Details of the Drug Combination

General Information of Drug Combination (ID: DCFPO5Z)

• Drug Combination Name: Letrozole + Digitoxin
• Indication: High grade ovarian serous adenocarcinoma; Status: Investigative [1]
• Component Drugs:
  Letrozole (DMH07Y3): Small molecular drug
  Digitoxin (DMWVIGP): Small molecular drug
• High-throughput Screening Result:
  Testing Cell Line: OVCAR-5
  Zero Interaction Potency (ZIP) Score: 4.17
  Bliss Independence Score: 7.35
  Loewe Additivity Score: 5.51
  LHighest Single Agent (HSA) Score: 7.9

Molecular Interaction Atlas of This Drug Combination

Indication(s) of Letrozole

Disease Entry	ICD 11	Status	REF
Estrogen-receptor positive breast cancer	N.A.	Approved	[2]
Hormonally-responsive breast cancer	2C60-2C65	Approved	[3]

Letrozole Interacts with 1 DTT Molecule(s)

DTT Name	DTT ID	UniProt ID	Mode of Action	REF
Aromatase (CYP19A1)	TTSZLWK	CP19A_HUMAN	Inhibitor	[5]

Letrozole Interacts with 3 DME Molecule(s)

DME Name	DME ID	UniProt ID	Mode of Action	REF
Cytochrome P450 3A4 (CYP3A4)	DE4LYSA	CP3A4_HUMAN	Metabolism	[6]
Aromatase (CYP19A1)	DEQX145	CP19A_HUMAN	Metabolism	[7]
Cytochrome P450 2A6 (CYP2A6)	DEJVYAZ	CP2A6_HUMAN	Metabolism	[8]

Letrozole Interacts with 7 DOT Molecule(s)

DOT Name	DOT ID	UniProt ID	Mode of Action	REF
Adenylate kinase isoenzyme 1 (AK1)	OT614AR3	KAD1_HUMAN	Increases ADR	[9]
Follitropin subunit beta (FSHB)	OTGLS283	FSHB_HUMAN	Increases Expression	[10]
Lutropin subunit beta (LHB)	OT5GBOVJ	LSHB_HUMAN	Increases Expression	[10]
G1/S-specific cyclin-D2 (CCND2)	OTDULQF9	CCND2_HUMAN	Decreases Expression	[11]
Cyclin-dependent kinase inhibitor 1 (CDKN1A)	OTQWHCZE	CDN1A_HUMAN	Increases Expression	[12]
Small ribosomal subunit protein eS6 (RPS6)	OTT4D1LN	RS6_HUMAN	Decreases Phosphorylation	[11]
Fibroblast growth factor 22 (FGF22)	OTVIX6J0	FGF22_HUMAN	Increases Expression	[13]

Indication(s) of Digitoxin

Disease Entry	ICD 11	Status	REF
Arrhythmia	BC9Z	Approved	[4]
Congestive cardiac insufficiency	BD1Z	Approved	[4]
Heart failure	BD10-BD13	Approved	[4]

Digitoxin Interacts with 1 DTT Molecule(s)

DTT Name	DTT ID	UniProt ID	Mode of Action	REF
Sodium/potassium-transporting ATPase (SPT ATPase)	TTQ38E9	AT1A1_HUMAN; AT1A2_HUMAN; AT1A3_HUMAN; AT1B1_HUMAN; AT1B2_HUMAN; AT1B3_HUMAN	Inhibitor	[14]

Digitoxin Interacts with 1 DTP Molecule(s)

DTP Name	DTP ID	UniProt ID	Mode of Action	REF
P-glycoprotein 1 (ABCB1)	DTUGYRD	MDR1_HUMAN	Substrate	[15]

Digitoxin Interacts with 3 DME Molecule(s)

DME Name	DME ID	UniProt ID	Mode of Action	REF
Cytochrome P450 3A4 (CYP3A4)	DE4LYSA	CP3A4_HUMAN	Metabolism	[16]
UDP-glucuronosyltransferase 1A1 (UGT1A1)	DEYGVN4	UD11_HUMAN	Metabolism	[17]
Sulfotransferase 1A1 (SULT1A1)	DEYWLRK	ST1A1_HUMAN	Metabolism	[18]

Digitoxin Interacts with 11 DOT Molecule(s)

DOT Name	DOT ID	UniProt ID	Mode of Action	REF
ATP-dependent translocase ABCB1 (ABCB1)	OTEJROBO	MDR1_HUMAN	Increases Transport	[19]
Serine/threonine-protein kinase Chk1 (CHEK1)	OTTTI622	CHK1_HUMAN	Decreases Expression	[20]
Baculoviral IAP repeat-containing protein 5 (BIRC5)	OTILXZYL	BIRC5_HUMAN	Decreases Expression	[20]
Serine/threonine-protein kinase Chk2 (CHEK2)	OT8ZPCNS	CHK2_HUMAN	Decreases Expression	[20]
Interleukin-8 (CXCL8)	OTS7T5VH	IL8_HUMAN	Decreases Secretion	[21]
Tyrosine-protein phosphatase non-receptor type 6 (PTPN6)	OT33XNZM	PTN6_HUMAN	Increases Expression	[22]
Cyclin-dependent kinase inhibitor 1 (CDKN1A)	OTQWHCZE	CDN1A_HUMAN	Decreases Expression	[20]
Cyclin-dependent kinase inhibitor 1B (CDKN1B)	OTNY5LLZ	CDN1B_HUMAN	Decreases Expression	[20]
Phosphatidylinositol 3,4,5-trisphosphate 3-phosphatase and dual-specificity protein phosphatase PTEN (PTEN)	OTOWDUNT	PTEN_HUMAN	Increases Expression	[22]
Cytochrome c (CYCS)	OTBFALJD	CYC_HUMAN	Increases Expression	[20]
E3 SUMO-protein ligase PIAS3 (PIAS3)	OT3TWH9R	PIAS3_HUMAN	Increases Expression	[22]

