Almost a third (29%) of babies with type 1 spinal muscular atrophy (SMA) treated with risdiplam (Evrysdi®) could sit unaided for at least 5 seconds by age 1, according to data published in The New England Journal of Medicine. This normally never occurs in untreated babies with the disease.

“These results have been further confirmed in the recently presented 24-month data showing Evrysdi continued to improve motor function, doubling the number of babies able to sit without support from month 12,” said Levi Garraway, MD, PhD, the chief medical officer of Genentech, the company developing the treatment, in a press release. “We will continue to work closely with governments and the SMA community to bring Evrysdi to as many people as possible.”

The data derive from FIREFISH, a pivotal phase 2 clinical trial testing the safety and efficacy of risdiplam in infants with type 1 SMA. They also showed that 78% of infants were classified as Hammersmith Infant Neurological Examination 2 (HINE-2) responders, meaning the infants improved in more milestones than they worsened. Motor functions evaluated in HINE-2 include head control, sitting, voluntary grasp, ability to kick, rolling, crawling, standing, and walking.

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 “Important motor milestones, such as sitting, rolling over and swallowing, are the fundamental building blocks that can help these babies achieve optimal outcomes with Evrysdi, potentially reducing the need for ventilation and increasing the rate of survival,” said Laurent Servais, MD, PhD, FIREFISH investigator and professor of pediatric neuromuscular diseases at the MDUK Oxford Neuromuscular Center, Oxford, England.

The results of the clinical trial also showed that the safety of risdiplam was consistent with its known safety profile. The most common serious adverse events were pneumonia, bronchiolitis, hypotonia, and respiratory failure, and the most common adverse events were upper respiratory tract infection, pneumonia, pyrexia, constipation, diarrhea, and maculopapular rash. Three infants had fatal complications but the investigators did not attribute these to risdiplam treatment.


Darras BT, Masson R, Mazurkiewicz-Bełdzińska M, et al. Risdiplam-treated infants with type 1 spinal muscular atrophy versus historical controls. N Engl J Med. 2021;385:427-435. doi:10.1056/NEJMoa2102047

Data for Genentech’s Evrysdi (risdiplam) published in New England Journal of Medicine shows significant improvement in survival and motor milestones in babies with type 1 spinal muscular atrophy (SMA). News release. Genentech; July 28, 2021.

Investigate safety, tolerability, PK, PD and efficacy of risdiplam (RO7034067) in infants with type 1 spinal muscular atrophy (FIREFISH). US National Library of Medicine. Last Updated July 20, 2021. Accessed July 29, 2021.