a routine proteinase K digestion protocol. K-ras mutations in codon 12 were screened using real-time PCR and melting curve analysis in LightCycler equipment. Wild-type PNA oligomer was used to increase the sensitivity of the assay. RESULTS: All baseline samples contained wild-type K-ras, while 10/23 (43%) of the follow-up samples carried a codon 12 mutation. Mutations were identified in 3 of the 11 in the tamoxifen group and in 7 of the 12 in the toremifene group. Seven were transitions (G-->A), and three were transversions (two G-->T, one G-->C). One of the mutations in the toremifene group was associated with a polypoid endometrium. All the other mutations were found in an atrophic (n = 6) or proliferative (n = 3) endometrium. CONCLUSIONS: Both tamoxifen and toremifene induce endometrial K-ras codon 12 mutations. The significance of this finding to endometrial carcinogenesis remains to be elucidated.

Antineoplastic Agents, Hormonal↗

Pharmacokinetics of the novel antiestrogenic agent toremifene in subjects with altered liver and kidney function.

OBJECTIVES: The pharmacokinetics of toremifene was investigated in an open study with four parallel groups of 10 subjects each. Subjects with impaired liver function (biopsy-proven liver disease), activated liver function (drug-induced), and impaired kidney function were compared with normal subjects. METHODS: A single oral 120 mg dose of toremifene was administered after an overnight fast, and blood samples were collected over 28 days. Serum levels of toremifene and its metabolites were determined; appropriate pharmacokinetic parameters were calculated and statistically evaluated. RESULTS: In normal subjects, the average peak level of 414 ng/ml toremifene was achieved at 3 hours after dosing, the terminal half-life was 6.2 days, apparent oral clearance was 5.1 L/hr, apparent volume of distribution was 958 L, and the fraction not bound to protein was 0.3%. The peak level (130 ng/ml) of the major metabolite, N-demethyltoremifene, appeared in serum with large variation in the time to peak level (median, 3 days) and a terminal half-life of 21.0 days. Low levels of deaminohydroxytoremifene were also measured, and two other metabolites could be quantified at some time points in some patients. The elimination rate of toremifene and the main metabolite was significantly increased in patients with activated liver function, resulting in decreased terminal half-lives (3.0 days and 4.5 days, respectively), and was decreased in patients with impaired liver function (10.9 days and 29.6 days, respectively). The subjects with impaired kidney function showed normal elimination kinetics. CONCLUSION: Liver, but not kidney, function should be taken into account when toremifene is administered.

Administration, Oral↗

Chemosensitizing effect of an antiestrogen, toremifene, on ovarian cancer.

The chemosensitizing effect of an antiestrogen, toremifene, was studied on 2 human ovarian cancer cell lines in vitro and on 3 fresh surgical ovarian tumor explants with the aid of the subrenal capsule assay (SRCA). Also, 11 patients with secondarily drug resistant, recurrent gynecologic cancer (8 ovarian and 3 uterine cancers) were treated with 240 mg toremifene daily for 1 week before each course of cytostatics. Toremifene potentiated the effect of doxorubicin on both cell lines. This was also the case on 1 cell line that was not completely resistant to doxorubicin. The SRCA showed a clear potentiating effect of toremifene only on the tumor overtly resistant to the combination of cisplatin, doxorubicin, and cyclophosphamide. Of the 11 patients treated with toremifene and cytostatics, the response of 8 patients was evaluable: 3 had partial response, 3 no change, and 2 progressive disease. Toremifene seems to have a chemopotentiating effect on gynecologic drug-resistant tumors.

Aged↗

Toremifene increases the expression of intercellular adhesion molecule-1 (ICAM-1) on MCF-7 breast cancer cells and Jurkat cells.

The present study was conducted to reveal the effect of the nonsteroidal anti-oestrogen toremifene on the expression of cell-surface molecules involved in the immunogenicity of tumours or the sensitivity of tumour cells to apoptotic cell death. We studied the effect of toremifene on the expression of HLA-DR, ICAM-1, costimulatory molecules CD80 and CD86, and the tumour necrosis factor receptor (TNF-R) family molecules CD27, CD30, CD40, TNF-R1, TNF-R2 and Fas (CD95) on MCF-7 breast cancer and Jurkat T cells. In addition, the effect of toremifene on Fas-mediated apoptosis was studied. Toremifene did not affect Fas expression or Fas-mediated apoptosis in Fas-resistant MCF-7 or Fas-sensitive Jurkat cells, but was found to increase the expression of ICAM-1 in both cell lines. In addition, toremifene increased the expression of CD40 and CD80 on MCF-7 cells. The expression of ICAM-1 in tumours plays an important role in the interaction of tumour cells and effector cells of the immune system. Therefore, we suggest that toremifene may modulate the immunogenicity of tumour cells by increasing the expression of ICAM-1.

