Risdiplam Five-Year Follow-Up: 91% of SMA Children Alive, Hitting Milestones

Children with Spinal Muscular Atrophy (SMA), a debilitating neuromuscular disease that can be fatal, were able to thrive and achieve development milestones on risdiplam (Evrysdi; Genetech) for five years on treatment, according to data presented at Cure SMA Research & Clinical Care Meeting, June 5 - 7, 2024.

The five-year, open-label extension of Genentech’s FIREFISH study showed that 91% of children on risdiplam were alive; 96% could swallow; 80% could feed without a feeding tube; and 59% could sit unaided for 30 seconds or more. The results are encouraging as untreated children with Type 1 SMA don’t typically live past age two.

“These long-term findings confirm the ongoing benefit of Evrysdi for children with Type 1 SMA,” said Professor Giovanni Baranello, M.D., Ph.D., UCL Great Ormond Street Institute of Child Health & Great Ormond Street Hospital, London, U.K., in a Genentech press release.

“Children treated with Evrysdi over [five] years have maintained or improved their ability to sit, stand and walk — critical skills for development and daily living. An overwhelming majority also maintained the ability to swallow and to eat without a feeding tube,” Baranello said.

SMA is a genetic disorder that causes muscle weakness and atrophy due to motor neuron loss in the spinal cord. The condition affects approximately 1 in 10,000 newborns who are typically diagnosed within the first year of life as development delays become apparent. While untreated children die or become ventilator-dependent by age 2.

Risdiplam is an oral small molecule treatment that impacts both the central nervous system and peripheral tissues. Patients receive the medicine daily in liquid form either by feeding tube or by mouth. The drug was first approved by the FDA in 2020 for patients as young as two-months old.

Patients in the study didn’t stop treatment due to any adverse events. In fact, adverse events overall decreased 66% between year 1 and the final year of the study. The most common conditions occurring during the study were upper respiratory tract infection, pyrexia and pneumonia. More importantly, hospitalizations declined during the treatment period, and 22 percent of treated children in the study didn’t require any hospitalizations.

Risdiplam is approved for use in more than 100 countries. The drug was developed by Genentech in collaboration with the SMA Foundation and PTC Therapeutics.