MSC2530818 is novel, potent, selective and orally available small molecule inhibitor of cyclin dependent kinase CDK8 with the IC50 of 2.6 nM. It has good kinase selectivity, high biochemical and cellular potency, microsomal stability, and a respectable oral bioavailability, among other excellent pharmacokinetic and pharmacodynamic properties. After WNT signaling is activated, β-catenin-dependent transcription is regulated by the mediator complex-associated cyclin-dependent kinase CDK8. Several lines of evidence imply that CDK8 may function as an oncogene during the course of colorectal cancer development. Following a high-throughput screening campaign, MSC2530818 was discovered and advanced through structure-based design. MSC2530818 showed enough potency and selectivity to move forward with preclinical in vivo safety and efficacy investigations.

Physicochemical Properties

Molecular Formula	C18H17CLN4O
Molecular Weight	340.8068
Exact Mass	340.11
Elemental Analysis	C, 63.44; H, 5.03; Cl, 10.40; N, 16.44; O, 4.69
CAS #	1883423-59-3
Related CAS #	1883423-59-3
PubChem CID	118879529
Appearance	White to off-white solid powder
LogP	3.3
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	3
Rotatable Bond Count	2
Heavy Atom Count	24
Complexity	468
Defined Atom Stereocenter Count	1
SMILES	CC1=C2C=C(C=NC2=NN1)C(=O)N3CCC[C@H]3C4=CC=C(C=C4)Cl
InChi Key	ODRITQGYYWHQGM-INIZCTEOSA-N
InChi Code	InChI=1S/C18H17ClN4O/c1-11-15-9-13(10-20-17(15)22-21-11)18(24)23-8-2-3-16(23)12-4-6-14(19)7-5-12/h4-7,9-10,16H,2-3,8H2,1H3,(H,20,21,22)/t16-/m0/s1
Chemical Name	[(2S)-2-(4-chlorophenyl)pyrrolidin-1-yl]-(3-methyl-2H-pyrazolo[3,4-b]pyridin-5-yl)methanone
Synonyms	MSC-2530818; MSC2530818; MSC 2530818
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	CDK8 (IC50 = 2.6 nM)
ln Vitro	MSC2530818 exhibits strong suppression of phospho-STAT1SER727 in SW620 human colorectal carcinoma cells (IC50=8 ± 2 nM) and binds to CDK8 and CDK19 with comparable affinity (4 nM). It also shows that in human cancer cell lines with constitutively activated WNT signaling, there is strong inhibition of WNT-dependent transcription. As a soluble CDK8 inhibitor, MSC2530818 exhibits low efflux ratio and high permeability in Caco-2 cells (ER = 1.5). Notably, it does not inhibit any subtype of cytochrome P450 (Cyp IC50s > 20 μM).
ln Vivo	MSC2530818 shows acceptable pharmacokinetics (PK) in all tested preclinical species (mouse, rat, dog). It shows decreased tumor growth rates in human SW620 colorectal carcinoma xenografts that have been established[1].
Enzyme Assay	Having an IC50 of 2.6 nM, MSC2530818 is a new, potent, selective, and oral small molecule inhibitor of cyclin-dependent kinase CDK8.
Cell Assay	In human cancer cell lines that have constitutively activated WNT signaling, SC2530818 exhibits strong suppression of WNT-dependent transcription. For instance, MSC2530818 inhibits the reporter-based luciferase readout in a number of cell lines carrying activating mutations in the WNT pathway, such as LS174T (a β-catenin mutant with an IC50 of 32±7 nM) and COLO205 (an APC mutant with an IC50 of 9±1 nM).It also shows inhibition of the WNT3a ligand-dependent reporter readout in PA-1 cells (IC50=52±30 nM). MSC2530818 shows minimal hERG inhibition and minimal activity in the CEREP panel. It is the only compound with activity below 10 μM, with an IC50 of 8.5 μM on the dopamine transporter. Additionally, MSC2530818 does not inhibit any cytochrome P450 subtypes and is a soluble CDK8 inhibitor with high permeability and low efflux ratio in Caco-2 cells.
Animal Protocol	Prepared in kolliphor 20% w/v in water; 50 mg/kg bid or 100 mg/kg qd; oral gavage Mice: The efficacy of MSC2530818 is then evaluated in female NCr athymic mice using a human colorectal cancer xenograft model, SW620. MSC2530818 (50 mg/kg bid or 100 mg/kg qd) is given orally to tumor-bearing mice for a duration of 16 days. Both body weight and tumor weights are measured and tracked[1].
References	[1]. J Med Chem . 2016 Oct 27;59(20):9337-9349. [2]. Cell Stem Cell . 2021 Jun 3;28(6):1105-1124.e19.

Solubility Data

Solubility (In Vitro)

DMSO: > 70 mg/mL Water: <1 mg/mL Ethanol: > 70 mg/mL

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 2.75 mg/mL (8.07 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 27.5 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: 2.75 mg/mL (8.07 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 27.5 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. Solubility in Formulation 3: ≥ 2.75 mg/mL (8.07 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (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 27.5 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.9342 mL	14.6709 mL	29.3419 mL
	5 mM	0.5868 mL	2.9342 mL	5.8684 mL
	10 mM	0.2934 mL	1.4671 mL	2.9342 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.