Antineoplastic Agents, Hormonal↗

Comparison of the effects of tamoxifen and toremifene on liver and kidney tumor promotion in female rats.

Female rats were subjected to a 70% partial hepatectomy and administered either diethylnitrosamine (10 mg/kg) or the solvent, trioctanoin. After a 2 day recovery from the surgery, the rats were placed on basal diet alone or containing phenobarbital (500 mg/kg diet), mestranol (0.2 mg/kg diet), tamoxifen (250 or 500 mg/kg diet) or toremifene (250, 500 or 750 mg/kg diet) for 6 or 18 months prior to killing. The liver and kidneys were prepared for pathological diagnoses. In addition, sections of liver from the 6 month killing were frozen and serially sectioned. The sections were stained for expression of the placental isozyme of glutathione S-transferase (GST), gamma glutamyl transpeptidase (GGT), canalicular ATPase (ATP) and glucose 6-phosphatase (G6P) and scored by quantitative stereology for number and volume fraction of liver occupied by altered hepatic foci (AHF) with alterations in these markers individually and combined (ANY). Each of the agents increased the volume fraction of liver occupied by AHF when the ANY category was used. Statistical increases in both the GGT-positive and G6P-deficient AHF populations were observed in the spontaneously as well as DEN-initiated groups treated with tamoxifen or toremifene. After 18 months of administration, the highest concentration of tamoxifen increased the incidence of malignant hepatic neoplasms in non-DEN-initiated rats. Toremifene, at the highest tested dose, increased the incidence of hepatocellular carcinomas in the DEN-initiated groups to a level one-third that observed with tamoxifen administration to DEN-initiated rats. Both tamoxifen and toremifene increased the incidence of hypernephromas in previously DEN-initiated rats. While both tamoxifen and toremifene are effective promoting agents for DEN-initiated lesions, tamoxifen is more potent than toremifene in the induction of rat hepatocarcinogenesis.

Adenosine Triphosphatases↗

Apoptosis in toremifene-induced growth inhibition of human breast cancer cells in vivo and in vitro.

BACKGROUND: Antiestrogens inhibit the stimulative effects of estrogens on breast cancer growth, but the mechanism(s) by which they trigger tumor regression are not completely understood. Growth retardation and tumor regression can be achieved by enhanced cell death and/or arrested cell proliferation. PURPOSE: Our aim was to investigate the effect of a new antiestrogen, toremifene, on human breast cancer cells grown either in culture or as tumors in nude mice. METHODS: The growth and morphology of in vitro cultured cells of the human breast cancer cell line MCF-7 were monitored by time-lapse video. MCF-7 cells and ZR-75-1 human breast cancer cells were grown as tumors in nude mice and subsequently examined by electron microscopy. The integrity of DNA isolated from these cells was determined by standard gel electrophoretic techniques. Northern blot hybridization analysis was used to determine the steady-state levels of the mRNAs for testosterone-repressed prostatic message-2 (TRPM-2), tumor growth factor beta-1 (TGF beta 1), and pS2 (a small, cysteine-rich protein of unknown function). RESULTS: Time-lapse video microscopy of the cell cultures indicated that treatment with 7.5 microM toremifene for 3 days caused approximately 60% of the cells to exhibit morphologic characteristics typical of cells undergoing programmed death, or apoptosis. The number of mitoses gradually decreased to zero over a 3- to 4-day period. Estrogen withdrawal for the same length of time resulted in an approximately equal number of apoptoses and mitoses. These changes were not associated with the pattern of DNA fragmentation, detectable as ladders in agarose gels, that is characteristic of the DNA of cells undergoing apoptosis. Elevated levels of TRPM-2 and TGF beta 1 mRNAs were observed in in vitro or in vivo grown tumor cells treated with 5-10 microM toremifene. Elevated levels of TRPM-2, but not TGF beta 1, mRNA were observed in the tumor cells after estrogen withdrawal. The steady-state level of pS2 mRNA in the tumor cells dropped in response to either toremifene treatment or estrogen withdrawal. CONCLUSION: Toremifene causes growth inhibition of estrogen-sensitive breast cancer cells by inducing some cells to undergo apoptosis and by inhibiting other cells from entering mitosis. The higher than normal amounts of TRPM-2 and TGF beta 1 protein that would likely result from the elevated levels of TRPM-2 and TGF beta 1 mRNAs measured in these cells after toremifene treatment may have an important role in the growth inhibition process. IMPLICATION: Apoptosis as an active, targeted process provides a potential new therapeutic approach for treating breast cancer.

