Reldesemtiv

Cytokinetics is a US biotech company that develops medicines acting directly on muscle. It ran COURAGE-ALS and announced the end of the programme after the results.

As motor neurons die, the signals reaching muscles weaken. Reldesemtiv binds to troponin, a protein that controls muscle contraction, making fast muscle fibres more sensitive to calcium so they contract more for the same signal. It was meant to ease weakness and fatigue, not to slow the disease itself.

An independent committee found at the second planned interim analysis that the trial met criteria for futility, meaning it was very unlikely to show a benefit. Cytokinetics stopped the trial in 2023 and, after presenting the full results in December 2023, ended development in ALS.

Cytokinetics announced on March 31, 2023 that the trial had met futility criteria at its second interim analysis and would stop. The full data, presented that December and published in 2025, confirmed no benefit.

In the published Phase 3 results (486 people), the ALSFRS-R score declined 1.1 points more on reldesemtiv than on placebo, a small difference in the wrong direction. A second analysis ranking several outcomes together (a "win ratio") also showed no benefit. Results come from a trial that was stopped early for futility. The earlier Phase 2 trial had missed its main goal too, but trends there led to the Phase 3 trial.

This is the most favourable result reported. See all key studies for the full picture.

COURAGE-ALS enrolled adults with ALS in general, not a specific genetic type, at sites in North America, Europe and Australia. Participants took two 150 mg tablets twice a day, or placebo, for 24 weeks, then everyone could take reldesemtiv for another 24 weeks.

Reldesemtiv is not available and there are no ALS trials recruiting. The registry lists COURAGE-ALS as terminated, with the last activity in July 2023.