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Goss PE, Ingle JN, Martino S, Robert NJ, Muss HB, Piccart MJ, Castiglione M, Tu D, Shepherd LE, Pritchard KI, Livingston RB, Davidson NE, Norton L, Perez EA, Abrams JS, Cameron DA, Palmer MJ, Pater JL. Randomized trial of letrozole following tamoxifen as extended adjuvant therapy in receptor-positive breast cancer: updated findings from NCIC CTG MA.17. J Natl Cancer Inst 2005; 97:1262-71. [PMID: 16145047 DOI: 10.1093/jnci/dji250] [Citation(s) in RCA: 789] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Most recurrences in women with breast cancer receiving 5 years of adjuvant tamoxifen occur after 5 years. The MA.17 trial, which was designed to determine whether extended adjuvant therapy with the aromatase inhibitor letrozole after tamoxifen reduces the risk of such late recurrences, was stopped early after an interim analysis showed that letrozole improved disease-free survival. This report presents updated findings from the trial. METHODS Postmenopausal women completing 5 years of tamoxifen treatment were randomly assigned to a planned 5 years of letrozole (n = 2593) or placebo (n = 2594). The primary endpoint was disease-free survival (DFS); secondary endpoints included distant disease-free survival, overall survival, incidence of contralateral tumors, and toxic effects. Survival was examined using Kaplan-Meier analysis and log-rank tests. Planned subgroup analyses included those by axillary lymph node status. All statistical tests were two-sided. RESULTS After a median follow-up of 30 months (range = 1.5-61.4 months), women in the letrozole arm had statistically significantly better DFS and distant DFS than women in the placebo arm (DFS: hazard ratio [HR] for recurrence or contralateral breast cancer = 0.58, 95% confidence interval [CI] = 0.45 to 0.76; P < .001; distant DFS: HR = 0.60, 95% CI = 0.43 to 0.84; P = .002). Overall survival was the same in both arms (HR for death from any cause = 0.82, 95% CI = 0.57 to 1.19; P = .3). However, among lymph node-positive patients, overall survival was statistically significantly improved with letrozole (HR = 0.61, 95% CI = 0.38 to 0.98; P = .04). The incidence of contralateral breast cancer was lower in women receiving letrozole, but the difference was not statistically significant. Women receiving letrozole experienced more hormonally related side effects than those receiving placebo, but the incidences of bone fractures and cardiovascular events were the same. CONCLUSION Letrozole after tamoxifen is well-tolerated and improves both disease-free and distant disease-free survival but not overall survival, except in node-positive patients.
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Affiliation(s)
- Paul E Goss
- Division of Hematology-Oncology, Massachusetts General Hospital, Boston, MA, USA.
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Pearce ST, Jordan VC. The biological role of estrogen receptors α and β in cancer. Crit Rev Oncol Hematol 2004; 50:3-22. [PMID: 15094156 DOI: 10.1016/j.critrevonc.2003.09.003] [Citation(s) in RCA: 220] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2003] [Indexed: 11/19/2022] Open
Abstract
The temporal and tissue-specific actions of estrogen are mediated by estrogen receptors alpha and beta. The ERs are steroid hormone receptors that modulate the transcription of target genes when bound to ligand. The activity of these transcription factors is regulated by a variety of factors, including ligand binding, phosphorylation, coregulators, and the effector pathway (ERE, AP1, SP1). The end result of target gene transcription is to modulate physiological processes, such as reproductive organ development and function, bone density, and unfortunately contribute to the growth and development of breast and endometrial cancer. The complex biological effects mediated by ER alpha and ER beta involve communication between many proteins and signaling pathways. An ultimate goal of current research is to enhance the value of the separate estrogen receptors as targets for therapeutic intervention.
