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Romaciclib hydrochloride (SEL-120-34A HCl; SEL12034A) is a novel, potent and selective ATP-competitiveinhibitor of CDK8(Cyclin-dependent kinase 8) with anticancer activity. It binds to the Mediator complex to control transcription. The kinase activities of CDK8/CycC and CDK19/CycC complexes are inhibited by SEL120-34A, with IC50s of 4.4 nM and 10.4 nM, respectively, and a Kdof 3 nM for CDK8. According to X-ray crystallography, SEL120-34A is a type I inhibitor that forms hydrophobic complementarities within the protein's front pocket and halogen bonds with its hinge region. In vitro, SEL120-34A prevents cancer cells' phosphorylation of STAT1 S727 and STAT5 S726. In vivo, the predominant mechanism of action has consistently been observed to be the regulation of STATs- and NUP98-HOXA9-dependent transcription. AML cells with increased STAT5 S726 levels and stem cell features responded differently to treatment with the compound. On the other hand, resistant cells demonstrated lineage commitment and tested negative for activated STAT5. Significant STAT5 S726 repression was correlated with in vivo efficacy in xenotransplanted AML models. Good pharmacokinetics, established safety, and in vivo effectiveness support SEL120-34A'scontinuedclinical development as a tailored treatment strategy for AML.
Physicochemical Properties
| Molecular Formula | C15H18BR2N4.XHCL |
| Molecular Weight | 450.599160432816 (mono-HCl) |
| Exact Mass | 449.964 (mono-HCl) |
| Elemental Analysis | C, 39.98; H, 4.25; Br, 35.47; Cl, 7.87; N, 12.43 |
| CAS # | 1609452-30-3 |
| Related CAS # | SEL120-34A monohydrochloride;2443816-41-7;SEL120-34A;1609522-33-9 |
| PubChem CID | 73776232 |
| Appearance | White to off-white solid powder |
| Hydrogen Bond Donor Count | 2 |
| Hydrogen Bond Acceptor Count | 3 |
| Rotatable Bond Count | 1 |
| Heavy Atom Count | 22 |
| Complexity | 390 |
| Defined Atom Stereocenter Count | 0 |
| SMILES | BrC1C(=C(C)C2=C3C=1CCCN3C(=N2)N1CCNCC1)Br.Cl |
| InChi Key | GQXLWUCQESKBSC-UHFFFAOYSA-N |
| InChi Code | InChI=1S/C15H18Br2N4.ClH/c1-9-11(16)12(17)10-3-2-6-21-14(10)13(9)19-15(21)20-7-4-18-5-8-20;/h18H,2-8H2,1H3;1H |
| Chemical Name | 6,7-dibromo-5-methyl-2-piperazin-1-yl-1,3-diazatricyclo[6.3.1.04,12]dodeca-2,4,6,8(12)-tetraene;hydrochloride |
| Synonyms | Romaciclib; SEL120-34A monohydrochloride; SEL-120-34A; SEL12034A; SEL120-34A HCl; SEL 120-34A; 1609522-33-9; UNII-6LGR0RYY5Q; SEL120-34A free base; CDK8-IN-2 free base; 6LGR0RYY5Q; 4H-Imidazo(4,5,1-ij)quinoline, 7,8-dibromo-5,6-dihydro-9-methyl-2-(1-piperazinyl)-; 7,8-DIBROMO-5,6-DIHYDRO-9-METHYL-2-(1-PIPERAZINYL)-4H-IMIDAZO(4,5,1-IJ)QUINOLINE; ...; Romaciclib; SEL 12034A; SEL-12034A |
| 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 Note: Please store this product in a sealed and protected environment, avoid exposure to moisture. |
| 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/CycC (IC50 = 4.4 nM); CDK19/CycC (IC50 = 10.4 nM); CDK9/cycT (IC50 = 1070 nM) SEL120-34A HCl is an ATP-competitive, selective inhibitor of CDK8, with IC50 values of 10.4 nM for CDK19/CycC and 4.4 nM for CDK8/CycC. SEL120-34A HCl only weakly suppresses CDK9 (IC50, 1070 nM) and exhibits no discernible inhibition on CDK1, 2, 4, 6, 5, 7, or 6. According to the effective inhibition range of STAT1 S727 and STAT5 S726, SEL120-34A HCl is active against a panel of AML cell lines (GI50<1 μM), including SKNO-1, KG-1, HEL-60, MOLM-16, MV-4-11, OciAML-2, MOLM-6, and OciAML-3 cells.[1] |
| ln Vitro |
SEL120-34A HCl is an ATP-competitive, selective inhibitor of CDK8, with IC50 values of 10.4 nM for CDK19/CycC and 4.4 nM for CDK8/CycC. SEL120-34A HCl only weakly suppresses CDK9 (IC50, 1070 nM) and exhibits no discernible inhibition on CDK1, 2, 4, 6, 5, 7, or 6. According to the effective inhibition range of STAT1 S727 and STAT5 S726, SEL120-34A HCl is active against a panel of AML cell lines (GI50<1 μM), including SKNO-1, KG-1, HEL-60, MOLM-16, MV-4-11, OciAML-2, MOLM-6, and OciAML-3 cells.