New Treatment Granted FDA Approval for Spinal Muscular Atrophy in Adults, Children

Officials with the FDA have approved risdiplam (Evrysdi™, PTC Therapeutics and Genentech) for treatment for spinal muscular atrophy (SMA) in adults and children aged 2 months and older.^1,2 Risdiplam is the first at-home, orally administered treatment for SMA in these populations, according to PTC.¹

Risdiplam is a survival motor neuron 2-directed RNA splicing modifier designed to treat SMA caused by mutations in chromosome 5q that lead to SMN protein deficiency. Risdiplam is designed to distribute evenly to all parts of the body, including the central nervous system. This treatment is administered to patients daily at home in liquid form by mouth or feeding tube.^1,2

“Given the majority of people with SMA in the US remain untreated, we believe Evrysdi, with its favorable clinical profile and oral administration, may offer meaningful benefits for many living with this rare neurological disease,” said Levi Garraway, MD, PhD, chief medical officer and head of Global Product Development, Genentech, in a prepared statement.²

Risdiplam showed clinically meaningful improvements in motor function and obtainment of developmental milestones across 2 trials in patients aged 2 months and older, and across all levels of disease severity, including types 1, 2, and 3 SMA. Infants achieved key motor milestones not normally seen in the natural course of the disease, such as the ability to sit without support.^1,2

Risdiplam also preserved vital functions and improved survival at 12 months, according to PTC. In particular, risdiplam improved survival without permanent ventilation compared to natural history when measured at 12 and 23 months.^1,2

Risdiplam has been studied in a robust clinical trial program in SMA with more than 450 patients and subjects. The program includes infants aged 2 months to adults aged 60 years with a range of symptoms and motor function including patients with scoliosis or joint contractures. Patients previously treated for SMA with other medications were also included.^1,2

The FDA’s approval is based on results from 2 clinical studies designed to represent a broad spectrum of patients living with SMA: FIREFISH in symptomatic infants aged 2 to 7 months; and SUNFISH, in children and adults aged 2 to 25 years. SUNFISH is the first and only placebo-controlled trial to include adults with types 2 and 3 SMA.^1,2

In FIREFISH, 41% of infants treated with the therapeutic dose achieved the ability to sit without support for at least 5 seconds as measured by the Bayley Scales of Infant and Toddler Development Third Edition (BSID-III). Additionally, 90% of infants were alive without permanent ventilation at 12 months of treatment, and reached 15 months of age or older. Left untreated pediatric patients with infantile-onset SMA would not be expected to be able to sit independently and only 25% of infants would be expected to survive without permanent ventilation beyond 14 months of age.^1,2

In SUNFISH, children and adults treated with risdiplam experienced a statistically significant and clinically meaningful improvement in motor function at 12 months (1.55 point mean difference; p = 0.0156) compared to placebo, as measured by a change in baseline on the Motor Function Measure-32 (MFM-32) scale.^1,2

Risdiplam demonstrated a favorable efficacy and safety profile, with the safety profile established across the FIREFISH and SUNFISH trials. The most common adverse reactions were fever, diarrhea, and rash in later-onset SMA. In infantile-onset SMA, the most common adverse events were similar and also included upper respiratory tract infection, pneumonia, constipation, and vomiting. There were no treatment-related safety findings leading to withdrawal from any study. Ophthalmological monitoring is not required.^1,2

Two additional clinical studies, JEWELFISH and RAINBOWFISH, are evaluating risdiplam in a broad range of people with SMA.²

A collaboration between PTC, the SMA Foundation, and Roche,¹ risdiplam will be available in the United States this month for direct delivery to patients' homes through Accredo Health Group Inc., an Express Scripts specialty pharmacy.^1,2

Marketed in the US by Genentech, a member of the Roche Group, risdiplam received an orphan drug designation from FDA in 2017.¹ The treatment also received priority review status from the FDA in 2019.³

REFERENCES

• PTC Therapeutics Announces FDA Approval of Evrysdi™ (risdiplam) for the Treatment of Spinal Muscular Atrophy in Adults and Children 2 months and older [news release]. South Plainfield, NJ; August 7, 2020: PTC Therapeutics website. https://ir.ptcbio.com/news-releases/news-release-details/ptc-therapeutics-announces-fda-approval-evrysditm-risdiplam Accessed August 10, 2020.
• FDA Approves Genentech’s Evrysdi (risdiplam) for Treatment of Spinal Muscular Atrophy (SMA) in Adults and Children 2 Months and Older [news release]. South San Francisco; August 7, 2020: Genentech website. https://www.gene.com/media/press-releases/14866/2020-08-07/fda-approves-genentechs-evrysdi-risdipla Accessed August 10, 2020.
• Risdiplam Granted Priority Review for Spinal Muscular Atrophy. Pharmacy Times website. https://www.pharmacytimes.com/news/risdiplam-granted-priority-review-for-spinal-muscular-atrophy Published November 25, 2019. Accessed August 10, 2020.