GSK503 (GSK-503) is a novel, potent and specific inhibitor of Enhancer of zeste homolog 2 (EZH2) methyltransferase inhibitor with potential antitumor activity. It inhibits EZH2 with Kiapp of 3 to 27 nM. GSK503 demostrates excellent antiproliferative activity and high in vivo antitumor efficacy in a melanoma mouse model.

Physicochemical Properties

Molecular Formula	C31H38N6O2
Molecular Weight	526.67
Exact Mass	526.305
CAS #	1346572-63-1
Related CAS #	1346572-63-1
PubChem CID	67469117
Appearance	White to gray solid powder
Density	1.2±0.1 g/cm3
Boiling Point	798.6±60.0 °C at 760 mmHg
Flash Point	436.8±32.9 °C
Vapour Pressure	0.0±2.8 mmHg at 25°C
Index of Refraction	1.648
LogP	3.3
Hydrogen Bond Donor Count	2
Hydrogen Bond Acceptor Count	5
Rotatable Bond Count	6
Heavy Atom Count	39
Complexity	984
Defined Atom Stereocenter Count	0
InChi Key	HRDQQHUKUIKFHT-UHFFFAOYSA-N
InChi Code	InChI=1S/C31H38N6O2/c1-19(2)37-18-21(4)29-25(30(38)33-17-26-20(3)13-22(5)34-31(26)39)14-24(15-27(29)37)23-7-8-28(32-16-23)36-11-9-35(6)10-12-36/h7-8,13-16,18-19H,9-12,17H2,1-6H3,(H,33,38)(H,34,39)
Chemical Name	N-((4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)methyl)-1-isopropyl-3-methyl-6-(6-(4-methylpiperazin-1-yl)pyridin-3-yl)-1H-indole-4-carboxamide
Synonyms	GSK 503; GSK503; GSK-503
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

ln Vitro	GSK503, which shares structural similarities with GSK126 and GSK343, inhibits the methyltransferase activity of both wild type and mutant EZH2 with a similar potency (Kiapp=3-27 nM). GSK503 exhibits a selectivity of over 2000 fold over other histone methyltransferases and over 200 fold over EZH1 (Kiapp=636 nM)[1].
ln Vivo	Conditional EZH2 ablation and GSK503 therapy nearly eliminate the production of metastases in a melanoma mouse model while stabilizing the illness through growth inhibition[2]. Normal melanocyte biology is not affected. In mice, GSK503 has good pharmacokinetics. After SRBC or NP-KLH immunization, GSK503 but not the vehicle suppresses the development of the germinal center, phenotyping the Ezh2 null phenotype. GC B-cell counts are decreased by flow cytometry, GC volume and quantity are decreased by immunohistochemistry, and the production of high affinity antibodies is hindered by GSK503 therapy [1].
Animal Protocol	Dissolved in 20% captisol; 150 mg/kg; i.p. injection Male SCID mice bearing SUDHL4 and SUDHL6 tumors
References	[1]. EZH2 is required for germinal center formation and somatic EZH2 mutations promote lymphoid transformation. Cancer Cell. 2013 May 13;23(5):677-92. [2]. The epigenetic modifier EZH2 controls melanoma growth and metastasis through silencing of distinct tumour suppressors. Nat Commun. 2015 Jan 22;6:6051.
Additional Infomation	GSK503 is a potent and specific inhibitor of EZH2 methyltransferase.

Solubility Data

Solubility (In Vitro)

DMSO: 100 mg/mL (189.8 mM) Water:<1 mg/mL Ethanol: 26 mg/mL warmed (49.4 mM)

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 2.5 mg/mL (4.75 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 2.5 mg/mL (4.75 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	1.8987 mL	9.4936 mL	18.9872 mL
	5 mM	0.3797 mL	1.8987 mL	3.7974 mL
	10 mM	0.1899 mL	0.9494 mL	1.8987 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.