Katja Prelle

Effects of estrogen, an ERα agonist and raloxifene on pressure overload induced cardiac hypertrophy.

The aim of this study was to investigate the effects of 17β-estradiol (E2), the selective ERα agonist 16α-LE2, and the selective estrogen receptor modulator (SERM) raloxifene on remodeling processes during the development of myocardial hypertrophy (MH) in a mouse model of pressure overload. Myocardial hypertrophy in ovariectomized female C57Bl/6J mice was induced by transverse aortic constriction (TAC). Two weeks after TAC, placebo treated mice developed left ventricular hypertrophy and mild systolic dysfunction. Estrogen treatment, but not 16α-LE2 or raloxifene reduced TAC induced MH compared to placebo. E2, 16α-LE2 and raloxifene supported maintenance of cardiac function in comparison with placebo. Nine weeks after induction of pressure overload, MH was present in all TAC groups, most pronounced in the raloxifene treated group. Ejection fraction (EF) was decreased in all animals. However, 16α-LE2 treated animals showed a smaller reduction of EF than animals treated with placebo. E2 and 16α-LE2, but not raloxifene diminished the development of fibrosis and reduced the TGFβ and CTGF gene expression. Treatment with E2 or 16α-LE2 but not with raloxifene reduced survival rate after TAC significantly in comparison with placebo treatment. In conclusion, E2 and 16α-LE2 slowed down the progression of MH and reduced systolic dysfunction after nine weeks of pressure overload. Raloxifene did not reduce MH but improved cardiac function two weeks after TAC. However, raloxifene was not able to maintain EF in the long term period.

Characterization of anastrozole effects, delivered by an intravaginal ring in cynomolgus monkeys

STUDY QUESTION Is it feasible to deliver anastrozole (ATZ), an aromatase inhibitor (AI), by a vaginal polymer-based drug delivery system in the cynomolgus monkey (Macaca fascicularis) to describe the pharmacokinetic profile? SUMMARY ANSWER The present study showed the effective release of ATZ into the systemic circulation from intravaginal rings in cynomolgus monkeys. WHAT IS KNOWN ALREADY ATZ is a marketed drug with well documented pharmacological and safety profiles for oral administration. Aromatase is the key enzyme catalyzing estrogen biosynthesis and is overexpressed in endometriotic lesions. AIs show therapeutic efficacy in endometriosis in exploratory clinical trials. STUDY DESIGN, SIZE, DURATION The pharmacokinetics of the in vivo release and the pharmacodynamic activity of ATZ released by intravaginal rings (IVR) were investigated in healthy cycling female cynomolgus monkeys in three different dose groups (n = 5) for one menstrual cycle. PARTICIPANTS/MATERIALS, SETTING, METHODS IVRs for the cynomolgus monkey, releasing three different doses of ATZ were designed and tested for in vitro/in vivo release for up to 42 days. For pharmacokinetic and pharmacodynamic evaluation, plasma samples were taken once daily from Day 1 to 3 and then every third day until menses occurred (17-42 days). MAIN RESULTS AND THE ROLE OF CHANCE ATZ was shown to be compatible with the IVR drug delivery system. An average in vivo release of 277 µg/day/animal of ATZ for one menstrual cycle was effective in causing a decrease of systemic estradiol (E₂) levels by ∼30% without inducing counter regulation such as the elevation of FSH or the formation of ovarian cysts. LIMITATIONS, REASONS FOR CAUTION The study was limited to three dose groups in which only the highest dose decreased the E₂ level. Hence, additional research with IVRs releasing higher amounts of ATZ is required to define the threshold for an ATZ-dependent ovarian stimulation in cynomolgus monkeys. WIDER IMPLICATIONS OF THE FINDINGS The release rate administered from IVRs is sufficient and in a range that supports feasibility of IVR administration of ATZ as a new approach for long-term therapy of estrogen-dependent diseases such as endometriosis in human.

Abstract 2828: Rapid identification of potent and highly selective, oral PTEFb Inhibitor BAY 1143572 with first in class potential

