Children with spinal muscular atrophy (SMA) type 1 maintained or continued to improve their abilities to sit, stand, or walk without support over 48 months of treatment with risdiplam, according to follow-up data from the open-label extension of the FIREFISH clinical trial.

Genentech, the manufacturer of Evrysdi® (risdiplam), announced that the study confirmed the long-term safety and efficacy of the drug for young children. All of the children who were alive at the time of the primary analysis were still alive at this 48-month follow-up analysis.

Natural history data suggest that most children with SMA type 1 require feeding support and most die within the first 2 years. However, 91% of children enrolled in the study were still alive at month 48 and 95% of those children maintained the ability to swallow. 

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Of the original 58 infants treated with risdiplam, 37 were able to sit without support for at least 5 seconds after 48 weeks of treatment. This number increased from 35 at month 24. The number of children who could sit without support for at least 30 seconds also increased from 23 at month 24 up to 36 at month 48. Additionally, 3 children gained the ability to stand alone and 1 gained the ability to walk alone between months 24 and 48. Untreated patients are never able to sit without support.

“The independence that comes with sitting, standing, and walking is transformational for children with SMA, and their families, and we are very encouraged by how these skills increased over 4 years of Evrysdi treatment for many children in this study,” said Levi Garraway, MD, PhD, Genentech’s chief medical officer and head of Global Product Development.

“Nine out of 10 patients in our studies remain on Evrysdi long-term and these data underscore its importance as an option for people with SMA across a broad range of age and disease types,” Garraway continued.

The safety profile of risdiplam treatment also improved during the study with the rate of adverse events decreasing by 71% between the first 12-month treatment period and the 4th. The rate of hospitalizations also decreased over this period. The most common adverse events included fever (62%), upper respiratory tract infections (62%), and pneumonia (48%).


Four-year follow-up data for Genentech’s Evrysdi show continued increase in number of children with a severe form of spinal muscular ​atrophy (SMA)​ able to sit, stand and walk. News release. Genentech; June 30, 2023.