Letrozole
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MedKoo CAT#: 100510

CAS#: 112809-51-5

Description: Letrozole, also known as CGS-20267, is a nonsteroidal inhibitor of estrogen synthesis with antineoplastic activity. As a third-generation aromatase inhibitor, letrozole selectively and reversibly inhibits aromatase, which may result in growth inhibition of estrogen-dependent breast cancer cells. Aromatase, a cytochrome P-450 enzyme localized to the endoplasmic reticulum of the cell and found in many tissues including those of the premenopausal ovary, liver, and breast, catalyzes the aromatization of androstenedione and testosterone into estrone and estradiol, the final step in estrogen biosynthesis.

Chemical Structure

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Letrozole
CAS# 112809-51-5
Product data Instruction

Theoretical Analysis

MedKoo Cat#: 100510
Name: Letrozole
CAS#: 112809-51-5
Chemical Formula: C17H11N5
Exact Mass: 285.10
Molecular Weight: 285.300
Elemental Analysis: C, 71.57; H, 3.89; N, 24.55

Price and Availability

Size Price Availability Quantity
1g USD 350 Ready to ship
2g USD 550 Ready to ship
200mg USD 110 Ready to ship
500mg USD 200 Ready to ship
5g USD 1050 Ready to ship
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Synonym: CGS20267; CGS-20267; CGS 20267; Abbreviation: LTZ. Brand name: Femara; Letoval.

IUPAC/Chemical Name: 4-[(4-cyanophenyl)-(1,2,4-triazol-1-yl)methyl]benzonitrile

InChi Key: HPJKCIUCZWXJDR-UHFFFAOYSA-N

InChi Code: InChI=1S/C17H11N5/c18-9-13-1-5-15(6-2-13)17(22-12-20-11-21-22)16-7-3-14(10-19)4-8-16/h1-8,11-12,17H

SMILES Code: N#CC1=CC=C(C(C2=CC=C(C#N)C=C2)N3N=CN=C3)C=C1

Appearance: White to light yellow crystalline powder.

Purity: >98% (or refer to the Certificate of Analysis)

Shipping Condition: Shipped under ambient temperature as non-hazardous chemical. This product is stable enough for a few weeks during ordinary shipping and time spent in Customs.

Storage Condition: Dry, dark and at 0 - 4 C for short term (days to weeks) or -20 C for long term (months to years).

Solubility: Soluble in DMSO, not in water

Shelf Life: >2 years if stored properly

Drug Formulation: This drug may be formulated in DMSO

Stock Solution Storage: 0 - 4 C for short term (days to weeks), or -20 C for long term (months).

HS Tariff Code: 2934.99.9001

Product Data:
Product Data
Instruction:
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Biological target: Letrozole (CGS 20267) is a potent, selective, reversible, and non-steroidal inhibitor of aromatase with an IC50 of 11.5 nM
In vitro activity: This study investigated the effect of letrozole on bone metabolism, focusing on osteoclastogenesis. Letrozole did not affect the viability, proliferation, or migration of bone marrow-derived macrophages (BMMs); however, it reduced the multinucleation of immature osteoclasts and subsequent bone resorption in vitro. Overall, letrozole inhibited the expression of dendritic cell-specific transmembrane protein (DC-STAMP), tartrate-resistant acid phosphatase, calcitonin receptor, and cathepsin K. Among them, the reduced expression of DC-STAMP was the most prominent. However, this downregulation of DC-STAMP expression following letrozole treatment was not related to the inhibition of major osteoclastogenesis pathways, such as the nuclear factor-κB (NF-κB), cFos, and nuclear factor of activated T cell c1 (NFATc1) pathways, but was attributed to the inhibition of p38, which is known to reside upstream of DC-STAMP expression. Notably, the anti-osteoclastogenic effect of letrozole was abolished following treatment with the p38 activator anisomycin. Contrary to expectations, these results strongly suggest a previously unknown anti-osteoclastogenic activity of letrozole, mediated by the downregulation of the p38/DC-STAMP pathway. Int J Mol Sci. 2020 Nov 9;21(21):8396. https://pubmed.ncbi.nlm.nih.gov/33182361/
In vivo activity: In this study, it was investigated whether letrozole treatment of pubertal female mice exerts organizational or activational effects on host physiology and the gut microbiome. In previous findings, letrozole treatment of female mice resulted in weight gain and abdominal adiposity compared to placebo mice. In this cohort, 5 weeks of letrozole treatment also resulted in increased body weight (Fig 4A). When body weight and parametrial fat were measured at the end of the experiment, placebo and letrozole-treated mice had similar body weights and amounts of parametrial fat relative to body weight post-pellet removal (Fig 4A and 4B). Since changes in the gut microbiome were reported to correlate with PCOS in both women and in rodent models, it was investigated whether letrozole treatment resulted in organizational or activational effects on the composition of the gut microbiome. The species richness (alpha diversity) of the gut microbiome in placebo and letrozole-treated female mice was analyzed using Faith’s PD estimate before (weeks 1–5) and after (weeks 9–13) pellet removal (Fig 6A). Similar to a previous report, placebo mice showed a significant positive correlation with alpha diversity during the first 5 weeks of the study that corresponded with puberty. In contrast, letrozole treatment of pubertal female mice did not result in a significant change in alpha diversity over time (RM-ANOVA: p = 0.059) (Fig 6A). After pellet removal, placebo mice did not demonstrate a positive correlation with alpha diversity over time and letrozole mice demonstrated similar alpha diversity to placebo-treated mice (Fig 6A). This study clearly showed that letrozole treatment of pubertal female mice resulted in activational effects on the reproductive axis. PLoS One. 2019; 14(9): e0223274. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6768472/

