title: Preclinical activity of the rational combination of selumetinib (AZD6244) in combination with vorinostat in KRAS-mutant colorectal cancer models.
abstract: OBJECTIVE
  Despite the availability of several active combination regimens for advanced colorectal cancer (CRC), the 5-year survival rate remains poor at less than 10%, supporting the development of novel therapeutic approaches. In this study, we focused on the preclinical assessment of a rationally based combination against KRAS-mutated CRC by testing the combination of the MEK inhibitor, selumetinib, and vorinostat, a histone deacetylase (HDAC) inhibitor.
  
  
  METHODS
  Transcriptional profiling and gene set enrichment analysis (baseline and posttreatment) of CRC cell lines provided the rationale for the combination. The activity of selumetinib and vorinostat against the KRAS-mutant SW620 and SW480 CRC cell lines was studied in vitro and in vivo. The effects of this combination on tumor phenotype were assessed using monolayer and 3-dimensional cultures, flow cytometry, apoptosis, and cell migration. In vivo, tumor growth inhibition, (18)F-fluoro-deoxy-glucose positron emission tomography (FDG-PET), and proton nuclear magnetic resonance were carried out to evaluate the growth inhibitory and metabolic responses, respectively, in CRC xenografts.
  
  
  RESULTS
  In vitro, treatment with selumetinib and vorinostat resulted in a synergistic inhibition of proliferation and spheroid formation in both CRC cell lines. This inhibition was associated with an increase in apoptosis, cell-cycle arrest in G(1), and reduced cellular migration and VEGF-A secretion. In vivo, the combination resulted in additive tumor growth inhibition. The metabolic response to selumetinib and vorinostat consisted of significant inhibition of membrane phospholipids; no significant changes in glucose uptake or metabolism were observed in any of the treatment groups.
  
  
  CONCLUSIONS
  These data indicate that the rationally based combination of the mitogen-activated protein kinase/extracellular signal-regulated kinase inhibitor, selumetinib, with the HDAC inhibitor vorinostat results in synergistic antiproliferative activity against KRAS-mutant CRC cell lines in vitro. In vivo, the combination showed additive effects that were associated with metabolic changes in phospholipid turnover, but not on FDG-PET, indicating that the former is a more sensitive endpoint of the combination effects.
authors.affiliation: Division of Medical Oncology, Department of Anesthesiology and Radiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA. pmorelli@cnio.es
authors.forename: M Pia
authors.initials: MP
authors.lastname: Morelli
authors.forename: John J
authors.initials: JJ
authors.lastname: Tentler
authors.forename: Gillian N
authors.initials: GN
authors.lastname: Kulikowski
authors.forename: Aik-Choon
authors.initials: AC
authors.lastname: Tan
authors.forename: Erica L
authors.initials: EL
authors.lastname: Bradshaw-Pierce
authors.forename: Todd M
authors.initials: TM
authors.lastname: Pitts
authors.forename: Amy M
authors.initials: AM
authors.lastname: Brown
authors.forename: Sujatha
authors.initials: S
authors.lastname: Nallapareddy
authors.forename: John J
authors.initials: JJ
authors.lastname: Arcaroli
authors.forename: Natalie J
authors.initials: NJ
authors.lastname: Serkova
authors.forename: Manuel
authors.initials: M
authors.lastname: Hidalgo
authors.forename: Fortunato
authors.initials: F
authors.lastname: Ciardiello
authors.forename: S Gail
authors.initials: SG
authors.lastname: Eckhardt
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001562:Benzimidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D016000:Cluster Analysis; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D056572:Histone Deacetylase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000008:administration & dosage / Q000494:pharmacology*; D008024:Ligands; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D049268:Positron-Emission Tomography; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras); D015398:Signal Transduction / Q000187:drug effects; D000077337:Vorinostat; D023041:Xenograft Model Antitumor Assays; D018631:ras Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C517975:AZD 6244; D001562:Benzimidazoles; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; C117307:KRAS protein, human; D008024:Ligands; D011518:Proto-Oncogene Proteins; D000077337:Vorinostat; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins