Thrombosis of acute superior mesenteric artery in a patient with breast cancer receiving toremifene therapy: a case report and literature review

It is widely recognized that cancer itself is related to increased risk of thromembolism. Venous thromboembolism is relatively common in breast cancer patients, but arterial thrombosis, especially acute superior mesenteric artery thrombosis (SMAT) associated with chemotherapy or endocrinotherapy, rarely occurs in breast cancer patients. There were few reports about acute SMAT in cancer patients who underwent chemotherapy, but no reports of acute SMAT caused by endocrine-therapy. We reported a 54-year-old patient with acute SMAT during toremifene treatment after breast cancer surgery. She underwent 4 cycles chemotherapy of TC regimen, then accepted toremifen endocrinotherapy because of positive estrogen receptor. She suffered from acute SMAT after 2 months toremifen treatment. Therefore, we consider that this case of acute SMAT may be a rare adverse event of toremifen. In view of the high risk and rarity of acute SMAT caused by toremifene, we suggest that except for venous thrombosis, arterial thrombosis in special position (ATSP) should be kept in mind during use of toremifene. Once a thrombotic event occurs, toremifene should be stopped immediately.

Serum lipid and bone metabolism effects of Toremifene vs. Letrozole as adjuvant therapy for postmenopausal early breast cancer patients: results of a multicenter open randomized study

A prospective randomized phase II trial was conducted to evaluate the time course effects of toremifene (TOR) and letrozole (LET), as adjuvant hormone therapy, on serum lipid profiles and bone metabolism in estrogen receptor (ER)-positive, postmenopausal breast cancer patients.Fifty-four postmenopausal breast cancer patients [ER positive, HER2 negative, T1–2, node metastases (n = 0–3), M0] who had undergone curative resection were enrolled. They were randomized to receive either TOR 40 mg/day or LET 2.5 mg/day as adjuvant hormone therapy. Serum lipids and bone markers were measured prior to, and again at 6, 12, and 24 months after initiation of treatment. Changes in serum lipids and bone markers were compared. Serum levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were decreased compared with the baseline values at 6 months in 6.5 and 14.0% of patients, respectively, receiving TOR. Lipid levels did not change in patients administered LET. Significant differences were observed in TC and LDL-C between the two groups at 12 and 24 months. In the TOR group, serum bone-specific alkaline phosphatase (BAP) was decreased by 25.0% at 12 months, and serum cross-linked N-telopeptide of type-I collagen (NTx) was decreased by 13.6% at 6 months, and these reductions were maintained for at least 24 months. In contrast, in the LET group, serum BAP did not change and NTx was increased by 16.0% at 6 months and by 18.6% at 24 months, as compared with the baseline.TOR and LET exert different effects on serum lipid profiles and bone metabolism markers. The effects of TOR, as adjuvant hormone therapy, on both lipids and bone metabolism in postmenopausal breast cancer patients are superior to those of LET.

[A Case of Liver Failure Induced by Toremifene in a Patient with Metastatic Breast Cancer]

A 67-year-old woman underwent total mastectomy, postoperative radiation therapy, and adjuvant hormonal therapy more than 9 years 4 months previously. There were no symptoms of recurrence for 3.5 years after completing adjuvant hormonal therapy. A hard mass appeared on the front chest wall and was diagnosed as recurrence of breast cancer histopathologically. A computed tomography (CT) scan revealed multiple metastases in the left side of the chest wall, in the left Level Ⅱ axillary lymph nodes, and in the left lung. The patient was prescribed high-dose tremifene (HD-TOR 120 mg/day). After less than 4 months, she presented with general fatigue and yellow skin, and was admitted with grade 4 hyperbilirubinemia and grade 3 hepatic dysfunction (AST and ALT). CT and magnetic resonance imaging (MRI) showed no abnormal findings in the liver or biliary tract. Drug-induced liver injury (DILI) caused by HD-TOR was suspected and this therapy was discontinued. The liver dysfunction showed a tendency to improve with conservative treatment and the patient was discharged on the 10th day of illness. She had almost recovered after 5.5 months. A liver biopsy, a drug-lymphocyte stimulation test, and other detailed examinations were not performed, but we judged this case to be one of liver failure caused by HD-TOR-induced DILI.

Selective Estrogen Receptor Modulator-Associated Nonalcoholic Fatty Liver Disease Improved Survival in Patients With Breast Cancer: A Retrospective Cohort Analysis

Selective estrogen receptor modulator (SERM)-associated nonalcoholic fatty liver disease (NAFLD) might be related to treatment efficacy in patients with breast cancer because of circulating estrogen antagonism. The aim of the study was to investigate the relationship between NAFLD and survival outcomes in patients with breast cancer who were treated with tamoxifen or toremifene. This single-center, retrospective, cohort study included 785 eligible patients who received tamoxifen or toremifene, after curative resection for breast cancer, at the Sun Yat-sen University Cancer Center between January 2005 and December 2009. Data were extracted from patient medical records. All patients underwent abdominal ultrasonography, at least once, at baseline and at the annual follow-up. Patients who were diagnosed with NAFLD on ultrasonography were classified into the NAFLD or the non-NAFLD arm at the 3-year follow-up visit. Univariate and multivariate Cox regression analyses were conducted to evaluate any associations between NAFLD and disease-free survival (DFS) or overall survival (OS). One hundred fifty-eight patients were diagnosed with NAFLD. Patients who developed NAFLD had better DFS and OS compared with those who did not. Univariate analyses revealed that the 5-year DFS rates were 91.56% and 85.01% for the NAFLD and non-NAFLD arms, respectively (hazard ratio [HR], 0.59; 95% confidence interval [CI], 0.37-0.96; log-rank P = 0.032). The 5-year OS rates were 96.64% and 93.31% for the NAFLD and non-NAFLD arms, respectively (HR, 0.39; 95% CI, 0.16-0.99; log-rank P = 0.039). Multivariate analysis revealed that NAFLD was an independent prognostic factor for DFS, improving the DFS rate by 41% compared with that in the non-NAFLD arm (HR, 0.59; 95% CI, 0.36-0.96; P = 0.033). SERM-associated NAFLD was independently associated with improved DFS and might be useful for predicting treatment responses in breast cancer patients treated with SERMs.

Phase II clinical trial of high-dose toremifene as primary hormone therapy in aromatase inhibitor-resistant breast cancer

BACKGROUND

Third-generation aromatase inhibitors(AIs)are now common in adjuvant hormone therapy for breast cancer in postmenopausal women. However, a suitable treatment has yet to be established for patients who develop cancer recurrence during or after adjuvant AI therapy.

PATIENTS AND METHODS

This prospective study evaluated the efficacy and safety of 120mg/day toremifene citrate(TOR-120)administered orally to 23 patients with recurrent breast cancer who were receiving or had received adjuvant AI therapy. Primary therapy for recurrence was TOR-120 monotherapy.

RESULTS

The response rate was 13. 0%(partial response: three patients), the clinical benefit rate was 78. 3%(partial response: three patients; long-term stable disease: 15 patients), and median time to progression was 8. 1 months. Grade 1 adverse events such as loss of appetite, sweating, flushing and edema face were observed.

CONCLUSION

TOR-120 monotherapy was effective and safe as a primary hormone therapy for recurrent breast cancer unresponsive to AIs.

Toremifene versus tamoxifen for advanced breast cancer

BACKGROUND

Toremifene (TOR) and tamoxifen (TAM) can both be used as treatments for advanced breast cancer.

OBJECTIVES

To compare the efficacy and safety of TOR with TAM in patients with advanced breast cancer.