Solubility Data

Solvent Max Conc. mg/mL Max Conc. mM
Solubility
DMSO 38.0 132.87

Preparing Stock Solutions

The following data is based on the product molecular weight 285.300000000000000000000000000000 Batch specific molecular weights may vary from batch to batch due to the degree of hydration, which will affect the solvent volumes required to prepare stock solutions.

Recalculate based on batch purity %
Concentration / Solvent Volume / Mass 1 mg 5 mg 10 mg
1 mM 1.15 mL 5.76 mL 11.51 mL
5 mM 0.23 mL 1.15 mL 2.3 mL
10 mM 0.12 mL 0.58 mL 1.15 mL
50 mM 0.02 mL 0.12 mL 0.23 mL
Formulation protocol: 1. Kim HJ, Seong HS, Choi Y, Heo SC, Kim YD. Letrozole Suppresses the Fusion of Osteoclast Precursors through Inhibition of p38Mediated DC-STAMP Pathway. Int J Mol Sci. 2020 Nov 9;21(21):8396. doi: 10.3390/ijms21218396. PMID: 33182361; PMCID: PMC7664929. 2. Dave N, Chow LM, Gudelsky GA, LaSance K, Qi X, Desai PB. Preclinical pharmacological evaluation of letrozole as a novel treatment for gliomas. Mol Cancer Ther. 2015 Apr;14(4):857-64. doi: 10.1158/1535-7163.MCT-14-0743. Epub 2015 Feb 18. PMID: 25695958; PMCID: PMC4631403. 3. Arroyo P, Ho BS, Sau L, Kelley ST, Thackray VG. Letrozole treatment of pubertal female mice results in activational effects on reproduction, metabolism and the gut microbiome. PLoS One. 2019 Sep 30;14(9):e0223274. doi: 10.1371/journal.pone.0223274. PMID: 31568518; PMCID: PMC6768472. 4. Torres PJ, Ho BS, Arroyo P, Sau L, Chen A, Kelley ST, Thackray VG. Exposure to a Healthy Gut Microbiome Protects Against Reproductive and Metabolic Dysregulation in a PCOS Mouse Model. Endocrinology. 2019 May 1;160(5):1193-1204. doi: 10.1210/en.2019-00050. PMID: 30924862; PMCID: PMC6482036.
In vitro protocol: 1. Kim HJ, Seong HS, Choi Y, Heo SC, Kim YD. Letrozole Suppresses the Fusion of Osteoclast Precursors through Inhibition of p38Mediated DC-STAMP Pathway. Int J Mol Sci. 2020 Nov 9;21(21):8396. doi: 10.3390/ijms21218396. PMID: 33182361; PMCID: PMC7664929. 2. Dave N, Chow LM, Gudelsky GA, LaSance K, Qi X, Desai PB. Preclinical pharmacological evaluation of letrozole as a novel treatment for gliomas. Mol Cancer Ther. 2015 Apr;14(4):857-64. doi: 10.1158/1535-7163.MCT-14-0743. Epub 2015 Feb 18. PMID: 25695958; PMCID: PMC4631403.
In vivo protocol: 1. Arroyo P, Ho BS, Sau L, Kelley ST, Thackray VG. Letrozole treatment of pubertal female mice results in activational effects on reproduction, metabolism and the gut microbiome. PLoS One. 2019 Sep 30;14(9):e0223274. doi: 10.1371/journal.pone.0223274. PMID: 31568518; PMCID: PMC6768472. 2. Torres PJ, Ho BS, Arroyo P, Sau L, Chen A, Kelley ST, Thackray VG. Exposure to a Healthy Gut Microbiome Protects Against Reproductive and Metabolic Dysregulation in a PCOS Mouse Model. Endocrinology. 2019 May 1;160(5):1193-1204. doi: 10.1210/en.2019-00050. PMID: 30924862; PMCID: PMC6482036.

