RIP2 kinase is a central component of the innate immune system and enables downstream signaling following activation of the pattern recognition receptors NOD1 and NOD2, leading to the production of inflammatory cytokines. Recently, several inhibitors of RIP2 kinase have been disclosed that have contributed to the fundamental understanding of the role of RIP2 in this pathway. However, because they lack either broad kinase selectivity or strong affinity for RIP2, these tools have only limited utility to assess the role of RIP2 in complex environments. We present, herein, the discovery and pharmacological characterization of GSK583, a next-generation RIP2 inhibitor possessing exquisite selectivity and potency. Having demonstrated the pharmacological precision of this tool compound, we report its use in elucidating the role of RIP2 kinase in a variety of in vitro, in vivo, and ex vivo experiments, further clarifying our understanding of the role of RIP2 in NOD1 and NOD2 mediated disease pathogenesis.

Transient Receptor Potential Vanilloid 4 (TRPV4) is a member of the Transient Receptor Potential (TRP) superfamily of cation channels. TRPV4 is expressed in the vascular endothelium in the lung and regulates the integrity of the alveolar septal barrier. Increased pulmonary vascular pressure evokes TRPV4-dependent pulmonary edema, and therefore, inhibition of TRPV4 represents a novel approach for the treatment of pulmonary edema associated with conditions such as congestive heart failure. Herein we report the discovery of an orally active, potent, and selective TRPV4 blocker, 3-(1,4'-bipiperidin-1'-ylmethyl)-7-bromo--(1-phenylcyclopropyl)-2-[3-(trifluoromethyl)phenyl]-4-quinolinecarboxamide (GSK2193874, ) after addressing an unexpected off-target cardiovascular liability observed from studies. GSK2193874 is a selective tool for elucidating TRPV4 biology both and .

RIP2 kinase was recently identified as a therapeutic target for a variety of autoimmune diseases. We have reported previously a selective 4-aminoquinoline-based RIP2 inhibitor GSK583 and demonstrated its effectiveness in blocking downstream NOD2 signaling in cellular models, rodent in vivo models, and human ex vivo disease models. While this tool compound was valuable in validating the biological pathway, it suffered from activity at the hERG ion channel and a poor PK/PD profile thereby limiting progression of this analog. Herein, we detail our efforts to improve both this off-target liability as well as the PK/PD profile of this series of inhibitors through modulation of lipophilicity and strengthening hinge binding ability. These efforts have led to inhibitor 7, which possesses high binding affinity for the ATP pocket of RIP2 (IC 50 = 1 nM) and inhibition of downstream cytokine production in human whole blood (IC 50 = 10 nM) with reduced hERG activity (14 μM).

RIP2 kinase has been identified as a key signal transduction partner in the NOD2 pathway contributing to a variety of human pathologies, including immune-mediated inflammatory diseases. Small-molecule inhibitors of RIP2 kinase or its signaling partners on the NOD2 pathway that are suitable for advancement into the clinic have yet to be described. Herein, we report our discovery and profile of the prodrug clinical compound, inhibitor 3, currently in phase 1 clinical studies. Compound 3 potently binds to RIP2 kinase with good kinase specificity and has excellent activity in blocking many proinflammatory cytokine responses in vivo and in human IBD explant samples. The highly favorable physicochemical and ADMET properties of 3 combined with high potency led to a predicted low oral dose in humans.