Discovery and synthesis of novel 4-aminopyrrolopyrimidine Tie-2 kinase inhibitors for the treatment of solid tumors.

The synthesis and biological evaluation of novel Tie-2 kinase inhibitors are presented. Based on the pyrrolopyrimidine chemotype, several new series are described, including the benzimidazole series by linking a benzimidazole to the C5-position of the 4-amino-pyrrolopyrimidine core and the ketophenyl series synthesized by incorporating a ketophenyl group to the C5-position. Medicinal chemistry efforts led to potent Tie-2 inhibitors. Compound 15, a ketophenyl pyrrolopyrimidine urea analog with improved physicochemical properties, demonstrated favorable in vitro attributes as well as dose responsive and robust oral tumor growth inhibition in animal models.

The Hedgehog signaling pathway as a target for anticancer drug discovery.

The Hedgehog (Hh) signaling pathway directs the development of multiple tissues during embryonic development, and contributes to tissue homeostasis in adults. Deficient Hh signaling results in defective embryogenesis; conversely, excessive Hh signaling is associated with an inherited cancer predisposition syndrome (Gorlin Syndrome), and a growing list of sporadic human cancers. It is now clear that multiple components of "The Hh Pathway" can be altered in tumors. The Hhs are morphogens that signal through effectors that are largely unprecedented in drug discovery, with many key concepts derived from studies in Drosophila melanogaster. However, studies in tumor cell lines have recently identified targets that can be exploited for the discovery of human Hh antagonists, with additional targets likely to emerge as the human pathway is further defined. Here, we review basic aspects of Hh signal transduction, with an emphasis on molecular targets for drug discovery. The use of first-generation Hh antagonists such as cyclopamine will also be discussed; such agents remain invaluable in ongoing efforts to validate drug discovery assays and survey tumor lines for Hh dependence. The various types and frequencies of Hh signaling defects in different human tumors will also be reviewed, as will the status of medicinal chemistry efforts to discover novel Hh antagonists. In section VI, we review assays from the literature that could be utilized to discover new Hh antagonists for the treatment of cancer.

Discovery of PF-04449913, a Potent and Orally Bioavailable Inhibitor of Smoothened.

Inhibitors of the Hedgehog signaling pathway have generated a great deal of interest in the oncology area due to the mounting evidence of their potential to provide promising therapeutic options for patients. Herein, we describe the discovery strategy to overcome the issues inherent in lead structure 1 that resulted in the identification of Smoothened inhibitor 1-((2R,4R)-2-(1H-benzo[d]imidazol-2-yl)-1-methylpiperidin-4-yl)-3-(4-cyanophenyl)urea (PF-04449913, 26), which has been advanced to human clinical studies.

Biochemical and pharmacological characterization of human c-Met neutralizing monoclonal antibody CE-355621.

The c-Met proto-oncogene is a multifunctional receptor tyrosine kinase that is stimulated by its ligand, hepatocyte growth factor (HGF), to induce cell growth, motility and morphogenesis. Dysregulation of c-Met function, through mutational activation or overexpression, has been observed in many types of cancer and is thought to contribute to tumor growth and metastasis by affecting mitogenesis, invasion, and angiogenesis. We identified human monoclonal antibodies that bind to the extracellular domain of c-Met and inhibit tumor growth by interfering with ligand-dependent c-Met activation. We identified antibodies representing four independent epitope classes that inhibited both ligand binding and ligand-dependent activation of c-Met in A549 cells. In cells, the antibodies antagonized c-Met function by blocking receptor activation and by subsequently inducing downregulation of the receptor, translating to phenotypic effects in soft agar growth and tubular morphogenesis assays. Further characterization of the antibodies in vivo revealed significant inhibition of c-Met activity (≥ 80% lasting for 72-96 h) in excised tumors corresponded to tumor growth inhibition in multiple xenograft tumor models. Several of the antibodies identified inhibited the growth of tumors engineered to overexpress human HGF and human c-Met (S114 NIH 3T3) when grown subcutaneously in athymic mice. Furthermore, lead candidate antibody CE-355621 inhibited the growth of U87MG human glioblastoma and GTL-16 gastric xenografts by up to 98%. The findings support published pre-clinical and clinical data indicating that targeting c-Met with human monoclonal antibodies is a promising therapeutic approach for the treatment of cancer.