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Version 2.5
Creation Date 2005-06-13 13:24:05
Update Date 2009-02-19 16:04:34
Primary Accession Number DB00990
Secondary Accession Number
  • APRD00144
Name Exemestane
Drug Type
  • Approved
  • Investigational
  • Small Molecule
Description Exemestane is an oral steroidal aromatase inhibitor used in the adjuvant treatment of hormonally-responsive (also called hormone-receptor-positive, estrogen-responsive) breast cancer in postmenopausal women. It acts as a false substrate for the aromatase enzyme, and is processed to an intermediate that binds irreversibly to the active site of the enzyme causing its inactivation.
Synonyms
  1. Exemestano [INN-Spanish]
  2. Exemestanum [INN-Latin]
  3. exemestane
Brand Names
  1. Aromasin
  2. Exemestance
Brand Mixtures Not Available
Chemical IUPAC Name (8R,9S,10R,13S,14S)-10,13-dimethyl-6-methylidene-7,8,9,11,12,14,15,16-octahydrocyclopenta[a]phenanthrene-3,17-dione
Chemical Formula C20H24O2
Chemical Structure Structure
CAS Registry Number 107868-30-4
InChI Identifier InChI=1/C20H24O2/c1-12-10-14-15-4-5-18(22)20(15,3)9-7-16(14)19(2)8-6-13(21)11-17(12)19/h6,8,11,14-16H,1,4-5,7,9-10H2,2-3H3/t14-,15-,16-,19+,20-/m0/s1
InChI Key BFYIZQONLCFLEV-DAELLWKTBA
KEGG Drug D00963 Link Image
KEGG Compound C08162 Link Image
PubChem Compound 60198 Link Image
PubChem Substance 196561 Link Image
ChEBI ID Not Available
PharmGKB ID Not Available
HET ID Not Available
GenBank ID Not Available
Drug ID Number [DIN] 02242705 Link Image
RxList Link http://www.rxlist.com/cgi/generic3/exemest.htm Link Image
PDRhealth Link Not Available
Wikipedia Link http://en.wikipedia.org/wiki/Exemestane Link Image
FDA Label
Material Safety Data Sheet (MSDS) Not Available
Synthesis Reference Pfizer Canada Inc, Patent Number: 1277656
Average Molecular Weight 296.4034
Monoisotopic Molecular Weight 296.1776
State Solid
Melting Point 155.13oC
Experimental Water Solubility Non-soluble Source: PhysProp
Predicted Water Solubility 6.83e-03 mg/mL Calculated using ALOGPS
Experimental LogP/Hydrophobicity 3.7 Source: PhysProp
Predicted LogP 2.67 Calculated using ALOGPS
Experimental LogS Not Available
Predicted LogS -4.64 Calculated using ALOGPS
Experimental Caco2 Permeability Not Available
pKa/Isoelectric Point Not Available
Mass Spectrum Not Available
MOL File Show Link Image | Download Link Image
SDF File Show Link Image | Download Link Image
PDB File Show Link Image | Download Link Image
2D Structure
3D Structure
Experimental PDB ID Not Available
Isomeric SMILES C[C@]12CC[C@H]3[C@@H](CC(=C)C4=CC(=O)C=C[C@]34C)[C@@H]1CCC2=O
Canonical SMILES CC12CCC3C(CC(=C)C4=CC(=O)C=CC34C)C1CCC2=O
Drug Category
  • Antineoplastic Agents
  • Aromatase Inhibitors
ATC Codes
AHFS Codes
  • 10:00.00
Indication For the treatment of advanced breast cancer in postmenopausal women whose disease has progressed following tamoxifen therapy.
Pharmacology Aromatase is an enzyme that converts hormones to estrogen in the body's adrenal glands. The aromatase inhibitors (AIs) are drugs that reduce estrogen levels by blocking the action of aromatase in the adrenal glands. The selective AIs (SAIs) selectively reduce levels of estrogen without interfering with levels of other steroid hormones that are produced by the adrenal gland. Drugs in this class include anastrozole (Arimidex ™), letrozole (Femara ™) and exemestane (Aromasin ™).