SEARCH METHODS

The Cochrane Breast Cancer Group's Specialised Register was searched (1 July 2011) using the codes for "toremifene", "fareston", "tamoxifen, "nolvadex, and "breast cancer". We also searched MEDLINE (via PubMed) (from inception to 1 July 2011), EMBASE (via Ovid) (from inception to 1 July 2011), The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 7, 2011), and the WHO International Clinical Trials Registry Platform search portal (1 July 2011). In addition, we screened the reference lists of relevant trials or reviews.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that compared the efficacy and safety, or both of TOR with TAM in women with advanced breast cancer. Trials that provided sufficient data on one of the following items: objective response rate (ORR), time to progression (TTP), overall survival (OS), and adverse events, were considered eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Studies were assessed for eligibility and quality. Two review authors independently extracted the following details: first author, publication year, country, years of follow-up, treatment arms, intention-to-treat (ITT) population size, menopausal status of patients, hormone receptor status, response criteria, efficacy and safety outcomes of TOR and TAM arms. Hazard ratios (HR) were derived for time-to-event outcomes, where possible, and response and adverse events were analysed as dichotomous variables. We used a fixed-effect model for meta-analysis unless there was significant between-study heterogeneity.

MAIN RESULTS

A total of 2061 patients from seven RCTs were included for final analysis, with 1226 patients in the TOR group and 835 patients in the TAM group. The ORR for the TOR group was 25.8% (316/1226) whereas, the ORR for the TAM group was 26.9% (225/835). The pooled risk ratio (RR) suggested that the ORRs were not statistically different between the two groups (RR 1.02, 95% confidence interval (CI) 0.88 to 1.18, P = 0.83). The median TTP was 6.1 months for the TOR group and 5.8 months for the TAM group. The median OS was 27.8 months for the TOR group and 27.6 months for the TAM group. There were no significant differences in TTP and OS between the two therapeutic groups (for TTP: HR 1.08, 95% CI 0.94 to 1.24; for OS: HR 1.02, 95% CI 0.86 to 1.20). The frequencies of most adverse events were also similar in the two groups, while headache seemed to occur less in the TOR group than in the TAM group (RR 0.14, 95% CI 0.03 to 0.74, P = 0.02). There was no significant heterogeneity between studies in most of the above meta-analyses. Sensitivity analysis did not alter the results.

AUTHORS' CONCLUSIONS

TOR and TAM are equally effective and the safety profile of the former is at least not worse than the latter in the first-line treatment of patients with advanced breast cancer. Thus, TOR may serve as a reasonable alternative to TAM when anti-oestrogens are applicable but TAM is not the preferred choice for some reason.

[Efficacy of high-dose toremifene as a second-line hormone therapy in patients with advanced or metastatic breast cancer resistant to aromatase inhibitor]

BACKGROUND

Aromatase inhibitors(AIs)are frequently employed for advanced or metastatic postmenopausal breast cancer as first-line hormone therapy. However, it is unknown which hormonal agent is the most appropriate after AI has failed.

PATIENTS AND METHODS

Five hormone-responsive postmenopausal women who used AI as a first-line hormone therapy for advanced or metastatic breast cancer, but AI failed, received high-dose toremifene therapy(HD-TOR: 120mg/day)in our hospital. Efficacy and safety were evaluated.

RESULTS

Patients were all-hormone sensitive, and only one case had HER2 overexpression. All patients had received anastrozole(ANA)as first-line hormone therapy. Of a total of 5 cases, 3 were evaluated as partial responses(PR), 1 was a long stable disease(L-SD), and 1 was a progressive disease(PD). The overall response rate (RR)was 60. 0%(3/5 cases)and the clinical benefit rate(CB)was 80. 0%(4/5 cases). Grade 1 dry mouth was observed in one case as an adverse event.

CONCLUSIONS

HD-TOR as a second-line therapy is optimal for advanced or metastatic AI resistance postmenopausal breast cancer.

[A retrospective study of high-dose toremifene treatment for patients with aromatase inhibitor refractory advanced or metastatic hormone receptor-positive breast cancer]

Aromatase inhibitors (AI) have largely replaced tamoxifen as the first-line of treatment for postmenopausal women with advanced or metastatic hormone-receptor-positive breast cancer. However, there is no established strategy for treating AI refractory cases. In this study, we investigated the efficacy of high-dose Toremifene therapy (HD-TOR). From January 2001 through April 2010, nineteen patients received 120 mg of TOR daily. The overall response rate was 36.8% (CR; 1, PR; 6), and the clinical benefit was 47.4%. The clinical benefit rate to each of the metastatic organs were: lung, 42.9%; bone, 13%; liver, 25%; and lymph node, 40%. A higher clinical benefit rate was observed in lung or lymph node metastases. The clinical benefit rate of HD-TOR as first to third-line therapy was 50%, which was more effective than that of fourth-line therapy. Our data suggests that HD-TOR may be one of the effective treatment strategies for patients with AI refractory advanced or metastatic hormone receptor-positive breast cancer.

[Efficacy and safety of high-dose toremifene for hormone-responsive advanced or metastatic breast cancer patients with failed prior treatment by aromatase inhibitors]

BACKGROUND

Recently, aromatase inhibitors (AI) are widely used in postoperative adjuvant therapy for breast cancer. Nevertheless, studies of postoperative therapeutic strategies for recurrent breast cancer are insufficient.

SUBJECTS AND METHOD

Data on 12 post-menopausal advanced/recurrent breast cancer patients in our department during June 2003- April 2007 were used for this study. No patient had responded to high-dose toremifene (TOR), a third-generation AI. Their therapeutic outcomes were analyzed retrospectively. The median observation period of the subjects was 16.1 months (4.0-40.9 months). Subjects were all hormone-sensitive. Overexpression of HER2 protein was found in only one case. During AI therapy immediately prior, exemestane (EXE) and anastrozole (ANA) had been given in nine and three cases, respectively.

RESULTS

The complete response rate of AI therapy was 16.7% (2/12). The clinical benefit rate was 58.3% (7/12). The median of time to progression (TTP) was 33.8 weeks. Neither the presence nor absence of past history of treatment with tamoxifen (TAM) or other chemotherapies affected the anti-tumor effect. Analysis by the site of metastasis or recurrence revealed that the therapeutic effects were better for non-life-threatening cases in the lung, pleura, soft tissue, etc. The severities of adverse effects were all less than grade 2; the major ones were flushing and sweating.

CONCLUSION

Results show that high-dose TOR given at an early stage can provide clinical benefits for post-menopausal advanced/recurrent breast cancer not responding to AI.

Ocular toxicity during adjuvant chemoendocrine therapy for early breast cancer

BACKGROUND

Others have reported ocular toxicity after adjuvant chemoendocrine therapy, but this study looked at ocular toxicity in similarly treated patients from large randomized clinical trials.

METHODS

Information was retrieved on incidence and timing of ocular toxicity from the International Breast Cancer Study Group (IBCSG) database of 4948 eligible patients randomized to receive tamoxifen or toremifene alone or in combination with chemotherapy (either concurrently or sequentially). Case reports of patients with ocular toxicity were evaluated to determine whether ocular toxicity occurred during chemotherapy and/or hormonal therapy. Additional information was obtained from participating institutions for patients in whom ocular toxicity occurred after chemotherapy but during administration of tamoxifen or toremifene.

RESULTS

Ocular toxicity was reported in 538 of 4948 (10.9%) patients during adjuvant treatment, mainly during chemotherapy. Forty-five of 4948 (0.9%) patients had ocular toxicity during hormone therapy alone, but only 30 (0.6%) patients had ocular toxicity reported either without receiving any chemotherapy or beyond 3 months after completing chemotherapy and, thus, possibly related to tamoxifen or toremifene. In 3 cases, retinal alterations, without typical aspects of tamoxifen toxicity, were reported; 4 patients had cataract (2 bilateral), 12 impaired visual acuity, 10 ocular irritation, 1 optical neuritis, and the rest had other symptoms.

CONCLUSION

Ocular toxicity during adjuvant therapy is a common side effect mainly represented by irritative symptoms due to chemotherapy. By contrast, ocular toxicity during hormonal therapy is rare and does not appear to justify a regular program of ocular examination. However, patients should be informed of this rare side effect so that they may seek prompt ophthalmic evaluation for ocular complaints.

A Double-blind Randomized Controlled Trial of Toremifen Therapy for Mastalgia

HYPOTHESIS

Toremifen is effective in reducing breast pain and does not increase the incidence of adverse events as a therapy for moderate to severe mastalgia.

