Joanne Philp

Inhibition of the Cardiomyocyte-Specific Kinase TNNI3K Limits Oxidative Stress, Injury, and Adverse Remodeling in the Ischemic Heart

Blocking the activity of a cardiomyocyte-specific protein kinase with a small-molecule inhibitor reduces oxidative stress, myocyte death, and adverse remodeling in the ischemic heart. Blocking Cardiac Kinase Prevents Heart Damage Restoring blood flow after a heart attack is essential; yet, rapid reperfusion of blood can cause adverse effects on heart cells (cardiomyocytes) via oxidative damage, calcium overload, and inflammation. To limit these effects, Vagnozzi and colleagues developed an inhibitor that targets a cardiomyocyte-specific kinase called TNNI3K, which may be intimately involved in signaling events after ischemia (blockage of blood flow) and reperfusion. The authors first confirmed that TNNI3K is up-regulated in tissues from patients with heart failure who were undergoing transplant. Mice that overexpressed active TNNI3K had larger infarcts than those with an inactive form of the kinase, as well as worse ischemic injury and cardiomyocyte death. Conversely, deletion of Tnni3k reduced infarct size and prevented cardiomyocyte death in mice. From the human tissues, the kinase appeared to be limited to cardiomyocytes, which lends itself to targeted therapy. Vagnozzi et al. administered two different small-molecule inhibitors during reperfusion to mice with ischemic injury and observed a reduction in left ventricle dysfunction, progressive remodeling, and fibrosis (a hardening of the heart tissue). The authors believe that these functional benefits stem from a concomitant reduction in superoxide production, p38 activation, and infarct size. This inhibition strategy will need to be tested in a large-animal model before translation. If successful, it could find immediate application to patients with chronic ischemic cardiomyopathy, where recurrent ischemia is followed by reperfusion. Percutaneous coronary intervention is first-line therapy for acute coronary syndromes (ACS) but can promote cardiomyocyte death and cardiac dysfunction via reperfusion injury, a phenomenon driven in large part by oxidative stress. Therapies to limit this progression have proven elusive, with no major classes of new agents since the development of anti-platelets/anti-thrombotics. We report that cardiac troponin I–interacting kinase (TNNI3K), a cardiomyocyte-specific kinase, promotes ischemia/reperfusion injury, oxidative stress, and myocyte death. TNNI3K-mediated injury occurs through increased mitochondrial superoxide production and impaired mitochondrial function and is largely dependent on p38 mitogen-activated protein kinase (MAPK) activation. We developed a series of small-molecule TNNI3K inhibitors that reduce mitochondrial-derived superoxide generation, p38 activation, and infarct size when delivered at reperfusion to mimic clinical intervention. TNNI3K inhibition also preserves cardiac function and limits chronic adverse remodeling. Our findings demonstrate that TNNI3K modulates reperfusion injury in the ischemic heart and is a tractable therapeutic target for ACS. Pharmacologic TNNI3K inhibition would be cardiac-selective, preventing potential adverse effects of systemic kinase inhibition.

Identification of a sulfonamide series of CCR2 antagonists.

A series of sulfonamide CCR2 antagonists was identified by high-throughput screening. Management of molecular weight and physical properties, in particular moderation of lipophilicity and study of pK(a), yielded highly potent CCR2 antagonists exhibiting good pharmacokinetic properties and improved potency in the presence of human plasma.

Identification of Purines and 7-Deazapurines as Potent and Selective Type I Inhibitors of Troponin I-Interacting Kinase (TNNI3K).

A series of cardiac troponin I-interacting kinase (TNNI3K) inhibitors arising from 3-((9H-purin-6-yl)amino)-N-methyl-benzenesulfonamide (1) is disclosed along with fundamental structure-function relationships that delineate the role of each element of 1 for TNNI3K recognition. An X-ray structure of 1 bound to TNNI3K confirmed its Type I binding mode and is used to rationalize the structure-activity relationship and employed to design potent, selective, and orally bioavailable TNNI3K inhibitors. Identification of the 7-deazapurine heterocycle as a superior template (vs purine) and its elaboration by introduction of C4-benzenesulfonamide and C7- and C8-7-deazapurine substituents produced compounds with substantial improvements in potency (>1000-fold), general kinase selectivity (10-fold improvement), and pharmacokinetic properties (>10-fold increase in poDNAUC). Optimal members of the series have properties suitable for use in in vitro and in vivo experiments aimed at elucidating the role of TNNI3K in cardiac biology and serve as leads for developing novel heart failure medicines.

GSK114: A selective inhibitor for elucidating the biological role of TNNI3K.

A series of selective TNNI3K inhibitors were developed by modifying the hinge-binding heterocycle of a previously reported dual TNNI3K/B-Raf inhibitor. The resulting quinazoline-containing compounds exhibit a large preference (up to 250-fold) for binding to TNNI3K versus B-Raf, are useful probes for elucidating the biological pathways associated with TNNI3K, and are leads for discovering novel cardiac medicines. GSK114 emerged as a leading inhibitor, displaying significant bias (40-fold) for TNNI3K over B-Raf, exceptional broad spectrum kinase selectivity, and adequate oral exposure to enable its use in cellular and in vivo studies.

In vivo activity of an azole series of CCR2 antagonists

Optimisation of a series of biaryl sulphonamides resulted in the identification of compound 14 [corrected] which demonstrated dose-dependent and strain-specific inhibition of monocyte recruitment in a thioglycollate-induced peritonitis model of inflammation. [Formula: see text]. [corrected].

4,6-Diaminopyrimidines as Highly Preferred Troponin I-Interacting Kinase (TNNI3K) Inhibitors.

Structure-guided progression of a purine-derived series of TNNI3K inhibitors directed design efforts that produced a novel series of 4,6-diaminopyrimidine inhibitors, an emerging kinase binding motif. Herein, we report a detailed understanding of the intrinsic conformational preferences of the scaffold, which impart high specificity for TNNI3K. Further manipulation of the template based on the conformational analysis and additional structure-activity relationship studies provided enhancements in kinase selectivity and pharmacokinetics that furnished an advanced series of potent inhibitors. The optimized compounds (e.g., GSK854) are suitable leads for identifying new cardiac medicines and have been employed as in vivo tools in investigational studies aimed at defining the role of TNNI3K within heart failure.