Mechanism of Action Breast cancer cell growth may be estrogen-dependent. Aromatase (exemestane) is the principal enzyme that converts androgens to estrogens both in pre- and postmenopausal women. While the main source of estrogen (primarily estradiol) is the ovary in premenopausal women, the principal source of circulating estrogens in postmenopausal women is from conversion of adrenal and ovarian androgens (androstenedione and testosterone) to estrogens (estrone and estradiol) by the aromatase enzyme in peripheral tissues. Estrogen deprivation through aromatase inhibition is an effective and selective treatment for some postmenopausal patients with hormone-dependent breast cancer. Exemestane is an irreversible, steroidal aromatase inactivator, structurally related to the natural substrate androstenedione. It acts as a false substrate for the aromatase enzyme, and is processed to an intermediate that binds irreversibly to the active site of the enzyme causing its inactivation, an effect also known as "suicide inhibition". Exemestane significantly lowers circulating estrogen concentrations in postmenopausal women, but has no detectable effect on adrenal biosynthesis of corticosteroids or aldosterone. Exemestane has no effect on other enzymes involved in the steroidogenic pathway up to a concentration at least 600 times higher than that inhibiting the aromatase enzyme.
Absorption 42%
Toxicity Convulsions
Protein Binding 90%
Biotransformation Hepatic
Half Life 24 hours
Dosage Forms
Form Route
Tablet Oral
Patient Information Show Link Image
Contraindications Show Link Image
Interactions Show Link Image
Drug Interactions Not Available
Food Interactions Not Available
Pathways Not Available
General References
  1. Coombes RC, Kilburn LS, Snowdon CF, Paridaens R, Coleman RE, Jones SE, Jassem J, Van de Velde CJ, Delozier T, Alvarez I, Del Mastro L, Ortmann O, Diedrich K, Coates AS, Bajetta E, Holmberg SB, Dodwell D, Mickiewicz E, Andersen J, Lonning PE, Cocconi G, Forbes J, Castiglione M, Stuart N, Stewart A, Fallowfield LJ, Bertelli G, Hall E, Bogle RG, Carpentieri M, Colajori E, Subar M, Ireland E, Bliss JM: Survival and safety of exemestane versus tamoxifen after 2-3 years' tamoxifen treatment (Intergroup Exemestane Study): a randomised controlled trial. Lancet. 2007 Feb 17;369(9561):559-70. [PubMed Link Image]
  2. Drugs.com Link Image
  3. Wikipedia Link Image
  4. RxList Link Image
Organisms Affected
  • Humans and other mammals
Phase 1 Metabolizing Enzymes
  1. Cytochrome P450 3A4 (CYP3A4)
Targets
  1. Cytochrome P450 19A1
Phase 1 Metabolizing Enzyme 1 [top]
Enzyme 1 Name Cytochrome P450 3A4 (CYP3A4)
Enzyme 1 Gene Name CYP3A4
Enzyme 1 SwissProt ID P08684 Link Image
Enzyme 1 SNPs SNPJam Report Link Image
Enzyme 1 Protein Sequence >sp|P08684|CP3A4_HUMAN Cytochrome P450 3A4 (EC 1.14.13.67) 
