Hartmut Rehwinkel

Characterization of ZK 245186, a novel, selective glucocorticoid receptor agonist for the topical treatment of inflammatory skin diseases

Background and purpose:  Glucocorticoids are highly effective in the therapy of inflammatory diseases. Their value, however, is limited by side effects. The discovery of the molecular mechanisms of the glucocorticoid receptor and the recognition that activation and repression of gene expression could be addressed separately opened the possibility of achieving improved safety profiles by the identification of ligands that predominantly induce repression. Here we report on ZK 245186, a novel, non‐steroidal, low‐molecular‐weight, glucocorticoid receptor‐selective agonist for the topical treatment of inflammatory dermatoses.

Pan-mutant IDH1 inhibitor BAY 1436032 for effective treatment of IDH1 mutant astrocytoma in vivo.

Mutations in codon 132 of isocitrate dehydrogenase (IDH) 1 are frequent in diffuse glioma, acute myeloid leukemia, chondrosarcoma and intrahepatic cholangiocarcinoma. These mutations result in a neomorphic enzyme specificity which leads to a dramatic increase of intracellular d-2-hydroxyglutarate (2-HG) in tumor cells. Therefore, mutant IDH1 protein is a highly attractive target for inhibitory drugs. Here, we describe the development and properties of BAY 1436032, a pan-inhibitor of IDH1 protein with different codon 132 mutations. BAY 1436032 strongly reduces 2-HG levels in cells carrying IDH1-R132H, -R132C, -R132G, -R132S and -R132L mutations. Cells not carrying IDH mutations were unaffected. BAY 1436032 did not exhibit toxicity in vitro or in vivo. The pharmacokinetic properties of BAY 1436032 allow for oral administration. In two independent experiments, BAY 1436032 has been shown to significantly prolong survival of mice intracerebrally transplanted with human astrocytoma carrying the IDH1R132H mutation. In conclusion, we developed a pan-inhibitor targeting tumors with different IDH1R132 mutations.

Identification of novel GLUT inhibitors

The compound class of 1H-pyrazolo[3,4-d]pyrimidines was identified using HTS as very potent inhibitors of facilitated glucose transporter 1 (GLUT1). Extensive structure-activity relationship studies (SAR) of each ring system of the molecular framework was established revealing essential structural motives (i.e., ortho-methoxy substituted benzene, piperazine and pyrimidine). The selectivity against GLUT2 was excellent and initial in vitro and in vivo pharmacokinetic (PK) studies are encouraging.

Discovery of indazole ethers as novel, potent, non-steroidal glucocorticoid receptor modulators.

A structure-based design approach led to the identification of a novel class of indazole ether based, non-steroidal glucocorticoid receptor (GR) modulators. Several examples were identified that displayed cell potency in the picomolar range, inhibiting LPS-induced TNF-α release by primary peripheral blood mononuclear cells (PBMCs). Additionally, an improved steroid hormone receptor binding selectivity profile, compared to classical steroidal GR agonists, was demonstrated. The indazole ether core tolerated a broad range of substituents allowing for modulation of the physiochemical parameters. A small sub-set of indazole ethers, with pharmacokinetic properties suitable for oral administration, was investigated in a rat antigen-induced joint inflammation model and demonstrated excellent anti-inflammatory efficacy.

Discovery of new selective glucocorticoid receptor agonist leads

We report on the discovery of two new lead series for the development of glucocorticoid receptor agonists. Firstly, the discovery of tetrahydronaphthalenes led to metabolically stable and dissociated compounds. Their binding mode to the glucocorticoid receptor could be elucidated through an X-ray structure. Closer inspection into the reaction path and analyses of side products revealed a new amino alcohol series also addressing the glucocorticoid receptor and demonstrating strong anti-inflammatory activity in vitro.

Abstract 2645: BAY 1436032: A highly selective, potent and orally available inhibitor of mutant forms of IDH1

Isocitrate dehydrogenase 1 (IDH1) is a metabolic enzyme that is frequently mutated in certain cancers, with incidence rates ranging from 7-90% for glioma, chondrosarcoma, intrahepatic cholangiocarcinoma and AML. Wildtype IDH1 (wtIDH1) catalyzes the conversion of isocitrate to α-ketoglutarate (αKG), while tumor-associated mutant IDH1 (mIDH1) catalyzes a rogue reaction: the production of 2-hydroxyglutarate (2-HG) from αKG. 2-HG therefore represents an “oncometabolite” that is believed to play a role in cancer by interfering with αKG-dependent enzymes, which in turn causes hypermethylation of histones/DNA and a block of normal cellular differentiation. Mutant IDH1 is a “driver” oncogene and the inhibition of this altered enzyme will decrease the growth of mIDH1 dependent tumors. We report for the first time the preclinical profile and structure of BAY 1436032, a novel selective mIDH1 inhibitor. An optimization program based on a high throughput screening resulted in the identification of the clinical candidate BAY 1436032 for the treatment of mIDH1 dependent cancer. BAY 1436032 is a double-digit nanomolar and selective pan-inhibitor of the enzymatic activity of various IDH1-R132X mutants in vitro and displayed potent inhibition of 2-HG release (nanomolar range) in patient derived and engineered cell lines expressing different IDH1 mutants. In line with the proposed mode of action, a concentration-dependent lowering of 2-HG was observed in vitro accompanied by differentiation and maturation of mIDH1 tumor cells. Furthermore, BAY 1436032 showed a favourable selectivity profile against wtIDH1/2 and a large panel of off-targets in vitro. To the best of our knowledge we were able to show for the first time single agent in vivo efficacy in mIDH1 patient derived glioma and intrahepatic cholangiocarcinoma solid tumor models with this clinical candidate along with monitoring of intratumoral 2-HG levels as a predictive biomarker. The BBB penetration profile of BAY 1436032 is further supported by preclinical data on in vivo brain-plasma ratios. In conclusion, our data provide in vitro and in vivo proof of concept for BAY 1436032 as a potent and highly selective inhibitor of mutant forms of IDH1. The start of a Phase I study with BAY 1436032 is currently in preparation to determine the safety, tolerability, pharmacokinetics and preliminary anti-tumor and pharmacodynamic biomarker responses in patients with solid tumors. Citation Format: Olaf Panknin, Stefan Pusch, Lena Herbst, Stefan Kaulfuss, Katja Zimmermann, Hartmut Rehwinkel, Roland Neuhaus, Sven Ring, Michael Bruning, Claudia Stark, Katja Prelle, Martin Michels, Michael Jeffers, Holger Hess-Stumpp, Karl Ziegelbauer, Michael Brands, Alwin Kramer, Andreas von Deimling. BAY 1436032: A highly selective, potent and orally available inhibitor of mutant forms of IDH1. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2645.

Abstract 3355: Inhibiting glyoxylase 1 as a strategy to target highly glycolytic cancer cells

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Cancer cells typically display altered glucose metabolism characterized by a preference of aerobic glycolysis (Warburg effect) resulting in higher levels of glycolytic waste including methylglyoxal (MG). GLO1 (Glyoxalase 1) functions in the detoxification of MG: MG reacts with glutathione to form hemithioacetal, which is converted into S-D-Lactoylglutathione by GLO1 and further metabolised into D-lactate by GLO2. When not detoxified, MG acts as a cytotoxic reagent by forming DNA- and protein-adducts (advanced glycation end products = AGEs) that subsequently lead to cell death. Therefore, GLO1 has been discussed as a potential anti-tumor target for highly glycolytic cancers. We confirmed previous reports that GLO1 expression is elevated in several tumor entities as compared to normal tissue. Tumor cells with high GLO1 expression levels are proposed to be highly dependent on GLO1 for removal of toxic MG. Therefore sensitivity to GLO1 inhibition was probed in a panel of cell lines covering lung, colon, breast, prostate and skin cancer with varying GLO1 amplification and expression levels. siRNA-mediated knock down of GLO1 did neither cause significant reduction of cellular proliferation nor significant induction of apoptosis in any of the tested tumor cells. Furthermore, treatment of these cells with a potent GLO1 inhibitor (Chiba et al. Bioorg Med Chem Lett. 2012, IC50=11 nM) did not affect proliferation or induce apoptosis at sub-µM concentrations. In addition, no increase in AGEs upon GLO1 inhibition could be detected by western blot. Activity of the GLO1 inhibitor was further tested under conditions expected to increase endogenous MG levels such as hypoxia and elevated glucotriose (via GAPDH inhibition). Furthermore, a spheroid assay was developed to test the GLO1 inhibitor in a 3D assay system, better reflecting in vivo tumor growth. Even under hypoxic or spheroidal assay conditions, proliferation of cancer cells could not be reduced upon GLO1 inhibition. We could demonstrate however that GLO1 inhibition in A375 melanoma and SW620 colon adenocarcinoma cells sensitized the cells to exogenous MG. Taken together we could not confirm earlier published data that GLO1 inhibition leads to reduced proliferation and induction of apoptosis in cancer cells that have elevated GLO1 expression levels. Being aware that cellular systems may not reflect the situation in vivo, we speculate that GLO1 function alone may be redundant in detoxifying MG. Other possible enzymes which have been linked to MG removal include aldose reductase. Simultaneous inhibition of both enzymes might be a strategy to target highly glycolytic cancers in the future. Citation Format: Sylvia Gruenewald, Michael Steckel, Andreas Timmermann, Hartmut Rehwinkel, Patrick Steigemann, Sylvia Zacharias, Alexander Walter, Marcus Bauser, Andrea Haegebarth. Inhibiting glyoxylase 1 as a strategy to target highly glycolytic cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3355. doi:10.1158/1538-7445.AM2014-3355