Karl Miranda

A novel kinase inhibitor establishes a predominant role for protein kinase D as a cardiac class IIa histone deacetylase kinase

Class IIa histone deacetylases (HDACs) repress genes involved in pathological cardiac hypertrophy. The anti‐hypertrophic action of class IIa HDACs is overcome by signals that promote their phosphorylation‐dependent nuclear export. Several kinases have been shown to phosphorylate class IIa HDACs, including calcium/calmodulin‐dependent protein kinase (CaMK), protein kinase D (PKD) and G protein‐coupled receptor kinase (GRK). However, the identity of the kinase(s) responsible for phosphorylating class IIa HDACs during cardiac hypertrophy has remained controversial. We describe a novel and selective small molecule inhibitor of PKD, bipyridyl PKD inhibitor (BPKDi). BPKDi blocks signal‐dependent phosphorylation and nuclear export of class IIa HDACs in cardiomyocytes and concomitantly suppresses hypertrophy of these cells. These studies define PKD as a principal cardiac class IIa HDAC kinase.

Identification of Orally Available Naphthyridine Protein Kinase D Inhibitors

A novel 2,6-naphthyridine was identified by high throughput screen (HTS) as a dual protein kinase C/D (PKC/PKD) inhibitor. PKD inhibition in the heart was proposed as a potential antihypertrophic mechanism with application as a heart failure therapy. As PKC was previously identified as the immediate upstream activator of PKD, PKD vs PKC selectivity was essential to understand the effect of PKD inhibition in models of cardiac hypertrophy and heart failure. The present study describes the modification of the HTS hit to a series of prototype pan-PKD inhibitors with routine 1000-fold PKD vs PKC selectivity. Example compounds inhibited PKD activity in vitro, in cells, and in vivo following oral administration. Their effects on heart morphology and function are discussed herein.

Identification of Potent and Selective Amidobipyridyl Inhibitors of Protein Kinase D

The synthesis and biological evaluation of potent and selective PKD inhibitors are described herein. The compounds described in the present study selectively inhibit PKD among other putative HDAC kinases. The PKD inhibitors of the present study blunt phosphorylation and subsequent nuclear export of HDAC4/5 in response to diverse agonists. These compounds further establish the central role of PKD as an HDAC4/5 kinase and enhance the current understanding of cardiac myocyte signal transduction. The in vivo efficacy of a representative example compound on heart morphology is reported herein.

Discovery and in Vivo Evaluation of Potent Dual CYP11B2 (Aldosterone Synthase) and CYP11B1 Inhibitors.

Aldosterone is a key signaling component of the renin-angiotensin-aldosterone system and as such has been shown to contribute to cardiovascular pathology such as hypertension and heart failure. Aldosterone synthase (CYP11B2) is responsible for the final three steps of aldosterone synthesis and thus is a viable therapeutic target. A series of imidazole derived inhibitors, including clinical candidate 7n, have been identified through design and structure-activity relationship studies both in vitro and in vivo. Compound 7n was also found to be a potent inhibitor of 11β-hydroxylase (CYP11B1), which is responsible for cortisol production. Inhibition of CYP11B1 is being evaluated in the clinic for potential treatment of hypercortisol diseases such as Cushings syndrome.

Discovery of Oral VEGFR-2 Inhibitors with Prolonged Ocular Retention That Are Efficacious in Models of Wet Age-Related Macular Degeneration

The benefit of intravitreal anti-VEGF therapy in treating wet age-related macular degeneration (AMD) is well established. Identification of VEGFR-2 inhibitors with optimal ADME properties for an ocular indication provides opportunities for dosing routes beyond intravitreal injection. We employed a high-throughput in vivo screening strategy with rodent models of choroidal neovascularization and iterative compound design to identify VEGFR-2 inhibitors with potential to benefit wet AMD patients. These compounds demonstrate preferential ocular tissue distribution and efficacy after oral administration while minimizing systemic exposure.