ALIPDLAMETWLLLAVSLVLLYLYGTHSHGLFKKLGIPGPTPLPFLGNILSYHKGFCMFD
MECHKKYGKVWGFYDGQQPVLAITDPDMIKTVLVKECYSVFTNRRPFGPVGFMKSAISIA
EDEEWKRLRSLLSPTFTSGKLKEMVPIIAQYGDVLVRNLRREAETGKPVTLKDVFGAYSM
DVITSTSFGVNIDSLNNPQDPFVENTKKLLRFDFLDPFFLSITVFPFLIPILEVLNICVF
PREVTNFLRKSVKRMKESRLEDTQKHRVDFLQLMIDSQNSKETESHKALSDLELVAQSII
FIFAGYETTSSVLSFIMYELATHPDVQQKLQEEIDAVLPNKAPPTYDTVLQMEYLDMVVN
ETLRLFPIAMRLERVCKKDVEINGMFIPKGWVVMIPSYALHRDPKYWTEPEKFLPERFSK
KNKDNIDPYIYTPFGSGPRNCIGMRFALMNMKLALIRVLQNFSFKPCKETQIPLKLSLGG
LLQPEKPVVLKVESRDGTVSGA
Drug Target 1 [top]
Target 1 ID 3811
Target 1 Name Cytochrome P450 19A1
Target 1 Synonyms
  1. Aromatase
  2. CYPXIX
  3. EC 1.14.14.1
  4. Estrogen synthetase
  5. P-450AROM
Target 1 Gene Name CYP19A1
Target 1 Protein Sequence >Cytochrome P450 19A1 
MVLEMLNPIHYNITSIVPEAMPAATMPVLLLTGLFLLVWNYEGTSSIPGPGYCMGIGPLI
SHGRFLWMGIGSACNYYNRVYGEFMRVWISGEETLIISKSSSMFHIMKHNHYSSRFGSKL
GLQCIGMHEKGIIFNNNPELWKTTRPFFMKALSGPGLVRMVTVCAESLKTHLDRLEEVTN
ESGYVDVLTLLRRVMLDTSNTLFLRIPLDESAIVVKIQGYFDAWQALLIKPDIFFKISWL
YKKYEKSVKDLKDAIEVLIAEKRRRISTEEKLEECMDFATELILAEKRGDLTRENVNQCI
LEMLIAAPDTMSVSLFFMLFLIAKHPNVEEAIIKEIQTVIGERDIKIDDIQKLKVMENFI
YESMRYQPVVDLVMRKALEDDVIDGYPVKKGTNIILNIGRMHRLEFFPKPNEFTLENFAK
NVPYRYFQPFGFGPRGCAGKYIAMVMMKAILVTLLRRFHVKTLQGQCVESIQKIHDLSLH
PDETKNMLEMIFTPRNSDRCLEH
Target 1 Number of Residues 511
Target 1 Molecular Weight 57884
Target 1 Theoretical pI 7.56
Target 1 GO Classification
Function
tetrapyrrole binding
heme binding
binding
ion binding
cation binding
transition metal ion binding
iron ion binding
catalytic activity
oxidoreductase activity
monooxygenase activity
Process
physiological process
metabolism
cellular metabolism
generation of precursor metabolites and energy
electron transport
Component
Not Available
Target 1 General Function Secondary metabolites biosynthesis, transport and catabolism
Target 1 Specific Function Catalyzes the formation of aromatic C18 estrogens from C19 androgens
Target 1 Pathways
Name SMPDB Link KEGG Link
Fatty acid metabolism SMP00051 Link Image map00071 Link Image
Target 1 Reactions
  • RH + reduced flavoprotein + O2 = ROH + oxidized flavoprotein + H2O
Target 1 Pfam Domain Function
Target 1 Signals
  • None
Target 1 Transmembrane Regions
  • None
Target 1 Essentiality Non-Essential
Target 1 GenBank ID Protein 179002 Link Image
Target 1 UniProtKB/Swiss-Prot ID P11511 Link Image
Target 1 UniProtKB/Swiss-Prot Entry Name CP19A_HUMAN Link Image
Target 1 PDB ID Not Available
Target 1 Cellular Location
  • Membrane
  • peripheral membrane protein
Target 1 Gene Sequence >1512 bp 
ATGGTTTTGGAAATGCTGAACCCGATACATTATAACATCACCAGCATCGTGCCTGAAGCC
ATGCCTGCTGCCACCATGCCAGTCCTGCTCCTCACTGGCCTTTTTCTCTTGGTGTGGAAT
TATGAGGGCACATCCTCAATACCAGGTCCTGGCTACTGCATGGGAATTGGACCCCTCATC
TCCCACGGCAGATTCCTGTGGATGGGGATCGGCAGTGCCTGCAACTACTACAACCGGGTA
TATGGAGAATTCATGCGAGTCTGGATCTCTGGAGAGGAAACACTCATTATCAGCAAGTCC