DESIGN AND PATIENTS

In a double-blind randomized controlled trial, patients with moderate to severe mastalgia received toremifen citrate, 30 mg daily, or a placebo tablet for 3 menstrual cycles and were followed up for breast pain score and adverse events. The serum levels of estradiol, progesterone, and prolactin were examined before treatment and correlated with the response rate to toremifen treatment.

RESULTS

Seventy-two (69.2%) of 104 patients receiving toremifen and 29 (31.9%) of 91 receiving placebo responded to the treatment, with reduction in breast pain score of more than 50% (P<.001). Among the patients with cyclical mastalgia, the response rate for toremifen was 76.7% (59/77), whereas the response rate for placebo was 34.8% (23/66; P<.001). In contrast, the response rate of patients with noncyclical mastalgia was 48.1% (13/27) for toremifen and 24.0% (6/25) for placebo (P = .09). Adverse events were observed in 44 (42.9%) of 104 patients receiving placebo and 46 (50.5%) of 91 patients receiving toremifen (P = .45). A positive correlation between baseline breast pain score and serum estradiol level was observed in patients with cyclical mastalgia (r = 0.35, P = .003).

CONCLUSIONS

Toremifen effectively relieves moderate and severe cyclical mastalgia and tends to exert a positive therapeutic effect on noncyclical mastalgia. In addition, toremifen therapy does not increase the incidence of intolerable adverse event. Therefore, it is a feasible therapy for mastalgia, especially cyclical mastalgia.

Bone mineral density and lipid changes during 5 years of follow-up in a study of prevention of breast cancer with toremifene in healthy, high-risk pre- and post-menopausal women

A double-blind, randomised, placebo-controlled pilot study was initiated to evaluate the feasibility of chemoprevention with toremifene 60 mg/day in healthy women at high risk for breast cancer. Enrolment in the study was terminated earlier than planned because of slow patient accrual, although 13% of patients continued for 5 years. The revised efficacy outcomes were change in bone mineral density (BMD) from baseline at four skeletal sites, plus effects on serum lipids. In premenopausal women there was a trend for sustained increase in BMD during toremifene therapy after year 1 in lumbar spine. In postmenopausal women, toremifene had little or no effect on BMD trends. Levels of total and low-density lipoprotein (LDL) cholesterol were largely unchanged from baseline in premenopausal women treated with toremifene but were often slightly lower than in the placebo group during follow-up. Total and LDL cholesterol levels declined slightly from baseline in the postmenopausal women and were, at several points during the first 3 years, significantly lower than in the corresponding placebo group (p < 0.01). We conclude that: (a) assessment of toremifene 60 mg/day in chemoprevention will require further clinical trials; (b) toremifene 60 mg/day has no substantive negative effects on BMD in pre- or postmenopausal women and may exert a minor favourable influence (in particular, the effects of toremifene 60 mg/day on BMD in premenopausal women may make the drug an attractive alternative to tamoxifen 20 mg/day for that patient subset); (c) lipid effects of toremifene 60 mg/day are, at minimum, neutral and may be modestly favourable for reducing cardiovascular risk.

Toremifene: an evaluation of its safety profile

Toremifene has been in clinical use for 8 years for the treatment of advanced hormone-sensitive breast cancer and the adjuvant treatment of early breast cancer. More than 350,000 patient treatment years have accumulated, sufficient to allow evaluation of its longer-term safety profile in comparison with tamoxifen and, where possible, with raloxifene and aromatase inhibitors. We reviewed all preclinical and clinical safety data from 1978 to 2004 and comparative clinical safety data between October 1995 and the end of 2004. Secondary endometrial cancer incidence was lower with toremifene than with tamoxifen and was similar to that with raloxifene. It is speculated that toremifene may unmask existing endometrial tumors rather than induce new events. The risk of stroke, pulmonary embolism, and cataract may be lower with toremifene than with tamoxifen and the risk of pulmonary embolism and deep vein thrombosis lower than with raloxifene. Beneficial estrogen agonistic effects were equivalent to those of tamoxifen regarding bone mineral density and superior regarding lipid profiles.

[Experience of high-dose toremifene treatment for postmenopausal women with metastatic breast cancer]

Toremifene (TOR), a selective estrogen receptor modulator (SERM), showed efficacy equivalent to Tamoxifen (TAM) in terms of the objective response rate, stable disease, time to progression and overall survival in patients with metastatic breast cancer (MBC). High-dose TOR is also effective for patients with TAM-resistant breast cancer. We tried to study retrospectively the efficacy and the safety of high-dose TOR treatment for patients with MBC in our hospital. Ten patients received TOR 120 mg daily. Most of the patients were treated with one or more endocrine agents before high-dose TOR. Objective response and clinical benefits were found in 3 patients (30%) and 7 patients (70%), respectively. Median time to progression and median overall survival were 9 months and 21.5 months, respectively. In our study,we found the efficacy for patients with hormone receptor negative, TAM resistance and aromatase inhibitor (AI)-resistance breast cancer. Adverse events induced by high-dose TOR treatment were tolerable. High-dose TOR may be one of the optional treatments for patients with MBC after TAM and AI treatment.

Toremifene and tamoxifen are equally effective for early-stage breast cancer: first results of International Breast Cancer Study Group Trials 12-93 and 14-93

BACKGROUND

Toremifene is a chlorinated derivative of tamoxifen, developed to improve its risk-benefit profile. The International Breast Cancer Study Group (IBCSG) conducted two complementary randomized trials for peri- and postmenopausal patients with node-positive breast cancer to compare toremifene versus tamoxifen as the endocrine agent and simultaneously investigate a chemotherapy-oriented question. This is the first report of the endocrine comparison after a median follow-up of 5.5 years.

PATIENTS AND METHODS

1035 patients were available for analysis: 75% had estrogen receptor (ER)-positive primary tumors, the median number of involved axillary lymph nodes was three and 81% received prior adjuvant chemotherapy.

RESULTS

Toremifene and tamoxifen yielded similar disease-free (DFS) and overall survival (OS): 5-year DFS rates of 72% and 69%, respectively [risk ratio (RR)=0.95; 95% confidence interval (CI)=0.76-1.18]; 5-year OS rates of 85% and 81%, respectively (RR = 1.03; 95% CI = 0.78-1.36). Similar outcomes were observed in the ER-positive cohort. Toxicities were similar in the two treatment groups with very few women (<1%) experiencing severe thromboembolic or cerebrovascular complications. Quality of life results were also similar. Nine patients developed early stage endometrial cancer (toremifene, six; tamoxifen, three).

CONCLUSIONS

Toremifene is a valid and safe alternative to tamoxifen in postmenopausal women with endocrine-responsive breast cancer.

Toremifene, a new agent for treatment of mastalgia: an open study

OBJECTIVE

Endocrine agents have been widely used in the treatment of mastalgia. Toremifene is an agent that predominantly has antiestrogenic properties with minimal estrogenic activities. This study was aimed at investigating this drug in the treatment of mastalgia and to evaluate its tolerability and efficacy.

METHODS

Seventeen premenopuasal women with a mean age of 37.7 years complaining of moderate to severe mastalgia received toremifene 60 mg daily. The treatment period was 12 weeks. 70% of patients had cyclical and 30% had noncyclical mastalgia.

RESULTS

All women with cyclical mastalgia responded to toremifene compared with only 75% of those with non-cyclical mastalgia. Four patients withdrew from the study after 4 weeks because of side effects, accounting for 23.5% of patients in the study.

CONCLUSION

This small study has shown that toremifene is an effective agent in the treatment of mastalgia, but a high incidence of side effects makes it ineligible as an agent of choice for treatment of mastalgia.

Ocular side-effects in breast cancer patients treated with tamoxifen and toremifene: a randomized follow-up study

PURPOSE

3Tamoxifen and toremifene are non-steroidal anti-oestrogens widely used in the treatment of advanced breast cancer and as adjuvant therapy following surgery in early stage disease. Tamoxifene has also been approved for use in reducing the incidence of breast cancer amongst high risk women. However, certain well documented adverse effects, mainly involving the reproductive organs, have been reported amongst users of both drugs. The aim of this study was to monitor the ocular side-effects of both of these commonly used anti-oestrogens.

