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Chemical Compound Review

LEROZOLE     4-[(4-cyanophenyl)-(1,2,4- triazol-1...

Synonyms: Letrozol, LETRAZOLE, Letoval, letrozole, Femara, ...
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Disease relevance of Femara


Psychiatry related information on Femara


High impact information on Femara

  • Role of androgens on MCF-7 breast cancer cell growth and on the inhibitory effect of letrozole [10].
  • In xenografts, combined treatment with ER down-regulator fulvestrant and letrozole, prevented increases in erbB-2 and activation of MAPK and was highly effective in inhibiting tumor growth throughout 29 weeks of treatment [11].
  • Expression of erbB-2 and p-Shc increased throughout treatment, whereas growth factor receptor binding protein 2 (Grb2) increased only in tumors proliferating on letrozole (weeks 28 and 56) [11].
  • Based on promising data involving reduction of contralateral breast cancer risk in adjuvant studies, several aromatase inhibitors, including letrozole, anastrozole, and exemestane, are being incorporated into trials evaluating their efficacy as preventive agents in women at increased risk [12].
  • Ovariectomized mice bearing tumor xenografts grown from aromatase-transfected estrogen receptor (ER)-positive human breast cancer cells (MCF-7Ca) were injected s.c. with 10 microg/d letrozole for up to 56 weeks [11].

Chemical compound and disease context of Femara


Biological context of Femara


Anatomical context of Femara


Associations of Femara with other chemical compounds

  • Total duration of endocrine therapy ("time to chemotherapy") was significantly longer (P =.005) for patients initially on letrozole (median, 16 months) than for patients initially on tamoxifen (median, 9 months) [13].
  • On-treatment levels of aromatase were detectable in 11 of 12 patients during treatment with anastrozole (mean percentage inhibition in the whole group, 97.3%) but in none of the 12 patients during treatment with letrozole (> 99.1% suppression in all patients; Wilcoxon, P =.0022, comparing the two drug regimens) [14].
  • Of the recombinant allozymes, only the double mutant (Arg39Cys264) displayed a significant change from the WT enzyme in inhibitor constant for the aromatase inhibitors exemestane and letrozole [26].
  • This issue was evaluated by assessing the effect of a blockade of estrogen synthesis on bone turnover markers in 42 normal women (mean age +/- SD, 69 +/- 5 years) randomly assigned to groups receiving the potent aromatase inhibitor letrozole or placebo for 6 months [27].
  • In both age groups, letrozole, but not placebo, significantly increased LH levels (339 and 323% in the young and the elderly, respectively) and T (146 and 99%, respectively) (P value of young vs. elderly was not significant) [28].
  • Letrozole consistently suppressed each plasma estrogen fraction below the levels recorded for anastrozole: E(2) (average suppression by 95.2% versus 92.8%; P = 0.018), E(1) (98.8% suppression versus 96.3%; P = 0.003), and E(1)S (98.9% suppression versus 95.3%; P = 0.003) [29].
  • In the L-BLP25 plus letrozole treatment group, statistically significant (P < 0.05) additive antitumor activity was observed, whereas tamoxifen plus L-BLP25 was not significantly different (P > 0.05) [30].

Gene context of Femara

  • Activation of mitogen-activated protein kinase in xenografts and cells during prolonged treatment with aromatase inhibitor letrozole [11].
  • Twenty-three of 92 tumors (25%) on tamoxifen and 14 of 93 on letrozole (15%) showed a paradoxical increase in Ki67 with treatment, and the majority of these cases was HER1/2 negative [31].
  • Aromatase is the enzyme responsible for the conversion of androgens into estrogens, and synthetic aromatase inhibitors such as letrozole, anastrozole, and exemestane have proven to be effective endocrine regimens for ER-positive breast cancer [32].
  • We have investigated the effect of HER-2 overexpression on resistance to the aromatase inhibitor letrozole in MCF-7 breast cancer cells stably expressing cellular aromatase (MCF-7/CA) [33].
  • We have previously shown that letrozole (a different type of NSS-AI) modifies blood IGF-1 levels, and the results of this study of the biological effects of anastrozole on the components of the IGF system confirm our previous observations [34].

