title: The Checkpoint Kinase 1 Inhibitor Prexasertib Induces Regression of Preclinical Models of Human Neuroblastoma.
abstract: Purpose:Checkpoint kinase 1 (CHK1) is a key regulator of the DNA damage response and a mediator of replication stress through modulation of replication fork licensing and activation of S and G2-M cell-cycle checkpoints. We evaluated prexasertib (LY2606368), a small-molecule CHK1 inhibitor currently in clinical testing, in multiple preclinical models of pediatric cancer. Following an initial assessment of prexasertib activity, this study focused on the preclinical models of neuroblastoma.Experimental Design:We evaluated the antiproliferative activity of prexasertib in a panel of cancer cell lines; neuroblastoma cell lines were among the most sensitive. Subsequent Western blot and immunofluorescence analyses measured DNA damage and DNA repair protein activation. Prexasertib was investigated in several cell line-derived xenograft mouse models of neuroblastoma.Results:Within 24 hours, single-agent prexasertib promoted γH2AX-positive double-strand DNA breaks and phosphorylation of DNA damage sensors ATM and DNA-PKcs, leading to neuroblastoma cell death. Knockdown of CHK1 and/or CHK2 by siRNA verified that the double-strand DNA breaks and cell death elicited by prexasertib were due to specific CHK1 inhibition. Neuroblastoma xenografts rapidly regressed following prexasertib administration, independent of starting tumor volume. Decreased Ki67 and increased immunostaining of endothelial and pericyte markers were observed in xenografts after only 6 days of exposure to prexasertib, potentially indicating a swift reduction in tumor volume and/or a direct effect on tumor vasculature.Conclusions:Overall, these data demonstrate that prexasertib is a specific inhibitor of CHK1 in neuroblastoma and leads to DNA damage and cell death in preclinical models of this devastating pediatric malignancy.Clin Cancer Res; 23(15); 4354-63. ©2017 AACR.
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
authors.forename: Caitlin D
authors.initials: CD
authors.lastname: Lowery
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
authors.forename: Alle B
authors.initials: AB
authors.lastname: VanWye
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
authors.forename: Michele
authors.initials: M
authors.lastname: Dowless
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
authors.forename: Wayne
authors.initials: W
authors.lastname: Blosser
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
authors.forename: Beverly L
authors.initials: BL
authors.lastname: Falcon
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
authors.forename: Julie
authors.initials: J
authors.lastname: Stewart
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Stephens
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Beckmann
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
authors.forename: Aimee
authors.initials: A
authors.lastname: Bence Lin
authors.affiliation: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana. stancato_louis@lilly.com.
authors.forename: Louis F
authors.initials: LF
authors.lastname: Stancato
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics*; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects; D006801:Humans; D051379:Mice; D009447:Neuroblastoma / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage*; D011719:Pyrazines / Q000008:administration & dosage*; D011720:Pyrazoles / Q000008:administration & dosage*; D015398:Signal Transduction / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D047428:Protein Kinase Inhibitors; D011719:Pyrazines; D011720:Pyrazoles; C000608121:prexasertib; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1