Animals↗

Binding of toremifene to human serum proteins.

The in vitro protein binding of toremifene in human serum was measured by ultracentrifugation using 3H-toremifene together with unlabeled toremifene, 50, 500, and 5000 ng/ml. Of the total radioactivity 99.7 per cent was bound to the proteins independent of the concentration of the unlabeled drug. Binding of toremifene to different protein fractions was studied by adding 3H-toremifene and 500 ng/ml of cold toremifene to normal serum. The serum samples were exposed to agarose gel electrophoresis to fractionate different proteins. The radioactivity was localized using a position-sensitive proportional counter. After that the proteins were visualized by staining. Of the total protein bound radioactivity 92 per cent was bound to albumin, about 6 per cent to beta 1 globulin fraction and about 2 per cent to a fraction between albumin and alpha 1 globulins, part of this probably to alpha 1 acid glycoprotein.

Blood Proteins↗

The effect of toremifene on bone and uterine histology and on bone resorption in ovariectomised rats.

The effect of the selective oestrogen receptor modulator, toremifene, to inhibit ovariectomy-induced bone loss was studied in rats. The oral doses were 0.3, 3.0 or 30 mg/kg/day for 2 months. 17beta-oestradiol (5 microg/kg/day, subcutaneously) was used as positive control. One group was also treated with a combination of 17beta-oestradiol (5 microg/kg) and toremifene (3.0 mg/kg). Biochemical markers were urinary hydroxyproline and calcium (adjusted with urinary creatinine levels) and the serum level of pyridinoline cross-linked carboxy terminal telopeptide, a bone specific collagen breakdown product. The femoral and sternal trabecular bone thickness served as histological parameters. Ovarectomy increased the levels of hydroxyproline and pyrodinoline and decreased the trabecular bone thickness compared to the sham-operated control group. This was inhibited by both test compounds but 17beta-oestradiol was more efficient. Toremifene did not reverse the ovariectomy-induced reduction of urinary calcium but inhibited the 17beta-oestradiol-related increase. When administered together with oestradiol, toremifene did not reverse the positive effect of 17beta-oestradiol on bone, however toremifene reversed the oestradiol-related uterothrophic effects. These findings indicate that the antagonistic features of toremifene dominate in the rat uterus the agonistic properties do in the bone.

Amino Acids↗

Antiproliferative properties of toremifene on AIDS-related Kaposi's sarcoma cells.

BACKGROUND: Kaposi's sarcoma (KS) is the most common neoplastic apoptosis manifestation of acquired immunodeficiency syndrome. Toremifene is known to upregulate transforming growth factor beta-1 (TGF-beta1), which is a growth-inhibitory factor for KS. We investigated the in vitro effect of toremifene on KS cells. METHODS: MTT assay was used to measure the growth of four KS cell lines and a human umbilical vein endothelial (HUVE) cell line after incubation with toremifene. Reverse transcription polymerase chain reaction and ELISA were used to measure the level of TGF-beta1. RESULTS: The IC(50) for the KS cells ranged from 2.2 to 3.2 microM, and 80% of the growth inhibition occurred within 24 h. Toremifene enhanced TGF-beta1 mRNA expression, and the level of TGF-beta1 increased from 103 to 473 pg/ml after 48 h of incubation. Toremifene had no effect on the growth of HUVE cells. CONCLUSION: Toremifene has a specific antiproliferative effect on KS cells. The stimulation of TGF-beta1 production may play a role in the antiproliferative process.

Acquired Immunodeficiency Syndrome↗

Tamoxifen and toremifene lower serum cholesterol by inhibition of delta 8-cholesterol conversion to lathosterol in women with breast cancer.

