- Phytochemicals: Current strategies for treating breast cancer. [Review]
- OLOncol Lett 2018; 15(5):7471-7478
- Females with early-stage metastatic, estrogen-dependent breast cancer are generally treated with surgery, radiation and chemotherapy, or with more targeted approaches such as aromatase inhibitors (an...
Females with early-stage metastatic, estrogen-dependent breast cancer are generally treated with surgery, radiation and chemotherapy, or with more targeted approaches such as aromatase inhibitors (anastrozole or letrozole) or anti-estrogens (tamoxifen). Despite widespread successful usage of these agents for the treatment of breast cancer, resistance, tumor relapse and metastasis remain the principal causes of mortality for patients with breast cancer. While numerous groups have made major contributions toward an improved understanding of resistance mechanisms, the currently insufficient grasp of the most critical pathways involved in resistance is evident in the inability to adequately treat and drastically improve patient outcomes in females with hormone-refractory breast cancer, including triple negative breast cancer. Therefore, further investigation of novel therapeutic approaches is paramount to reveal previously unconsidered agents that could be utilized to treat metastatic disease. Numerous naturally occurring phytochemicals have recently gained interest as potential therapeutic breast cancer agents appear to directly affect estrogen-dependent and estrogen-independent breast cancer cell proliferation, potentially via affecting breast cancer stem cell populations. While numerous natural compounds have exhibited promise, they are limited by their bioavailability. Therefore, to effectively treat future hormone-refractory breast tumors, it is critical to adequately refine and formulate these agents for effective therapeutic use and delivery. Herein, the literature on the current state of phytochemicals is reviewed, including their limitations and potential as targeted therapies for breast cancer.
- Practical consensus recommendations on duration of adjuvant hormonal therapy in breast cancer. [Journal Article]
- SASouth Asian J Cancer 2018 Apr-Jun; 7(2):142-145
- Optimization of adjuvant systemic therapy in women with early-stage hormone receptor-positive breast cancer includes the consideration of chemotherapy and duration of hormone therapy. Adjuvant hormon...
Optimization of adjuvant systemic therapy in women with early-stage hormone receptor-positive breast cancer includes the consideration of chemotherapy and duration of hormone therapy. Adjuvant hormonal therapy significantly improves long-term survival of breast cancer patients with hormone receptor-positive disease. Despite the proven clinical efficacy of tamoxifen and aromatase inhibitors, many breast cancer survivors either fail to take the correct dosage at the prescribed frequency (adherence) or discontinue therapy (persistence). Expert oncologist discussed on the duration of adjuvant hormonal therapy for improvement of OS and quality of life of breast cancer patients by providing reduction in recurrence and mortality. This expert group used data from published literature, practical experience and opinion of a large group of academic oncologists to arrive at this practical consensus recommendations for the benefit of community oncologists.
- Increased long QT and torsade de pointes reporting on tamoxifen compared with aromatase inhibitors. [Journal Article]
- HHeart 2018 May 02
- CONCLUSIONS: SERMs are associated with more reports of drug-induced LQT, TdP and ventricular arrhythmias compared with AIs. This finding is consistent with oestradiol-like properties of SERMs on the heart as opposed to effects of oestrogen deprivation and testosterone increase induced by AIs.
- Aromatase inhibitors in premenopausal women with breast cancer: the state of the art and future prospects. [Review]
- COCurr Oncol 2018; 25(2):e168-e175
- Approximately 11% of patients with breast cancer (bca) are diagnosed before menopause, and because in most of those patients the tumour expresses a hormone receptor, treatment with endocrine interven...
Approximately 11% of patients with breast cancer (bca) are diagnosed before menopause, and because in most of those patients the tumour expresses a hormone receptor, treatment with endocrine interventions can be applied in any setting of disease (early or advanced). In the past, hormonal treatment consisted only of the estrogen receptor modulator tamoxifen, associated with luteinizing hormone-releasing hormone (lhrh); more recently, aromatase inhibitors (ais) have come into widespread use. The ais interfere with the last enzymatic step of estrogen synthesis in which androgens are converted into estrogens. Initially, the ais were used alone in postmenopausal patients to prevent disease recurrence, but together with lhrh analogs, they can be used in premenopausal patients to produce better estrogen suppression than can be achieved with tamoxifen plus a lhrh analog. Using a systematic review of the scientific literature (prospective and retrospective studies), we set out to assess the efficacy of ais compared with other endocrine therapy in various disease settings (neoadjuvant, adjuvant, metastatic).
- Biophysical characterization of Aptenodytes forsteri cytochrome P450 aromatase. [Journal Article]
- JIJ Inorg Biochem 2018 Apr 07; 184:79-87
- Cytochrome P450 19 (CYP19, aromatase) catalyzes the conversion of androgens to estrogens in a sequence of three reactions that each depend on NADPH and O2. Aromatase is a phylogenetically-ancient enz...
Cytochrome P450 19 (CYP19, aromatase) catalyzes the conversion of androgens to estrogens in a sequence of three reactions that each depend on NADPH and O2. Aromatase is a phylogenetically-ancient enzyme and its breadth of expression in other species has highlighted distinct physiological functions. In songbirds, estrogen production is required for programming the neural circuits controlling song and in the determination of sex in fish and reptiles. This work describes the expression, purification, and biophysical characterization of Aptenodytes forsteri (Emperor penguin, af) aromatase. Using human cytochrome P450 reductase as a redox partner, afCYP19 displayed similar substrate turnover and LC/MS/MS confirmed that afCYP19 catalyzes the transformations through the intermediates 19-hydroxy- and 19-oxo-androstenedione. Androstenedione and anastrozole had the highest affinity for the enzyme and were followed closely by 19-hydroxyandrostenedione and testosterone. The affinity of 19-oxo-androstenedione for afCYP19 was ten-fold lower. The time-dependent changes in the Soret bands observed in stopped-flow mixing experiments of the steroidal ligands and the inhibitor anastrozole with afCYP19 were best described by a two-step binding mechanism. In summary, these studies describe the first biophysical characterization of an avian aromatase that displays strikingly similar enzyme kinetics and ligand binding properties to the human enzyme and could serve as a convenient model system for studies of the enigmatic transformation of androgens to estrogens.
- The role of androgens on periodontal repair in female rats. [Journal Article]
- JPJ Periodontol 2018; 89(4):486-495
- CONCLUSIONS: The blockage of androgen receptors significantly impair bone repair in females through mechanisms that are different from those related to estrogen receptors.
- Erythematous Maculopapular Eruption Induced by Anastrozole: The First Case. [Journal Article]
- AJAm J Ther 2018 Apr 09
- Bioequivalence of Oral Formulations of Anastrozole in Healthy Chinese Male Volunteers: A Randomized, Single-Dose, Two-Period, Two-Sequence Crossover Study. [Journal Article]
- CPClin Pharmacol Drug Dev 2018 Apr 16
- Anastrozole is currently used as first-line treatment in locally advanced or metastatic breast cancer. A generic anastrozole tablet was developed to offer an alternative to the marketed tablet formul...
Anastrozole is currently used as first-line treatment in locally advanced or metastatic breast cancer. A generic anastrozole tablet was developed to offer an alternative to the marketed tablet formulation. The aim of the current study was to evaluate the bioequivalence between the test and reference formulations of anastrozole in a single-dose, 2-period, 2-sequence crossover study with a 14-day washout interval. A total of 20 healthy male Chinese volunteers were enrolled and completed the study, after oral administration of a single dose of 1.0-mg test and reference formulations of anastrozole. The blood samples were collected at different times and were determined by a fully validated high-pressure liquid chromatography-tandem mass spectrometry method. The evaluated pharmacokinetic parameters, including Cmax , AUC0-t , and AUC0-∞ , were assessed for bioequivalence based on current guidelines. The observed pharmacokinetic parameters of anastrozole of the test drug were similar to those of the reference formulation. The 90% confidence intervals of test/reference ratios for Cmax , AUC0-t , and AUC0-∞ were within the bioequivalence acceptance range of 80%-125%. The results obtained from these healthy Chinese subjects in this study suggest that the test formulation of anastrozole 1.0-mg tablet is bioequivalent to the reference formulation (Arimidex 1.0-mg tablet).
- Personalized prevention in high risk individuals: Managing hormones and beyond. [Journal Article]
- BBreast 2018; 39:139-147
- Increasing numbers of women are being identified at 'high-risk' of breast cancer, defined by The National Institute of Health and Care Excellence (NICE) as a 10-year risk of ≥8%. Classically women ha...
Increasing numbers of women are being identified at 'high-risk' of breast cancer, defined by The National Institute of Health and Care Excellence (NICE) as a 10-year risk of ≥8%. Classically women have been so identified through family history based risk algorithms or genetic testing of high-risk genes. Recent research has shown that assessment of mammographic density and single nucleotide polymorphisms (SNPs), when combined with established risk factors, trebles the number of women reaching the high risk threshold. The options for risk reduction in such women include endocrine chemoprevention with the selective estrogen receptor modulators tamoxifen and raloxifene or the aromatase inhibitors anastrozole or exemestane. NICE recommends offering anastrozole to postmenopausal women at high-risk of breast cancer as cost effectiveness analysis showed this to be cost saving to the National Health Service. Overall uptake to chemoprevention has been disappointingly low but this may improve with the improved efficacy of aromatase inhibitors, particularly the lack of toxicity to the endometrium and thrombogenic risks. Novel approaches to chemoprevention under investigation include lower dose and topical tamoxifen, denosumab, anti-progestins and metformin. Although oophorectomy is usually only recommended to women at increased risk of ovarian cancer it has been shown in numerous studies to reduce breast cancer risks in the general population and in those with mutations in BRCA1/2. However, recent evidence from studies that have confined analysis to true prospective follow up have cast doubt on the efficacy of oophorectomy to reduce breast cancer risk in BRCA1 mutation carriers, at least in the short-term.
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- Progression-free Survival With First-line Endocrine-based Therapies Among Postmenopausal Women With HR+/HER2- Metastatic Breast Cancer:: A Network Meta-analysis. [Review]
- CTClin Ther 2018; 40(4):628-639.e3
- CONCLUSIONS: Pal + AI, LEE + AI, Ful250 + AI, or Ful500 as first-line treatment for HR+/HER2- mBC had longer PFS than AI alone. Given the lack of head-to-head clinical trials comparing the efficacy of recently approved first-line ETs for HR+/HER2- mBC, these results have important clinical implications for the treatment of HR+/HER2- mBC in the first-line setting.