Figure 2.

Concentration-dependent response curve of mavacamten (MYK-461) in multiple myofibril-based systems. Myofibrils were assayed at pCa50 values of 6.25, 6.00, and 6.00 for bovine cardiac (1 mg/ml), rabbit skeletal (0.25 mg/ml), and human cardiac (1 mg/ml) respectively. Final assay conditions contained 2% DMSO with varying concentrations of mavacamten. Data were normalized to a DMSO control for each myofibril type assayed and analyzed using a four parameter fit (GraphPad Prism) to determine IC₅₀ values of mavacamten. DMSO control rates of 0.097 ± 0.0002 μm/s, 0.158 ± 0.01 μm/s, and 0.104 ± 0.005 μm/s were measured for bovine cardiac, rabbit skeletal, and human cardiac myofibrils, respectively.