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    1: Keskin U, Ercan CM, Yilmaz A, Babacan A, Korkmaz C, Duru NK, Ergun A. Random-start controlled ovarian hyperstimulation with letrozole for fertility preservation in cancer patients: case series and review of literature. J Pak Med Assoc. 2014 Jul;64(7):830-2. Review. PubMed PMID: 25255597. 2: Liu A, Zheng C, Lang J, Chen W. Letrozole versus clomiphene citrate for unexplained infertility: a systematic review and meta-analysis. J Obstet Gynaecol Res. 2014 May;40(5):1205-16. doi: 10.1111/jog.12393. Review. PubMed PMID: 24754848. 3: Song Y, Li Z, Wu X, Wang X, Xiao J, Wang B. Effectiveness of the antagonist/letrozole protocol for treating poor responders undergoing in vitro fertilization/intracytoplasmic sperm injection: a systematic review and meta-analysis. Gynecol Endocrinol. 2014 May;30(5):330-4. doi: 10.3109/09513590.2013.875997. Epub 2014 Jan 24. Review. PubMed PMID: 24456013. 4: Fan L, Liedke PE, Isakoff SJ, St Louis J, Ryan PD, Goss PE. Intermittent letrozole therapy for metastatic breast cancer: case reports and literature review. Clin Breast Cancer. 2014 Apr;14(2):e41-5. doi: 10.1016/j.clbc.2013.10.009. Epub 2013 Oct 25. Review. PubMed PMID: 24342729. 5: Dahhan T, Balkenende E, van Wely M, Linn S, Goddijn M. Tamoxifen or letrozole versus standard methods for women with estrogen-receptor positive breast cancer undergoing oocyte or embryo cryopreservation in assisted reproduction. Cochrane Database Syst Rev. 2013 Nov 8;11:CD010240. doi: 10.1002/14651858.CD010240.pub2. Review. PubMed PMID: 24213953. 6: Kar S. Current evidence supporting "letrozole" for ovulation induction. J Hum Reprod Sci. 2013 Apr;6(2):93-8. doi: 10.4103/0974-1208.117166. Review. PubMed PMID: 24082649; PubMed Central PMCID: PMC3778612. 7: Riemsma R, Forbes CA, Amonkar MM, Lykopoulos K, Diaz JR, Kleijnen J, Rea DW. Systematic review of lapatinib in combination with letrozole compared with other first-line treatments for hormone receptor positive(HR+) and HER2+ advanced or metastatic breast cancer(MBC). Curr Med Res Opin. 2012 Aug;28(8):1263-79. doi: 10.1185/03007995.2012.707643. Epub 2012 Jul 16. Review. PubMed PMID: 22738819. 8: Cohen MH, Johnson JR, Justice R, Pazdur R. Approval summary: letrozole (Femara® tablets) for adjuvant and extended adjuvant postmenopausal breast cancer treatment: conversion of accelerated to full approval. Oncologist. 2011;16(12):1762-70. doi: 10.1634/theoncologist.2011-0287. Epub 2011 Nov 16. Review. PubMed PMID: 22089970; PubMed Central PMCID: PMC3248775. 9: Barnadas A, Estévez LG, Lluch-Hernández A, Rodriguez-Lescure A, Rodriguez-Sanchez C, Sanchez-Rovira P. An overview of letrozole in postmenopausal women with hormone-responsive breast cancer. Adv Ther. 2011 Dec;28(12):1045-58. doi: 10.1007/s12325-011-0075-4. Epub 2011 Nov 7. Review. PubMed PMID: 22068628. 