The Food and Drug Administration (FDA) has accepted for Priority Review the supplemental New Drug Application (sNDA) for risdiplam for use in presymptomatic infants less than 2 months of age with spinal muscular atrophy (SMA).

Risdiplam is a survival motor neuron 2 (SMN2) splicing modifier that is currently marketed under the brand name Evrysdi®. It is FDA-approved for the treatment of SMA in patients 2 months of age and older. 

The sNDA includes data from the open-label, single-arm phase 2 RAINBOWFISH study ( Identifier: NCT03779334), which evaluated the efficacy and safety of risdiplam in 25 infants aged from birth to 6 weeks old (at first dose) with genetically diagnosed SMA who were not yet presenting symptoms.

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Interim results showed that 80% of patients 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,” said Stuart W. Peltz, PhD, CEO, PTC Therapeutics. “The granting of the Priority Review for Evrysdi recognizes this and the significant need to treat babies with SMA as early as possible.”


  1. FDA grants Evrysdi® Priority Review based on results from treating presymptomatic infants with spinal muscular atrophy. News release. PTC Therapeutics, Inc. Accessed January 25, 2022.
  2. Presymptomatic infants with spinal muscular atrophy achieved same motor milestones as healthy children after treatment with Evrysdi™ in RAINBOWFISH. News release. PTC Therapeutics, Inc. June 11, 2021. Accessed January 25, 2022.

This article originally appeared on MPR