Risdiplam Meets Primary Endpoint in SMA Type 2, 3

Stuart W. Peltz, PhD

Interim results from part 2 of the phase 2/3 SUNFISH trial (NCT02908685) of risdiplam (PTC Therapeutics) show positive results in patients with spinal muscular atrophy (SMA) type 2 or 3, with the study meeting its primary endpoint of change from baseline in the Motor Function Measure 32 (MFM-32) scale after 1 year of treatment with the drug, formerly known as RG7916.

The 2-part, double-blind, placebo-controlled trial enrolled patients aged 2 to 25 with SMA type 2 or 3. The part 1 dose-finding portion of the study included 51 patients and evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of several risdiplam dose levels. Part 2 of the trial included 180 non-ambulant patients with type 2 or 3 SMA and assessed the safety and efficacy, as measured by change in the MFM-32 scale, of the risdiplam dose level selected from part 1 for 24 months. MFM-32 is used to evaluate the gross motor function of patients with neurological disorders such as SMA.

After 12 months of treatment, the study met its primary endpoint of change from baseline in MFM-32 compared with placebo. The study affirmed the consistent safety profile of risdiplam from previous trials. No patients experienced any treatment-related safety issues, and there was high tolerability among patients assessed. Notably, no patients withdrew from the study for safety-related issues.

Risdiplam is designed to increase and sustain SMN protein levels throughout the central nervous system and peripheral tissues of the body. The drug is an investigational, oral, first-in-class, mRNA-splicing modifier designed specifically for the treatment of SMA. Genentech originally lead the clinical development of risdiplam as part of a collaboration with the SMA Foundation and PTC Therapeutics.

"We are very pleased with the results of the SUNFISH study and are excited to move one step closer to bringing risdiplam globally to all patients living with SMA. The SUNFISH trial shows that risdiplam continues to demonstrate its disease-modifying properties and compelling safety profile," said Stuart W. Peltz, PhD, chief executive officer of PTC Therapeutics, in a statement.

In addition to SUNFISH, there are 3 other ongoing trials (FIREFISH, JEWELFISH, RAINBOWFISH) evaluating the efficacy of risdiplam in people with SMA. Specific data from part 2 of the SUNFISH study will be presented at an upcoming medical congress.

REFERENCE
Genentech’s Risdiplam Meets Primary Endpoint in Pivitol SUNFISH Trial In People With Type 2 or 3 Spinal Muscular Atrophy [news release]. San Francisco, CA: Genentech. November 10, 2019. businesswire.com/news/home/20191110005058/en/Genentech’s-Risdiplam-Meets-Primary-Endpoint-Pivotal-SUNFISH. Accessed: November 11, 2019.