10: Regan MM, Price KN, Giobbie-Hurder A, Thürlimann B, Gelber RD; International Breast Cancer Study Group and BIG 1-98 Collaborative Group. Interpreting Breast International Group (BIG) 1-98: a randomized, double-blind, phase III trial comparing letrozole and tamoxifen as adjuvant endocrine therapy for postmenopausal women with hormone receptor-positive, early breast cancer. Breast Cancer Res. 2011 May 26;13(3):209. doi: 10.1186/bcr2837. Review. PubMed PMID: 21635709; PubMed Central PMCID: PMC3218925. 11: He D, Jiang F. Meta-analysis of letrozole versus clomiphene citrate in polycystic ovary syndrome. Reprod Biomed Online. 2011 Jul;23(1):91-6. doi: 10.1016/j.rbmo.2011.03.024. Epub 2011 Apr 3. Review. PubMed PMID: 21550852. 12: Steed HL, Chu QS. Aromatase inhibition: a potential target for the management of recurrent or metastatic endometrial cancer by letrozole: more questions than answers? Expert Opin Investig Drugs. 2011 May;20(5):681-90. doi: 10.1517/13543784.2011.566862. Epub 2011 Mar 18. Review. PubMed PMID: 21413907. 13: Geisler J. Differences between the non-steroidal aromatase inhibitors anastrozole and letrozole--of clinical importance? Br J Cancer. 2011 Mar 29;104(7):1059-66. doi: 10.1038/bjc.2011.58. Epub 2011 Mar 1. Review. PubMed PMID: 21364577; PubMed Central PMCID: PMC3068499. 14: Merriam P, Sikov WM. Clinical utility of the combination of lapatinib and letrozole in the management of hormone receptor-positive and HER2-positive advanced breast cancer. Breast Cancer (Dove Med Press). 2011 Oct 26;3:139-50. doi: 10.2147/BCTT.S12150. Review. PubMed PMID: 24367183; PubMed Central PMCID: PMC3846896. 15: Pritts EA. Letrozole for ovulation induction and controlled ovarian hyperstimulation. Curr Opin Obstet Gynecol. 2010 Aug;22(4):289-94. doi: 10.1097/GCO.0b013e32833beebf. Review. PubMed PMID: 20592587. 16: Sylvestre VT, Dunton CJ. Treatment of recurrent endometrial stromal sarcoma with letrozole: a case report and literature review. Horm Cancer. 2010 Apr;1(2):112-5. doi: 10.1007/s12672-010-0007-9. Epub 2010 Jan 29. Review. PubMed PMID: 21761354. 17: Dellapasqua S, Colleoni M. Letrozole. Expert Opin Drug Metab Toxicol. 2010 Feb;6(2):251-9. doi: 10.1517/17425250903540246. Review. PubMed PMID: 20095792. 18: Guarneri V. Lapatinib plus letrozole for postmenopausal patients with advanced HER2(+)/HR(+) breast cancer. Expert Rev Anticancer Ther. 2009 Nov;9(11):1549-57. doi: 10.1586/era.09.124. Review. PubMed PMID: 19895239. 19: Keating GM. Letrozole: a review of its use in the treatment of postmenopausal women with hormone-responsive early breast cancer. Drugs. 2009 Aug 20;69(12):1681-705. doi: 10.2165/10482340-000000000-00000. Review. PubMed PMID: 19678717. 20: Nabholtz JM, Mouret-Reynier MA, Durando X, Van Praagh I, Al-Sukhun S, Ferriere JP, Chollet P. Comparative review of anastrozole, letrozole and exemestane in the management of early breast cancer. Expert Opin Pharmacother. 2009 Jun;10(9):1435-47. doi: 10.1517/14656560902953738. Review. PubMed PMID: 19445563.