title: CCT244747 is a novel potent and selective CHK1 inhibitor with oral efficacy alone and in combination with genotoxic anticancer drugs.
abstract: OBJECTIVE
  Many tumors exhibit defective cell-cycle checkpoint control and increased replicative stress. CHK1 is critically involved in the DNA damage response and maintenance of replication fork stability. We have therefore discovered a novel potent, highly selective, orally active ATP-competitive CHK1 inhibitor, CCT244747, and present its preclinical pharmacology and therapeutic activity.
  
  
  METHODS
  Cellular CHK1 activity was assessed using an ELISA assay, and cytotoxicity a SRB assay. Biomarker modulation was measured using immunoblotting, and cell-cycle effects by flow cytometry analysis. Single-agent oral CCT244747 antitumor activity was evaluated in a MYCN-driven transgenic mouse model of neuroblastoma by MRI and in genotoxic combinations in human tumor xenografts by growth delay.
  
  
  RESULTS
  CCT244747 inhibited cellular CHK1 activity (IC(50) 29-170 nmol/L), significantly enhanced the cytotoxicity of several anticancer drugs, and abrogated drug-induced S and G(2) arrest in multiple tumor cell lines. Biomarkers of CHK1 (pS296 CHK1) activity and cell-cycle inactivity (pY15 CDK1) were induced by genotoxics and inhibited by CCT244747 both in vitro and in vivo, producing enhanced DNA damage and apoptosis. Active tumor concentrations of CCT244747 were obtained following oral administration. The antitumor activity of both gemcitabine and irinotecan were significantly enhanced by CCT244747 in several human tumor xenografts, giving concomitant biomarker modulation indicative of CHK1 inhibition. CCT244747 also showed marked antitumor activity as a single agent in a MYCN-driven neuroblastoma.
  
  
  CONCLUSIONS
  CCT244747 represents the first structural disclosure of a highly selective, orally active CHK1 inhibitor and warrants further evaluation alone or combined with genotoxic anticancer therapies.
authors.affiliation: Cancer Research UK Cancer Therapeutics Unit, Division of Cancer Therapeutics, The Institute of Cancer Research, Sutton, United Kingdom. Mike.Walton@icr.ac.uk
authors.forename: Mike I
authors.initials: MI
authors.lastname: Walton
authors.forename: Paul D
authors.initials: PD
authors.lastname: Eve
authors.forename: Angela
authors.initials: A
authors.lastname: Hayes
authors.forename: Melanie R
authors.initials: MR
authors.lastname: Valenti
authors.forename: Alexis K
authors.initials: AK
authors.lastname: De Haven Brandon
authors.forename: Gary
authors.initials: G
authors.lastname: Box
authors.forename: Albert
authors.initials: A
authors.lastname: Hallsworth
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Smith
authors.forename: Kathy J
authors.initials: KJ
authors.lastname: Boxall
authors.forename: Michael
authors.initials: M
authors.lastname: Lainchbury
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Matthews
authors.forename: Yann
authors.initials: Y
authors.lastname: Jamin
authors.forename: Simon P
authors.initials: SP
authors.lastname: Robinson
authors.forename: G Wynne
authors.initials: GW
authors.lastname: Aherne
authors.forename: John C
authors.initials: JC
authors.lastname: Reader
authors.forename: Louis
authors.initials: L
authors.lastname: Chesler
authors.forename: Florence I
authors.initials: FI
authors.lastname: Raynaud
authors.forename: Suzanne A
authors.initials: SA
authors.lastname: Eccles
authors.forename: Ian
authors.initials: I
authors.lastname: Collins
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Garrett
mesh_terms: D000284:Administration, Oral; D000631:Aminopyridines / Q000008:administration & dosage*; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D000071877:Checkpoint Kinase 1; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D009374:Neoplasms, Experimental / Q000188:drug therapy / Q000378:metabolism; D009447:Neuroblastoma / Q000188:drug therapy / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D011743:Pyrimidines / Q000008:administration & dosage*
chemical_list: C577959:3-((1-(dimethylamino)propan-2-yl)oxy)-5-((4-methoxy-5-(1-methyl-1H-pyrazol-4-yl)pyridin-2-yl)amino)pyrazine-2-carbonitrile; D000631:Aminopyridines; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse