Toxicity of antiestrogens

Small-molecule inhibitors of breast cancer-related targets: Potential therapeutic agents for breast cancer

Despite dramatic advances in cancer research and therapy, breast cancer remains a tricky health problem and represents a top biomedical research priority. Nowadays, breast cancer is still the leading cause of malignancy-related deaths in women, and incidence and mortality rates of it are expected to increase significantly the next years. Currently more and more researchers are interested in the study of breast cancer by its arising in young women. The common treatment options of breast cancer are chemotherapy, immunotherapy, hormone therapy, surgery, and radiotherapy. Most of them require chemical agents, such as PARP inhibitors, CDK4/6 inhibitors, and HER2 inhibitors. Recent studies suggest that some targets or pathways, including BRD4, PLK1, PD-L1, HDAC, and PI3K/AKT/mTOR, are tightly related to the occurrence and development of breast cancer. This article reviews the interplay between these targets and breast cancer and summarizes the progress of current research on small molecule inhibitors of these anti-breast cancer targets. The review aims to provide structural and theoretical basis for designing novel anti-breast cancer agents.

Metastasis: A Bane of Breast Cancer Therapy

The underlying mechanisms of metastasis in patients with breast cancer is still poorly understood. Approximately 6% of patients with breast cancer present with metastasis at the time of diagnosis. Metastatic breast cancer is difficult to treat and patients with breast cancer with distant metastasis have a significantly lower 5-year survival rate compared to patients with localised breast cancer (27% and 99%, respectively). During breast cancer progression, tumour cells first metastasise to nearby draining lymph nodes and then to distant organs, primarily bone, lungs, liver, and brain. In this brief review, the authors discuss breast cancer metastasis, the role of epithelial–mesenchymal transition and the contributions of the immune system to the metastatic process. The authors also briefly discuss whether there is any relationship between tumour size and metastatic potential, and recent advances in treatment for metastatic breast cancer. The studies highlighted suggest that immunotherapy may play a more significant role in future patient care for metastatic breast cancer.

Drug repurposing for breast cancer therapy: Old weapon for new battle

Despite tremendous resources being invested in prevention and treatment, breast cancer remains a leading cause of cancer deaths in women globally. The available treatment modalities are very costly and produces severe side effects. Drug repurposing that relate to new uses for old drugs has emerged as a novel approach for drug development. Repositioning of old, clinically approved, off patent non-cancer drugs with known targets, into newer indication is like using old weapons for new battle. The advances in genomics, proteomics and information computational biology has facilitated the process of drug repurposing. Repositioning approach not only fastens the process of drug development but also offers more effective, cheaper, safer drugs with lesser/known side effects. During the last decade, drugs such as alkylating agents, anthracyclins, antimetabolite, CDK4/6 inhibitor, aromatase inhibitor, mTOR inhibitor and mitotic inhibitors has been repositioned for breast cancer treatment. The repositioned drugs have been successfully used for the treatment of most aggressive triple negative breast cancer. The literature review suggest that serendipity plays a major role in the drug development. This article describes the comprehensive overview of the current scenario of drug repurposing for the breast cancer treatment. The strategies as well as several examples of repurposed drugs are provided. The challenges associated with drug repurposing are discussed.

Chemoprevention of LA7-Induced Mammary Tumor Growth by SM6Met, a Well-Characterized Cyclopia Extract

Breast cancer (BC) is the leading cause of cancer-related deaths in women. Chemoprevention of BC by using plant extracts is gaining attention. SM6Met, a well-characterized extract of Cyclopia subternata with reported selective estrogen receptor subtype activity, has shown tumor suppressive effects in a chemically induced BC model in rats, which is known to be estrogen responsive. However, there is no information on the estrogen sensitivity of the relatively new orthotopic model of LA7 cell-induced mammary tumors. In the present study, the potential chemopreventative and side-effect profile of SM6Met on LA7 cell-induced tumor growth was evaluated, as was the effects of 17β-estradiol and standard-of-care (SOC) endocrine therapies, such as tamoxifen (TAM), letrozole (LET), and fulvestrant (FUL). Tumor growth was observed in the tumor-vehicle control group until day 10 post tumor induction, which declined afterward on days 12-14. SM6Met suppressed tumor growth to the same extent as TAM, while LET, but not FUL, also showed substantial anti-tumor effects. Short-term 17β-estradiol treatment reduced tumor volume on days prior to day 10, whereas tumor promoting effects were observed during long-term treatment, which was especially evident at later time points. Marked elevation in serum markers of liver injury, which was further supported by histological evaluation, was observed in the vehicle-treated tumor control, TAM, LET, and long-term 17β-estradiol treatment groups. Alterations in the lipid profiles were also observed in the 17β-estradiol treatment groups. In contrast, SM6Met did not augment the increase in serum levels of liver injury biomarkers caused by tumor induction and no effect was observed on lipid profiles. In summary, the results from the current study demonstrate the chemopreventative effect of SM6Met on mammary tumor growth, which was comparable to that of TAM, without eliciting the negative side-effects observed with this SOC endocrine therapy. Furthermore, the results of this study also showed some responsiveness of LA7-induced tumors to estrogen and SOC endocrine therapies. Thus, this model may be useful in evaluating potential endocrine therapies for hormone responsive BC.

Genotoxic and mutagenic studies of teratogens in developing rat and mouse

In this review, genotoxic and mutagenic effects of teratogenic chemical agents in both rat and mouse have been reviewed. Of these chemicals, 97 are drugs and 33 are pesticides or belong to other groups. Large literature searches were conducted to determine the effects of chemicals on chromosome abnormalities, sister chromatid exchanges, and micronucleus formation in experimental animals such as rats and mice. In addition, studies that include unscheduled DNA synthesis, DNA adduct formations, and gene mutations, which help to determine the genotoxicity or mutagenicity of chemicals, have been reviewed. It has been estimated that 46.87% of teratogenic drugs and 48.48% of teratogenic pesticides are positive in all tests. So, all of the teratogens involved in this group have genotoxic and mutagenic effects. On the other hand, 36.45% of the drugs and 21.21% of the pesticides have been found to give negative results in at least one test, with the majority of the tests giving positive results. However, only 4.16% of the drugs and 18.18% of the pesticides were determined to give negative results in the majority of the tests. Among tests with major negative results, 12.50% of the teratogenic drugs and 12.12% of the teratogenic pesticides were negative in all conducted tests.

Breast Cancer: Conventional Diagnosis and Treatment Modalities and Recent Patents and Technologies

Breast cancer is the most prevalent cancer among women worldwide. However, increased survival is due to the dramatic advances in the screening methods, early diagnosis, and breakthroughs in treatments. Over the course of the last decade, many acquisitions have taken place in this critical field of research in the pharmaceutical industry. Advances in molecular biology and pharmacology aided in better understanding of breast cancer, enabling the design of smarter therapeutics able to target cancer and respond to its microenvironment efficiently. Patents and research papers investigating diagnosis and treatment strategies for breast cancer using novel technologies have been surveyed for the past 15 years. Various nanocarriers have been introduced to improve the therapeutic efficacy of anticancer drugs, including liposomes, polymeric micelles, quantum dots, nanoparticles, and dendrimers. This review provides an overview of breast cancer, conventional therapy, novel technologies in the management of breast cancer, and rational approaches for targeting breast cancer.

HIGHLIGHTS

Breast cancer is the most common cancer in women worldwide. However, survival rates vary widely, optimistically heading toward a positive trend. Increased survival is due to the drastic shift in the screening methods, early diagnosis, and breakthroughs in treatments.Different strategies of breast cancer classification and staging have evolved over the years. Intrinsic (molecular) subtyping is essential in clinical trials and well understanding of the disease.Many novel technologies are being developed to detect distant metastases and recurrent disease as well as to assess response to breast cancer management.Intensive research efforts are actively ongoing to take novel breast cancer therapeutics to potential clinical application.Most of the recent research papers and patents discuss one of the following strategies: the development of new drug entities that specifically target the breast tumor cells; tailor designing a novel carrier system that can multitask and multifunction as a drug carrier, targeting vehicle and even as a diagnostic tool, direct conjugation of a therapeutic drug moiety with a targeting moiety, diagnostic moiety or pharmacokinetics altering moiety; or the use of innovative nontraditional approaches such as genetic engineering, stem cells, or vaccinations.

Tamoxifen induces the development of hernia in mice by activating MMP-2 and MMP-13 expression

Hernia is a disease with defects in collagen synthesis/metabolism. However, the underlying mechanisms for hernia formation have not been fully defined. Tamoxifen is a selective estrogen receptor modulator and used for patients with breast cancer. Tamoxifen also has pleiotropic and side effects. Herein, we report that tamoxifen treatment resulted in an appearance of a large bulge in the low abdomen between the hind legs in male but not in female mice. The autopsy demonstrated that the low abdominal wall was broken and a large amount of intestine herniated out of the abdominal cavity. Histological analysis indicated that tamoxifen caused structural abnormalities in the low abdominal wall which were associated with decreased type II collagen content. Furthermore, we determined increased matrix metalloproteinase-2 (MMP-2) and MMP-13 expression in the tissue. In vitro, tamoxifen induced MMP-2 and MMP-13 expression in fibroblasts. The promoter activity analysis and ChIP assay demonstrate that induction of MMP-13 expression was associated with activation of JNK-AP-1 and ERK1/2 signaling pathways while induction of MMP-2 expression was related to activation of the ERK1/2 signaling pathway. Taken together, our study establishes a novel murine hernia model, defines a severe side effect of tamoxifen, and suggests a caution to male patients receiving tamoxifen treatment.

Toxicity and adverse effects of Tamoxifen and other anti-estrogen drugs

Breast cancer is a heterogeneous disease affecting thousands of people every year. Multiple factors are responsible in causing breast cancer while a number of treatment options are also available for the disease. Tamoxifen is the most widely used anti-estrogen for the treatment of hormone-dependent breast cancer. The specific drug is used as a hormonal therapy for patients who exhibit estrogen receptor positive breast cancer. The pharmacological activity of Tamoxifen is dependent on its conversion to its active metabolite, endoxifen, by CYP2D6. Tamoxifen reduces the risk of recurrence and death from breast cancer when given as adjuvant therapy and provides effective palliation for patients with metastatic breast cancer. In this review we focus on the role of Tamoxifen in breast cancer treatment including mechanisms and side-effects. Finally, we discuss in detail the exciting prospects that lie ahead.

Effects of toremifene versus tamoxifen on breast cancer patients: a meta-analysis

Toremifene and tamoxifen are both selective estrogen receptor modulators used in the treatment of breast cancer patients. Therefore, we carried out a meta-analysis to achieve a more precise evaluation of the effects of toremifene versus tamoxifen on breast cancer patients, including the efficacy and safety, and the effects on the uterus, lipids, and bone. Comprehensive literature searches were conducted using the electronic databases and reference lists to include randomized controlled trials (RCTs) that compared toremifene with tamoxifen for breast cancer patients. Two reviewers independently selected studies and abstracted data. Data were analyzed by Review Manager, version 5.0. Twenty-three trials (7242 patients) were included. For early stage breast cancer, toremifene was associated with higher 5-year survival rates (OR 1.25, 95 % CI 1.04, 1.50), more vaginal discharge (OR 1. 32, 95 % CI 1.01, 1.73), a greater decrease in serum triglyceride levels (SMD -1.01, 95 % CI -1.89, -0.14), a smaller decrease in LDL cholesterol levels (SMD 0.45, 95 % CI 0.07, 0.84) and in bone mineral density in Ward's triangle (SMD -0.36, 95 % CI -0.71, -0.01), and a greater increase in HDL cholesterol levels (SMD 0.43, 95 % CI 0.08, 0.77) than tamoxifen. For advanced breast cancer patients, toremifene was associated with more vaginal bleeding (OR 0.45, 95 % CI 0.26, 0.80) and a greater decrease in serum triglyceride levels (SMD -1.15, 95 % CI -1.90, -0.39) than tamoxifen. Available evidence showed that toremifene could be an alternative option to tamoxifen for both early and advanced breast cancer patients. However, the methodological quality of the included studies was low. More rigorous RCTs are needed to confirm the results of this meta-analysis in the future.