PURPOSE: Long-term effects of tamoxifen and toremifene, a new antiestrogen that closely resembles tamoxifen, were investigated on serum lipids and cholesterol metabolism. PATIENTS AND METHODS: The study group consisted of 24 postmenopausal Finnish women with advanced breast cancer from an international multicenter study of 415 patients. Cholesterol metabolism was evaluated by measuring the cholesterol precursor (delta 8-cholestenol, desmosterol, and lathosterol, reflecting cholesterol synthesis) and plant sterol (markers of cholesterol absorption) and cholestanol levels by gas-liquid chromatography. RESULTS: Tamoxifen and toremifene lowered significantly serum low-density lipoprotein (LDL) cholesterol levels after 12 months of treatment by 16% and 15%, with no change in high-density lipoprotein (HDL) cholesterol or serum triglyceride levels. Serum delta 8-cholestenol was increased 40- and 55-fold during toremifene and tamoxifen treatment, respectively, while the increase of desmosterol less than doubled and was lacking for lathosterol by toremifene. Plant sterols and cholestanol were only inconsistently increased in serum. CONCLUSION: Tamoxifen and toremifene inhibit the conversion of delta 8-cholestenol to lathosterol so that serum total and LDL cholesterol levels are lowered by downregulation of cholesterol synthesis. Thus, inhibition of the delta 8-isomerase may be the major hypolipidemic effect of these agents. Reduced risk of coronary artery disease will probably occur also during long-term toremifene treatment, because the drug reduces cholesterol and its synthesis, similarly to tamoxifen.

Antineoplastic Agents, Hormonal↗

Clinical pharmacokinetics of toremifene.

Toremifene is a chlorinated triphenylethylene derivative of tamoxifen approved for use in the treatment of patients with metastatic breast cancer. Toremifene is well tolerated in patients, and common adverse effects of this drug include vasomotor symptoms such as hot flashes and vaginal discharge. This compound is administered to patients orally at a dose of 60 mg/day, although alternative methods of administration have been investigated. Oral bioavailability is estimated to be approximately 100%. At steady state, toremifene and its metabolites are highly protein bound (>95%). Toremifene is metabolised in the liver by cytochrome P450 enzymes, and it is eliminated primarily in the faeces following enterohepatic circulation. The half-life of toremifene is approximately 5 days, and steady state is reached by 6 weeks depending on the dose given. The pharmacokinetics of toremifene have been shown to be altered by certain liver conditions, but age and kidney function do not appear to be as significant.

Animals↗

Phase IIA clinical trial to test the efficacy and safety of Toremifene in men with high-grade prostatic intraepithelial neoplasia.

Men with high-grade prostatic intraepithelial neoplasia (PIN) evident on prostate biopsy are at high risk for the eventual development of prostate cancer. The ability to reverse high-grade PIN may reduce the incidence or delay the development of prostate cancer. Toremifene (GTx-006, Acapodene trade mark ) is a selective estrogen receptor modulator that has been shown in the transgenic mouse model of prostate cancer to eliminate high-grade PIN and reduce the incidence of prostate cancer. This study was aimed at the evaluation of the safety and efficacy of toremifene in men diagnosed with high-grade PIN. This was an open-label, phase IIA clinical trial that enrolled 21 men (mean age, 64.7 years) with evidence of high-grade PIN on biopsy within 6 months of entry into the study. Eighteen of these men (86%) completed toremifene treatment (60 mg/day orally for 4 months) and then underwent follow-up prostate biopsy (8 cores) to determine high-grade PIN status. The effect of the drug on serum prostate-specific antigen (PSA), percentage of free PSA, testosterone, estradiol, and quality of life was also measured. After toremifene treatment, 72% of these 18 men (vs. 17.9% of historical controls) had no high-grade PIN on subsequent prostate biopsies. Mean PSA trended higher, and percentage of free PSA was increased. Quality of life was not significantly affected by treatment. There were 3 mild adverse events, and no serious adverse events. Toremifene appeared to reduce high-grade PIN in this small, exploratory trial. The drug was well tolerated. A double-blind, dose-finding, randomized, placebo-controlled phase IIB/III study is currently open to further study toremifene's activity against high-grade PIN and prostate cancer incidence.

Administration, Oral↗

Major difference in the hepatocarcinogenicity and DNA adduct forming ability between toremifene and tamoxifen in female Crl:CD(BR) rats.