PTEFb (positive transcription elongation factor b) is a heterodimer of the transcriptional control kinase CDK9 (Cyclin-dependent kinase 9) and Cyclin T. PTEFb phosphorylates and activates RNA polymerase II. PTEFb inhibition causes rapid depletion of short-lived mRNA transcripts and their associated protein products involved in proliferation and survival like Myc, or Mcl-1 which results in cell death of addicted tumor cells. We previously disclosed the profile of the lead compound PTEFb BAY1, a nanomolar PTEFb inhibitor with 50-fold selectivity within the CDK family and cellular potency of about 1 μM in proliferation assays on various human tumor cell lines [1]. PTEFb BAY1 also revealed in vivo efficacy in a human acute myeloid leukemia (AML) xenograft model in nude mice. However, the lead compound also displayed certain limitations in ADME properties like low aqueous solubility and a strong recognition by efflux transporters in the Caco2 assay. Based on these findings, extensive lead optimisation efforts led to the rapid identification of BAY 1143572 which is a more potent and highly selective, orally available PTEFb inhibitor with first-in-class potential. BAY 1143572 has a high aqueous solubility, reduced drug efflux and a moderate oral bioavailability across species that allows daily as well as intermittent dosing schedules in animal models. BAY 1143572 revealed strong in vitro and in vivo anti-tumor efficacy with various cell-lines. BAY 1143572 is currently being evaluated in a Phase I study to determine the safety, tolerability, pharmacokinetics and initial pharmacodynamic biomarker response in patients with advanced cancer. This presentation will highlight the key learnings from our PTEFb lead optimization program. [1]: AACR, April 5-9, 2014, San Diego, Poster Presentation, Abstract 4538, Cancer Res October 1, 2014, 74:4538; doi:10.1158/1538-7445.AM2014-4538 Citation Format: Ulrich TJ Luecking, Arne Scholz, Philip Lienau, Gerhard Siemeister, Dirk Kosemund, Rolf Bohlmann, Knut Eis, Mark Gnoth, Ildiko Terebesi, Kirstin Meyer, Katja Prelle, Ray Valencia, Stuart Ince, Franz von Nussbaum, Dominik Mumberg, Karl Ziegelbauer, Bert Klebl, Axel Choidas, Peter Nussbaumer, Matthias Baumann, Carsten Schultz-Fademrecht, Gerd Ruehter, Jan Eickhoff, Michael Brands. Rapid identification of potent and highly selective, oral PTEFb Inhibitor BAY 1143572 with first in class potential. [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 2828. doi:10.1158/1538-7445.AM2015-2828

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 984: Identification of potent and highly selective PTEFb inhibitor BAY 1251152 for the treatment of cancer: from p.o. to i.v. application via scaffold hops

PTEFb/CDK9 mediated transcription of short-lived anti-apoptotic survival proteins like Mcl-1 and Myc plays a critical role in cancer cell growth and survival in various tumor entities including AML. In addition, these survival proteins play important roles in the development of resistance to chemotherapy. We previously disclosed the preclinical profile of BAY 1143572, the first selective, orally available PTEFb/CDK9 inhibitor that entered clinical development [1-3]. BAY 1143572 had low nanomolar activity against PTEFb/CDK9, an at least 50-fold selectivity against other CDKs in enzymatic assays and broad anti-proliferative activity against a panel of tumour cell lines with sub-micromolar IC50 values. BAY 1143572 also showed single agent in vivo efficacy at tolerated doses in various xenograft tumour models in mice and rats upon once daily oral administration. To fully explore future treatment options using selective PTEFb/CDK9 inhibitors we initiated a follow-up program to identify novel PTEFb/CDK9 inhibitors for treatment of cancer with increased potency enabling i.v. treatment of patients. Extensive lead optimisation efforts, including various scaffold hops, led to the identification of BAY 1251152. In comparison to oral BAY 1143572, BAY 1251152 shows significantly increased biochemical (IC50 CDK9 = 3 nM) and cellular potency (IC50 MOLM13 = 29 nM), increased selectivity against CDK2 as well as high permeability and no efflux. The significantly reduced therapeutic dose and high solubility of BAY 1251152 enable the desired i.v. application. BAY 1251152 demonstrated excellent efficacy upon i.v. treatment in xenograft models (e.g. MOLM13) in mice and rats. BAY 1251152 is currently being evaluated in Phase I studies (NCT02635672; NCT02745743) to determine the safety, tolerability, pharmacokinetics and initial pharmacodynamic biomarker response in patients with advanced cancer. This presentation will highlight the key learnings from our PTEFb/CDK9 i.v. lead optimization program and disclose the structure of BAY 1251152 for the first time. [1]: 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 3022. [2]: 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 DDT02-02. doi:10.1158/1538-7445.AM2015-DDT02-02. [3]: 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 2828. doi:10.1158/1538-7445.AM2015-2828 Citation Format: Ulrich T. Luecking, Arne Scholz, Dirk Kosemund, Rolf Bohlmann, Hans Briem, Philip Lienau, Gerhard Siemeister, Ildiko Terebesi, Kirstin Meyer, Katja Prelle, Ray Valencia, Stuart Ince, Franz von Nussbaum, Dominik Mumberg, Karl Ziegelbauer, Michael Brands. Identification of potent and highly selective PTEFb inhibitor BAY 1251152 for the treatment of cancer: from p.o. to i.v. application via scaffold hops [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 984. doi:10.1158/1538-7445.AM2017-984