Update of carcinogenicity studies in animals and humans of 535 marketed pharmaceuticals

This survey is a compendium of information retrieved on carcinogenicity in animals and humans of 535 marketed pharmaceuticals whose expected clinical use is continuous for at least 6 months or intermittent over an extended period of time. Of the 535 drugs, 530 have the result of at least one carcinogenicity assay in animals, and 279 (52.1%) of them gave a positive response in at least one assay. Only 186 drugs (34.8%) have retrievable information on carcinogenicity in humans, and 104 of them gave to a variable extent evidence of a potential carcinogenic activity. Concerning the correlation between results obtained in animals and epidemiological findings, 58 drugs gave at least one positive result in carcinogenicity assays performed in animals and to a variable extent displayed evidence of carcinogenicity in humans, but 97 drugs tested positive in animals and were noncarcinogenic in humans or vice versa. Our findings, which are in agreement with previous studies, indicate that the evaluation of the benefit/carcinogenic risk ratio should be always made in prescribing a drug.

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.

Tetracycline inducible gene manipulation in serotonergic neurons

The serotonergic (5-HT) neuronal system has important and diverse physiological functions throughout development and adulthood. Its dysregulation during development or later in adulthood has been implicated in many neuropsychiatric disorders. Transgenic animal models designed to study the contribution of serotonergic susceptibility genes to a pathological phenotype should ideally allow to study candidate gene overexpression or gene knockout selectively in serotonergic neurons at any desired time during life. For this purpose, conditional expression systems such as the tet-system are preferable. Here, we generated a transactivator (tTA) mouse line (TPH2-tTA) that allows temporal and spatial control of tetracycline (Ptet) controlled transgene expression as well as gene deletion in 5-HT neurons. The tTA cDNA was inserted into a 196 kb PAC containing a genomic mouse Tph2 fragment (177 kb) by homologous recombination in E. coli. For functional analysis of Ptet-controlled transgene expression, TPH2-tTA mice were crossed to a Ptet-regulated lacZ reporter line (Ptet-nLacZ). In adult double-transgenic TPH2-tTA/Ptet-nLacZ mice, TPH2-tTA founder line L62-20 showed strong serotonergic β-galactosidase expression which could be completely suppressed with doxycycline (Dox). Furthermore, Ptet-regulated gene expression could be reversibly activated or inactivated when Dox was either withdrawn or added to the system. For functional analysis of Ptet-controlled, Cre-mediated gene deletion, TPH2-tTA mice (L62-20) were crossed to double transgenic Ptet-Cre/R26R reporter mice to generate TPH2-tTA/Ptet-Cre/R26R mice. Without Dox, 5-HT specific recombination started at E12.5. With permanent Dox administration, Ptet-controlled Cre-mediated recombination was absent. Dox withdrawal either postnatally or during adulthood induced efficient recombination in serotonergic neurons of all raphe nuclei, respectively. In the enteric nervous system, recombination could not be detected. We generated a transgenic mouse tTA line (TPH2-tTA) which allows both inducible and reversible transgene expression and inducible Cre-mediated gene deletion selectively in 5-HT neurons throughout life. This will allow precise delineation of serotonergic gene functions during development and adulthood.

A comparison of survival outcomes and side effects of toremifene or tamoxifen therapy in premenopausal estrogen and progesterone receptor positive breast cancer patients: a retrospective cohort study

BACKGROUND

In premenopausal women, endocrine adjuvant therapy for breast cancer primarily consists of tamoxifen alone or with ovarian suppressive strategies. Toremifene is a chlorinated derivative of tamoxifen, but with a superior risk-benefit profile. In this retrospective study, we sought to establish the role of toremifene as an endocrine therapy for premenopausal patients with estrogen and/or progesterone receptor positive breast cancer besides tamoxifen.

METHODS

Patients with early invasive breast cancer were selected from the breast tumor registries at the Sun Yat-Sen Memorial Hospital (China). Premenopausal patients with endocrine responsive breast cancer who underwent standard therapy and adjuvant therapy with toremifene or tamoxifen were considered eligible. Patients with breast sarcoma, carcinosarcoma, concurrent contralateral primary breast cancer, or with distant metastases at diagnosis, or those who had not undergone surgery and endocrine therapy were ineligible. Overall survival and recurrence-free survival were the primary outcomes measured. Toxicity data was also collected and compared between the two groups.