The hepatoproliferative effects of 2 antiestrogens, tamoxifen and toremifene, were compared in a sequential 15-month study in which 2 doses of each compound were administered by daily gavage to female Sprague-Dawley rats for up to 12 months. The doses were 11.3 and 22.6 mg/kg for tamoxifen and 12 and 24 mg/kg for toremifene. There were scheduled sacrifices at 3, 6, 12, and 15 months, the latter including a 3-month recovery period from the 12th through the 14th month. In the chronic toxicity study, tamoxifen at 22.6 mg/kg produced 100% incidence of hepatocellular carcinoma at the 12- and 15-month sacrifice intervals and 67% and 71% incidences at the 11.3-mg/kg dose. Sequential observations showed an increased incidence of glutathione S-transferase-positive foci of hepatocellular alteration by 3 months with tamoxifen in the absence of hepatotoxicity, with the first liver carcinoma appearing by 6 months of treatment. Unscheduled deaths occurring beyond 7.5 months in the tamoxifen treated groups were due in almost all cases to liver cancer. In striking contrast, toremifene did not produce any hepatoproliferative effects at 12- and 24-mg/kg dose levels, nor in a pilot study at 48 mg/kg. The 24-mg/kg dose of toremifene exerted an inhibiting effect on foci of hepatocellular alteration in rat liver detectable by glutathione S-transferase immunohistochemistry at 3 months and by conventional histology at 12 months. An antiproliferative effect was also evident in mammary gland and anterior pituitary where both toremifene and tamoxifen suppressed tumor incidence in comparison to the control group. The ability of these drugs to modify rat liver DNA after p.o. administration was investigated using the 32P-postlabeling assay. Administration of tamoxifen at 45 mg/kg for 7 days produced liver DNA nucleoside modifications represented by 7 spots on the autoradiogram. Unlike tamoxifen, toremifene did not produce any modified bases in rat liver DNA detectable by the 32P-postlabeling technique. The dose levels of tamoxifen that are strongly hepatocarcinogenic in the rat are compared with doses used in humans in various applications. Taking internal drug exposure into account, we conclude that the margin of safety for use of tamoxifen as an endocrine prophylactic agent for healthy, but breast cancer prone, women is questionable.

Adenoma↗

Phase I and II studies of toremifene.

Toremifene (Fareston) is a triphenylethylene derivative structurally similar to tamoxifen (Nolvadex) that was selected for development based on its in vitro activity against breast cancer and its lesser uterotrophic effect than tamoxifen in rat models. In phase I and II studies conducted in several countries, toremifene was well tolerated over a wide range of doses (10 to 680 mg/d). The major side effects were hot flashes, nausea, and vomiting. Toremifene's excretion half-life is 5 days. It produces a modest decline in serum levels of luteinizing hormone, follicle-stimulating hormone, and antithrombin III, as well as an increase in sex hormone-binding globulin levels. In studies in which toremifene was used as first-line therapy in patients with estrogen receptor (ER)-positive or ER-unknown tumors, response rates to doses of 40 to 60 mg/day ranged from 30% to 54%. In two larger studies of patients who had proved refractory to tamoxifen therapy, toremifene produced an objective response rate of 4% to 5%. When patients with stable disease were added to those with objective responses, 27% to 28% of patients were considered to derive clinical benefit from toremifene. The dose range chosen for further study was 40 to 60 mg/d.

Animals↗

Mitotic activity, apoptosis and TRPM-2 mRNA expression in DMBA-induced rat mammary carcinoma treated with anti-estrogen toremifene.

Anti-estrogen toremifene inhibits growth of the 7,12-dimethylbenz(a)anthracene(DMBA)-induced rat mammary carcinoma. The changes in proliferation and cell death were studied in detail. Proliferation was measured by counting mitotic figures in histologic sections, expressed by volume-corrected mitotic index (M/V INDEX). Respective volume corrected apoptotic index (A/V INDEX) was measured by counting apoptotic nuclei in the same sections. The presence of apoptotic cells was confirmed by transmission electron microscopy. In the untreated tumors, both mitosis and apoptosis were frequent. In the toremifene-treated tumors, the mean M/V INDEX was about half of the mean M/V INDEX in the untreated control tumors. The mean A/V INDEX in the toremifene-treated tumors was about 3/4 of the mean A/V INDEX in the controls. In toremifene-treated tumors, A/V INDEX was strongly correlated with TRPM-2-gene expression, which was also enhanced when compared with the controls. TRPM-2 gene has been associated with programmed cell death induced by hormonal ablation in prostate- and breast-cancer cells. No such correlation was seen in control tumors. These findings suggest that, in the DMBA-tumor model, toremifene affects the cell turnover by inhibiting mitotic activity and modifying abundant spontaneous apoptosis. In this model, the inhibition of tumor growth results mostly from reduction of mitotic activity.

