title: Combination therapy with potent PI3K and MAPK inhibitors overcomes adaptive kinome resistance to single agents in preclinical models of glioblastoma.
abstract: BACKGROUND
  Glioblastoma (GBM) is the most common and aggressive primary brain tumor. Prognosis remains poor despite multimodal therapy. Developing alternative treatments is essential. Drugs targeting kinases within the phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) effectors of receptor tyrosine kinase (RTK) signaling represent promising candidates.
  
  
  METHODS
  We previously developed a non-germline genetically engineered mouse model of GBM in which PI3K and MAPK are activated via Pten deletion and KrasG12D in immortalized astrocytes. Using this model, we examined the influence of drug potency on target inhibition, alternate pathway activation, efficacy, and synergism of single agent and combination therapy with inhibitors of these 2 pathways. Efficacy was then examined in GBM patient-derived xenografts (PDX) in vitro and in vivo.
  
  
  RESULTS
  PI3K and mitogen-activated protein kinase kinase (MEK) inhibitor potency was directly associated with target inhibition, alternate RTK effector activation, and efficacy in mutant murine astrocytes in vitro. The kinomes of GBM PDX and tumor samples were heterogeneous, with a subset of the latter harboring MAPK hyperactivation. Dual PI3K/MEK inhibitor treatment overcame alternate effector activation, was synergistic in vitro, and was more effective than single agent therapy in subcutaneous murine allografts. However, efficacy in orthotopic allografts was minimal. This was likely due to dose-limiting toxicity and incomplete target inhibition.
  
  
  CONCLUSIONS
  Drug potency influences PI3K/MEK inhibitor-induced target inhibition, adaptive kinome reprogramming, efficacy, and synergy. Our findings suggest that combination therapies with highly potent, brain-penetrant kinase inhibitors will be required to improve patient outcomes.
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Robert S
authors.initials: RS
authors.lastname: McNeill
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Demitra A
authors.initials: DA
authors.lastname: Canoutas
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Stuhlmiller
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Harshil D
authors.initials: HD
authors.lastname: Dhruv
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: David M
authors.initials: DM
authors.lastname: Irvin
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Ryan E
authors.initials: RE
authors.lastname: Bash
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Angus
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Herring
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Simon
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Kasey R
authors.initials: KR
authors.lastname: Skinner
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Juanita C
authors.initials: JC
authors.lastname: Limas
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Ralf S
authors.initials: RS
authors.lastname: Schmid
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Marni B
authors.initials: MB
authors.lastname: Siegel
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Amanda E D
authors.initials: AED
authors.lastname: Van Swearingen
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hadler
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Erik P
authors.initials: EP
authors.lastname: Sulman
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Jann N
authors.initials: JN
authors.lastname: Sarkaria
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Carey K
authors.initials: CK
authors.lastname: Anders
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Lee M
authors.initials: LM
authors.lastname: Graves
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Berens
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Johnson
authors.affiliation: Pathobiology and Translational Science Graduate Program, Departments of Pathology and Laboratory Medicine, Biology, Pharmacology, Genetics, Medicine, and Neurology, Divisions of Neuropathology and Hematology/Oncology, Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, Proteomics Core Facility, Neurosciences Center, Carolina Institute for Developmental Disabilities, and Biological and Biomedical Sciences Program, University of North Carolina (UNC) School of Medicine, Chapel Hill, North Carolina; Cancer & Cell Biology Division, TGen, Phoenix, Arizona; Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas.
authors.forename: C Ryan
authors.initials: CR
authors.lastname: Miller
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D004357:Drug Synergism; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D020928:Mitogen-Activated Protein Kinases
keywords: MAPK; PI3K; genetically engineered mice; glioblastoma; kinase inhibitors