METHODS

Sixty postmenopausal (age range 50-79 years) breast cancer patients were randomized into adjuvant tamoxifen or toremifene therapy groups for 3 years. Prior to commencement of medication, a thorough ocular examination was undertaken. The first follow-up visit took place after 6 months and the remaining three at 12-month intervals thereafter.

RESULTS

Sixteen patients had cataract at the first visit (seven in the tamoxifen group and nine in the toremifene group). Ten patients developed cataract during the study period (five in each group), giving annual cataract rates of 6.8% and 6.2% in the tamoxifen and toremifene groups, respectively. Three patients had macular crystals at the first visit (one in the tamoxifen group and two in the toremifene group). The crystals remained stable throughout the follow-up. Macular drusen were diagnosed in five patients at the first ophthalmological check-up (two in the tamoxifen and three in the toremifene group). Two patients in the toremifene group developed drusen maculopathy during follow-up visits. Yellowish spots in the macular area were found in one tamoxifen-treated patient at the second visit. At the final visit after 3.5 years' follow-up the spots had disappeared. No abnormal corneal findings or keratopathy were documented during the follow-up.

CONCLUSION

We observed no serious ocular side-effects among the 60 breast cancer patients treated with tamoxifen or toremifene over a 3.5-year period.

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.

Evolving uses of hormonal agents for breast cancer therapy

BACKGROUND

During the past decade, a number of new hormonal therapies (HTs) have been developed, including the selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs), and estrogen receptor (ER) antagonists. Their uses in breast cancer are continually evolving as new clinical trial results become available. Although tamoxifen, the most widely used HT for breast cancer, was originally approved for and used in the treatment of metastatic breast cancer (MBC), its effectiveness as MBC therapy led to its subsequent assessment and use as adjuvant and risk-reduction therapy for breast cancer. However, tamoxifen is not universally effective in these settings and is associated with infrequent known toxicities such as increased risk of thromboembolism and endometrial cancer; therefore, a search for more effective and more tolerable HTs has evolved.

OBJECTIVE

This article reviews the data supporting the use of newer HTs as initial treatment of MBC and their potential use as adjuvant, neoadjuvant, and chemopreventive therapies.

METHODS

Articles for inclusion in this manuscript were identified through the following searches, limited to English-language publications: MEDLINE (mid 1960s to January 2002), American Society of Oncology abstracts (1997-2001), and San Antonio Breast Cancer Symposium abstracts (2001 and 2002). The following search terms were used: breast cancer, breast cancer guidelines, hormonal therapies, tamoxifen, toremifine, letrozole, anastrozole, exemestane, megestrol acetate, fulvestrant, and ICI 182,780.

RESULTS

Recent studies have focused on newer agents as initial and subsequent treatment of MBC, adjuvant or neoadjuvant treatments of breast cancer, and chemopreventive agents in both healthy women and women with a history of ductal carcinoma in situ (DCIS). Results of clinical trials comparing AIs with tamoxifen as first-line MBC treatment show that AIs are as effective as, or more effective than, tamoxifen and are associated with fewer serious adverse events. Tamoxifen remains the gold standard for adjuvant therapy. However, preliminary results of ongoing clinical trials comparing tamoxifen with anastrozole suggest that anastrozole may be the superior agent. Both tamoxifen and the AIs have been shown to be active in the neoadjuvant treatment of breast cancer. Trial results have shown that tamoxifen is effective for breast cancer prevention in patients at high risk of developing breast cancer but who are otherwise healthy, patients with a history of DCIS, and patients with lobular carcinoma in situ.

CONCLUSIONS

Although tamoxifen has been the gold standard of HT for breast cancer, results of ongoing trials assessing the newer HTs as initial, neoadjuvant, adjuvant, and chemopreventive therapies may substantially change our current clinical practice patterns.

Tamoxifen and toremifene treatment of breast cancer and risk of subsequent endometrial cancer: a population-based case-control study

A population-based case-control study was performed to evaluate the risk of endometrial cancer related to tamoxifen or toremifene treatment. All patients with breast cancer diagnosis since 1980 in Finland who subsequently developed an endometrial cancer by the end of 1995 and 3 matched controls were identified among the 38,000 breast cancer patients of the Finnish Cancer Registry database. Detailed information on treatment of breast cancer and potential confounders was collected from hospital records. The OR for tamoxifen treatment (59 cases), adjusted for significant cofactors (increased risk associated with obesity, low parity and PR positivity) was 2.9 (95% CI 1.8-4.7). The OR for toremifene (3 cases) was 0.9 (95% CI 0.3-3.9). The OR related to adjuvant tamoxifen treatment reached its maximum 2-5 years after the beginning of treatment (OR 5.1, 95% CI 2.1-13), while the OR for tamoxifen used for palliative treatment of advanced breast cancer was especially high after a lag of over 5 years (OR 9.5, 95% CI 2.5-36). The risk increase due to tamoxifen was slightly higher if the age at initiation was below 55, and risk was more pronounced among patients with well-differentiated endometrial cancer than patients with cancers of clinical grades 2 or 3. According to our results, treatment with tamoxifen increases the risk of endometrial cancer. Due to the rare use of toremifene up to the mid-1990s, the risk assessment concerning it was inconclusive.

A phase II trial of interferon-alpha and toremifene in advanced renal cell cancer patients

Treatment options for patients with metastatic renal cell carcinoma are limited. Interferon-alpha has an overall response rate of 10-15% in phase II and III clinical trials and is considered a standard option for patients. Though the anti-estrogen toremifene has shown only modest single agent activity in renal cell carcinoma, evidence for synergy of anti-estrogens with interferon-alpha exists in renal cell and other cancers. Therefore, a phase II trial was undertaken to test the combination of interferon-alpha and toremifene in advanced renal cell carcinoma. Thirteen patients with measurable metastatic or unresectable local disease were treated with interferon-alpha at a dose of 5 million units/m2 three times a week and daily oral toremifene at 300 mg daily in divided doses. Patients were treated for 12 weeks and then restaged. Clinical response was the primary endpoint of the trial. Four patients (31%) had evidence of stable disease at 12 weeks, while the remaining nine patients (69%) progressed on treatment. Toxicity was moderate, with grade 2 or 3 fatigue, nausea and anorexia each noted in 31% of patients. We conclude that the combination of interferon-alpha plus toremifene demonstrates no significant activity in advanced renal cell carcinoma.

Evaluation of the cytotoxicity of selected systemic and intravitreally dosed drugs in the cultures of human retinal pigment epithelial cell line and of pig primary retinal pigment epithelial cells

The cytotoxicity of the selected systemic and intravitreally dosed drugs tamoxifen, toremifene, chloroquine, 5-fluorouracil, gentamicin and ganciclovir was studied in retinal pigment epithelium (RPE) in vitro. The cytotoxicity was assayed in the human RPE cell line D407 and the pig RPE cell culture using the WST-1 test, which is an assay of cell proliferation and viability. The effects of experimental conditions on the WST-1 test (cell density, serum content in the culture medium, the exposure time) were evaluated. The EC50 values in tamoxifen-treated D407 cells ranged between 6.7 and 8.9 micromol/l, and in pig RPE cells between 10.1 and 12.2 micromol/l, depending on the cell density used. The corresponding values for toremifene were 7.4 to 11.1 micromol/l in D407 cells and 10.0 to 11.6 micromol/l in pig RPE cells. In chloroquine-treated cells, the EC50 values were 110.0 micromol/l for D407 cells and 58.4 micromol/l for pig RPE cells. Gentamicin and ganciclovir did not show any toxicity in micromolar concentrations. The exposure time was a significant factor, especially when the drug did not induce cell death, but was antiproliferative (5-fluorouracil). Serum protected the cells from the toxic effects of the drugs. Both cell cultures were most sensitive to tamoxifen and toremifene, and next to chloroquine. The drug toxicities obtained in the present study were quite similar in both cell types; that is, the pig RPE cells and the human D 407 cell line, despite the differences in, for example, the growth rate and melanin contents of the cell types. Owing to the homeostatic functions important for the whole neuroretina, RPE is an interesting in vitro model for the evaluation of retinal toxicity, but, in addition to the WST-1 test, more specific tests and markers based on the homeostatic functions of the RPE are needed.

Toxicity of antiestrogens

The object of this article is to review briefly the preclinical and clinical safety of some antiestrogens. Tamoxifen, toremifene, droloxifene, and idoxifene are polyphenylethylene antiestrogens, whereas the pure antiestrogen, ICI 182,780 or faslodex, as well as raloxifene, is of a different structure. Tamoxifen has been shown to be genotoxic in several studies. It induces unscheduled DNA synthesis in rat hepatocytes and micronuclei in MCL-5 a cells in vitro. Tamoxifen also induces aneuploidy in rat liver in vivo and chromosome aberrations and micronuclei in mouse bone marrow. Toremifene has also shown to be genotoxic, but to a far lower extent, by inducing micronuclei in MCL-5 a cells in vitro and by inducing aneuploidy in rat liver in vivo. Tamoxifen has been shown to be hepatocarcinogenic in the rat in at least four independent long-term studies. The initiation of tumors in the rat is the result of metabolic activation by cytochrome P450 isoenzymes to an electrophile(s) that binds irreversibly to DNA. The other antiestrogens have not been shown to be carcinogenic in rodents. In several independent clinical studies, the risk of endometrial cancer has increased among tamoxifen-treated women. After reviewing the available data, the International Agency for Research on Cancer concluded that there was sufficient evidence to show that tamoxifen is a class I human carcinogen. The increased risk for endometrial cancer occurs predominantly among women who are 50 years old or older and who have been treated with tamoxifen. It is not yet clear whether the uterine tumor formation is a result of genetic mechanisms, analogous to those seen in the rat liver or due to the estrogen agonist action of tamoxifen. However, the other antiestrogens with a more or less similar intrinsic estrogenic potential have not been shown to be carcinogenic in humans.

Comparative tolerability of first-generation selective estrogen receptor modulators in breast cancer treatment and prevention

In general, the selective estrogen receptor modulators (SERMs) currently indicated for the treatment and prevention of breast cancer, i.e. tamoxifen and toremifene, are fairly well tolerated. However, tamoxifen has been shown to induce hepatocellular carcinomas in rats, but not in humans, and can increase the risk of endometrial cancer in humans by two to three times. Other potentially serious adverse effects which have been associated with tamoxifen and toremifene therapy include vasomotor symptoms, an increased risk of venous thromboembolic events, and an increased incidence of cataracts and ocular toxicity, fatty liver, and nonmalignant hepatic and uterine changes. In addition, long term tamoxifen use almost always results in resistance to the drug and, indeed, has actually been shown to promote tumour proliferation in human breast cancer cells. Both tamoxifen and toremifene display drug interactions with a variety of drug classes. The adverse events associated with these compounds have raised significant concerns regarding their widespread use for the treatment and prevention of breast cancer. In addition, because of the weakness and scarcity of the data on toremifene, any conclusions about its tolerability remain tentative until outcomes of ongoing clinical trials in the adjuvant setting are known. A third SERM, raloxifene, is the focus of several large randomised trials examining its efficacy in the prevention of breast cancer. At present, each potential adverse event needs to be weighed against potential benefits in the decision to undergo SERM treatment. An array of therapies is currently available for patients with breast cancer and women at increased risk of disease; the risk-to-benefit ratio for each agent should be carefully examined in determining the most advantageous regimen.

[A case of locally recurrent breast cancer in which phlebothrombosis of the right leg after hormonal therapy using a high dose of toremifene citrate]

A 72-year-old female had undergone mastectomy at the age of 67 for right breast cancer (T2a, n1 alpha, positive for ER). In the surgery the pectoralis muscle was preserved. For adjuvant therapy, 20 mg/day of tamoxifen was orally administered for 5 years. Six years after surgery, relapse was detected in the right major pectoralis muscle. Irradiation at this site and oral administration of 120 mg/day of toremifene citrate were started. The patient had a medical history of diabetes, and the control of her blood sugar was poor. About 2 months after oral administration of toremifene citrate was started, flares with blebs and swelling were observed in the right lower leg, suggesting acute phlebothrombosis of the right lower limb. The symptoms were ameliorated by intravenous administration of heparin and an antibiotic. In administering a high dose of toremifene citrate to patients with complications, careful follow-up is needed.

Activity of high-dose toremifene plus cisplatin in platinum-treated non-small-cell lung cancer: a phase II California Cancer Consortium Trial

PURPOSE

Although cisplatin is an important agent in non-small-cell lung cancer (NSCLC), de novo resistance is common and acquired resistance emerges rapidly during therapy. Proposed mediators of platinum resistance include the protein kinase C (PKC) signal transduction pathway and associated c-FOS overexpression. While estrogen administration has been reported to upregulate PKC and c-FOS expression, the triphenylethylenes tamoxifen and toremifene potentiate platinum cytotoxicity by inhibition of PKC. Downregulation of c-FOS expression has been reported to result from PKC inhibition. In view of these findings, we hypothesized that toremifene would reverse platinum resistance and that this interaction would be influenced by tumor estrogen receptor (ER) status.

MATERIALS AND METHODS

A phase II trial of high-dose toremifene (600 mg orally daily on days 1-7) plus cisplatin (50 mg/m2 intravenously on days 4 and 11) every 28 days in NSCLC patients was conducted. A group of 30 patients with metastatic NSCLC who had been previously treated with platinum-based therapy were enrolled.

RESULTS

All of the 30 patients were assessable for toxicity and 28 for tumor response. Therapy was well tolerated with minimal hematologic and non-hematologic toxicity. Common toxicity criteria grade 3 hematologic toxicity was seen in only three patients. Five patients achieved a partial response for an overall response rate of 18% (95% CI 6-37). Median overall survival was 8.1 months (95% CI 5.4-17). To assess PKC, ER, and c-Fos expression by immunohistochemistry, 12 informative pretreatment patient tumor specimens were obtained. Four patient tumor specimens were positive for one or both PKC isoforms (alpha and epsilon) while c-Fos was overexpressed in three. None of the responding patient tumors exhibited c-FOS or PKC-epsilon overexpression. ER expression was found to be infrequent (8%), contrasting with previous reports in this tumor type.

CONCLUSION

While this phase II study indicates that high-dose toremifene plus cisplatin is feasible, active, and well tolerated in NSCLC patients previously treated with platinum compounds, the mechanism of action remains unclear. Further study of this regimen is warranted.

Prospective study on gynaecological effects of two antioestrogens tamoxifen and toremifene in postmenopausal women

To assess and compare the gynaecological consequences of the use of 2 antioestrogens we examined 167 postmenopausal breast cancer patients before and during the use of either tamoxifen (20 mg/day, n = 84) or toremifene (40 mg/day, n = 83) as an adjuvant treatment of stage II-III breast cancer. Detailed interview concerning menopausal symptoms, pelvic examination including transvaginal sonography (TVS) and collection of endometrial sample were performed at baseline and at 6, 12, 24 and 36 months of treatment. In a subgroup of 30 women (15 using tamoxifen and 15 toremifene) pulsatility index (PI) in an uterine artery was measured before and at 6 and 12 months of treatment. The mean (+/-SD) follow-up time was 2.3 +/- 0.8 years. 35% of the patients complained of vasomotor symptoms before the start of the trial. This rate increased to 60.0% during the first year of the trial, being similar among patients using tamoxifen (57.1%) and toremifene (62.7%). Vaginal dryness, which was present in 6.0% at baseline, increased during the use of tamoxifen (26.2%) and toremifene (24.1%). Endometrial thickness increased from baseline (3.9 +/- 2.7 mm) to 6.8 +/- 4.2 mm at 6 months (P< 0.001), and no difference emerged between the 2 regimens in this regard. Before the start of the antioestrogen regimen, the endometrium was atrophic in 71 (75.5%) and proliferative in 19 of 94 (20.2%) samples; 4 patients had benign endometrial polyps. During the use of antioestrogen altogether 339 endometrial samples were taken (159 in tamoxifen group, 180 in toremifene group). The endometrium was proliferative more often in the tamoxifen group (47.8%) than in the toremifene group (32.2%) (P< 0.0001). 20 patients had a total of 24 polyps (17 in tamoxifen and 9 in toremifene group, P< 0.05) during the use of antioestrogens. One patient in the toremifene group developed endometrial adenocarcinoma at 12 months, and one patient had breast cancer metastasis on the endometrium. Tamoxifen failed to affect the PI in the uterine artery, but toremifene reduced it by 15.0% (P< 0.05) by 12 months. In conclusion, tamoxifen and toremifene cause similarly vasomotor and vaginal symptoms. Neither regimen led to the development of premalignant endometrial changes. Our data suggest that so close endometrial surveillance as used in our study may not be mandatory during the first 3 years of use of antioestrogen treatment.

