Cytokinetics is developing reldesemtiv, a fast skeletal muscle troponin activator (FSTA), as a potential treatment for people living with debilitating diseases and conditions associated with muscular weakness, and/or muscle fatigue, including ALS and SMA.

Reldesemtiv is an investigational drug candidate intended to slow the rate of calcium release from the regulatory troponin complex of fast skeletal muscle fibers. Contraction of skeletal muscles is driven by the sarcomere, the fundamental unit of muscle contraction, which contains myosin, a protein which converts chemical energy into mechanical force through its interaction with another protein, actin. This interaction is regulated by other proteins including troponin and tropomyosin, and is dependent on changes in calcium. By slowing the rate of calcium release, reldesemtiv sensitizes the sarcomere to calcium, leading to an increase in muscle contractility.

Reldesemtiv is currently the subject of COURAGE-ALS (Clinical Outcomes Using Reldesemtiv on ALSFRS-R in a Global Evaluation in ALS), a Phase 3, multi-center, double-blind, randomized, placebo-controlled trial of reldesemtiv expected to enroll approximately 555 patients with ALS. The primary efficacy endpoint will be change from baseline to 24 weeks in ALSFRS-R. Secondary endpoints include combined assessment of ALSFRS-R total score, time to onset of respiratory insufficiency and survival time up to week 24 using a joint rank test; change from baseline to 24 weeks for vital capacity; ALSAQ-40; and bilateral handgrip strength. For more information on the trial, click here.