References

• [1] CheMBL Affinity Phenotypic Cellular Interaction Assay ID: CHEMBL1125966
• [2] Letrozole FDA Label
• [3] URL: http://www.guidetopharmacology.org Nucleic Acids Res. 2015 Oct 12. pii: gkv1037. The IUPHAR/BPS Guide to PHARMACOLOGY in 2016: towards curated quantitative interactions between 1300 protein targets and 6000 ligands. (Ligand id: 5209).
• [4] URL: http://www.guidetopharmacology.org Nucleic Acids Res. 2015 Oct 12. pii: gkv1037. The IUPHAR/BPS Guide to PHARMACOLOGY in 2016: towards curated quantitative interactions between 1300 protein targets and 6000 ligands. (Ligand id: 6782).
• [5] Aromatase inhibitors--theoretical concept and present experiences in the treatment of endometriosis. Zentralbl Gynakol. 2003 Jul-Aug;125(7-8):247-51.
• [6] Inhibition of drug metabolizing cytochrome P450s by the aromatase inhibitor drug letrozole and its major oxidative metabolite 4,4'-methanol-bisbenzonitrile in vitro. Cancer Chemother Pharmacol. 2009 Oct;64(5):867-75.
• [7] Double-blind, randomised, multicentre endocrine trial comparing two letrozole doses, in postmenopausal breast cancer patients. Eur J Cancer. 1999 Feb;35(2):208-13.
• [8] Letrozole concentration is associated with CYP2A6 variation but not with arthralgia in patients with breast cancer. Breast Cancer Res Treat. 2018 Nov;172(2):371-379.
• [9] ADReCS-Target: target profiles for aiding drug safety research and application. Nucleic Acids Res. 2018 Jan 4;46(D1):D911-D917. doi: 10.1093/nar/gkx899.
• [10] Aromatase inhibition, testosterone, and seizures. Epilepsy Behav. 2004 Apr;5(2):260-3. doi: 10.1016/j.yebeh.2003.12.001.
• [11] Dual inhibition of mTOR and estrogen receptor signaling in vitro induces cell death in models of breast cancer. Clin Cancer Res. 2005 Jul 15;11(14):5319-28. doi: 10.1158/1078-0432.CCR-04-2402.
• [12] Synergistic activity of letrozole and sorafenib on breast cancer cells. Breast Cancer Res Treat. 2010 Nov;124(1):79-88. doi: 10.1007/s10549-009-0714-5. Epub 2010 Jan 7.
• [13] Clomiphene citrate versus letrozole: molecular analysis of the endometrium in women with polycystic ovary syndrome. Fertil Steril. 2011 Oct;96(4):1051-6. doi: 10.1016/j.fertnstert.2011.07.1092.
• [14] Treatment of congestive heart failure--current status of use of digitoxin. Eur J Clin Invest. 2001;31 Suppl 2:10-7.
• [15] The association of ABCB1 polymorphisms and elevated serum digitoxin concentrations in geriatric patients. Eur J Clin Pharmacol. 2008 Apr;64(4):367-72.
• [16] Species differences in the toxicity and cytochrome P450 IIIA-dependent metabolism of digitoxin. Mol Pharmacol. 1991 Nov;40(5):859-67.
• [17] Use of a human liver microsome bank in drug glucuronidation studies. Toxicol In Vitro. 1991;5(5-6):559-62.
• [18] Hydroxysteroid sulfotransferase and a specific UDP-glucuronosyltransferase are involved in the metabolism of digitoxin in man. Naunyn Schmiedebergs Arch Pharmacol. 1992 Aug;346(2):226-33.
• [19] Heterogeneous transport of digitalis-like compounds by P-glycoprotein in vesicular and cellular assays. Toxicol In Vitro. 2016 Apr;32:138-45. doi: 10.1016/j.tiv.2015.12.009. Epub 2015 Dec 17.
• [20] Digitoxin and a synthetic monosaccharide analog inhibit cell viability in lung cancer cells. Toxicol Appl Pharmacol. 2012 Jan 1;258(1):51-60. doi: 10.1016/j.taap.2011.10.007. Epub 2011 Oct 18.
• [21] Digitoxin mimics gene therapy with CFTR and suppresses hypersecretion of IL-8 from cystic fibrosis lung epithelial cells. Proc Natl Acad Sci U S A. 2004 May 18;101(20):7693-8. doi: 10.1073/pnas.0402030101. Epub 2004 May 10.
• [22] Digitoxin promotes apoptosis and inhibits proliferation and migration by reducing HIF-1 and STAT3 in KRAS mutant human colon cancer cells. Chem Biol Interact. 2022 Jan 5;351:109729. doi: 10.1016/j.cbi.2021.109729. Epub 2021 Oct 28.