Marian Raschke

Novel Mps1 Kinase Inhibitors with Potent Antitumor Activity.

Monopolar spindle 1 (Mps1) has been shown to function as the key kinase that activates the spindle assembly checkpoint (SAC) to secure proper distribution of chromosomes to daughter cells. Here, we report the structure and functional characterization of two novel selective Mps1 inhibitors, BAY 1161909 and BAY 1217389, derived from structurally distinct chemical classes. BAY 1161909 and BAY 1217389 inhibited Mps1 kinase activity with IC50 values below 10 nmol/L while showing an excellent selectivity profile. In cellular mechanistic assays, both Mps1 inhibitors abrogated nocodazole-induced SAC activity and induced premature exit from mitosis (“mitotic breakthrough”), resulting in multinuclearity and tumor cell death. Both compounds efficiently inhibited tumor cell proliferation in vitro (IC50 nmol/L range). In vivo, BAY 1161909 and BAY 1217389 achieved moderate efficacy in monotherapy in tumor xenograft studies. However, in line with its unique mode of action, when combined with paclitaxel, low doses of Mps1 inhibitor reduced paclitaxel-induced mitotic arrest by the weakening of SAC activity. As a result, combination therapy strongly improved efficacy over paclitaxel or Mps1 inhibitor monotreatment at the respective MTDs in a broad range of xenograft models, including those showing acquired or intrinsic paclitaxel resistance. Both Mps1 inhibitors showed good tolerability without adding toxicity to paclitaxel monotherapy. These preclinical findings validate the innovative concept of SAC abrogation for cancer therapy and justify clinical proof-of-concept studies evaluating the Mps1 inhibitors BAY 1161909 and BAY 1217389 in combination with antimitotic cancer drugs to enhance their efficacy and potentially overcome resistance. Mol Cancer Ther; 15(4); 583–92. ©2016 AACR.

Comparison of the Mesoscale Discovery and Luminex multiplex platforms for measurement of urinary biomarkers in a cisplatin rat kidney injury model

INTRODUCTION In the past years several new urinary nephrotoxicity biomarkers have been qualified for use in preclinical studies by the FDA and EMA. Subsequently, kits have been developed to measure these urinary biomarkers on multiplex platforms such as the electro-chemiluminescent based immunoassay from MesoScale Discovery (MSD) and the bead-based immunoassay using Luminex xMAP technology (LMX). The aim of the present study was to compare the two multiplex platforms with respect to the capability of their qualified urinary biomarker panels to measure an increase of these biomarkers relative to histopathological changes in an animal model of nephrotoxicity. METHODS For comparison of the two platforms we used urine samples from a study with the well-characterized nephrotoxin cisplatin (Cp) in male Wistar rats. The following five biomarkers were measured on both platforms: glutathione S-transferase α (αGST), clusterin (CLU), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL, a.k.a. lipocalin-2) and osteopontin (OPN). The measurements were compared with respect to both the fold increase observed for each biomarker and the absolute concentrations measured in relation to traditional endpoints for nephrotoxicity in clinical pathology and histopathology. RESULTS The platform comparison revealed the expected increases of urinary biomarkers after Cp treatment with similar results at the fold change level enabling consistent detection of kidney injury. The comparison of the absolute concentrations of biomarkers measured in the two platforms showed differences, the extent of which was analyte-dependent. DISCUSSION By comparison of two widely used multiplex platforms, MSD and LMX, for the detection of renal toxicity biomarkers in urine, we observed the expected increases of these biomarkers in response to Cp administration. Depending on the marker, significant differences could be found when comparing the absolute concentrations thus suggesting that baseline levels for each platform will have to be set separately.

