CK-2066260

CK-2066260 is an investigational **small-molecule fast skeletal muscle troponin activator** and **calcium sensitizer** developed by Cytokinetics as part of its skeletal muscle contractility program, historically in collaboration with Astellas. It binds selectively and directly to the **fast skeletal muscle troponin complex**, slowing the off-rate of calcium from troponin and thereby increasing myofibrillar calcium sensitivity in fast skeletal muscle without increasing free cytosolic calcium. In preclinical and translational studies, CK-2066260 increased submaximal force, power, and fatigue resistance and improved exercise performance in models of muscle weakness and peripheral artery insufficiency; it has also been described as a first-generation structural analogue of tirasemtiv, with reldesemtiv representing a later-generation compound in the same fast skeletal muscle troponin activator class.