Results From a Phase II Trial of Reldesemtiv For Treating Spinal Muscular Atrophy Have Been Announced

Data from a Phase II clinical trial of the experimental treatment reldesemtiv for the treatment of spinal muscular atrophy has been announced. The drug has shown positive effects in the study. The full article can be read here, at GlobeNewswire.
Spinal muscular atrophy (SMA) is a serious genetic disorder that leads to muscle weakness and difficulty moving. People with the condition may experience symptoms such as weak limbs, problems sitting up or walking around, muscle tremors (shaking), difficulty breathing and swallowing, and problems with bones and joints. However, people experience the condition differently. SMA is also made up of several sub-types, each with its own typical constellation of symptoms. Generally, type 1 occurs at the youngest age (under six months old) and is considered the most severe. Type 2 tends to appear between seven and eighteen months, and is less severe than type 1. Type 3 affects children over eighteen months, while type 4 affects adults; these two types don’t usually affect life expectancy. Approximately one in every 6,000 people is born with a form of SMA.
Reldesemtiv, an experimental treatment for SMA under development by Cytokinetics Incorporated has been evaluated in a Phase II clinical trial. The results were presented at this year’s Annual Cure SMA Conference. The double-blind, placebo-controlled study enrolled 70 patients with types II, III, or IV SMA, 39 of whom were assigned to Cohort 1 and 31 of whom were in Cohort 2. Two-thirds of patients received reldesemtiv, and one third were given a placebo. Patients in Cohort 1 received a dose of 150mg, while for Cohort 2 this dose was increased to 450mg, both administered twice per day.

The results showed that the experimental drug increased the time to muscle fatigue, and that this was dose and concentration dependent. The time taken to reach muscle fatigue was measured at baseline and after four and eight weeks of treatment, using tests including the Six Minute Walk Distance (6MWD) test.

The first Cohort, given 150mg of reldesemtiv, was found to have increased by 10.86 meters compared to the placebo at the four-week point. At the eight-week point, this figure was 7.72m. For the second Cohort receiving a higher dosage, the week four improvement in 6MWD compared to the placebo was 35.63m, and at week eight 24.89m. One other test, called maximal expiratory pressure, also showed improvement in patients taking reldesemtiv compared to those on the placebo. However, multiple other tests did not show a meaningful difference between the placebo and non-placebo groups.
The drug’s safety was also assessed; four patients discontinued treatment following serious adverse effects, but none were thought to be caused by reldesemtiv.
Reldesemtiv is a fast skeletal muscle troponin activator (FSTA). It is thought to make the sarcomere (a type of muscle tissue) more sensitive to calcium. As a result, skeletal muscles should be more able to contract.

Anna Hewitt

Anna Hewitt

Anna is from England and recently finished her undergraduate degree. She has an interest in medicine and enjoys writing. In her spare time she likes to cook, hike, and hang out with cats.

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