mk-1775 and Glioblastoma

A rapid, sensitive, and robust aqueous normal-phase chromatography method coupled with tandem mass spectrometry was developed and validated for the quantitation of AZD1775, a Wee-1 inhibitor, in human plasma and brain tumor tissue. Sample preparation involved simple protein precipitation with acetonitrile. Chromatographic separation was achieved on ethylene bridged hybrid stationary phases (i.e., Waters XBridge Amide column) under an isocratic elution with the mobile phase consisting of acetonitrile/ammonium formate in water (10mM, pH 3.0) (85:15,v/v) at a flow rate of 0.8mL/min for 5min. The lower limit of quantitation (LLOQ) was 0.2ng/mL of AZD1775 in plasma and tissue homogenate. The calibration curve was linear over AZD1775 concentration range of 0.2-1000ng/mL in plasma and tissue homogenate. The intra- and inter-day precision and accuracy were within the generally accepted criteria for bioanalytical method (<15%). The method was successfully applied to assess the penetration of AZD1775 across the blood-brain tumor barrier, as assessed by the unbound brain-to-plasma ratio, in patients with glioblastoma.

Topics: Brain; Brain Neoplasms; Cell Cycle Proteins; Chromatography, High Pressure Liquid; Glioblastoma; Humans; Limit of Detection; Nuclear Proteins; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones; Tandem Mass Spectrometry

Despite intense research efforts, glioblastoma remains an incurable brain tumor with a dismal median survival time of 15 months. Thus, identifying new therapeutic targets is an urgent need. Here, we show that the lysine methyltransferase SETD8 is overexpressed in 50% of high-grade gliomas. The small molecule SETD8 inhibitor UNC0379, as well as siRNA-mediated inhibition of SETD8, blocked glioblastoma cell proliferation, by inducing DNA damage and activating cell cycle checkpoints. Specifically, in p53-proficient glioblastoma cells, SETD8 inhibition and DNA damage induced p21 accumulation and G1/S arrest whereas, in p53-deficient glioblastoma cells, DNA damage induced by SETD8 inhibition resulted in G2/M arrest mediated by Chk1 activation. Checkpoint abrogation, by the Wee1 kinase inhibitor adavosertib, induced glioblastoma cell lines and primary cells, DNA-damaged by UNC0379, to progress to mitosis where they died by mitotic catastrophe. Finally, UNC0379 and adavosertib synergized in restraining glioblastoma growth in a murine xenograft model, providing a strong rationale to further explore this novel pharmacological approach for adjuvant glioblastoma treatment.

Topics: Animals; Apoptosis; Cell Line, Tumor; G2 Phase Cell Cycle Checkpoints; Glioblastoma; Humans; Infant, Newborn; Infant, Newborn, Diseases; Mice; Tumor Suppressor Protein p53

The strategy of using biologically targeted therapeutics for cancer has yet to translate into effective treatment of gliomas. The neuro-oncology community is beginning to recognize that phase 0 studies should be performed to account for the impact of the blood-brain barrier on the ability of a therapeutic to reach its target(s).

Topics: Brain Neoplasms; Glioblastoma; Humans; Pyrazoles; Pyrimidines; Pyrimidinones

Determining the penetration of drugs across the blood-brain barrier is a significant challenge in central nervous system drug development. The use of a mechanistic physiologically based pharmacokinetic model can predict drug exposures in the brain without needing

Topics: Adult; Blood-Brain Barrier; Glioblastoma; Humans; Pyrazoles; Pyrimidines; Pyrimidinones

