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Encouraging Results Of A New Muscle Drug For SMA

Encouraging results of a new muscle drug for SMA

Cytokinetics announced results of a recently completed clinical trial of reldesemtiv in SMA. The data suggest that this new experimental drug for SMA increases endurance and respiratory function even over a short period of 8 weeks.

The double-blinded placebo-controlled clinical trial attempted to find out the effects of reldemsetiv (formely: CK-2127107) on muscle endurance. Seventy participants with SMA type 2 and 3 took the compound for 8 weeks, following which their performance was evaluated.

Cytokinetics, the company behind reldesemtiv, provided the following details in their recent press release:

The study showed dose- and concentration-dependent increases in time to muscle fatigue as measured by changes from baseline in Six Minute Walk Distance (6MWD), a sub-maximal exercise test of aerobic capacity and endurance, and Maximal Expiratory Pressure (MEP), a measure of strength of respiratory muscles, after eight weeks of treatment with reldesemtiv.

The study, which examined two dose levels of reldesemtiv, 150 mg or 450 mg twice daily, demonstrated dose-dependent increases in 6MWD in ambulatory patients as measured at both post-baseline time points, week four and week eight. In the 150 mg twice daily group, the increase vs. placebo was 10.86 meters (p=0.2531) after four weeks of treatment with reldesemtiv and 7.72 meters (p=0.4684) after eight weeks of treatment. In the 450 mg twice daily group, the increase vs. placebo was 35.63 meters (p=0.0037) at week four and 24.89 meters (p=0.0584) at week eight. There was also a statistically significant correlation between Cmax, or peak concentration of reldesemtiv, and change from baseline in 6MWD, with a slope estimate of 9.53 meters/(µg/mL) (p=0.0086).

The study also showed increases vs. placebo in MEP. In the 150 mg twice daily group, the increase in MEP was 5.95 cm H2O (p=0.2276) after four weeks of treatment with reldesemtiv and 11.69 cm H2O (p=0.0378) after eight weeks of treatment. In the 450 mg twice daily group, the increase in MEP compared to placebo was 9.17 cm H2O (p=0.0855) after four weeks of treatment with reldesemtiv and 13.15 cm H2O (p=0.0298) after eight weeks of treatment. Other assessments in the study, including the Hammersmith Functional Motor Score Extended, Revised Upper Limb Module, Timed Up-and-Go and Forced Vital Capacity did not demonstrate meaningful differences between reldesemtiv versus placebo.

The statistical significance of the above results is unclear, however the compound definitely warrants further testing, and Cytokinetics has already announced their intention to develop reldesemtiv further.

It is encouraging to see that research is progressing towards new drugs to help to restoring the muscle function that has been lost to SMA.

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