[1] SEL120-34A inhibited CDK8 kinase activity in KG-1 acute myeloid leukemia (AML) cell lysates in a dose-dependent manner (1-100 nM) in competition with ATP-analogue probes. [1] SEL120-34A inhibited interferon-γ (IFNγ)-induced phosphorylation of STAT1 at serine 727 (S727) in HCT-116 colorectal cancer cells in a dose-dependent manner. [1] SEL120-34A inhibited phosphorylation of STAT5 at serine 726 (S726) but not tyrosine 694 (Y694) in SET-2 cells carrying the JAK2 V617F mutation. [1] SEL120-34A (1 μM) significantly repressed serum-induced mRNA expression of immediate early response (IER) genes EGR1 and FOS in quiescent HCT-116 cells. [1] SEL120-34A decreased mRNA expression of interferon-responsive genes IRF9 and STAT1 in HCT-116 and Colo-205 cells treated with IFNγ or IFNα. [1] SEL120-34A inhibited the growth of responder AML cell lines (e.g., KG-1, MV4-11) with half-maximal growth inhibitory concentration (GI₅₀) values below 1 μM in extended viability assays. Non-responder cell lines (e.g., MOLM13) had GI₅₀ > 1 μM. [1] SEL120-34A treatment in KG-1 cells led to sustained inhibition of STAT5 S726 and STAT1 S727 phosphorylation up to 6 days and induced apoptosis, as indicated by cleaved caspase-3. [1] Sensitivity to SEL120-34A in AML cell lines correlated with high basal levels of phosphorylated STAT5 S726 and STAT1 S727. [1] |
| ln Vivo |
SEL120-34A (30, 60 mg/kg, p.o.) suppresses tumor growth in mice bearing MV4-11 cancer cells. Moreover, oral administration of 30 mg/kg stops the growth of KG-1-derived tumors[1]. In Colo-205 colorectal cancer xenograft models in mice, oral administration of SEL120-34A (5-60 mg/kg, BID for 3 days) led to dose-dependent inhibition of STAT1 S727 and STAT5 S726 phosphorylation in tumor tissues at 16 hours post-dose. Near-complete inhibition was observed at 60 mg/kg. [1] Whole transcriptome analysis of Colo-205 xenograft tissues from mice treated with SEL120-34A (30 mg/kg) showed significant downregulation of interferon-responsive and STAT-regulated genes (e.g., IRF9, ISG15, STAT1). [1] In subcutaneous AML xenograft models (KG-1 and MV4-11 cells) in SCID mice, once-daily oral administration of SEL120-34A (25 mg/kg for KG-1, 50 mg/kg for MV4-11) completely arrested KG-1 tumor growth and reduced MV4-11 tumor volume without significant body weight loss. [1] In KG-1 tumors from treated mice, SEL120-34A induced dose-dependent inhibition of STAT5 S726 phosphorylation. In MV4-11 tumors, it also repressed total STAT5 levels and the oncogenic protein MCL-1, and induced apoptosis indicated by cleaved PARP. [1] |
| Enzyme Assay |
A radiometric protein kinase assay was used to measure the activities of CDK8/Cyclin C and CDK19/Cyclin C protein kinases. IC₅₀ values for SEL120-34A were determined by constructing a dose-response curve and examining inhibition of kinase activity at Km ATP concentrations. [1] A time-resolved fluorescence resonance energy transfer (TR-FRET) based kinase binding assay for CDK8/Cyclin C was performed according to the manufacturer's instructions to assess compound binding. [1] Kinase capture experiments were performed in cell lysates using an ATP-desthiobiotin probe. Lysates were incubated with the probe, then captured kinases were pulled down with agarose beads and analyzed by Western blot to assess competition by SEL120-34A. [1] |
| Cell Assay |
At 2.5 ×105 per well, HCT-116 are seeded onto 6-well plates. The next day, cells are starved of 0.5% FBS for 24 hours to synchronize them, and then they are pretreated for 1 hour with either 0.1% DMSO or SEL120-34A at the indicated concentration. Finally, they are supplemented with 10% FBS, IFNg, or IFNa in the presence of the inhibitor for 4 hours. The cells undergo a 5-minute centrifugation at 1300 rpm in 4°C, a single ice-cold PBS wash, and storage at -80°C. For gene expression analysis (IER and IFN-responsive genes), HCT-116 and Colo-205 cells were seeded, synchronized by serum starvation (0.5% FBS for 24 h), pretreated with SEL120-34A or vehicle for 1-2 hours, and then stimulated with 10% FBS, IFNγ, or IFNα in the continued presence of the compound. Cells were harvested at various time points, RNA was extracted, treated with DNase I, and mRNA levels were quantified by reverse transcription followed by quantitative PCR (qRT-PCR). [1] For extended cytotoxicity tests, AML cell lines grown in suspension were plated in 96-well plates in triplicate. Cells were incubated with serially diluted concentrations of SEL120-34A or vehicle. Cell viability was periodically assessed using a metabolic dye (AlamarBlue). On designated days, an aliquot of culture from each well was transferred to fresh medium containing the compound to maintain cell density. Dose-response curves were plotted, and GI₅₀ values were interpolated. [1] For phosphoprotein analysis by Western blot, cells (e.g., KG-1, HCT-116, SET-2) were treated with SEL120-34A at indicated concentrations and times. Cells were lysed, proteins were separated by SDS-PAGE, transferred to membranes, and probed with antibodies against phosphorylated and total forms of STAT1, STAT5, RNA polymerase II C-terminal domain (RNAPII CTD), and other proteins. [1] |