RESULTS

Of the 810 patients reviewed, 452 patients were analyzed in the study: 240 received tamoxifen and 212 received toremifene. The median and mean follow up times were 50.8 and 57.3 months, respectively. Toremifene and tamoxifen yielded similar overall survival values, with 5-year overall survival rates of 100% and 98.4%, respectively (p = 0.087). However, recurrence-free survival was significantly better in the toremifene group than in the tamoxifen group (p = 0.022). Multivariate analysis showed that recurrence-free survival improved independently with toremifene (HR = 0.385, 95% CI = 0.154-0.961; p = 0.041). Toxicity was similar in the two treatment groups with no women experiencing severe complications, other than hot flashes, which was more frequent in the toremifene patients (p = 0.049). No patients developed endometrial cancer.

CONCLUSION

Toremifene may be a valid and safe alternative to tamoxifen in premenopausal women with endocrine-responsive breast cancer.

Sulfation of 4-hydroxy toremifene: individual variability, isoform specificity, and contribution to toremifene pharmacogenomics

Toremifene (TOR) is a selective estrogen receptor modulator used in adjuvant therapy for breast cancer and in clinical trials for prostate cancer prevention. The chemical structure of TOR differs from that of tamoxifen (TAM) by the presence of a chlorine atom in the ethyl side chain, resulting in a more favorable toxicity spectrum with TOR. In addition, some patients who fail on TAM therapy benefit from high-dose TOR therapy. Several studies have indicated that functional genetic variants in the TAM metabolic pathway influence response to therapy, but pharmacogenomic studies of patients treated with TOR are lacking. In this study, we examined individual variability in sulfation of 4-hydroxy TOR (4-OH TOR) (the active metabolite of TOR) in human liver cytosols from 104 subjects and found approximately 30-fold variation in activity. 4-OH TOR sulfation was significantly correlated (r = 0.98, P < 0.0001) with β-naphthol sulfation (diagnostic for SULT1A1) but not with 17β estradiol sulfation, a diagnostic substrate for SULT1E1(r = 0.09, P = 0.34). Examination of recombinant sulfotransferases (SULTs) revealed that SULT1A1 and SULT1E1 catalyzed 4-OH TOR sulfation, with apparent Km values of 2.6 and 6.4 μM and Vmax values of 8.5 and 5.5 nmol x min(-1) x mg protein(-1), respectively. 4-OH TOR sulfation was inhibited by 2,6-dichloro-4-nitrophenol (IC50 = 2.34 ± 0.19 μM), a specific inhibitor of SULT1A1. There was also a significant association between SULT1A1 genotypes and copy number and 4-OH TOR sulfation in human liver cytosols. These results indicate that variability in sulfation could contribute to response to TOR in the treatment of breast and prostate cancer.

Toremifene is an effective and safe alternative to tamoxifen in adjuvant endocrine therapy for breast cancer: results of four randomized trials

Compared to tamoxifen, the efficacy and side effects of toremifene in adjuvant endocrine therapy for breast cancer were not very clear. This meta-analysis was conducted to give a more precise estimation of the efficacy and severe side effects of toremifene given in the adjuvant setting in comparison to tamoxifen. The electronic database PubMed was searched for randomized trials comparing toremifene with tamoxifen as adjuvant therapies. Four randomized trials published in three articles were eligible, including 1,890 pooled cases treated with toremifene and 1,857 cases treated with tamoxifen. Compared to patients in tamoxifen group, patients in toremifene group did not have a significantly different overall survival rate (risk ratio (RR): 1.07, 95% confidence interval (CI): 0.97-1.19, P = 0.994 for heterogeneity) or a disease-free survival (DFS) rate (RR: 1.05, 95% CI: 0.95-1.17, P = 0.431 for heterogeneity) at the end of the follow-up time. The rates of thromboembolic events in toremifene group, including deep vein thrombosis (odds ratio (OR): 0.68, 95% CI: 0.40-1.17, P = 0.926 for heterogeneity), cerebrovascular accident (OR: 0.59, 95% CI: 0.32-1.09, P = 0.438 for heterogeneity), and pulmonary embolism (OR: 0.91, 95% CI: 0.42-2.01, P = 0.618 for heterogeneity), were not significantly different from those in tamoxifen group. The rates of endometrial polyps and endometrial cancer between the two groups were almost the same. This meta-analysis suggested that toremifene was as effective as tamoxifen in the adjuvant setting for both perimenopausal and postmenopausal breast cancer patients with similar severe adverse effects to tamoxifen. Toremifene was a convincing and safe change for tamoxifen in adjuvant endocrine therapy.