In Vivo Pig-a gene mutation assay: Guidance for 3Rs-friendly implementation

The rodent Pig‐a assay is an in vivo method for the detection of gene mutation, where lack of glycosylphosphatidylinositol‐anchored proteins on the surface of circulating red blood cells (RBCs) serves as a reporter for Pig‐a gene mutation. In the case of rats, the frequency of mutant phenotype RBCs is measured via fluorescent anti‐CD59 antibodies and flow cytometry. The Pig‐a assay meets the growing expectations for novel approaches in animal experimentation not only focusing on the scientific value of the assay but also on animal welfare aspects (3Rs principles), for example, amenable to integration into pivotal rodent 28‐day general toxicology studies. However, as recommended in the Organisation for Economic Co‐operation and Development Test Guidelines for genotoxicity testing, laboratories are expected to demonstrate their proficiency. While this has historically involved the extensive use of animals, here we describe an alternative approach based on a series of blood dilutions covering a range of mutant frequencies. The experiments described herein utilized either non‐fluorescent anti‐CD59 antibodies to provide elevated numbers of mutant‐like cells, or a low volume blood sample from a single N‐ethyl‐N‐nitrosourea treated animal. Results from these so‐called reconstruction experiments from four independent laboratories showed good overall precision (correlation coefficients: 0.9979–0.9999) and accuracy (estimated slope: 0.71–1.09) of mutant cell scoring, which was further confirmed by Bland–Altman analysis. These data strongly support the use of reconstruction experiments for training purposes and demonstrating laboratory proficiency with very few animals, an ideal situation given the typically conflicting goals of demonstrating laboratory proficiency and reducing the use of animals. Environ. Mol. Mutagen. 57:678–686, 2016.

Abstract 3090: Novel Mps1 kinase inhibitors with potent anti-tumor activity

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Cell cycle deregulation represents one of the hallmarks of cancer and consequently cell cycle arrest is the predominant mode of action for a number of antimitotic cancer drugs (e.g. taxanes and vinca alkaloids). Targeted disruption of the cell cycle checkpoint offers a novel approach to cancer treatment since tumor cells will not arrest in mitosis despite DNA damage or unattached/misattached chromosomes resulting in aneuploidy and cell death. Mps1, a mitotic kinase that is overexpressed in several human cancers, has been shown to function as the key kinase which activates the spindle assembly checkpoint (SAC) to secure proper distribution of chromosomes to daughter cells. Here, we disclose for the first time the structure and functional characterization of two novel Mps1 inhibitors, BAY 1161909 and BAY 1217389, derived from structurally distinct chemical classes. BAY 1161909 and BAY 1217389 inhibited Mps1 kinase activity with IC50 values below 10 nM while showing an excellent selectivity profile against a broad panel of kinases. In cellular mechanistic assays, BAY 1161909 and BAY 1217389 abrogated nocodazole-induced SAC activity, inducing premature exit from mitosis (“mitotic breakthrough”), which results in multinuclearity and tumor cell death. Both compounds efficiently inhibited tumor cell proliferation in vitro (IC50 values in low nanomolar range), showing a similar inhibitory pattern in a broad panel of tumor cell lines. In vivo, the Mps1 inhibitors BAY 1161909 and BAY 1217389 achieved moderate efficacy in monotherapy in tumor xenograft studies (tumor growth inhibition ∼ 50%). However, according to its unique mode of action, when combined with paclitaxel, at the maximum tolerated dose, low doses of Mps1 inhibitor reduced paclitaxel-induced mitotic arrest in line with weakening of SAC activity. Consequently, combination therapy strongly improved efficacy over paclitaxel or Mps1 inhibitor mono-treatment in a broad range of xenograft models including those being intrinsically paclitaxel-insensitive as well as those with acquired paclitaxel resistance. Both Mps1 inhibitors showed good tolerability without adding toxicity to paclitaxel monotherapy. Our findings validate the innovative concept of SAC abrogation and justify clinical proof of concept studies evaluating Mps1 inhibitors BAY 1161909 and BAY 1217389 in combination with antimitotic cancer drugs in order to enhance their efficacy and potentially overcome resistance. BAY 1161909 is currently in a phase I clinical trial ([NCT02138812][1]), start of clinical investigation of BAY 1217389 is planned. To our knowledge BAY 1161909 and BAY 1217389 are the first Mps1 inhibitors in clinical trials. Citation Format: Antje Margret Wengner, Gerhard Siemeister, Marcus Koppitz, Volker Schulze, Dirk Kosemund, Ulrich Klar, Detlef Stoeckigt, Roland Neuhaus, Philip Lienau, Benjamin Bader, Stefan Prechtl, Olaf Doehr, Marian Raschke, Oliver von Ahsen, Cem Elbi, Ingmar Bruns, Martin Michels, Bertolt Kreft, Franz von Nussbaum, Michael Brands, Dominik Mumberg, Karl Ziegelbauer. Novel Mps1 kinase inhibitors with potent anti-tumor activity. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3090. doi:10.1158/1538-7445.AM2015-3090 [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT02138812&atom=%2Fcanres%2F75%2F15_Supplement%2F3090.atom