FDA Approves Evrysdi (risdiplam) for All Ages Including Infants Under Two Months with Spinal Muscular Atrophy

Today, Genentech, a subsidiary of Roche, announced that the U.S. FDA has approved the expansion of the use of its oral therapy Evrysdi (risdiplam) to treat spinal muscular atrophy (SMA) in infants under 2 months of age. The press release noted that Evrysdi has already been approved for the treatment of SMA patients of all ages, including children and adults.

SMA is a severe progressive neuromuscular disease. The condition is typically caused by the absence or dysfunction of the survival motor neuron (SMN) protein, affecting the patient's movement, breathing, swallowing, and multiple organs including the spleen, heart, and pancreas, even posing a life-threatening risk. The SMN protein is crucial for maintaining healthy motor neurons and enabling movement. In the human body, both the SMN1 and SMN2 genes can produce SMN protein, with the SMN1 gene playing a dominant role while the SMN2 gene accounts for approximately 10% of SMN protein production.

Evrysdi is an RNA splicing modifier targeting SMN2. Although the SMN2 gene in the human body can also express SMN protein, due to mRNA splicing errors, the level of normal SMN protein expression is very low and cannot compensate for the lack of SMN protein caused by SMN1 gene mutations. Evrysdi increases the level of functional SMN protein by modulating the mRNA splicing of the SMN2 gene. After taking this medicine, it can be evenly distributed to all parts of the body, including the central nervous system (CNS). Patients can take it daily at home in liquid form via oral or feeding tube administration.

This approval is based on interim efficacy and safety data from the Phase 2 RAINBOWFISH clinical trial. The trial results showed that most infants treated with Evrysdi before symptom onset reached key motor milestones after 12 months of treatment, such as sitting unassisted and standing, with more than half able to walk. Among infants with 2 or 3 copies of the SMN2 gene, 100% were able to sit independently, 67% could stand, and 50% could walk independently after one year of Evrysdi treatment. All infants survived at 12 months and did not require permanent ventilation.

"Evrysdi's approval for treating presymptomatic infants is particularly significant because early treatment of SMA before symptoms appear can help children achieve motor milestones," said Dr. Richard Finkel, principal investigator of the clinical trial and a researcher at St. Jude Children’s Research Hospital. "SMA has been included in newborn screening tests, and this approval provides an opportunity for infants to begin treatment at home shortly after diagnosis."

References:

[1] FDA Approves Genentech’s Evrysdi (risdiplam) for Use in Babies Under Two Months With Spinal Muscular Atrophy (SMA). Retrieved May 31, 2022, from https://www.businesswire.com/news/home/20220530005033/en

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