A new phase 4 clinical trial evaluating the safety and effectiveness of risdiplam in children with spinal muscular atrophy (SMA) who experienced a plateau or decline in function following gene therapy with onasemnogene abeparvovec is now open. 

The open-label, single-arm, multicenter study sponsored by Hoffmann-La Roche aims to recruit 28 patients aged less than 2 years who are genetically diagnosed with the disease and have 2 copies of the SMN2 gene. 

During the trial, patients will be given the currently approved dose of risdiplam once a day for 72 weeks. This will be followed by a 1-year extension period.

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The primary outcome measure will be the change from baseline in the Bayley Scales of Infant and Toddler Development raw score at week 72.

Read more about the etiology of SMA

Secondary outcome measures will include: the change from baseline in bulbar/swallowing function, percentage of patients with a gross and fine motor quotient between 80 and 110, percentage of patients with improvement or no change in respiratory illness, percentage of patients within the third percentile of the normal ranges for weight and height to age ratios, number of hospitalizations due to respiratory illness, percentage of patients with adverse and serious adverse events, and percentage of patients who discontinue treatment due to adverse events.

The study is not yet recruiting participants. The estimated study start date is July 31, 2023, and the estimated completion date is March 31, 2028. 

Patients who have been treated with another investigational therapy before the initiation of this study, participants with concomitant or previous administration of an exon-skipping drug, patients needing invasive ventilation or tracheostomy, and those who have a feeding tube are not eligible to take part in the study. Full eligibility criteria can be found on the trial website.

Onasemnogene abeparvovec, marketed under the brand name Zolgensma®, is a gene therapy indicated for patients with all types of SMA before the age of 2 years. 

Risdiplam, sold under the brand name Evrysdi®, is an exon-skipping drug for the treatment of children and adults with SMA.


A study evaluating the effectiveness and safety of risdiplam administered in pediatric patients with spinal muscular atrophy who experienced a plateau or decline in function after gene therapy. ClinicalTrials.gov. May 17, 2023. Accessed June 6, 2023.