On Nov. 10, Genentech, a member of the Roche Group, announced positive results from the second part of its pivotal phase 2/3 SUNFISH clinical trial assessing risdiplam in patients with spinal muscular atrophy (SMA) types 2 or 3. The study met its primary endpoint, which was change from baseline in the Motor Function Measure 32 (MFM-32) scale after one year of treatment with risdiplam, compared to placebo. The safety profile was consistent with previous risdiplam studies; no patient withdrew from the study because of treatment-related safety issues, and no new safety issues were identified. The company plans to share the data from the study at an upcoming medical congress.
SMA is caused by a mutated or missing survival motor neuron 1 gene (SMN1) that prevents the body from making enough survival motor neuron protein (SMN). In addition to the SMN1 gene, there is also an SMN2 gene that serves as a “backup” gene for making the SMN protein, though it is not fully functional. Risdiplam is an investigational SMN2-splicing modifier designed to help the SMN2 gene produce more SMN protein. Risdiplam’s development is part of a collaboration between Genentech, PTC Therapeutics, and the SMA Foundation.
About the trial
Results from the dose-finding first part of the trial, which tested risdiplam in 51 patients aged 2 to 25 years with SMA types 2 or 3, showed that treatment with risdiplam led to a greater than two-fold increase in median levels of SMN protein in the blood after one year of treatment.
At the 24th Annual Congress of the World Muscle Society (WMS) held last month in Copenhagen, Denmark, Genentech presented interim data from the pivotal second part of the study, which was designed to evaluate motor function using the MFM-32 scale. Among 43 patients treated over a period of 12 months, 58% had at least a three-point improvement from baseline in MFM-32 total score. Since then, the study results have showed statistically significant improvements in motor function among additional enrolled participants.
MFM-32 is a scale used to evaluate motor function in people with neurological disorders, including SMA.
For more information about the current results, read the company’s press release. Risdiplam is currently being evaluated in four clinical trials in people with SMA. To learn more about the FIREFISH, SUNFISH, JEWELFISH, and RAINBOWFISH trials, visit ClinicalTrials.gov and enter “NCT02913482,” “NCT02908685,” “NCT03032172,” and “NCT03779334,” respectively, in the search box.