Encouraging interim data has been shared from two studies of risdiplam (RG7916), a drug being researched as a potential treatment for spinal muscular atrophy types 1, 2, and 3. For more information about these results, click here to view the source press release at PR Newswire.
About Spinal Muscular Atrophy
Spinal muscular atrophy (SMA) is a rare genetic neuromuscular condition that leads to progressive muscle weakness and wasting (atrophy). There are several forms of SMA, including types 1, 2, and 3, which are the forms risdiplam is currently being researched for. Types 1, 2, and 3 all begin in childhood, although around different ages.
Research into Risdiplam
The investigational drug Risdiplam is being researched for SMA in three clinical trials: Firefish, Sunfish, and Jewelfish. Firefish is a safety and dose escalation study, Sunfish is comparing the effects of risdiplam to those of a placebo, and Jewelfish will investigate the safety of risdiplam in people who have taken part in a study involving an SMN2 splicing therapy before. PTC Therapeutics has recently announced interim clinical data from the Firefish and Sunfish studies, which supports the effectiveness of the drug.
Data from Firefish
According to the released data, at day 245 of treatment almost half (43%) of infants were able to sit with or without support, and three infants out of fourteen were able to sit unassisted. A spokesperson for PTC Therapeutics described these results as “remarkable” in a dose-finding study. 90% of the infants on the study remain alive.
Data from Sunfish
The Sunfish study involved patients with SMA types 2 and 3. Of those that were given risdiplam for one year or more, over half (63%) showed a median motor function increase of 3.13 points compared to baseline. Patients with these types of SMA typically decline by between 0.85 and 0.67 points over the course of a year, so this increase appears to be an extremely positive outcome.
Overall, risdiplam was found to be generally safe, and, so far, no patients have withdrawn as a result of drug-related safety findings.