Excellent outcomes with adjuvant toremifene or tamoxifen in early stage breast cancer

BACKGROUND

Fareston (toremifene) and tamoxifen, both selective estrogen receptor modulators, are therapeutically equivalent treatments for metastatic breast cancer. We hypothesized that toremifene as compared with tamoxifen given as adjuvant therapy for early stage breast cancer would result in equivalent survival with an improved side effect profile, therefore, providing superior therapeutic efficacy.

METHODS

The North American Fareston versus Tamoxifen Adjuvant trial assigned 1813 perimenopausal or postmenopausal women with hormone receptor (HR)-positive invasive breast cancer to adjuvant treatment with either tamoxifen or toremifene. The primary outcomes evaluated were disease-free survival (DFS) and overall survival (OS).

RESULTS

Median follow-up was 59 months. The baseline characteristics of the 2 treatment groups were well-balanced. On the basis of intent-to-treat, 5-year actuarial DFS was not significantly different between tamoxifen and toremifene (91.2% [standard error of the mean [SE] 1.2%] vs 91.2% [SE 1.1%], respectively). Similarly, 5-year actuarial OS was not significantly different between tamoxifen and toremifene (92.7% [SE 1.1%] vs 93.7% [SE 1.0%], respectively). Controlling for patient age, tumor size, and tumor grade, a Cox multivariate survival analysis found no difference between patients randomized to toremifene versus tamoxifen in terms of OS (OR = 0.951; 95% confidence interval [CI], 0.623-1.451, P = .951) or DFS (OR = 1.037; 95% CI, 0.721-1.491, P = .846). Adverse events were similar in the 2 groups.

CONCLUSIONS

Women treated with adjuvant hormonal therapy enjoyed excellent DFS and OS. No significant differences were found between treatment with either tamoxifen or toremifene. Treatment of HR-positive patients with either tamoxifen or toremifene is appropriate.

Second non-breast primary cancer following adjuvant therapy for early breast cancer: a report from the International Breast Cancer Study Group

The incidence of second non-breast primary cancer following adjuvant treatment was evaluated using data from patients enrolled from 1978 to 1999 in four International Breast Cancer Study Group (IBCSG) trials. The occurrence of these tumours as sites of the first failure was assessed separately for two treatment comparisons: toremifene versus tamoxifen for 5 years in 1035 patients in IBCSG Trials 12-93 and 14-93 with a median follow-up of 8 years and endocrine therapy (toremifene or tamoxifen) versus chemo-endocrine therapy (CMF or AC plus toremifene or tamoxifen) in 1731 patients from IBCSG Trials III, VII and 12-93, with a combined median follow-up of 14 years. No significant differences in second non-breast primary tumours were observed in either comparison. In particular, the incidences of second primary uterine tumours with toremifene and tamoxifen were similar and no significant increase of secondary leukaemias was observed with chemo-endocrine therapy compared with endocrine therapy.

Cancer chemotherapy II: atypical hepatic injuries

Although chemotherapy generally is accompanied by regular testing for liver enzyme abnormalities, atypical reactions may occur that escape ordinary detection, because hepatocyte injury is not the primary event. The presence of fatty liver, mitochondrial changes, and even biliary abnormalities can be associated with normal or nearly normal liver enzyme levels. This article discusses unique aspects of liver damage associated with cancer chemotherapy. These unique reactions merit special attention and a special vigilance from clinicians.

Toxicity of ligand-dependent Cre recombinases and generation of a conditional Cre deleter mouse allowing mosaic recombination in peripheral tissues

Ligand-activated Cre recombinases are widely used for studying gene function in vitro and in conditional mouse models. To compare ligand-dependent Cre recombinases, different Cre estrogen receptor fusions were introduced into the ROSA26 locus of embryonic stem (ES) cells and assayed for genotoxicity and recombination efficiency. Of the tested recombinases, the CreERT2 variant showed no toxicity and was highly responsive to ligand induction. To constitutively express CreERT2 in mice and also to clarify whether the CreERT2 system displays background activity, we generated a knock-in mouse line harboring the CreERT2 coding region under the control of the ROSA26 locus. Analysis of this ROSA26-CreERT2 deleter mouse with different reporter strains revealed ubiquitous recombination in the embryo and partial recombination in peripheral and hematopoietic tissues but no effective CreERT2 expression in the brain. Furthermore, using flow cytometry, we found low-level background recombination in noninduced bitransgenic ROSA26-CreERT2/EGFP reporter mice. To determine whether background activity poses a general problem for conducting conditional in vivo experiments with the ROSA26-CreERT2 deleter, we used a sensitive conditional skin cancer model. In this assay, cancer induction was completely restricted to induced bitransgenic CreERT2/K-Ras(V12) mice, whereas noninduced control animals did not show any sign of cancer, indicating the usefulness of the ROSA-CreERT2 system for regulating conditional gene expression in vivo. The ROSA26-CreERT2 deleter strain will be a convenient experimental tool for studying gene function under circumstances requiring partial induction of recombination in peripheral tissues and will be useful for uncovering previously unknown or unsuspected phenotypes.

