(E/Z)-Rigosertib sodium (formerly known as ON-01910; ON01910; Estybon), the sodium salt of Rigosertib, is a novel, potent and non-ATP-competitive inhibitor of PLK1 with potential anticancer activity. In a cell-free assay, it inhibits PLK1 with an IC50 of 9 nM. Rigosertib exhibits no activity against Plk3 and a 30-fold increase in selectivity against Plk2. It may be possible to treat cancer with rigosertib. Polo-like kinase1 (Plk1) is inhibited by rigosertib, which causes reversible cell arrest at the G1 and G2 stage without apoptosis in normal cells and selective G2/M arrest followed by apoptosis in a variety of tumor cells. When used in conjunction with other chemotherapeutic agents, this agent may show synergistic antitumor activity.

Physicochemical Properties

Molecular Formula	C21H24NNAO8S
Molecular Weight	473.47
Exact Mass	473.112
Elemental Analysis	C, 55.86; H, 5.58; N, 3.10; O, 28.35; S, 7.10
CAS #	1225497-78-8
Related CAS #	Rigosertib sodium;592542-60-4;Rigosertib;592542-59-1
PubChem CID	23696523
Appearance	white solid powder
LogP	2.622
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	9
Rotatable Bond Count	11
Heavy Atom Count	32
Complexity	684
Defined Atom Stereocenter Count	0
SMILES	S(/C(/[H])=C(\[H])/C1C(=C([H])C(=C([H])C=1OC([H])([H])[H])OC([H])([H])[H])OC([H])([H])[H])(C([H])([H])C1C([H])=C([H])C(=C(C=1[H])N([H])C([H])([H])C(=O)[O-])OC([H])([H])[H])(=O)=O.[Na+]
InChi Key	VLQLUZFVFXYXQE-USRGLUTNSA-M
InChi Code	InChI=1S/C21H25NO8S.Na/c1-27-15-10-19(29-3)16(20(11-15)30-4)7-8-31(25,26)13-14-5-6-18(28-2)17(9-14)22-12-21(23)24;/h5-11,22H,12-13H2,1-4H3,(H,23,24);/q;+1/p-1/b8-7+;
Chemical Name	sodium;2-[2-methoxy-5-[[(E)-2-(2,4,6-trimethoxyphenyl)ethenyl]sulfonylmethyl]anilino]acetate
Synonyms	ON-01910; Rigosertib sodium; ON01910; ON 01910; brand name: Estybon
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