Analytical, diagnostic and therapeutic context of Femara


  1. Letrozole for advanced breast cancer. Hoctin-Boes, G., Yates, R., Steinberg, M. J. Clin. Oncol. (1998) [Pubmed]
  2. Letrozole, a new oral aromatase inhibitor for advanced breast cancer: double-blind randomized trial showing a dose effect and improved efficacy and tolerability compared with megestrol acetate. Dombernowsky, P., Smith, I., Falkson, G., Leonard, R., Panasci, L., Bellmunt, J., Bezwoda, W., Gardin, G., Gudgeon, A., Morgan, M., Fornasiero, A., Hoffmann, W., Michel, J., Hatschek, T., Tjabbes, T., Chaudri, H.A., Hornberger, U., Trunet, P.F. J. Clin. Oncol. (1998) [Pubmed]
  3. Reversible pancytopenia caused by oral letrozole assumption in a patient with recurrent breast cancer. Sperone, P., Gorzegno, G., Berruti, A., Familiari, U., Dogliotti, L. J. Clin. Oncol. (2002) [Pubmed]
  4. Phase III, multicenter, double-blind, randomized study of letrozole, an aromatase inhibitor, for advanced breast cancer versus megestrol acetate. Buzdar, A., Douma, J., Davidson, N., Elledge, R., Morgan, M., Smith, R., Porter, L., Nabholtz, J., Xiang, X., Brady, C. J. Clin. Oncol. (2001) [Pubmed]
  5. Effects of the antiestrogen tamoxifen and the aromatase inhibitor letrozole on serum hormones and bone characteristics in a preclinical tumor model for breast cancer. Núñez, N.P., Jelovac, D., Macedo, L., Berrigan, D., Perkins, S.N., Hursting, S.D., Barrett, J.C., Brodie, A. Clin. Cancer Res. (2004) [Pubmed]
  6. Letrozole treatment of precocious puberty in girls with the McCune-Albright syndrome: a pilot study. Feuillan, P., Calis, K., Hill, S., Shawker, T., Robey, P.G., Collins, M.T. J. Clin. Endocrinol. Metab. (2007) [Pubmed]
  7. Changes in breast cancer transcriptional profiles after treatment with the aromatase inhibitor, letrozole. Miller, W.R., Larionov, A.A., Renshaw, L., Anderson, T.J., White, S., Murray, J., Murray, E., Hampton, G., Walker, J.R., Ho, S., Krause, A., Evans, D.B., Dixon, J.M. Pharmacogenet. Genomics (2007) [Pubmed]
  8. Aromatase inhibitors and bipolar mood disorder: a case report. Goodwin, G.M. Bipolar disorders. (2006) [Pubmed]
  9. Letrozole Versus Testosterone. A Single-Center Pilot Study of HIV-Infected Men Who Have Sex with Men on Highly Active Anti-Retroviral Therapy (HAART) with Hypoactive Sexual Desire Disorder and Raised Estradiol Levels. Richardson, D., Goldmeier, D., Frize, G., Lamba, H., De Souza, C., Kocsis, A., Scullard, G. The journal of sexual medicine (2007) [Pubmed]
  10. Role of androgens on MCF-7 breast cancer cell growth and on the inhibitory effect of letrozole. Macedo, L.F., Guo, Z., Tilghman, S.L., Sabnis, G.J., Qiu, Y., Brodie, A. Cancer Res. (2006) [Pubmed]
  11. Activation of mitogen-activated protein kinase in xenografts and cells during prolonged treatment with aromatase inhibitor letrozole. Jelovac, D., Sabnis, G., Long, B.J., Macedo, L., Goloubeva, O.G., Brodie, A.M. Cancer Res. (2005) [Pubmed]
  12. Prevention of hormone-related cancers: breast cancer. Dunn, B.K., Wickerham, D.L., Ford, L.G. J. Clin. Oncol. (2005) [Pubmed]
