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Presymptomatic infants with spinal muscular atrophy (SMA) who were treated with risdiplam (Evrysdi™) reached significant motor milestones such as sitting unaided, rolling, crawling, standing, and walking independently, according to preliminary data presented at the virtual 2021 Spinal Muscular Atrophy Conference.

The data come from RAINBOWFISH, an ongoing open-label, single-arm, multicenter study investigating the efficacy, safety, pharmacokinetics, and pharmacodynamics of risdiplam in babies (N=25), from birth to 6 weeks old (at first dose), with genetically diagnosed SMA, who are not yet presenting symptoms.

Risdiplam, RG7916, C22H23N7O molecule for the
treatment of spinal muscular atrophy.
Credit: Getty Images

The preliminary efficacy data showed that the 5 babies treated with risdiplam for at least 12 months accomplished sitting without support, rolling, and crawling. Of the 5, 2 had 2 single motor neuron (SMN) copies, and three had >2 copies. Four infants were able to stand unaided and walk independently. In addition, 4 babies reached a maximum score of 64 on the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) scale, and one scored 63.

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Stuart W. Peltz, PhD, chief executive officer of PTC Therapeutics, said “it is incredible to see that presymptomatic SMA infants are able to achieve developmental milestones consistent with healthy children.”

“These results broaden our knowledge of Evrysdi in babies younger than 2 months of age and adds to the proven efficacy data in a broad range of SMA patients,” he added.

Read more about Evrysdi.

In addition to the RAINBOWFISH trial, results of the JEWELFISH trial were also presented at the conference, held June 9-11, 2021. JEWELFISH is the first open-label experimental trial that assessed the safety, tolerability, pharmacokinetics, and pharmacodynamics in people with SMA aged 6 months to 60 years. The trial recruited 174 patients and is expected to conclude in December 2024. Data from JEWELFISH showed a steady safety profile and >2-fold increase in SMN protein levels. 

“These data from JEWELFISH add to the growing body of evidence supporting the use of Evrysdi in patients from 1 to 60 years of age,” Levi Garraway, MD, PhD, Roche’s chief medical officer and head of global product development said.), “We are hopeful that Evrysdi will continue to help address unmet treatment needs of the diverse SMA community.”

Risdiplam is an oral, disease modifying therapy approved by the US Food and Drug Administration (FDA) for the treatment of SMA in patients aged 2 months and older. It is approved in 44 countries, with approvals pending in an additional 32 countries. 

PTC Therapeutics is a global biopharmaceutical company focused on the discovery, development, and commercialization of clinically differentiated medicines that provide benefits to patients with rare disorders. Roche leads the clinical development of Evrysdi as part of a collaboration with the SMA Foundation and PTC Therapeutics.

SMA affects 1 in 10,000 babies and, when left untreated, is the leading cause of infant casualties.


Pre-symptomatic infants with spinal muscular atrophy achieved same motor milestones as healthy children after treatment with Evrysdi™ in RAINBOWFISH. News release. PTC Therapeutics; June 11, 2021.New Roche data for Evrysdi show improved motor function in pre-symptomatic babies after one year and confirm safety profile in previously treated people with spinal muscular atrophy (SMA). News release. Roche; June 11, 2021.