Toremifene for premenstrual mastalgia: a randomised, placebo-controlled crossover study

OBJECTIVE

To investigate the efficacy of toremifene in the treatment of premenstrual mastalgia.

DESIGN

Double-blind, placebo-controlled crossover study.

SETTING

Three Finnish general practices from the districts of Satakunta Central Hospital and Tampere University Hospital. POPULATION A total of 62 women aged 25-45 years with premenstrual mastalgia during at least three previous menstrual cycles.

METHODS

Women were randomised to receive toremifene 20 mg daily or placebo from day 15 of the menstrual cycle until menstruation for three consecutive cycles. After a wash-out cycle, the women were crossed over to receive placebo or toremifene for three additional cycles.

MAIN OUTCOME MEASURES

Cyclic breast pain relief assessed by visual analogue scale (VAS) score. Quality-of-life scores assessed by a modified 36-item Finnish Depression Scale, with a score ranging from 0 to 108. Acceptability of treatment.

RESULTS

About 32 women were randomised to receive toremifene first and 30 to receive placebo first. Twenty-nine and 27 participants in the groups treated with toremifene first or placebo first completed the treatment, respectively. There were significant reductions in VAS scores in both groups after three treatment cycles. This was significantly greater in the toremifene-treated group (VAS: 1.8 in the toremifene group and 3.7 in the placebo group, P= 0.004). Treatment effect between treatment cycles was significant (P= 0.001). Quality of life was similar during the toremifene and placebo cycles. CONCLUSION This study demonstrates that the antiestrogenic compound, toremifene, is able to relieve premenstrual breast pain without major adverse effects. There was a 64% reduction in median pain scores in the toremifene-treated cycles compared with a 26% reduction in placebo-treated cycles.

Inhibitory effects of idoxifene on hepatic fibrosis in rats

AIM

To investigate the effects of a tissue-specific selective estrogen receptor modulator, idoxifene, on hepatic fibrosis in rats.

METHODS

Hepatic fibrosis was induced by dimethylnitrosamine (DMN) in male rats. The DMN model of hepatic fibrosis and the hepatocytes undergoing oxidative stress were treated with idoxifene respectively. The effect of idoxifene on hepatic fibrosis in the DMN model was examined by immunohistochemistry. Effects of idoxifene on antioxidant enzyme levels of copper, zinc-dependent superoxide dismutase (CuZn-SOD), and cellular glutathione peroxidase (GSHPx) were measured by ELISA. Effects of idoxifene on activation, proliferation, and apoptosis of culture-activated hepatic stellate cells (HSC) were analysed by immunohistochemistry, bromodeoxyuridine (BrdU) uptake, and flow cytometry, respectively.

RESULTS

Idoxifene could markedly suppress DMN-induced hepatic fibrosis in male rats. A treatment of 0.4 mg x kg(-1) x d(-1) of idoxifene reduced the protein levels of collagen in the DMN model by 41.19% (P<0.05). Protein level of CuZn-SOD and activitiy of GSHPx in liver treated with DMN plus 0.4 mg/kg/d of idoxifene were 2.65 times (P<0.05) and 2.08 times greater (P<0.05) than that of liver treated with DMN alone respectively. The protein level of CuZn-SOD and activity of GSHPx in cultured rat hepatocytes treated with ferric nitrilotriacetate (FeNTA) plus 1 multiply 10(-7) mol/L of idoxifene were 3.43 times (P<0.05) and 2.52 times (P<0.05) greater than that treated with FeNTA alone. Idoxifene could inhibit HSC activation. Compared with the control, the uptake of BrdU in HSC cultured with 1 multiply 10(-7) mol/L of idoxifene was reduced by 51.87 % (P<0.05), and the number of apoptotic HSCs cultured with 1 multiply 10(-7) mol/L of idoxifene increased by 94.52% (P<0.05).

