Abstract 12726: Novel, Potent, and Highly Selective Calcium/Calmodulin-Dependent Protein Kinase II (CaMKII) Inhibitors Reduce Substrate Phosphorylation in Rat Hearts and Prolong Survival in a Mouse Model of Severe Heart Failure

Abstract

Introduction: CaMKII is a target of longstanding interest in drug development and has been validated in multiple preclinical models of heart failure, as well as in arrhythmia diseases, including catecholaminergic polymorphic ventricular tachycardia and atrial fibrillation. We describe here the pharmacological profiles of a novel oral CaMKII inhibitor, CRD-2015. We demonstrate the ability of CRD-2015 to reduce substrate phosphorylation in rat hearts, and to strongly prolong survival in the calsequestrin transgenic (CSQ-Tg) mouse model of severe heart failure. Results: CRD-2015 is a potent (IC 50 0.62nM), highly selective CaMKII inhibitor. Oral administration of CRD-2015 dose-dependently decreased phospholamban (P-PLN) and ryanodine receptor 2 (P-RyR2) phosphorylation at their CaMKII-specific sites (Thr17 and Ser2814, respectively) in normal rat hearts, with strong correlation between the plasma concentrations (PK) and the reduction in phosphorylation (PD) (Figure, A). In CSQ-Tg mice, CRD-2015 also decreased cardiac P-PLN and P-RyR2 in a dose-dependent manner. Chronic administration of CRD-2015 prolonged survival in a dose-dependent manner (Figure, B). At the maximum dose level, all CSQ-Tg mice survived for 27 days (n=15/15) with the treatment of CRD-2015, while no mice survived past 24 days in the vehicle-treated group (n=0/15). Similar dose and concentration-dependent reductions in P-PLN and P-RyR2 and prolongation of survival in CSQ-Tg mice were also detected with a second potent (IC 50 0.40nM) and selective CaMKII inhibitor, CRD-2959. Conclusions: Our novel CaMKII inhibitor, CRD-2015 shows a clear PK/PD relationship in normal rats and prolongs survival in a mouse model of severe heart failure. These results demonstrate the successful creation of specific CaMKII inhibitors with efficacy in preclinical models and support their clinical development for the treatment of heart failure and other cardiovascular diseases.