Glioblastoma (GBM) is the most common malignant primary brain cancer. With a median survival of about a year, new approaches to treating this disease are necessary. To identify signaling molecules regulating GBM progression in a genetically engineered murine model of proneural GBM, we quantified phosphotyrosine-mediated signaling using mass spectrometry. Oncogenic signals, including phosphorylated ERK MAPK, PI3K, and PDGFR, were found to be increased in the murine tumors relative to brain. Phosphorylation of CDK1 pY15, associated with the G2 arrest checkpoint, was identified as the most differentially phosphorylated site, with a 14-fold increase in phosphorylation in the tumors. To assess the role of this checkpoint as a potential therapeutic target, syngeneic primary cell lines derived from these tumors were treated with MK-1775, an inhibitor of Wee1, the kinase responsible for CDK1 Y15 phosphorylation. MK-1775 treatment led to mitotic catastrophe, as defined by increased DNA damage and cell death by apoptosis. To assess the extensibility of targeting Wee1/CDK1 in GBM, patient-derived xenograft (PDX) cell lines were also treated with MK-1775. Although the response was more heterogeneous, on-target Wee1 inhibition led to decreased CDK1 Y15 phosphorylation and increased DNA damage and apoptosis in each line. These results were also validated in vivo, where single-agent MK-1775 demonstrated an antitumor effect on a flank PDX tumor model, increasing mouse survival by 1.74-fold. This study highlights the ability of unbiased quantitative phosphoproteomics to reveal therapeutic targets in tumor models, and the potential for Wee1 inhibition as a treatment approach in preclinical models of GBM. Mol Cancer Ther; 15(6); 1332-43. ©2016 AACR.

Topics: Animals; Biomarkers, Tumor; Brain Neoplasms; CDC2 Protein Kinase; Cell Cycle Proteins; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Glioblastoma; Humans; Mass Spectrometry; Mice; Molecular Targeted Therapy; Nuclear Proteins; Phosphorylation; Protein-Tyrosine Kinases; Proteomics; Pyrazoles; Pyrimidines; Pyrimidinones; Xenograft Model Antitumor Assays

Wee1 regulates key DNA damage checkpoints, and in this study, the efficacy of the Wee1 inhibitor MK-1775 was evaluated in glioblastoma multiforme (GBM) xenograft models alone and in combination with radiation and/or temozolomide.. In vitro MK-1775 efficacy alone and in combination with temozolomide, and the impact on DNA damage, was analyzed by Western blotting and γH2AX foci formation. In vivo efficacy was evaluated in orthotopic and heterotopic xenografts. Drug distribution was assessed by conventional mass spectrometry (MS) and matrix-assisted laser desorption/ionization (MALDI)-MS imaging.. GBM22 (IC50 = 68 nmol/L) was significantly more sensitive to MK-1775 compared with five other GBM xenograft lines, including GBM6 (IC50 >300 nmol/L), and this was associated with a significant difference in pan-nuclear γH2AX staining between treated GBM22 (81% cells positive) and GBM6 (20% cells positive) cells. However, there was no sensitizing effect of MK-1775 when combined with temozolomide in vitro. In an orthotopic GBM22 model, MK-1775 was ineffective when combined with temozolomide, whereas in a flank model of GBM22, MK-1775 exhibited both single-agent and combinatorial activity with temozolomide. Consistent with limited drug delivery into orthotopic tumors, the normal brain to whole blood ratio following a single MK-1775 dose was 5%, and MALDI-MS imaging demonstrated heterogeneous and markedly lower MK-1775 distribution in orthotopic as compared with heterotopic GBM22 tumors.. Limited distribution to brain tumors may limit the efficacy of MK-1775 in GBM.

Topics: Animals; Blood-Brain Barrier; Cell Cycle Proteins; Dacarbazine; Disease Models, Animal; DNA Damage; Glioblastoma; Humans; Mice; Nuclear Proteins; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones; Temozolomide; Tumor Burden; Xenograft Model Antitumor Assays

To identify therapeutic targets for glioblastoma (GBM), we performed genome-wide CRISPR-Cas9 knockout (KO) screens in patient-derived GBM stem-like cells (GSCs) and human neural stem/progenitors (NSCs), non-neoplastic stem cell controls, for genes required for their in vitro growth. Surprisingly, the vast majority GSC-lethal hits were found outside of molecular networks commonly altered in GBM and GSCs (e.g., oncogenic drivers). In vitro and in vivo validation of GSC-specific targets revealed several strong hits, including the wee1-like kinase, PKMYT1/Myt1. Mechanistic studies demonstrated that PKMYT1 acts redundantly with WEE1 to inhibit cyclin B-CDK1 activity via CDK1-Y15 phosphorylation and to promote timely completion of mitosis in NSCs. However, in GSCs, this redundancy is lost, most likely as a result of oncogenic signaling, causing GBM-specific lethality.