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Affiliation(s)
- Sandra Timm Pearce
- Robert H. Lurie Comprehensive Cancer Center, The Feinberg School of Medicine, Olson Pavilion, Room 8258, Northwestern University, 303 E. Chicago Avenue, Chicago, IL 60611, USA
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Goss PE, Ingle JN, Martino S, Robert NJ, Muss HB, Piccart MJ, Castiglione M, Tu D, Shepherd LE, Pritchard KI, Livingston RB, Davidson NE, Norton L, Perez EA, Abrams JS, Therasse P, Palmer MJ, Pater JL. A randomized trial of letrozole in postmenopausal women after five years of tamoxifen therapy for early-stage breast cancer. N Engl J Med 2003; 349:1793-802. [PMID: 14551341 DOI: 10.1056/nejmoa032312] [Citation(s) in RCA: 1290] [Impact Index Per Article: 61.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND In hormone-dependent breast cancer, five years of postoperative tamoxifen therapy--but not tamoxifen therapy of longer duration--prolongs disease-free and overall survival. The aromatase inhibitor letrozole, by suppressing estrogen production, might improve the outcome after the discontinuation of tamoxifen therapy. METHODS We conducted a double-blind, placebo-controlled trial to test the effectiveness of five years of letrozole therapy in postmenopausal women with breast cancer who have completed five years of tamoxifen therapy. The primary end point was disease-free survival. RESULTS A total of 5187 women were enrolled (median follow-up, 2.4 years). At the first interim analysis, there were 207 local or metastatic recurrences of breast cancer or new primary cancers in the contralateral breast--75 in the letrozole group and 132 in the placebo group--with estimated four-year disease-free survival rates of 93 percent and 87 percent, respectively, in the two groups (P< or =0.001 for the comparison of disease-free survival). A total of 42 women in the placebo group and 31 women in the letrozole group died (P=0.25 for the comparison of overall survival). Low-grade hot flashes, arthritis, arthralgia, and myalgia were more frequent in the letrozole group, but vaginal bleeding was less frequent. There were new diagnoses of osteoporosis in 5.8 percent of the women in the letrozole group and 4.5 percent of the women in the placebo group (P=0.07); the rates of fracture were similar. After the first interim analysis, the independent data and safety monitoring committee recommended termination of the trial and prompt communication of the results to the participants. CONCLUSIONS As compared with placebo, letrozole therapy after the completion of standard tamoxifen treatment significantly improves disease-free survival.
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Affiliation(s)
- Paul E Goss
- Division of Hematology-Oncology, Princess Margaret Hospital, Toronto, ON, Canada.
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Abstract
Tamoxifen has dominated endocrine treatment of breast cancer for over two decades. It is useful in metastatic breast cancer, adjuvant therapy, preoperative treatment, ductal carcinoma-in-situ and chemoprevention. However, breast cancer may be refractory to tamoxifen or develop resistance to it with ongoing treatment. This resistance involves several mechanisms including receptor mutation causing 'estrogen hypersensitivity' and an increasing agonist effect of tamoxifen. Megestrol (megestrol acetate), in North America, and aminoglutethimide, in Europe, have been the traditional second line therapies after tamoxifen in advanced breast cancer. Aromatase (estrogen synthetase) inhibitors are a logical alternative to tamoxifen to antagonise the effects of estrogen on breast cancer. The third-generation non-steroidal aromatase inhibitors anastrozole, letrozole and vorozole, and the steroidal inhibitor exemestane, have been studied after tamoxifen versus either megestrol or aminoglutethimide. They showed enhanced efficacy and significantly superior toxicity profiles. Compliance with the inhibitors was also significantly better than with the traditional treatments. Aromatase inhibitors have most recently been shown to be superior to tamoxifen as initial therapy and are being extensively tested in the adjuvant setting after, or instead of, tamoxifen. Pilot studies of chemoprevention are also being undertaken. The aromatase inhibitors are an important new addition to the armamentarium of breast cancer therapy.
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Affiliation(s)
- Paul E Goss
- Breast Cancer Prevention Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada.
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Oehler MK, Hague S, Rees MCP, Bicknell R. Adrenomedullin promotes formation of xenografted endometrial tumors by stimulation of autocrine growth and angiogenesis. Oncogene 2002; 21:2815-21. [PMID: 11973640 DOI: 10.1038/sj.onc.1205374] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2001] [Revised: 01/22/2002] [Accepted: 01/31/2002] [Indexed: 11/09/2022]
Abstract
The angiogenic peptide adrenomedullin (ADM) has been implicated as a mediator of the increased risk of endometrial hyperplasia and cancer resulting from the use of tamoxifen for the treatment and prevention of breast cancer. ADM has been shown to be induced by tamoxifen in the endometrium and to be a growth factor for endometrial endothelial cells in vitro. We have now shown ADM to be strongly angiogenic in the mouse subcutaneous sponge angiogenesis assay. To examine the role of ADM in tumor growth, the ADM cDNA was transfected into endometrial carcinoma cells followed by xenografting into athymic mice. Two endometrial cancer cell lines were employed, those in which transfection and expression of ADM resulted in no effect on growthin vitro (Ishikawa cells) and those in which expressionof exogenous ADM stimulated in vitro growth (RL95.2 cells). A clear enhancement of tumor growth was seen with both cell lines but the effect was far greater with the RL95.2 cells. We conclude that ADM is pro-tumorigenic by stimulating either angiogenesis alone or by stimulating angiogenesis and carcinoma cell growth directly. The combined activities lead to a striking increase in tumor growth. These results provide the first direct evidence of tumorigenic activity of ADM and provide further support for ADMs involvement in tamoxifen induced endometrial neoplasia.
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Ragaz J. Adjuvant trials of aromatase inhibitors: determining the future landscape of adjuvant endocrine therapy. J Steroid Biochem Mol Biol 2001; 79:133-41. [PMID: 11850217 DOI: 10.1016/s0960-0760(01)00159-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This review will discuss the role of aromatase inhibitors (AIs) in the adjuvant setting, and will summarize major strategies behind individual adjuvant trials using aromatase inhibitors. Studies with the third generation AIs including anastrozole, letrozole and exemestane, have shown better outcome and improved therapeutic ratio over second line hormonal approaches (i.e. progestins or aminoglutethimide) and, more recently, over tamoxifen also. These promising results have led recently to testing of AIs in the adjuvant setting for postmenopausal patients. Most trials now in progress are evaluating the role of new AIs versus tamoxifen (T) given x 5 years, which in most institutions is currently the standard hormonal adjuvant therapy for breast cancer. Three adjuvant approaches are being tested. First is the use of AI+T x 5 years in combination versus each agent alone, as reflected in the recently completed ATAC trial. Second is a sequential approach T first x 2-3 years followed by AIs x 2-3 years, or the other way round; and third, T x 5 years followed by AIs for additional 5 years (i.e. total duration of adjuvant hormones of 10 years). Many patients in the above trials will survive their first cancer. Hence, the non-oncological outcomes known to be affected by hormones are of rising importance. Therefore, the assessment of lipids as surrogates for cardiovascular morbidity, and of bone mineral status, as a marker for osteoporosis/bone fractures, is an important component of these trials. Also discussed in this review are proposals for future studies of AIs with focus on hormone resistance, such as early alteration of multiple hormonal agents or their intermittent use, the impact of the new generation of SERMs or 'pure' antiestrogens on activity of AIs, and the rising importance of AIs interacting with biologicals, cytokines or hormone modulators.
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Affiliation(s)
- J Ragaz
- British Columbia Cancer Agency, 600, West 10th Avenue, British Columbia, V5Z 4E6, Vancouver, Canada.
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Abstract
The human estrogen receptor-alpha (hER) is a ligand-activated transcription factor that functions as a homodimer. We sought to further understand the molecular processes involved in dimerization, and to develop a reagent that may function as an antiestrogen independent of the ligand binding site. To this end, we designed a 16-residue 'dimer-interface' oligopeptide derived from the helical region of the hER which is directly involved in dimerization. This peptide, termed the I-box peptide, has a high helical propensity in aqueous solution. The I-box peptide blocks hER action by causing aggregation and precipitation of both the ligand-bound and apo-hER. This effect is dependent on the helical nature of the peptide. A single Ile to Pro mutation in the helical region of the I-box peptide significantly reduces the helical content and abolishes the precipitation activity. Furthermore, the peptide activity appears to be specific for the hER. The I-box peptide does not significantly affect other proteins or steroid receptors tested. A homologous peptide derived from the nuclear receptor RXRalpha dimer interface, and a LXXLL-containing peptide from the coactivator TIF2 have no detectable in vitro effect on hER function or solubility. Our data suggest that rationally designed molecules capable of affecting steroid receptor quaternary structures may be potential avenues for the development of specific inhibitors of this class of proteins.
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Affiliation(s)
- M R Yudt
- Department of Biochemistry and Biophysics, Box 712, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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Jordan VC. Molecular biology of the estrogen receptor aids in the understanding of tamoxifen resistance and breast cancer prevention with raloxifene. Recent Results Cancer Res 1999; 152:265-76. [PMID: 9928564 DOI: 10.1007/978-3-642-45769-2_25] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- V C Jordan
- Robert H. Lurie Cancer Comprehensive Cancer Center, Northwestern University Medical School, Chicago, IL 60611, USA
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Jordan VC. Antiestrogenic action of raloxifene and tamoxifen: today and tomorrow. J Natl Cancer Inst 1998; 90:967-71. [PMID: 9665143 DOI: 10.1093/jnci/90.13.967] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Understanding the Antiestrogenic Actions of Raloxifene and a Mechanism of Drug Resistance to Tamoxifen. Breast Cancer 1998; 5:99-106. [PMID: 11091634 DOI: 10.1007/bf02966681] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Tonetti DA, O'Regan R, Tanjore S, England G, Jordan VC. Antiestrogen stimulated human endometrial cancer growth: laboratory and clinical considerations. J Steroid Biochem Mol Biol 1998; 65:181-9. [PMID: 9699872 DOI: 10.1016/s0960-0760(98)00011-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The new antiestrogen toremifene (TOR) is currently on the market for the treatment of advanced breast cancer in postmenopausal women. TOR is known to exhibit a similar efficacy profile as tamoxifen (TAM) in the treatment of advanced breast cancer and there are studies to suggest that the beneficial side effects of TAM on bone and blood lipids are also achieved with TOR. However, the data concerning the action of TOR on the endometrium is sorely lacking. In light of the estrogenic effect of TAM on the uterus and the 2-3-fold increased incidence in endometrial carcinoma detected in patients receiving TAM therapy, it is imperative to investigate the effect of TOR on endometrial carcinoma. We compared the actions of TAM and TOR on the EnCa101 human endometrial tumor model and find that both antiestrogens have similar growth stimulatory effects. To investigate a potential mechanism of antiestrogen-stimulated endometrial tumor growth, we have examined known activators of the AP-1 signal transduction pathway, the protein kinase C (PKC) family of isozymes, in the EnCa101 human endometrial tumor model. We find that increased PKC isozyme expression correlates with hormone-independent breast cancer as well as antiestrogen-stimulated endometrial cancer.
