FDA Gives Priority Review to Risdiplam in SMA for Infants Younger Than 2 Months

Risdiplam is approved for children older than 2 months with spinal muscular atrophy (SMA); an expanded approval would include the youngest infants before they show symptoms.

PTC Therapeutics said Tuesday that the FDA has granted priority review of a supplemental new drug application (sNDA) for Evrysdi (risdiplam) to expand the indication to include presymptomatic infants younger than 2 months with genetically confirmed spinal muscular atrophy (SMA).

Risdiplam was first approved by the FDA in August 2020 for children 2 months and older; it is the first oral drug given at home for infants and children with SMA.

SMA is a rare disease with different subtypes, type 0 through type 4; risdiplam is designed to treat SMA by increasing and sustaining the production of the SMN protein, which is critical for building and maintaining motor development.

Infants with SMA may appear fine at birth but fail to meet milestones ,and without intervention, they live for about 2 years.

The sNDA submission was based on interim data from the RAINBOWFISH study (NCT03779334), an open-label, single-arm, multicenter study, investigating the efficacy, safety, pharmacokinetics, and pharmacodynamics of risdiplam in infants (n = 25) from birth to 6 weeks (at first dose) who are not yet presenting symptoms.

In the study, which is still recruiting, 80% of presymptomatic infants with SMA treated with risdiplam for at least 12 months achieved motor milestones such as sitting without support, rolling, crawling, standing unaided, and walking independently.

"The results demonstrating that almost all of the presymptomatic infants achieved motor milestones comparable to healthy infants is tremendous," Stuart W. Peltz, PhD, CEO of PTC Therapeutics, said in a statement. "The granting of the priority review for Evrysdi recognizes this and the significant need to treat babies with SMA as early as possible. We are proud that such a transformative treatment for patients living with SMA came from our splicing platform."

Risplidam was based on PTC's splicing platform; it is sold by Roche and in the United States by Genentech.

This story was edited on January 26, 2022 to remove an incorrect description of risplidam.