Research and Non-Clinical Development, Cytokinetics, South San Francisco, CA, USA.
Structural Motility, Institut Curie, Université Paris Sciences et Lettres, Sorbonne Université, CNRS UMR144, Paris, France.
Nat Cardiovasc Res. 2024 Aug;3(8):1003-1016. doi: 10.1038/s44161-024-00505-0. Epub 2024 Jul 23.
Hypertrophic cardiomyopathy (HCM) is an inherited disease of the sarcomere resulting in excessive cardiac contractility. The first-in-class cardiac myosin inhibitor, mavacamten, improves symptoms in obstructive HCM. Here we present aficamten, a selective small-molecule inhibitor of cardiac myosin that diminishes ATPase activity by strongly slowing phosphate release, stabilizing a weak actin-binding state. Binding to an allosteric site on the myosin catalytic domain distinct from mavacamten, aficamten prevents the conformational changes necessary to enter the strongly actin-bound force-generating state. In doing so, aficamten reduces the number of functional myosin heads driving sarcomere shortening. The crystal structure of aficamten bound to cardiac myosin in the pre-powerstroke state provides a basis for understanding its selectivity over smooth and fast skeletal muscle. Furthermore, in cardiac myocytes and in mice bearing the hypertrophic R403Q cardiac myosin mutation, aficamten reduces cardiac contractility. Our findings suggest aficamten holds promise as a therapy for HCM.
肥厚型心肌病（HCM）是一种肌节遗传性疾病，导致心肌过度收缩。首创的肌球蛋白抑制剂 mavacamten 可改善梗阻性 HCM 的症状。在这里，我们介绍了 aficamten，一种选择性的心肌球蛋白小分子抑制剂，通过强烈减缓磷酸盐释放来降低 ATP 酶活性，稳定弱的肌动蛋白结合状态。与 mavacamten 不同，aficamten 结合在肌球蛋白催化结构域的变构位点上，可阻止进入强肌动蛋白结合力生成状态所需的构象变化。这样，aficamten 减少了驱动肌节缩短的功能肌球蛋白头部的数量。与预功状态下的心肌球蛋白结合的 aficamten 的晶体结构为理解其对平滑肌和快速肌的选择性提供了基础。此外，在心肌细胞和携带肥厚性 R403Q 肌球蛋白突变的小鼠中，aficamten 降低了心肌收缩力。我们的研究结果表明，aficamten 有望成为治疗 HCM 的一种方法。
