Risdiplam Data Reinforce Potential as Therapy for Spinal Muscular Atrophy

Infants with type 1 spinal muscular atrophy (SMA) achieved key motor milestones 1 year after treatment with the investigational therapy risdiplam, according to new data presented at the American Academy of Neurology Annual Meeting.

Risdiplam is an orally administered survival motor neuron-2 splicing modifier for SMA, a severe and progressive neuromuscular disease that causes devastating muscle atrophy and disease-related complications.

At the meeting, new data were presented from the dose-finding Part 1 of the FIREFISH and SUNFISH trials for the therapy.

Part 1 of the FIREFISH trial was a dose-escalation study with 21 infants that aimed to evaluate the safety profile of risdiplam in infants and determine the dose for Part 2. Among the 21 infants enrolled, the median duration of treatment was 14.8 months, with 19 infants treated for more than 12 months.

Key findings from the trial showed that:

• Among the 17 infants who received the dose selected for Part 2 of the study, 41.2% were able to sit without support for at least 5 seconds, assessed by the Gross Motor Scale of the Bayley Scales of Infant and Toddler Development—Third Edition.
• 64.7% of infants were able to sit with or without support and 52.9% achieved upright head control after 12 months of treatment as assessed by the Hammersmith Infant Neurological Examination Module 2.
• 5.9% achieved the milestone of standing by the 12-month time point.

This study also assessed motor function with the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders, a scale used for infants with Type 1 SMA. Overall, 58.8% of infants in the therapeutically dosed group achieved a CHOP-INTEND total score of 40 points or more, with a median change of 17.5 points from baseline to month 12, according to the data.

“The continued improvements in motor milestones and function in the FIREFISH study to date are meaningful for this typical SMA Type 1 population where the majority of babies started treatment at nearly 7 months old,” FIREFISH study lead investigator Giovanni Baranello, MD, Carlo Besta Neurological Research Institute Foundation, Developmental Neurology Unit, said in a statement. “These encouraging findings further validate a treatment approach that increases survival motor neuron protein in both the central nervous system and throughout the body.”

Additionally, data from the dose-finding part 1 of the SUNFISH trial reinforced risdiplam as a promising therapy for patients aged 2 to 25 years old with type 2 or type 3 SMA. An exploratory efficacy analysis assessed motor function, using the Motor Function Measure-32 (MFM32) scale. Among the 43 patients assessed at all visits up to month 12, 58% saw an improvement of at least 3 points on the scale from baseline, including 71% among patients aged 2 to 11 years old and 42% aged 12 to 25 years old, according to the study. The change from baseline in total MFM32 score is the primary efficacy endpoint in the ongoing part 2 of the trial.

Risdiplam is currently being investigated in 4 multicenter trials involving patients with SMA: FIREFISH, SUNFISH, JEWELFISH, and RAINBOWFISH. Overall, no treatment-related safety findings leading to withdrawal have been observed to date in the trials.

Reference

Genentech Presents Data from the Risdiplam Pivotal FIREFISH and SUNFISH Studies in Spinal Muscular Atrophy at the 2019 AAN Annual Meeting [news release]. Genentech. https://www.gene.com/media/press-releases/14787/2019-05-06/genentech-presents-data-from-the-risdipl. Accessed May 8, 2019.