Toremifene-induced fatty liver and NASH in breast cancer patients with breast-conservation treatment

We have described fatty liver, diagnosed by computed tomography scanning (CT) in more than 30% of patients with breast cancer who received tamoxifen. Therefore, it is urgent to elucidate the frequency and the degree of fatty liver induced by toremifene, an analogue of tamoxifen, which is also used in breast cancer. We enrolled 52 breast cancer patients who were treated with breast-conservation treatment and administered oral toremifene for 3-5 years as adjuvant endocrine therapy. We evaluated the degree of fatty liver by abdominal CT performed annually. CT demonstrated toremifene-induced fatty liver in four (7.7%) of 52 breast cancer patients. Toremifene-induced fatty liver did not correlate with abnormal levels of AST, ALT, GGT or total cholesterol. One patient who demonstrated moderate fatty liver by CT was histologically diagnosed as non-alcoholic steatohepatitis (NASH) by liver biopsy. The incidence of toremifene-induced fatty liver was significantly lower than that induced by tamoxifen. Accordingly, in terms of fatty liver and NASH, toremifene is considered to be more appropriate agent than tamoxifen. Though toremifene is less likely to induce fatty liver, the possibility remains that toremifene-induced steatohepatitis occurs. Because the diagnosis of fatty liver or NASH can be easily missed if only a blood test is performed, it is necessary to screen fatty liver by annual CT examination for patients who receive an antiestrogen agent.

Safety and efficacy results of a randomized trial comparing adjuvant toremifene and tamoxifen in postmenopausal patients with node-positive breast cancer. Finnish Breast Cancer Group

PURPOSE

In this multicenter trial, toremifene 40 mg/d was compared with tamoxifen 20 mg/d, both given orally for 3 years to postmenopausal, axillary node-positive women after breast surgery.

PATIENTS AND METHODS

The first 899 patients (toremifene, n = 459; tamoxifen, n = 440) of the total of 1,480 patients accrued to the trial were included in this scheduled safety analysis. The mean follow-up time was 3.4 years.

RESULTS

The two treatment groups were well balanced with respect to patient and disease characteristics. The subjective side-effect profile was similar in both treatment groups. Slightly more vascular complications (deep vein thromboses, cerebrovascular events, and pulmonary embolisms) were seen among tamoxifen-treated patients (5.9%) as compared with toremifene-treated patients (3.5%) (P: =.11), whereas bone fractures (P: =.09) and vaginal leukorrhea (P: =.05) were more common in the toremifene group. The number of subsequent second cancers was similar. The breast cancer recurrence rate was 23.1% (n = 106) in the toremifene group and 26.1% (n = 115) in the tamoxifen group (P: =.31). When only patients with estrogen receptor (ER)-positive cancer were considered (n = 556), the risk for breast cancer recurrence was nonsignificantly lower among the toremifene-treated women, with a hazards ratio of 0.74 (90% confidence interval, 0.52 to 1.04; P: =.14). The mean time to breast cancer recurrence and overall survival were similar in both groups.

CONCLUSION

The side-effect profile of toremifene resembles that of tamoxifen. The efficacy of toremifene seems to be no less than that of tamoxifen. The trend for fewer breast cancer recurrences in the ER-positive subgroup is encouraging, but a longer follow-up is needed to confirm this.

Toremifene as a substitute for adjuvant tamoxifen in breast cancer patients

BACKGROUND

Toremifene is a new antiestrogen, which in nonclinical studies appears less carcinogenic than tamoxifen. Clinical trials of adjuvant toremifene vs. tamoxifen in breast cancer patients are ongoing. This study aimed to evaluate the short-term effects of changing from adjuvant tamoxifen to toremifene.

PATIENTS AND METHODS

Twenty postmenopausal breast cancer patients receiving adjuvant tamoxifen, 20 mg/day, were switched to toremifene 60 mg/day. The effects on the uterus were evaluated prospectively by transvaginal ultrasound; tolerability was assessed clinically.

RESULTS

In 14 patients who had uterine abnormalities (endometrial thickening or polyps) under tamoxifen, no significant changes occurred during a median of 18 months (range 7-24) of toremifene treatment. Out of six patients who had entered the study due to intolerance to tamoxifen, however, 3 tolerated toremifene well.

CONCLUSION

Toremifene does not modify previous uterine changes induced by tamoxifen. For some patients who do not tolerate tamoxifen, however, switching to toremifene may allow the continuation of adjuvant antiestrogenic therapy.

Dose-dependent hormonal effects of toremifene in postmenopausal breast cancer patients

PURPOSE

The purpose of the study was to compare hormonal effects of three toremifene doses, 20 mg (TOR20), 40 mg (TOR40) and 60 mg (TOR60) administered daily, in postmenopausal women with advanced breast cancer.

METHODS

The study was randomized and open label in three parallel groups. Biochemical variables were identified as the serum concentrations of follicle stimulating hormone (FSH), luteinizing hormone (LH) and sex hormone binding globulin (SHBG). The changes were compared with objective clinical responses and to progression-free time. Adverse reactions and liver function test (aspartate aminotransferase, ASAT) were assessed for safety.

RESULTS

A total of 260 patients were randomly grouped (90 to TOR20, 81 to TOR40 and 89 to TOR60). Of these patients 29, 29 and 22 completed at least 3 months of treatment and the results were analyzed for biochemical variables. All treatments had intrinsic estrogen agonist activity by decreasing of serum FSH and LH and by increasing of SHBG during the first 3 months (P < 0.01). Dose TOR20 showed slightly longer times to exert maximum estrogenic effects than did the two higher doses. No increases in liver function tests were seen in any of the groups. Objective response rates were 24.4, 39.5 and 32.6% (P = 0.01) and median times-to-progression were 206, 189 and 196 days in TOR20, TOR40 and TOR60, respectively (P = 0.913). Fewer responses were observed in the TOR20 group than in TOR40 (P = 0.05). Adverse events were reported in 19, 23 and 30 patients in the treatment groups (P = 0.20). The most frequently reported events were hot flushes and nausea. These were mostly mild or moderate, and only 1.5% of treatments was discontinued due to toxicity.

CONCLUSIONS

Toremifene doses of 40 and 60 mg daily were effective and safe treatments of breast cancer in postmenopausal women, and no differences in their biochemical or clinical effects were seen. Toremifene at 20 mg/day had similar but slightly less potent antiestrogenic and estrogenic effects than the two higher doses.

Meta-analysis of trials comparing toremifene with tamoxifen and factors predicting outcome of antiestrogen therapy in postmenopausal women with breast cancer

Meta-analysis of all clinical data was conducted to compare toremifene 40-60 mg/day (TOR) with tamoxifen 20-40 mg/day (TAM) in postmenopausal women with estrogen receptor (ER) positive or ER unknown advanced breast cancer and assess factors predicting treatment outcome. Data from five randomized parallel group studies (all studies) were combined. Efficacy variables were the response rate in all studies and also the time to treatment failure and survival in the three major studies (pivotal studies). Of the 1421 patients, 725 received TOR and 696 TAM. Response rates were 24.0% and 25.3%, respectively (p = 0.675) with 95% confidence interval (95% CI) for the difference -5.3 to 3.4. Of the 1157 patients in the pivotal studies, 75% had progressed and 50% expired. Median treatment times were 4.9 months in TOR and 5.3 months in TAM groups (p = 0.762, hazard ratio 0.98 with 95% CI 0.87-1.11). Median survival times were 31.0 (TOR) and 33.1 (TAM) months (p = 0.758, hazard ratio 0.98 with 95% CI 0.83-1.15). All results are consistent with the criteria of statistical equivalence between TOR and TAM. More patients in TAM (20%) than in TOR (14%, p = 0.007) discontinued the treatment prematurely but overall the treatments were well tolerated. As the treatments were equally effective all data were analyzed together for predictive factors. High tumor ER concentration, long disease free time, soft tissue metastases, few metastatic sites, and good performance status all independently predicted longer survival (p<0.001). Previous adjuvant tamoxifen predicted shorter survival (p = 0.008). Objective response to treatment or disease stabilization for at least 12 months both predicted prolonged survival (p = 0.001). TOR 60 mg/day and TAM are equally effective and well tolerated in the treatment of advanced breast cancer in postmenopausal women. Probability of survival may be predicted based on patient characteristics and on the initial response to the treatment.