TCAAGTATGTTCCACATAATGAAGCACAATCATTACAGCTCTCGATTCGGCAGCAAACTT
GGGCTGCAGTGCATCGGTATGCATGAGAAAGGCATCATATTTAACAACAATCCAGAGCTC
TGGAAAACAACTCGACCCTTCTTTATGAAAGCTCTGTCAGGCCCCGGCCTTGTTCGTATG
GTCACAGTCTGTGCTGAATCCCTCAAAACACATCTGGACAGGTTGGAGGAGGTGACCAAT
GAATCGGGCTATGTGGACGTGTTGACCCTTCTGCGTCGTGTCATGCTGGACACCTCTAAC
ACGCTCTTCTTGAGGATCCCTTTGGACGAAAGTGCTATCGTGGTTAAAATCCAAGGTTAT
TTTGATGCATGGCAAGCTCTCCTCATCAAACCAGACATCTTCTTTAAGATTTCTTGGCTA
TACAAAAAGTATGAGAAGTCTGTCAAGGATTTGAAAGATGCCATAGAAGTTCTGATAGCA
GAAAAAAGACGCAGGATTTCCACAGAAGAGAAACTGGAAGAATGTATGGACTTTGCCACT
GAGTTGATTTTAGCAGAGAAACGTGGTGACCTGACAAGAGAGAATGTGAACCAGTGCATA
TTGGAAATGCTGATCGCAGCTCCTGACACCATGTCTGTCTCTTTGTTCTTCATGCTATTT
CTCATTGCAAAGCACCCTAATGTTGAAGAGGCAATAATAAAGGAAATCCAGACTGTTATT
GGTGAGAGAGACATAAAGATTGATGATATACAAAAATTAAAAGTGATGGAAAACTTCATT
TATGAGAGCATGCGGTACCAGCCTGTCGTGGACTTGGTCATGCGCAAAGCCTTAGAAGAT
GATGTAATCGATGGCTACCCAGTGAAAAAGGGGACAAACATTATCCTGAATATTGGAAGG
ATGCACAGACTCGAGTTTTTCCCCAAACCCAATGAATTTACTCTTGAAAATTTTGCAAAG
AATGTTCCTTATAGGTACTTTCAGCCATTTGGCTTTGGGCCCCGTGGCTGTGCAGGAAAG
TACATCGCCATGGTGATGATGAAAGCCATCCTCGTTACACTTCTGAGACGATTCCACGTG
AAGACATTGCAAGGACAGTGTGTTGAGAGCATACAGAAGATACACGACTTGTCCTTGCAC
CCAGATGAGACTAAAAACATGCTGGAAATGATCTTTACCCCAAGAAGCTCAGACAGGTGT
CTGGAACACTAG
Target 1 GenBank Gene ID
Target 1 GeneCard ID CYP19A1 Link Image
Target 1 GenAtlas ID CYP19A1 Link Image
Target 1 HGNC ID HGNC:2594 Link Image
Target 1 Chromosome Location 15
Target 1 Locus 15q21.1
Target 1 SNPs SNPJam Report Link Image
Target 1 General References
  1. Harada N, Ogawa H, Shozu M, Yamada K, Suhara K, Nishida E, Takagi Y: Biochemical and molecular genetic analyses on placental aromatase (P-450AROM) deficiency. J Biol Chem. 1992 Mar 5;267(7):4781-5. [PubMed Link Image]
  2. Mahendroo MS, Means GD, Mendelson CR, Simpson ER: Tissue-specific expression of human P-450AROM. The promoter responsible for expression in adipose tissue is different from that utilized in placenta. J Biol Chem. 1991 Jun 15;266(17):11276-81. [PubMed Link Image]
  3. Toda K, Terashima M, Mitsuuchi Y, Yamasaki Y, Yokoyama Y, Nojima S, Ushiro H, Maeda T, Yamamoto Y, Sagara Y, et al.: Alternative usage of different poly(A) addition signals for two major species of mRNA encoding human aromatase P-450. FEBS Lett. 1989 Apr 24;247(2):371-6. [PubMed Link Image]
  4. Pompon D, Liu RY, Besman MJ, Wang PL, Shively JE, Chen S: Expression of human placental aromatase in Saccharomyces cerevisiae. Mol Endocrinol. 1989 Sep;3(9):1477-87. [PubMed Link Image]
  5. Means GD, Mahendroo MS, Corbin CJ, Mathis JM, Powell FE, Mendelson CR, Simpson ER: Structural analysis of the gene encoding human aromatase cytochrome P-450, the enzyme responsible for estrogen biosynthesis. J Biol Chem. 1989 Nov 15;264(32):19385-91. [PubMed Link Image]