Topics: CDC2 Protein Kinase; Cell Cycle Proteins; Cell Survival; CRISPR-Cas Systems; Cyclin B; ErbB Receptors; Gene Library; Genome, Human; Glioblastoma; Humans; Membrane Proteins; Microscopy, Video; Mitosis; Neoplastic Stem Cells; Nuclear Proteins; Phosphorylation; Protein Serine-Threonine Kinases; Protein-Tyrosine Kinases; Proto-Oncogene Proteins c-akt; Pyrazoles; Pyrimidines; Pyrimidinones; RNA Interference; Time-Lapse Imaging; Tumor Suppressor Protein p53

We investigated the efficacy of the Wee1 inhibitor MK-1775 in combination with radiation for the treatment of pediatric high-grade gliomas (HGGs), including diffuse intrinsic pontine gliomas (DIPGs).. Gene expression analysis was performed for 38 primary pediatric gliomas (3 grade I, 10 grade II, 11 grade III, 14 grade IV) and 8 normal brain samples using the Agilent 4 × 44 K array. Clonogenic survival assays were carried out in pediatric and adult HGG cell lines (n = 6) to assess radiosensitizing effects of MK-1775. DNA repair capacity was evaluated by measuring protein levels of γ-H2AX, a marker of double strand DNA breaks. In vivo activity of MK-1775 with radiation was assessed in 2 distinct orthotopic engraftment models of pediatric HGG, including 1 derived from a genetically engineered mouse carrying a BRAF(V600E) mutation, and 1 xenograft model in which tumor cells were derived from a patient's DIPG.. Wee1 is overexpressed in pediatric HGGs, with increasing expression positively correlated with malignancy (P = .007 for grade III + IV vs I + II) and markedly high expression in DIPG. Combination treatment of MK-1775 and radiation reduced clonogenic survival and increased expression of γ-H2AX to a greater extent than achieved by radiation alone. Finally, combined MK-1775 and radiation conferred greater survival benefit to mice bearing engrafted, orthotopic HGG and DIPG tumors, compared with treatment with radiation alone (BRAF(V600E) model P = .0061 and DIPG brainstem model P = .0163).. Our results highlight MK-1775 as a promising new therapeutic agent for use in combination with radiation for the treatment of pediatric HGGs, including DIPG.

Topics: Animals; Brain Neoplasms; Cell Cycle Proteins; Cell Death; Cell Line, Tumor; Chemoradiotherapy; Glioblastoma; Humans; Mice; Mice, Transgenic; Nuclear Proteins; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones

Topics: Animals; Brain Neoplasms; Cell Cycle Proteins; Glioblastoma; Humans; Nuclear Proteins; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones

The purpose of this study was to determine the capacity of MK-1775, a potent Wee-1 inhibitor, to abrogate the radiation-induced G(2) checkpoint arrest and modulate radiosensitivity in glioblastoma cell models and normal human astrocytes. The radiation-induced checkpoint response of established glioblastoma cell lines, glioblastoma neural stem (GNS) cells, and astrocytes were determined in vitro by flow cytometry and in vivo by mitosis-specific staining using immunohistochemistry. Mechanisms underlying MK-1775 radiosensitization were determined by mitotic catastrophe and γH2AX expression. Radiosensitivity was determined in vitro by the clonogenic assay and in vivo by tumor growth delay. MK-1775 abrogated the radiation-induced G(2) checkpoint and enhanced radiosensitivity in established glioblastoma cell lines in vitro and in vivo, without modulating radiation response in normal human astrocytes. MK-1775 appeared to attenuate the early-phase of the G(2) checkpoint arrest in GNS cell lines, although the arrest was not sustained and did not lead to increased radiosensitivity. These results show that MK-1775 can selectively enhance radiosensitivity in established glioblastoma cell lines. Further work is required to determine the role Wee-1 plays in checkpoint activation of GNS cells.

Topics: Animals; Brain Neoplasms; Cell Cycle Proteins; Cell Line, Tumor; G2 Phase Cell Cycle Checkpoints; Glioblastoma; Humans; Mice; Mice, Nude; Molecular Targeted Therapy; Nuclear Proteins; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones; Radiation Tolerance; Radiation-Sensitizing Agents; Up-Regulation; Xenograft Model Antitumor Assays