Synthesis of novel anilinoquinolines as c-fms inhibitors

Recent advances in colony stimulating factor-1 receptor/c-FMS as an emerging target for various therapeutic implications

Colony stimulating factor-1 (CSF-1) is one of the most common proinflammatory cytokine responsible for various inflammatory disorders. It has a remarkable role in the development and progression of osteoarthritis, cancer and other autoimmune disease conditions. The CSF-1 acts by binding to the receptor, called colony stimulating factor-1 receptor (CSF-1R) also known as c-FMS resulting in the cascade of signalling pathway causing cell proliferation and differentiation. Interleukin-34 (IL-34), recently identified as another ligand for CSF-IR, is a cytokine protein. Both, CSF-1 and IL-34, although two distinct cytokines, follow the similar signalling pathway on binding to the same receptor, CSF-1R. Like CSF-1, IL-34 promotes the differentiation and survival of monocyte, macrophages and osteoclasts. This CSF-1R/c-FMS is over expressed in many cancers and on tumour associated macrophages, consequently, have been exploited as a drug target for promising treatment for cancer and inflammatory diseases. Some CSF-1R/c-FMS inhibitors such as ABT-869, Imatinib, AG013736, JNJ-40346527, PLX3397, DCC-3014 and Ki20227 have been successfully used in these disease conditions. Many c-FMS inhibitors have been the candidates of clinical trials, but suffer from some side effects like cardiotoxicity, vomiting, swollen eyes, diarrhoea, etc. If selectivity of cFMS inhibition is achieved successfully, side effects can be overruled and this approach may become a novel therapy for treatment of various therapeutic interventions. Thus, successful targeting of c-FMS may result in multifunctional therapy. With this background of information, the present review focuses on the recent developments in the area of CSF-1R/c-FMS inhibitors with emphasis on crystal structure, mechanism of action and various therapeutic implications in which c-FMS plays a pivotal role. The review on structure activity relationship of various compounds acting as the inhibitors of c-FMS which gives the selection criteria for the development of novel molecules is also being presented.

Novel cinnoline-based inhibitors of LRRK2 kinase activity

Leucine rich repeat kinase 2 (LRRK2) has been implicated in the pathogenesis of Parkinson's disease (PD). Inhibition of LRRK2 kinase activity is a therapeutic approach that may lead to new treatments for PD. Herein we report the discovery of a series of cinnoline-3-carboxamides that are potent against both wild-type and mutant LRRK2 kinase activity in biochemical assays. These compounds are also shown to be potent inhibitors in a cellular assay and to have good to excellent CNS penetration.

FMS Kinase Inhibitors: Current Status and Future Prospects

FMS, first discovered as the oncogene responsible for Feline McDonough Sarcoma, is a type III receptor tyrosine kinase that binds to the macrophage or monocyte colony-stimulating factor (M-CSF or CSF-1). Signal transduction through that binding results in survival, proliferation, and differentiation of monocyte/macrophage lineage. Overexpression of CSF-1 and/or FMS has been implicated in a number of disease states such as the growth of metastasis of certain types of cancer, in promoting osteoclast proliferation in bone osteolysis, and many inflammatory disorders. Inhibition of CSF-1 and/or FMS may help treat these pathological conditions. This article reviews FMS gene, FMS kinase, CSF-1, IL-34, and their roles in bone osteolysis, cancer biology, and inflammation. Monoclonal antibodies, FMS crystal structure, and small molecule FMS kinase inhibitors of different chemical scaffolds are also reviewed.

Functional CSF-1 receptors are located at the nuclear envelope and activated via the p110δ isoform of PI 3-kinase

Colony stimulating factor-1 (CSF-1) and its receptor (CSF-1R) are key regulators of macrophage biology, and their elevated expression in cancer cells has been linked to poor prognosis. CSF-1Rs are thought to function at the plasma membrane. We show here that functional CSF-1Rs are present at the nuclear envelope of various cell types, including primary macrophages, human cancer cell lines, and primary human carcinomas. In response to CSF-1, added to intact cells or isolated nuclei, nucleus-associated CSF-1R became phosphorylated and triggered the phosphorylation of Akt and p27 inside the nucleus. Extracellularly added CSF-1 was also found to colocalize with nucleus-associated CSF-1Rs. All these activities were found to depend selectively on the activity of the p110δ isoform of phosphoinositide 3-kinase (PI3K). This finding was related to the p110δ-dependent translocation of exogenous CSF-1 to the nucleus-associated CSF-1Rs, correlating with a prominent role of p110δ in activation of the Rab5 GTPase, a key regulator of the endocytic trafficking. siRNA-silencing of Rab5a phenocopied p110δ inactivation and nuclear CSF-1 signaling. Our work demonstrates for the first time the presence of functional nucleus-associated CSF-1Rs, which are activated by extracellular CSF-1 by a mechanism that involves p110δ and Rab5 activity. These findings may have important implications in cancer development.

c-FMS inhibitors: a patent review

INTRODUCTION

Macrophages are key drivers of both the innate and adaptive immune systems. The cellular receptor for CSF-1 and IL-34, c-FMS, is a key component of the mechanism(s) by which macrophages are regulated. Several drug discovery programs aimed at uncovering inhibitors of the tyrosine kinase activity of this receptor are now entering clinical phase, and the prospect of readjusting the behavior of macrophages in a number of pathological situations, such as inflammation and cancer, is now on us.

AREAS COVERED

In this review, we evaluate the available patent literature on the topic of small molecule inhibitors of c-FMS. By way of background, we review the biology of c-FMS and make an analysis of the therapeutic opportunities that a small molecule c-FMS inhibitor might present. In order to place the pharmacology in perspective, we examine the literature concerning the role of the CSF-1-IL-34-c-FMS axis in macrophage function as well as cell types related to macrophages, such as the osteoclast, the dendritic cell and microglia, and provide a background to the understanding of the therapeutic opportunities for c-FMS inhibitors as well as potential obstacles that could limit their use.

EXPERT OPINION

The c-FMS receptor is a hot target for the development of novel regulators of macrophage behavior. Some nice candidates have been developed by a number of groups, and their recent entry into clinical phase testing means that we are now on the cusp of a fuller understanding of the role of these important regulators of the innate and adaptive immune systems in the development of cancer and inflammatory diseases.

Discovery of 2-(alpha-methylbenzylamino) pyrazines as potent Type II inhibitors of FMS

A series of 2-(alpha-methylbenzylamino) pyrazines have shown to be potent inhibitors of the FMS tyrosine receptor kinase. Details of SAR studies, modeling and synthesis of compounds within this series are reported.

Pyridyl and thiazolyl bisamide CSF-1R inhibitors for the treatment of cancer

The bisamide class of kinase inhibitors was identified as being active against CSF-1R. The synthesis and SAR of pyridyl and thiazolyl bisamides are reported, along with the pharmacokinetic properties and in vivo activity of selected examples.