RESUMEN
Late sodium current (late INa) is enhanced during ischemia by reactive oxygen species (ROS) modifying the Nav 1.5 channel, resulting in incomplete inactivation. Compound 4 (GS-6615, eleclazine) a novel, potent, and selective inhibitor of late INa, is currently in clinical development for treatment of long QT-3 syndrome (LQT-3), hypertrophic cardiomyopathy (HCM), and ventricular tachycardia-ventricular fibrillation (VT-VF). We will describe structure-activity relationship (SAR) leading to the discovery of 4 that is vastly improved from the first generation late INa inhibitor 1 (ranolazine). Compound 4 was 42 times more potent than 1 in reducing ischemic burden in vivo (S-T segment elevation, 15 min left anteriorior descending, LAD, occlusion in rabbits) with EC50 values of 190 and 8000 nM, respectively. Compound 4 represents a new class of potent late INa inhibitors that will be useful in delineating the role of inhibitors of this current in the treatment of patients.
RESUMEN
Improved peptide-based inhibitors of human beta tryptase were discovered using information gleaned from tripeptide library screening and structure-guided design methods, including fragment screening. Our efforts sought to improve this class of inhibitors by replacing the traditional Lys or Arg P1 element. The optimized compounds display low nanomolar potency against the mast cell target and several hundred-fold selectivity with respect to serine protease off targets. Thus, replacement of Lys/Arg at P1 in a peptide-like scaffold does not need to be accompanied by a loss in target affinity.