SCH900776

• CAT Number: I005338
• CAS Number: 891494-63-6
• Molecular Formula: C15H18BrN7
• Molecular Weight: 376.3
• Purity: ≥95%
• Target: Chk
• Solubility: DMSO > 50 mg/mL Ethanol 3 mg/mL
• Storage: 3 years -20C powder
• IC50: 3 nM(Chk1)
• InChI: InChI=1S/C15H18BrN7/c1-22-8-10(6-19-22)11-7-20-23-14(17)12(16)13(21-15(11)23)9-3-2-4-18-5-9/h6-9,18H,2-5,17H2,1H3/t9-/m1/s1
• InChIKey: GMIZZEXBPRLVIV-SECBINFHSA-N
• SMILES: NC1=C(Br)C([C@@H]2CCCNC2)=NC3=C(C4=CN(C)N=C4)C=NN31

SCH900776 is a potent, selective and orally bioavailable inhibitor of checkpoint kinase Chk1 (IC50 = 3 nM), highly selective against Chk2 (IC50 = 1500 nM) and cyclin-dependent kinase CDK2 (IC50 = 160 nM).IC50 Value: 3 nM(Chk1)Target: Chk1in vitro: SCH 900776 is a less potent inhibitor of Chk2 and CDK2 with IC50 of 1.5 μM and 0.16 μM, respectively. SCH 900776 shows no significant inhibition of cytochrome P450 human liver microsomal isoforms 1A2, 2C9, 2C19, 2D6, and 3A4. SCH 900776 induces a dose-dependent loss of DNA replication capability 24 hours after hydroxyurea exposure. SCH 900776 enhances the γ-H2AX response of hydroxyurea, 5-fluoruracil, and cytarabine. In combination with an antimetabolite, SCH 900776 induces accumulation of γ-H2AX within 2 hours, indicative of replication fork collapse and double stranded DNA breaks. Additionally, SCH 900776 suppresses accumulation of the Chk1 pS296 autophosphorylation in a dose-dependent manner. Exposure of proliferating WS1 cells to SCH 900776 is associated with rapid, dose-dependent accumulation of Chk1 pS345, indicating that cycling populations of normal cells induce Chk1 pS345 following exposure to SCH 900776 as part of a futile cycle, perhaps driven by AT-family kinases and DNA-PK.in vivo: Administered 30 minutes after gemcitabine, 4 mg/kg SCH 900776 is sufficient to induce the γ-H2AX biomarker while 8 mg/kg leads to enhanced tumor pharmacodynamic and regression responses relative to gemcitabine or SCH 900776 alone. Dose escalation of SCH 900776 (16 mg/kg and 32 mg/kg) induces incremental improvements in tumor response. Importantly, doses of SCH 900776 associate with robust biomarker activation and improved tumor response are not associated with enhanced toxicity of gemcitabine on hematological parameters in BALB/c mice.SCH900776 exposure phenocopies short interfering RNA-mediated CHK1 ablation and interacts synergistically with DNA antimetabolite agents in vitro and in vivo to selectively induce dsDNA breaks and cell death in tumor cell backgrounds. Chk1 inhibitor SCH 900776 abrogates cytarabine-induced S-phase arrest and enhances cytarabine cytotoxicity in acute leukemia cell lines and leukemic blasts in vitro.

Reference

1:Mol Cancer Ther. 2012 Feb;11(2):427-38. doi: 10.1158/1535-7163.MCT-11-0406. Epub 2011 Dec 27. Preclinical development of the novel Chk1 inhibitor SCH900776 in combination with DNA-damaging agents and antimetabolites.Montano R,Chung I,Garner KM,Parry D,Eastman A, PMID: 22203733 PMCID: PMC3277678 DOI: 10.1158/1535-7163.MCT-11-0406 Abstract: Many anticancer agents damage DNA and arrest cell-cycle progression primarily in S or G(2) phase of the cell cycle. Previous studies with the topoisomerase I inhibitor SN38 have shown the efficacy of the Chk1 inhibitor UCN-01 to overcome this arrest and induce mitotic catastrophe. UCN-01 was limited in clinical trials by unfavorable pharmacokinetics. SCH900776 is a novel and more selective Chk1 inhibitor that potently inhibits Chk1 and abrogates cell-cycle arrest induced by SN38. Like UCN-01, abrogation of SN38-induced arrest enhances the rate of cell death but does not increase overall cell death. In contrast, SCH900776 reduced the growth-inhibitory concentration of hydroxyurea by 20- to 70-fold. A similar magnitude of sensitization was observed with cytarabine. A 5- to 10-fold sensitization occurred with gemcitabine, but no sensitization occurred with cisplatin, 5-fluorouracil, or 6-thioguanine. Sensitization occurred at hydroxyurea concentrations that marginally slowed DNA replication without apparent activation of Chk1, but this led to dependence on Chk1 that increased with time. For example, when added 18 hours after hydroxyurea, SCH900776 induced DNA double-strand breaks consistent with rapid collapse of replication forks. In addition, some cell lines were highly sensitive to SCH900776 alone, and these cells required lower concentrations of SCH900776 to sensitize them to hydroxyurea. We conclude that some tumors may be very sensitive to the combination of SCH900776 and hydroxyurea. Delayed administration of SCH900776 may be more effective than concurrent treatment. SCH900776 is currently in phase I clinical trials, and these results provide the rationale and schedule for future clinical trials.