Catalog No.S1458

VX-745 is a potent and selective inhibitor of p38α with IC50 of 10 nM, 22-fold greater selectivity versus p38β and no inhibition to p38γ.

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VX-745 Chemical Structure

VX-745 Chemical Structure
Molecular Weight: 436.26

Validation & Quality Control

Quality Control & MSDS

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Product Information

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  • Research Area
  • VX-745 Mechanism

Product Description

Biological Activity

Description VX-745 is a potent and selective inhibitor of p38α with IC50 of 10 nM, 22-fold greater selectivity versus p38β and no inhibition to p38γ.
Targets p38α [1] p38β [1]
IC50 10 nM 220 nM
In vitro VX-745 selectively inhibits p38α and p38β MAPK with IC50 of 10 nM and 220 nM, respectively, but not p38γ MAPK and a large panel of other kinases, with IC50 larger than 20 µM. In a human peripheral blood mononuclear cell (PBMC) assay, VX-745 provides IC50 of 56 and 52 nM for IL-1β and TNFα, respectively. VX-745 blocks IL-6 and IL-8 production induced by IL-1 and TNFα, and COX-2 synthesis mediated by LPS and IL-1β. [1-3] VX-745 (60 nM-20 µM) inhibits IL-6 and VEGF secretion in bone marrow stromal cells (BMSCs), without affecting their viability. VX-745 also inhibits TNF-α-induced IL-6 secretion in BMSCs. VX-745 inhibits both multiple myeloma (MM) cell proliferation and IL-6 secretion in BMSCs triggered by adherence of MM cells to BMSCs, suggesting that VX-745 can inhibit paracrine multiple myeloma (MM) cell growth in the BM milieu and overcome cell adhesion-related drug resistance. [4]
In vivo VX-745 is effective against adjuvant-induced arthritis (AA) in the rat with ED50 of 5 mg/kg. Histological scores for VX-745 in AA rats are 93% inhibition of bone resorption and 56% inhibition of inflammation. In the classical cartilage-induced arthritis model, VX-745 exhibits a dose-responsive decrease in severity score. [1-3] In a type II collagen-induced arthritis (CIA) mice model, VX-745 (2.5, 5, and 10 mg/kg) has 27%, 31%, and 44% improvement in the inflammatory scores, respectively, when compared to vehicle-treated mice. In addition, histological scores show a 32-39% protection of bone and cartilage erosion by VX-745. [5]
Features A potent and selective inhibitor to p38α and p38β MAPK.

Protocol(Only for Reference)

Kinase Assay: [5]

Spectrophotometric coupled-enzyme assay The IC50 for the inhibition of p38α and p38β homologs are obtained by a spectrophotometric coupled-enzyme assay. A fixed concentration of enzyme (15 nM of p38α or p38β) is incubated with VX-745 in DMSO for 10 min. at 30 °C in 0.1 M HEPES buffer, pH 7.5, containing 10% glycerol, 10 mM MgCl2, 2.5 mM phosphoenolpyruvate, 200 µM NADH, 150 µg/mL pyruvate kinase, 50 µg/mL lactate dehydrogenase, and 200 µM EGF receptor peptide (KRELVEPLTPSGEAPNQALLR). The reaction is initiated with 100 µM and 70 µM ATP for p38α and p38β assays, respectively. The decrease of absorbance at 340 nm is monitored to follow the rate of the reaction. IC50 is evaluated from the rate data as a function of the inhibitor concentration.

Cell Assay: [4]

Cell lines Human bone marrow stromal cells (BMSCs) and multiple myeloma (MM) cells
Concentrations 60 nM - 20 μM, dissolved in DMSO.
Incubation Time 48 hours
Method BMSCs (5 × 104 cells/well) or MM cells (3 × 104 cells/well) are incubated in 96-well culture plates in the presence or absence of VX-745 for 48 hours at 37 °C. DNA synthesis is measured by [3H]-thymidine ([3H]TdR) uptake. Cells are pulsed with [3H]TdR (0.5 μCi/well [.0185 MBq]) during the last 8 hours of 48-hour cultures. Growth inhibition of both MM cells and BMSCs by VX-745 is also assessed by measuring 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) dye absorbance.

Animal Study: [5]

Animal Models Type II collagen-induced arthritis (CIA) mice model (DBA/1J)
Formulation Dissolved in 100% polyethylene glycol
Dosages 2.5, 5, and 10 mg/kg
Administration Oral gavage twice daily

Conversion of different model animals based on BSA (Value based on data from FDA Draft Guidelines)

SpeciesMouseRatRabbitGuinea pigHamsterDog
Weight (kg)
Body Surface Area (m2)0.0070.0250.
Km factor36128520
Animal A (mg/kg) = Animal B (mg/kg) multiplied by  Animal B Km
Animal A Km

For example, to modify the dose of resveratrol used for a mouse (22.4 mg/kg) to a dose based on the BSA for a rat, multiply 22.4 mg/kg by the Km factor for a mouse and then divide by the Km factor for a rat. This calculation results in a rat equivalent dose for resveratrol of 11.2 mg/kg.

Rat dose (mg/kg) = mouse dose (22.4 mg/kg) ×  mouse Km(3)  = 11.2 mg/kg
rat Km(6)


[1] Decicco C, et al. American Chemical Society, 2000, IDDB3.

[2] Haddad JJ, Curr Opin Investig Drugs, 2001, 2(8), 1070-1076.

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Clinical Trial Information( data from http://clinicaltrials.gov, updated on 2016-07-30)

NCT Number Recruitment Conditions Sponsor
Start Date Phases
NCT02423200 Recruiting Alzheimers Disease EIP Pharma, LLC April 2015 Phase 2
NCT02423122 Recruiting Alzheimers Disease|Mild Cognitive Impairment EIP Pharma, LLC April 2015 Phase 2

Chemical Information

Download VX-745 SDF
Molecular Weight (MW) 436.26


CAS No. 209410-46-8
Storage 3 years -20℃powder
2 years -80℃in solvent
Synonyms N/A
Solubility (25°C) * In vitro DMSO 15 mg/mL (34.38 mM)
Water <1 mg/mL
Ethanol <1 mg/mL
In vivo 30% PEG400+0.5% Tween80+5% propylene glycol 30 mg/mL
* <1 mg/ml means slightly soluble or insoluble.
* Please note that Selleck tests the solubility of all compounds in-house, and the actual solubility may differ slightly from published values. This is normal and is due to slight batch-to-batch variations.
Chemical Name 5-(2,6-dichlorophenyl)-2-(2,4-difluorophenylthio)-6H-pyrimido[1,6-b]pyridazin-6-one

Tech Support

Answers to questions you may have can be found in the inhibitor handling instructions. Topics include how to prepare stock solutions, how to store inhibitors, and issues that need special attention for cell-based assays and animal experiments.

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Cell Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID
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