| Animal Protocol |
SCID/beige C.B17 female mice xenografted with Colo-205 tumors 5, 15, 30 and 60 mg/kg BID oral For pharmacodynamic studies in Colo-205 xenografts, mice bearing subcutaneous tumors (~250 mm³) were randomly grouped and administered SEL120-34A orally (per os, PO) at doses of 5, 15, 30, or 60 mg/kg, twice daily (BID), for a total of 3 days. The compound was freshly dissolved in water. Tumors were collected 16 hours after the last dose for analysis. [1] For efficacy studies in AML xenografts (KG-1 and MV4-11), SCID/beige mice were inoculated subcutaneously with leukemia cells. When tumors reached ~100 mm³, mice were randomly grouped and treated orally with SEL120-34A (25 or 50 mg/kg) or vehicle (water) once daily. Tumor volumes and body weights were monitored regularly. [1] For toxicology assessment, healthy immunocompetent CD-1 female mice were administered SEL120-34A orally at indicated doses or vehicle twice daily for 14 days. Body weight and general condition were monitored daily. Blood was collected at the end of the study for hematology analysis. [1] |
| ADME/Pharmacokinetics |
Following oral administration of 60 mg/kg SEL120-34A (BID) to mice bearing Colo-205 xenografts, a mean plasma concentration exceeding 700 ng/mL was measured 16 hours after the last dose. [1] SEL120-34A exhibited favorable pharmacokinetics, including high bioavailability after oral administration and metabolic stability, enabling in vivo efficacy studies. [1] |
| Toxicity/Toxicokinetics |
A 14-day toxicology study in healthy CD-1 mice showed that subchronic oral administration of SEL120-34A was not associated with significant alterations in peripheral blood hematology parameters. [1] In efficacy studies with AML xenograft models, treatment with SEL120-34A at effective doses (25 and 50 mg/kg, QD) did not cause appreciable loss in body weight. [1] |
| References |
[1]. SEL120-34A is a novel CDK8 inhibitor active in AML cells with high levels of serine phosphorylation of STAT1 and STAT5 transactivation domains. Oncotarget. 2017 May 16;8(20):33779-33795. |
| Additional Infomation |
CDK8/19 Inhibitor RVU120 is an orally bioavailable inhibitor of cyclin-dependent kinases 8 and 19 (CDK8/19), with potential antineoplastic and chemoprotective activities. Upon oral administration, CDK8/19 inhibitor RVU120 targets, binds to and inhibits the activity of CDK8/19, which prevents activation of CDK8/19-mediated oncogenic signaling pathways, blocks selective transcription of various tumor-promoting genes, and inhibits proliferation of CDK8/19-overexpressing tumor cells. CDK8/19, serine/threonine kinases involved in the regulation of the cell cycle, are overexpressed in certain cancer cell types and play key roles in tumor cell proliferation. SEL120-34A is a novel, ATP-competitive, and selective inhibitor of CDK8. [1] X-ray crystallography revealed that SEL120-34A is a type I inhibitor that binds to the ATP-binding site of CDK8, forming halogen bonds with the hinge region and hydrophobic complementarities within the front pocket. A key interaction with Arg356, unique to CDK8, contributes to selectivity. [1] The primary pharmacological effect of SEL120-34A is the inhibition of serine phosphorylation (S727 and S726) in the transactivation domains of STAT1 and STAT5, respectively. [1] Transcriptional profiling indicates that SEL120-34A selectively affects genes regulated by STATs and the NUP98-HOXA9 signaling pathway, with significant downregulation of interferon-responsive genes in vivo. [1] SEL120-34A shows differential efficacy in AML, preferentially targeting cells with high levels of phosphorylated STAT5 S726 and stem cell characteristics, while cells negative for activated STAT5 and showing lineage commitment are resistant. [1] Phosphorylated STAT5 S726 and STAT1 S727 are proposed as predictive biomarkers for sensitivity to CDK8 inhibitors like SEL120-34A in AML. [1] |
Solubility Data
| Solubility (In Vitro) |
Water: ~90 mg/mL Ethanol: ˂1 mg/mL DMSO: 1~62.5 mg/mL |
| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 2.08 mg/mL (Infinity 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 20.8 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: ≥ 2.08 mg/mL (Infinity 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 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 3: 2.08 mg/mL (Infinity mM) 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 20.8 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.) |