CONCLUSION

Idoxifene showed inhibitory action on hepatic fibrosis in male rats.

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.

Toxicity of selected cationic drugs in retinoblastomal cultures and in cocultures of retinoblastomal and retinal pigment epithelial cell lines

Tamoxifen and toremifene are antiestrogenic drugs successfully used in the therapy of breast cancer. Rheumatoid arthritis and malaria have been treated with chloroquine for decades. Unfortunately, tamoxifen and chloroquine are reported to induce retinal changes as a side effect. We now studied the effects of tamoxifen, toremifene, and chloroquine on the viability of the human retinoblastomal cell line Y79, using the WST-1 test or measurement of the cellular ATP content. The studies were made on Y79 cell cultures and on cocultures of Y79 cells and retinal pigment epithelial cell line ARPE-19. The cocultures were used to clarify the effect of retinal pigment epithelium on toxicity to Y79 cells. In the coculture, the drugs were applied to ARPE-19 cells growing in the culture inserts on top of Y79 cells and the viability of ARPE-19 and Y79 cells was assessed separately. Tamoxifen, toremifene, and chloroquine reduced dose-dependently the viability of Y79 cells after 24-h exposure. The ARPE-19 cells proved to be protective after chloroquine exposure in the coculture. The results shed light on the toxicity of tamoxifen and chloroquine in Y79 cells in vitro. With the coculture we were able to simulate the in vivo route of chloroquine to the retina via the retinal pigment epithelium.

Investigating abnormal bleeding on HRT or tamoxifen: the role of ultrasonography

In western countries hormone replacement therapy (HRT) is a widely used therapeutic and/or preventive medication in post-menopausal women. Its impact on the endometrium has been extensively investigated. The critical issue is whether and how to monitor the endometrium in women who are taking HRT. Transvaginal ultrasound is a potential candidate for this role. Evidence for the efficiency of transvaginal sonography (TVS) in this context is limited. The criteria used to define a normal or abnormal result in women taking HRT are based largely on data from post-menopausal women who are not taking this treatment. This extrapolation is probably reasonable as long as some degree of caution is used. The use of normative data from post-menopausal women for those taking selective oestrogen receptor modulators (SORMs) is not advised and should be utilized only in the context of research studies as insufficient data exist on which to base cut-off values to discriminate between normal and abnormal endometria.

Aging May Be Associated with Concentrations of Tamoxifen and Its Metabolites in Breast Cancer Patients

BACKGROUND

Although tamoxifen (TAM) is the predominant adjuvant therapy for estrogen receptor positive (ER(+)) breast tumors, 50% of breast cancer patients do not respond positively to this therapy, or they experience adverse side effects. This variability in TAM responsiveness may be due to differences in TAM metabolism that stem from differences in race, age, and body mass index (BMI). Thus, the purpose of this study was to test the hypothesis that race, age, and BMI are associated with the metabolism of TAM to two primary metabolites, N-desmethyltamoxifen (N-DMT) and 4-hydroxytamoxifen (4-OHT).

METHODS

The study design was cross-sectional, and data were analyzed using independent sample t tests and multiple linear regression models. Breast cancer patients (n = 99) taking TAM for at least 30 days were recruited from a local hospital clinic. Each participant provided informed consent, completed a questionnaire, and donated a blood sample. The questionnaire was used to ascertain race, age, and BMI. The blood samples were used to measure plasma concentrations of TAM, N-DMT, and 4-OHT.

RESULTS

Plasma concentrations of TAM, N-DMT, and 4-OHT differed among individual patients. Age, but not race and BMI, was positively associated with plasma concentrations of TAM and N-DMT, even after adjustment for potential confounders (p = 0.02 for TAM and p = 0.03 for N-DMT).

CONCLUSIONS

This study suggests that aging may alter the metabolism of TAM. As increased levels of TAM and TAM metabolites may provide a possible explanation for why older women taking TAM are at increased risk for adverse side effects, future studies should determine whether age-related differences in the concentrations of TAM and TAM metabolites are associated with differences in TAM toxicity or responsiveness.