Discovery of BAY-298 and BAY-899: Tetrahydro-1,6-naphthyridine-Based, Potent, and Selective Antagonists of the Luteinizing Hormone Receptor Which Reduce Sex Hormone Levels in Vivo

The human luteinizing hormone receptor (hLH-R) is a member of the glycoprotein hormone family of G-protein-coupled receptors (GPCRs), activated by luteinizing hormone (hLH) and essentially involved in the regulation of sex hormone production. Thus, hLH-R represents a valid target for the treatment of sex hormone-dependent cancers and diseases (polycystic ovary syndrome, uterine fibroids, endometriosis) as well as contraception. Screening of the Bayer compound library led to the discovery of tetrahydrothienopyridine derivatives as novel, small-molecule (SMOL) hLH-R inhibitors and to the development of BAY-298, the first nanomolar hLH-R antagonist reducing sex hormone levels in vivo. Further optimization of physicochemical, pharmacokinetic, and safety parameters led to the identification of BAY-899 with an improved in vitro profile and proven efficacy in vivo. BAY-298 and BAY-899 serve as valuable tool compounds to study hLH-R signaling in vitro and to interfere with the production of sex hormones in vivo.

Novel TIE-2 inhibitor BAY-826 displays in vivo efficacy in experimental syngeneic murine glioma models

Targeting the vascular endothelial growth factor signaling axis in glioblastoma inevitably leads to tumor recurrence and a more aggressive phenotype. Therefore, other angiogenic pathways, like the angiopoietin/tunica interna endothelial cell kinase (TIE) signaling axis, have become additional targets for therapeutic intervention. Here, we explored whether targeting the receptor tyrosine kinase TIE-2 using a novel, highly potent, orally available small molecule TIE-2 inhibitor (BAY-826) improves tumor control in syngeneic mouse glioma models. BAY-826 inhibits TIE-2 phosphorylation in vitro and in vivo as demonstrated by suppression of Angiopoietin-1- or Na₃ VO₄ -induced TIE-2 phosphorylation in glioma cells or extracts of lungs from BAY-826-treated mice. There was a trend toward prolonged survival upon single-agent treatment in two of four models (SMA-497 and SMA-540) and there was a significant survival benefit in one model (SMA-560). Co-treatment with BAY-826 and irradiation was ineffective in one model (SMA-497), but provided synergistic prolongation of survival in another (SMA-560). Decreased vessel densities and increased leukocyte infiltration were observed, but might be independent processes as the effect was also observed in single treatment modalities. These data demonstrate that TIE-2 inhibition may improve tumor response to treatment in highly vascularized tumors such as glioblastoma.

Delineation of experimental liver tumors in rabbits by a new ultrasound contrast agent and stimulated acoustic emission

RATIONALE AND OBJECTIVES

A new ultrasound contrast agent (SH U 563 A), consisting of hollow biodegradable polymeric microparticles, and a new imaging technique (stimulated acoustic emission) were used for delineation of experimental liver tumors. After intravenous injection, these microparticles are phagocytosed by cells of the reticuloendothelial system (RES) and create a color-coded signal using color Doppler. Because of the different distribution of phagocytic cells in healthy liver tissue and tumors, the delineation of focal lesions was to be tested.

METHODS

Sixteen rabbits with VX2 liver tumors received doses of 0.15-mL SH U 563 A per kilogram of body weight intravenously. Liver investigations (UM9, HD1, L10.5, ATL, Bothell, USA) were performed in vivo before and after SH U 563 A application in B and color Doppler modes. Additionally, the liver and spleen of these rabbits were examined ex vivo in color Doppler. The sonographic diagnosis was confirmed by pathology.

RESULTS

After application of SH U 563 A, the healthy liver tissue of all rabbits was characterized by a typical mosaic color pattern in vivo and ex vivo, using color Doppler. Entire VX2 liver tumors were detectable exclusively in color Doppler after SH U 563 A application. This was possible in 14 of 16 rabbits in vivo and in all 16 livers ex vivo. Furthermore, all ex vivo investigated spleens were color enhanced homogeneously. Sonographic diagnoses were in accordance with pathologic findings.

CONCLUSIONS

SH U 563 A, combined with stimulated acoustic emission, provides potential for delineation of small isoechogenic liver lesions by sonography.