9,10-Dimethyl-1,2-benzanthracene↗

Comparison between the effects of tamoxifen and toremifene on the uterus in postmenopausal breast cancer patients.

Antiestrogens have been widely used in the treatment of breast cancer patients. We wanted to compare the uteral and vaginal effects of tamoxifen to those of toremifene. Thirty-one gynecologically asymptomatic postmenopausal breast cancer patients with an intact uterus were randomized to receive 20 mg of tamoxifen (N = 16) or 60 mg of toremifene (N = 15) as an adjuvant treatment. Gynecological examination with vaginal ultrasonography, Pap smear, endometrial biopsy, hysteroscopy, and curettage was performed before the treatment, and at 6 and 12 months of treatment. Endometrial thickness was found to increase significantly during the treatment to the same extent in both groups. Proliferation or other estrogenic effects in the endometrium were observed in 8 of 14 patients in the tamoxifen group and in 3 of 10 patients in the toremifene group. Three polyps occurred and previously present uterine fibroids increased in size in 3 of 10 patients during the study. Estrogenic changes in Pap smear were observed in all patients. There was no significant difference between tamoxifen and toremifene in any of the parameters investigated. Our results suggest that tamoxifen and toremifene produce comparable estrogenic effects in the uterus and vagina.

Adult↗

Phase I clinical and pharmacokinetics study of high-dose toremifene in postmenopausal patients with advanced breast cancer.

Toremifene is an antiestrogen that binds strongly to estrogen receptors (ER). A total of 19 previously treated postmenopausal women with metastatic breast cancer whose performance status was good and whose ER status was positive or unknown were studied to determine the maximum tolerated dose of toremifene. Cohorts of patients received 200, 300, or 400 mg/m2 p.o. daily until relapse or unacceptable toxicity had occurred. Nausea, vomiting, and dizziness were dose-related. Three of five patients receiving 400 mg/m2 experienced moderate or severe vomiting and another developed reversible disorientation and hallucinations. Mild sweating, peripheral edema, vaginal discharge, and hot flushes were encountered at all doses. Reversible corneal pigmentation was identified in seven cases but was not of clinical importance. The pharmacokinetics of toremifene was studied weekly and in detail on day 42 using a high-performance liquid chromatographic (HPLC) assay that identified the parent compound and three active metabolites, N-desmethyltoremifene, (deaminohydroxy)toremifene, and didemethyltoremifene. Steady state was achieved at 1-3 weeks. The toremifene area under the curve and the maximal concentration were dose-dependent at high doses. The recommended phase II dose is 300 mg/m2 p.o. daily.

Adult↗

Phase II trials with toremifene in advanced breast cancer: a review.

The antitumor activity of the new triphenylethylene drug toremifene has been studied in advanced breast cancer of postmenopausal women as first line treatment at dose levels of 20, 60, and 240 mg, and as second line or later treatment at high dose levels of 200-240 mg. The response rates (complete + partial response) have been 21% with 20 mg (14 patients), 52% with 60 mg (93 patients in three separate trials), and 68% with 240 mg (38 patients) as first line treatment. After failure on previous therapy (hormonal or chemotherapy) the response rates have been about 10% with 200 mg of toremifene (71 patients in two different trials). In patients whose disease had previously responded to tamoxifen with at least stabilization, the response rate with toremifene has been 23%; but among unselected patients, including patients progressing during adjuvant tamoxifen, the response rate (CR + PR) with toremifene in tamoxifen failures has been 3%. If long lasting (more than 5 months) stabilization of the disease is also considered, a further 20% of previously treated patients have benefitted from toremifene. The treatment has been well tolerated at all dose levels. The most reported side effects have been hot flushes (8-19%) and nausea (8%). 0-6% of patients in different trials have interrupted the treatment because of side effects.

Antineoplastic Agents↗