Targets	PLK1 (IC50 = 9 nM); PDGFR (IC50 = 18 nM); Bcr-Abl (IC50 = 32 nM); Flt1 (IC50 = 42 nM); Src (IC50 = 155 nM)
ln Vitro	Rigosertib, which has an IC50 of 9 nM, is a non-ATP-competitive inhibitor of PLK1. Moreover, rigosertib shows inhibition with an IC50 of 18-260 nM against PLK2, PDGFR, Flt1, BCR-ABL, Fyn, Src, and CDK1. 94 distinct tumor cell lines, including BT27, MCF-7, DU145, PC3, U87, A549, H187, RF1, HCT15, SW480, and KB cells, exhibit cell killing activity in response to rigosertib, with an IC50 of 50–250 nM. Rigosertib, however, has little to no effect in normal cells, such as HFL, PrEC, HMEC, and HUVEC, unless the concentration is higher than 5–10 μM. Rigosertib (100-250 nM) causes spindle abnormalities and apoptosis in HeLa cells.[1] With an IC50 of 50-100 nM, rigorsertib also inhibits a number of multidrug-resistant tumor cell lines, such as MES-SA, MES-SA/DX5a, CEM, and CEM/C2a. Rigosertib (0.25–5 μM) causes an accumulation of cells with subG1 DNA content, initiates apoptotic pathways, and inhibits cell cycle progression in G2/M phase in DU145 cells. Rigosertib (50 nM-0.5 μM) causes caspase 3/7 activation and viability loss in A549 cells.[2] According to a recent study, rigosertib causes CLL (chronic lymphocytic leukemia) cells to undergo apoptosis without harming healthy B-cells or T-cells. Additionally, rigorsertib inhibits the migration of leukemic cells induced by SDF-1 and nullifies the pro-survival effect of follicular dendritic cells on CLL cells.[3]
ln Vivo	Rigosertib (250 mg/kg) significantly inhibits tumor growth in mouse xenograft models of MCF-7, MIA-PaCa, and Bel-7402 cells.[1] A mouse xengraft model of BT20 cells demonstrates the inhibitory effect of rigosertib (200 mg/kg) on tumor growth.[2]
Enzyme Assay	For 30 minutes at room temperature, recombinant PLK1 (10 ng) is incubated with varying concentrations of rigosertib in a 15 µL reaction mixture (50 mM HEPES, 10 mM MgCl2, 1 mM EDTA, 2 mM Dithiothreitol, 0.01% NP-40 [pH 7.5]). 20 µL (15 µL enzyme + inhibitor, 2 µL 1 mM ATP), 2 µL of γ32P-ATP (40 μCi), and 1 µL of recombinant Cdc25C (100 ng) or casein (1 μg) substrates are used in kinase reactions, which are carried out for 20 min at 30 °C. Boiling in 20 µL of 2× Laemmli buffer for 2 minutes ends the reaction. 18% SDS-PAGE is used to separate phosphorylated substrates. After drying, the gels are exposed to X-ray film for three to ten minutes.
Cell Assay	One day later, different concentrations of Rigosertib are added to six-well dishes containing 1×105 cells/mL/well of tumor cells that have been plated. After treatment for 96 hours, cell counts are obtained from duplicate wells. By using trypan blue exclusion, the total number of viable cells is found.
Animal Protocol	Mouse (female athymic, NCR-nu/nu) xenograft models of Bel-7402, MCF-7, and MIA-PaCa cells 250 mg/kg Intraperitonially
References	[1]. Cancer Cell . 2005 Mar;7(3):275-86. [2]. J Med Chem . 2011 Sep 22;54(18):6254-76. [3]. Clin Cancer Res . 2012 Apr 1;18(7):1979-91.
Additional Infomation	Rigosertib sodium is the sodium salt of rigosertib. It is an anti-cancer agent which has been granted Orphan Drug Designation by the FDA for use in patients with myelodysplastic syndromes (MDS). It has a role as a microtubule-destabilising agent, an antineoplastic agent, an EC 2.7.11.21 (polo kinase) inhibitor and an apoptosis inducer. It contains a rigosertib(1-). Rigosertib Sodium is the sodium salt form of rigosertib, a synthetic benzyl styryl sulfone analogue and Ras mimetic, with potential antineoplastic activity. Upon administration, rigosertib targets and binds to Ras-binding domain (RBD) found in many Ras effector proteins, including Raf kinase and phosphatidylinositol 3-kinase (PI3K). This prevents Ras from binding to its targets and inhibits Ras-mediated signaling pathways, including Ras/Raf/Erk, Ras/CRAF/polo-like kinase1 (Plk1), and Ras/ PI3K/Akt signaling pathways. This induces cell cycle arrest and apoptosis and inhibits proliferation in a variety of susceptible tumor cells. See also: Rigosertib (annotation moved to).

Solubility Data

Solubility (In Vitro)	DMSO: ~95 mg/mL (~200.6 mM) Water: ~95 mg/mL (~200.6 mM) Ethanol: <1 mg/mL
Solubility (In Vivo)	Saline: 30 mg/mL  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.1121 mL	10.5603 mL	21.1207 mL
	5 mM	0.4224 mL	2.1121 mL	4.2241 mL
	10 mM	0.2112 mL	1.0560 mL	2.1121 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.