  13. Phase III study of letrozole versus tamoxifen as first-line therapy of advanced breast cancer in postmenopausal women: analysis of survival and update of efficacy from the International Letrozole Breast Cancer Group. Mouridsen, H., Gershanovich, M., Sun, Y., Perez-Carrion, R., Boni, C., Monnier, A., Apffelstaedt, J., Smith, R., Sleeboom, H.P., Jaenicke, F., Pluzanska, A., Dank, M., Becquart, D., Bapsy, P.P., Salminen, E., Snyder, R., Chaudri-Ross, H., Lang, R., Wyld, P., Bhatnagar, A. J. Clin. Oncol. (2003) [Pubmed]
  14. Influence of letrozole and anastrozole on total body aromatization and plasma estrogen levels in postmenopausal breast cancer patients evaluated in a randomized, cross-over study. Geisler, J., Haynes, B., Anker, G., Dowsett, M., Lønning, P.E. J. Clin. Oncol. (2002) [Pubmed]
  15. Letrozole, a new oral aromatase inhibitor: randomised trial comparing 2.5 mg daily, 0.5 mg daily and aminoglutethimide in postmenopausal women with advanced breast cancer. Letrozole International Trial Group (AR/BC3). Gershanovich, M., Chaudri, H.A., Campos, D., Lurie, H., Bonaventura, A., Jeffrey, M., Buzzi, F., Bodrogi, I., Ludwig, H., Reichardt, P., O'Higgins, N., Romieu, G., Friederich, P., Lassus, M. Ann. Oncol. (1998) [Pubmed]
  16. Management of cancer-treatment-induced bone loss in postmenopausal women undergoing adjuvant breast cancer therapy: a Z-FAST update. Brufsky, A. Semin. Oncol. (2006) [Pubmed]
  17. Signaling pathways of apoptosis activated by aromatase inhibitors and antiestrogens. Thiantanawat, A., Long, B.J., Brodie, A.M. Cancer Res. (2003) [Pubmed]
  18. Fetal lung maturation in estrogen-deprived baboons. Pepe, G.J., Ballard, P.L., Albrecht, E.D. J. Clin. Endocrinol. Metab. (2003) [Pubmed]
  19. Impact of tamoxifen on the pharmacokinetics and endocrine effects of the aromatase inhibitor letrozole in postmenopausal women with breast cancer. Dowsett, M., Pfister, C., Johnston, S.R., Miles, D.W., Houston, S.J., Verbeek, J.A., Gundacker, H., Sioufi, A., Smith, I.E. Clin. Cancer Res. (1999) [Pubmed]
  20. Expression of functional estrogen receptors in human fetal male external genitalia. Crescioli, C., Maggi, M., Vannelli, G.B., Ferruzzi, P., Granchi, S., Mancina, R., Muratori, M., Forti, G., Serio, M., Luconi, M. J. Clin. Endocrinol. Metab. (2003) [Pubmed]
  21. Letrozole in the extended adjuvant treatment of postmenopausal women with history of early-stage breast cancer who have completed 5 years of adjuvant tamoxifen. Mann, B.S., Johnson, J.R., Kelly, R., Sridhara, R., Williams, G., Pazdur, R. Clin. Cancer Res. (2005) [Pubmed]
  22. Letrozole Reduces Estrogen and Gonadotropin Exposure in Women with Breast Cancer Undergoing Ovarian Stimulation before Chemotherapy. Oktay, K., Hourvitz, A., Sahin, G., Oktem, O., Safro, B., Cil, A., Bang, H. J. Clin. Endocrinol. Metab. (2006) [Pubmed]
  23. Regulation of placental vascular endothelial growth/permeability factor expression and angiogenesis by estrogen during early baboon pregnancy. Albrecht, E.D., Robb, V.A., Pepe, G.J. J. Clin. Endocrinol. Metab. (2004) [Pubmed]
  24. Estrogen elicits cortical zone-specific effects on development of the primate fetal adrenal gland. Albrecht, E.D., Aberdeen, G.W., Pepe, G.J. Endocrinology (2005) [Pubmed]
  25. Letrozole as a potent inhibitor of cell proliferation and expression of metalloproteinases (MMP-2 and MMP-9) by human epithelial breast cancer cells. Mitropoulou, T.N., Tzanakakis, G.N., Kletsas, D., Kalofonos, H.P., Karamanos, N.K. Int. J. Cancer (2003) [Pubmed]