Effects of the antiestrogens tamoxifen, toremifene, and ICI 182,780 on endometrial cancer growth

BACKGROUND

Tamoxifen has been shown to promote the growth of human endometrial tumors implanted in athymic mice, and it has been associated with a twofold to threefold increase in endometrial cancer. Toremifene, a chlorinated derivative of tamoxifen, and ICI 182,780, a pure antiestrogen, are two new antiestrogens being developed for the treatment of breast cancer. The effects of these drugs on endometrial cancer are currently unknown. Our objective was to evaluate the effects of toremifene and ICI 182,780 on the growth of human endometrial cancer in athymic mice.

METHODS

Athymic, ovariectomized mice were implanted with human endometrial tumors and treated with estrogen, tamoxifen, or the new antiestrogens.

RESULTS

The effects of tamoxifen and toremifene on the growth of either tamoxifen-stimulated or tamoxifen-naive endometrial tumors in athymic mice were not substantially different. ICI 182,780 inhibited the growth of tamoxifen-stimulated endometrial cancer, in both the presence and the absence of estrogen.

CONCLUSIONS

Toremifene and tamoxifen produce identical effects in our endometrial cancer models. Therefore, it is possible that toremifene, like tamoxifen, may be associated with an increased incidence of endometrial cancer. In contrast, ICI 182,780 inhibited tamoxifen-stimulated endometrial cancer, both in the presence and in the absence of estrogen, suggesting that this drug may be safe with regard to the endometrium, even if it is used following tamoxifen, and that it may not result in an increased incidence of endometrial cancer. Indeed, it is even possible that ICI 182,780 may prove useful as an adjuvant agent in early stage endometrial cancer.

Antiestrogen therapy: uncertainties and risk assessment

Tamoxifen is by far the most clinically tested antiestrogenic drug currently used as adjuvant therapy for breast cancer and it continues to provide considerable benefit in this setting. The balance from clinical trials indicates a strong association between the use of tamoxifen and an increase in uterine tumors (three to sixfold). In rats, tamoxifen is a mutagenic, genotoxic hepatocarcinogen. These actions are not related to its estrogen antagonist activity but have been shown to be as a result of metabolic activation of this drug by cytochrome P450 enzymes, resulting in irreversible binding to cellular DNA. The mechanism of endometrial cancer associated with tamoxifen treatment is unclear, although there are two plausible hypotheses: (1), tamoxifen causes damage and mutation to DNA in uterine cells or (2), it promotes the development of endometrial tumors through its estrogen agonist activity. The evidence for a genotoxic effect of tamoxifen in the uterus is highly contentious and, on balance, we have concluded that it is more likely that the estrogenic effects of tamoxifen promote tumor development.

Tamoxifen and toremifene in breast cancer: comparison of safety and efficacy

PURPOSE

Tamoxifen is currently the standard hormonal treatment of breast cancer, both for metastatic disease and in the adjuvant setting. A new antiestrogen, toremifene, was approved recently for use in managing metastatic breast cancer in postmenopausal women.

METHODS

Toremifene is structurally similar to tamoxifen, differing only by a single chlorine atom, and has a similar pharmacologic profile. The major difference between the two compounds is in the preclinical activity; chronic, high-dose tamoxifen is hepatocarcinogenic in the rat, whereas toremifene is not. Neither agent is hepatocarcinogenic in mice, hamsters, or humans; therefore, clinical relevance of the rat data may not be significant.

RESULTS

In a worldwide phase III trial, the two agents demonstrated comparable efficacy and safety against metastatic breast cancer. Both agents have shown a significant hypocholesterolemic effect after long-term administration.

CONCLUSION

Due to the paucity of long-term clinical data on toremifene, important unresolved questions remain, which include its effects on bone mineral density, the frequency of cardiac events, and the risk for endometrial cancer. Tamoxifen has been associated with maintenance of bone mineral density, a reduction in cardiac events, and a slightly increased risk of endometrial cancer. Toremifene is not likely to be used as second-line therapy after tamoxifen failure due to cross-resistance, and its ultimate place in therapy of advanced breast cancer remains to be determined.

Toremifene. A review of its pharmacological properties and clinical efficacy in the management of advanced breast cancer

The triphenylethylene antiestrogen toremifene is a chlorinated derivative of the antiestrogen tamoxifen, an agent which has been widely and successfully used in the treatment of breast cancer. Clinical trials investigating the efficacy of toremifene as first-line endocrine therapy in postmenopausal women with advanced breast cancer (estrogen receptor status positive or unknown) have shown this drug to have similar antitumour activity to that of tamoxifen. In multicentre comparative trials, objective responses (complete and partial) occurred in 20 to 29% of patients treated with toremifene (60 to 240 mg/day) and in 19 to 37.5% of tamoxifen (20 or 40 mg/day) recipients. The duration of response, time to disease progression and median overall survival time were generally similar in both treatment groups. Toremifene is well tolerated. Most drug-related adverse effects are mild or moderate in severity and rarely necessitate discontinuation of therapy. The tolerability profile of toremifene is similar to that reported for tamoxifen, the most common adverse effects being hot flushes, sweating, nausea and/or vomiting, dizziness, oedema, and vaginal discharge and/or bleeding. Thus, toremifene provides an equally effective and well tolerated alternative to tamoxifen for the first-line endocrine therapy of postmenopausal advanced breast cancer. Preclinical studies showing toremifene to have a lower carcinogenic potential than tamoxifen indicate that toremifene may be a preferable agent for long term treatment regimens; however, these findings require confirmation in the clinical setting.

Open phase II study of high-dose toremifene as first-line therapy for advanced breast cancer

In an open phase II study conducted in Finland and Latvia, 73 postmenopausal women were treated with 240 mg of toremifene (Fareston) as first-line therapy for advanced breast cancer. Among the 56 patients evaluable for responses, 59% achieved objective responses [complete response (CR) plus partial response (PR)], 29% showed no change (NC), and 12% had progressive disease (PD). When all treated patients were included, the objective response rate was 47%. Several very long durations of responses up to 86 months and survival durations up to 95 months were observed. In assessable patients, the best objective response rates were seen in those with soft-tissue (74%) and visceral (60%) disease. In 54% of patients with very large inoperable primary cancers, a PR was achieved. Half of patients reported side effects, about 60% of which were mild; 30%, moderate; and 5%, severe. Based on response rate and safety, high-dose toremifene is useful as first-line therapy for advanced breast cancer.

Phase III trials of toremifene vs tamoxifen

Three pivotal phase III trials conducted in North America and Europe served as the basis for the application for approval of toremifene (Fareston) by the FDA. These trials demonstrated that 60 mg/d of toremifene is safe and effective in the treatment of advanced breast cancer in postmenopausal women. The studies also indicated that, on the basis of antitumor efficacy, as well as safety, toremifene is at least equivalent to tamoxifen and may have some long-term advantages.