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Affiliation(s)
- D A Tonetti
- Robert H. Lurie Cancer Center, Northwestern University Medical Center, Chicago, IL 60611, USA
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Abstract
During the past 20 years, the hormonal therapy of choice for the treatment of breast cancer has been the antiestrogen, tamoxifen. The use of tamoxifen has been proved to produce a favorable response and survival advantage in patients whose tumors are classified as estrogen receptor-positive (ER+)/progesterone receptor-positive (PR+). Additionally, tamoxifen is the only drug known to reduce the incidence of contralateral disease. This drug produces relatively few harmful side effects, while exhibiting several beneficial effects such as maintaining bone density and reducing the incidence of myocardial infarction in the postmenopausal woman. However, tumors eventually acquire a tamoxifen-resistant or tamoxifen-stimulated phenotype, resulting in disease recurrence. Several mechanisms have been proposed to account for tamoxifen-resistant breast cancer, in the hope of developing a more effective first-line or perhaps second-line treatment strategy. One popular theory is the occurrence of a mutation in the estrogen receptor, the drug target. A plethora of studies have reported the detection of estrogen receptor mRNA splice variants, and it has been suggested that the accumulation of these variant mRNAs are responsible for the development of tamoxifen-resistant breast cancer. In this review, several questions will be posed to address the suitability of both laboratory and clinical evidence to support this hypothesis. Although there is adequate data generated in the laboratory, there is, as yet, no compelling evidence to suggest that mutation of the estrogen receptor is the molecular mechanism producing tamoxifen-stimulated growth in human breast and endometrial cancer.
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Affiliation(s)
- D A Tonetti
- Robert H. Lurie Cancer Center, Northwestern University Medical School, Chicago, IL 60611, U.S.A
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Levenson AS, Catherino WH, Jordan VC. Estrogenic activity is increased for an antiestrogen by a natural mutation of the estrogen receptor. J Steroid Biochem Mol Biol 1997; 60:261-8. [PMID: 9219916 DOI: 10.1016/s0960-0760(96)00184-7] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The estrogen receptor (ER) functions as a ligand-activated transcription factor which mediates the actions of estrogens and antiestrogens in target tissues. Other investigators have shown that artificial point mutations in the transcriptional activation domain AF-2 of the ligand binding domain (LBD) of the ER can increase the estrogenic properties of antiestrogens, determined by transcriptional activation of estrogen-responsive reporter constructs cotransfected into cells. Although these data provide valuable information about ER function there is no evidence that these mutations occur naturally. We have taken a different approach and examined the naturally occurring codon 351 asp --> tyr mutation in the LBD of ER to stimulate the expression of an endogenous target gene. This approach avoids dependence on artificial reporter constructs and their idealized estrogen response elements (EREs). In this report we describe the regulation of transforming growth factor alpha (TGF alpha) mRNA by estradiol and the antiestrogens keoxifene and ICI 182,780 in our stable transfectants of ER-negative MDA-MB-231 breast cancer cells, which express either the wild-type (S30 cells) or codon 351 asp --> tyr mutant ER (BC-2 cells). The mutant receptor was identified in a tamoxifen-stimulated human breast tumor. Our results demonstrate, for the first time, that a naturally occurring mutation in the ER changes the pharmacology of the antiestrogen keoxifene by increasing estrogenic activity, and that keoxifene exhibits a gene-specific estrogen-like effect with mutant ER but not with wild-type ER. The pure antiestrogen ICI 182,780 maintained complete antagonistic activities in both ER transfectants, demonstrating that its action is unaffected by the mutation.
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Affiliation(s)
- A S Levenson
- Robert H. Lurie Cancer Center, Northwestern University Medical School, Chicago, IL 60611, USA
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