  6. Corbin CJ, Graham-Lorence S, McPhaul M, Mason JI, Mendelson CR, Simpson ER: Isolation of a full-length cDNA insert encoding human aromatase system cytochrome P-450 and its expression in nonsteroidogenic cells. Proc Natl Acad Sci U S A. 1988 Dec;85(23):8948-52. [PubMed Link Image]
  7. Harada N: Cloning of a complete cDNA encoding human aromatase: immunochemical identification and sequence analysis. Biochem Biophys Res Commun. 1988 Oct 31;156(2):725-32. [PubMed Link Image]
  8. Evans CT, Ledesma DB, Schulz TZ, Simpson ER, Mendelson CR: Isolation and characterization of a complementary DNA specific for human aromatase-system cytochrome P-450 mRNA. Proc Natl Acad Sci U S A. 1986 Sep;83(17):6387-91. [PubMed Link Image]
  9. Chen SA, Besman MJ, Sparkes RS, Zollman S, Klisak I, Mohandas T, Hall PF, Shively JE: Human aromatase: cDNA cloning, Southern blot analysis, and assignment of the gene to chromosome 15. DNA. 1988 Jan-Feb;7(1):27-38. [PubMed Link Image]
  10. Simpson ER, Evans CT, Corbin CJ, Powell FE, Ledesma DB, Mendelson CR: Sequencing of cDNA inserts encoding aromatase cytochrome P-450 (P-450AROM). Mol Cell Endocrinol. 1987 Aug;52(3):267-72. [PubMed Link Image]
  11. 3964273 Chen S, Shively JE, Nakajin S, Shinoda M, Hall PF: Amino terminal sequence analysis of human placenta aromatase. Biochem Biophys Res Commun. 1986 Mar 28;135(3):713-9.
  12. 7690033 Mahendroo MS, Mendelson CR, Simpson ER: Tissue-specific and hormonally controlled alternative promoters regulate aromatase cytochrome P450 gene expression in human adipose tissue. J Biol Chem. 1993 Sep 15;268(26):19463-70.
  13. 8117272 Honda S, Harada N, Takagi Y: Novel exon 1 of the aromatase gene specific for aromatase transcripts in human brain. Biochem Biophys Res Commun. 1994 Feb 15;198(3):1153-60.
  14. 8265607 Ito Y, Fisher CR, Conte FA, Grumbach MM, Simpson ER: Molecular basis of aromatase deficiency in an adult female with sexual infantilism and polycystic ovaries. Proc Natl Acad Sci U S A. 1993 Dec 15;90(24):11673-7.
  15. 8530621 Morishima A, Grumbach MM, Simpson ER, Fisher C, Qin K: Aromatase deficiency in male and female siblings caused by a novel mutation and the physiological role of estrogens. J Clin Endocrinol Metab. 1995 Dec;80(12):3689-98.
  16. 9211678 Carani C, Qin K, Simoni M, Faustini-Fustini M, Serpente S, Boyd J, Korach KS, Simpson ER: Effect of testosterone and estradiol in a man with aromatase deficiency. N Engl J Med. 1997 Jul 10;337(2):91-5.
Target 1 Drug References
  1. Chen X, Ji ZL, Chen YZ: TTD: Therapeutic Target Database. Nucleic Acids Res. 2002 Jan 1;30(1):412-5. [PubMed Link Image]

This project is supported by Genome Alberta & Genome Canada, a not-for-profit organization that is leading Canada's national genomics strategy with $600 million in funding from the federal government. This project is also supported in part by GenomeQuest, Inc., an enterprise genomic information company serving the life science community.