Comparison of toremifene and tamoxifen in post-menopausal patients with advanced breast cancer: a randomized double-blind, the 'nordic' phase III study

The study was planned to compare, in a prospective double-blind randomized trial, the efficacy and safety of toremifene (TOR) and tamoxifen (TAM) in post-menopausal patients with advanced breast cancer who have not had prior systemic therapy for advanced disease. Four hundred and fifteen post-menopausal patients with oestrogen receptor (ER)-positive or ER-unknown advanced breast cancer were randomly assigned to receive daily either 60 mg TOR or 40 mg TAM. The patients were stratified to measurable and non-measurable but evaluable groups. They were assessed for response to therapy, time to progression (TTP), time to treatment failure (TTF), response duration, overall survival and drug toxicity. Two hundred and fourteen patients were randomized into TOR and 201 into TAM treatment. The response rate (complete + partial) was 31.3% for TOR and 37.3% for TAM (P = 0.215). The 95% confidence interval (CI) for the 6% difference was -15.1% to 3.1%. The median TTP was 7.3 months for TOR and 10.2 months for TAM (P = 0.047). The 95% CI for the hazard ratio of 0.80 was 0.64-1.00. A percentage of the TOR patients (9.8%) and the TAM patients (18.9%) discontinued the treatment prematurely (P = 0.011) for various reasons. Consequently, the median TTF of 6.3 vs 8.5 months did not differ significantly (P = 0.271). The hazard ratio was 0.89 and the subsequent 95% CI 0.73-1.09. The median overall survival was 33.0 months for TOR and 38.7 months for TAM (P = 0.645). The hazard ratio was 0.94 with 95% CI of 0.73-1.22. The transient difference in TTP may be related to an imbalance in ER content of the tumours. When only patients with ER-positive tumours were considered (n = 238), no difference between two treatments was seen (P = 0.578). TAM was associated with an overall slightly higher frequency of adverse drug reactions than TOR (44.3 vs 39.3%) and a higher discontinuation rate due to these events (3.5% vs 0.9%). Treatment-emerged moderate dizziness (P = 0.026) and cataracts (P = 0.026) were more frequent among TAM than among TOR patients. In conclusion, TOR (60 mg day(-1)) and TAM (40 mg day(-1)) are equally effective and safe in the treatment of advanced post-menopausal ER-positive or ER-unknown breast cancer.

Toremifene concentration and multidrug resistance in lung tumors

In this pharmacokinetics study, concentrations of toremifene (TOR), a new antiestrogen, were measured after a 7-day oral treatment in serum, lung, and tumor tissue to determine the optimal dose of TOR for the modulation of clinical multidrug resistance in patients with lung cancer. Target levels of the antiestrogen were based on previous in vitro studies. Altogether, 18 patients with operable lung tumors were studied. TOR was given in an open, nonrandomized, phase I study at three different dose levels. The medication consisted of oral TOR given for 7 days at either 240, 480, or 600 mg/day before surgical removal of the tumor. At least five patients were scheduled to be included at each dose level, with all five receiving the full course of therapy before escalation of the dose. Blood samples for serum TOR concentration measurements were taken on days 0 and 7. Specimens of tumor and normal lung tissue of approximately 0.5 g were taken on day 7. The concentrations of TOR and its metabolites were determined in serum, lung, and tumor tissue at different dose levels. Altogether, 12 evaluable patients completed the scheduled treatment. The concentrations measured in serum, lung, and tumor tissue increased along with the dose used, such that the highest TOR values were achieved at 600 mg/day, with mean values being 4.9 mumol/l, 175.0 mumol/g, and 122.7 mumol/g, respectively. The concentrations of TOR and its metabolite N-demethyltoremifene were highest in lung tissue, but the values measured in tumor specimens were also well above the respective concentrations detected in serum samples. The TOR doses of 240 and 480 mg/day were well tolerated. One patient in the group treated at 600 mg/day had to discontinue the treatment because of headache and nausea. TOR given at doses ranging from 480 to 600 mg/day for 7 days will produce serum, lung, and tumor concentrations of the parent drug and its metabolites that have been shown to reverse multidrug resistance of cancer cells in vitro. As the 480-mg/day dose of TOR produced tumor concentrations high enough to reverse multidrug resistance without producing adverse drug reactions, the dose recommended for the foreseen clinical trials in the reversal of multidrug resistance would be 480 mg/day for 7 days.

[Hormone therapy of advanced renal cancer with high-dose toremifene (Fareston)]

Toremifene (Fareston)-a novel antiestrogenic drug with a triphenylethylene structure-has been effective in the treatment of postmenopausal breast cancer patients. It is safely administered even in high doses up to 300 mg/day. The purpose of the study was to investigate the effect and tolerability of high dose toremifene in the treatment of patients with advanced renal cell carcinoma (RCC). Thirty six patients started the treatment with toremifene 300 mg/day. There were 26 males and 10 females. Mean age was 56.0 years, range 35-75 years. Nineteen patients were nephrectomized. One patient was not evaluable for response because of too short treatment time. The response rate was 17.1%, including 1 CR (2.9%) lasting for 121 + weeks and 5 PR (14.3%) with the mean duration of 39.8 + weeks. Ten cases of NC (28.6%) had the mean duration of 23.7 weeks. There were no significant differences in response rate when patients with lung metastases only were compared to patients with metastases of other sites with or without lung metastases. Total pain control was achieved in 45% and partial control in 20% of those patients who had pains in the beginning of the treatment. Ten patients (27.8%) had adverse reactions which led to discontinuation of the treatment in one case. It can be concluded that high-dose toremifene is an effective and safe means of palliative treatment in advanced RCC.

Randomized comparison of tamoxifen and two separate doses of toremifene in postmenopausal patients with metastatic breast cancer

PURPOSE

To perform a randomized three-arm comparison of tamoxifen (TAM; 20 mg/d) and two separate doses of toremifene (TOR; 60 mg/d [TOR60] and 200 mg/d [TOR200]) in postmenopausal patients with hormone receptor-positive or -unknown metastatic breast cancer.

MATERIALS AND METHODS

Six hundred forty-eight patients with hormone receptor-positive or -unknown metastatic breast cancer were randomly assigned to receive TAM (n = 215), TOR60 (n = 221), or TOR200 (n = 212).

RESULTS

The combined response rates (by intent to treat) were as follows;: TAM, 44%; TOR60, 50%; and TOR200, 48%. Complete and partial response rates were as follows: TAM, 19%; TOR60, 21%, and TOR200, 23% (not statistically different). Median times to progression and overall survival were not significantly different. Adverse events (lethal, serious but nonlethal, and important but non-life-threatening) were similar in all three arms, except that patients in the TOR200 arm had a statistically significantly increased rate of nausea (37% v 26% and 26% for TOR200, TAM, and TOR60, respectively; P = .027). Quality-of-life assessments were not different among the three arms.

CONCLUSION

The activity, toxicity, and side effects of TOR in postmenopausal women with hormone receptor-positive or -unknown metastatic breast cancer are similar if not equivalent to those of TAM. We detected no clear evidence of a dose-response effect for TOR. TOR60 is an effective and safe agent for the treatment of postmenopausal women with hormone receptor-positive metastatic breast cancer and can be considered an alternative to TAM as first-line treatment for such patients.

High dose toremifene for estrogen and progesterone receptor negative metastatic breast cancer: a phase II trial of the Cancer and Leukemia Group B (CALGB)

In pre-clinical and limited clinical studies, high doses ( > or = 200 mg/day) of the triphenylethylene derivative toremifene showed activity in estrogen receptor (ER) negative and ER-unknown metastatic breast cancer after progression on tamoxifen, and a mechanism of action independent of hormone receptor binding was speculated. The CALGB conducted a Phase II trial (CALGB 8945) to test the efficacy of high dose toremifene in a population of patients who had hormone receptor-negative, metastatic breast cancer with limited prior chemotherapy exposure, good performance status, and measurable disease. Twenty eligible patients received toremifene at a dose of 400 mg/day orally for 8 weeks. Toxicity was minimal. Nausea was reported by 20% of the patients, lightheadedness by 20%, weight loss by 20%, and hot flashes by 15%. There was no grade 3-4 toxicity. No objective responses were observed, and 5 of 6 patients with stable disease at 8 weeks developed progressive disease at 11 to 33 weeks. High dose toremifene (400 mg/day) is well-tolerated but imparts no detectable activity in hormone receptor-negative, metastatic breast cancer.