  26. Human aromatase: gene resequencing and functional genomics. Ma, C.X., Adjei, A.A., Salavaggione, O.E., Coronel, J., Pelleymounter, L., Wang, L., Eckloff, B.W., Schaid, D., Wieben, E.D., Adjei, A.A., Weinshilboum, R.M. Cancer Res. (2005) [Pubmed]
  27. Role of low levels of endogenous estrogen in regulation of bone resorption in late postmenopausal women. Heshmati, H.M., Khosla, S., Robins, S.P., O'Fallon, W.M., Melton, L.J., Riggs, B.L. J. Bone Miner. Res. (2002) [Pubmed]
  28. Comparative assessment in young and elderly men of the gonadotropin response to aromatase inhibition. T'Sjoen, G.G., Giagulli, V.A., Delva, H., Crabbe, P., De Bacquer, D., Kaufman, J.M. J. Clin. Endocrinol. Metab. (2005) [Pubmed]
  29. Letrozole is superior to anastrozole in suppressing breast cancer tissue and plasma estrogen levels. Geisler, J., Helle, H., Ekse, D., Duong, N.K., Evans, D.B., Nordbø, Y., Aas, T., Lønning, P.E. Clin. Cancer Res. (2008) [Pubmed]
  30. L-BLP25 Vaccine plus Letrozole Induces a TH1 Immune Response and Has Additive Antitumor Activity in MUC1-Expressing Mammary Tumors in Mice. Mehta, N.R., Wurz, G.T., Burich, R.A., Greenberg, B.E., Griffey, S., Gutierrez, A., Bell, K.E., McCall, J.L., Wolf, M., Degregorio, M. Clin. Cancer Res. (2012) [Pubmed]
  31. Letrozole inhibits tumor proliferation more effectively than tamoxifen independent of HER1/2 expression status. Ellis, M.J., Coop, A., Singh, B., Tao, Y., Llombart-Cussac, A., Jänicke, F., Mauriac, L., Quebe-Fehling, E., Chaudri-Ross, H.A., Evans, D.B., Miller, W.R. Cancer Res. (2003) [Pubmed]
  32. Biochemical and biological characterization of a novel anti-aromatase coumarin derivative. Chen, S., Cho, M., Karlsberg, K., Zhou, D., Yuan, Y.C. J. Biol. Chem. (2004) [Pubmed]
  33. ErbB receptor signaling and therapeutic resistance to aromatase inhibitors. Shin, I., Miller, T., Arteaga, C.L. Clin. Cancer Res. (2006) [Pubmed]
  34. Short-term effects of anastrozole treatment on insulin-like growth factor system in postmenopausal advanced breast cancer patients. Ferrari, L., Martinetti, A., Zilembo, N., Pozzi, P., Buzzoni, R., La Torre, I., Gattinoni, L., Catena, L., Vitali, M., Celio, L., Seregni, E., Bombardieri, E., Bajetta, E. J. Steroid Biochem. Mol. Biol. (2002) [Pubmed]
  35. Fertility preservation in breast cancer patients: a prospective controlled comparison of ovarian stimulation with tamoxifen and letrozole for embryo cryopreservation. Oktay, K., Buyuk, E., Libertella, N., Akar, M., Rosenwaks, Z. J. Clin. Oncol. (2005) [Pubmed]
  36. Letrozole is more effective neoadjuvant endocrine therapy than tamoxifen for ErbB-1- and/or ErbB-2-positive, estrogen receptor-positive primary breast cancer: evidence from a phase III randomized trial. Ellis, M.J., Coop, A., Singh, B., Mauriac, L., Llombert-Cussac, A., Jänicke, F., Miller, W.R., Evans, D.B., Dugan, M., Brady, C., Quebe-Fehling, E., Borgs, M. J. Clin. Oncol. (2001) [Pubmed]
  37. Effect of exemestane on tamoxifen pharmacokinetics in postmenopausal women treated for breast cancer. Hutson, P.R., Love, R.R., Havighurst, T.C., Rogers, E., Cleary, J.F. Clin. Cancer Res. (2005) [Pubmed]
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