A new phase 4 clinical trial assessing risdiplam in patients with spinal muscular atrophy (SMA) who were previously treated with nusinersen is now open.

Risdiplam is considered a reasonable alternative to nusinersen based on previous clinical trial data because it eliminates the risk of mechanical failure, intrathecal bleeding, and central nervous system infection associated with the use of subcutaneous intrathecal catheters required to deliver nusinersen to the body.

The new clinical trial aims to recruit 10 patients, aged 2 to 35 years, at the Clinic for Special Children in Strasburg, Pennsylvania who have biallelic SMN1 gene deletions and 3 to 4 copies of the SMN2 gene and were previously treated with nusinersen for at least 22 months.

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During the trial, participants will cross over to open-label risdiplam monotherapy for 36 months.

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The primary outcome measure of the study will be the performance of the patients on the 9-hole peg test between their dominant and nondominant hands. Secondary outcome measures will include changes in lower and upper limb function, grip strength, overall motor function, and pulmonary function. The frequency and type of adverse events will also be assessed. 

The trial is not yet recruiting participants. The estimated start date is September 15, 2022, and the estimated completion date is June 15, 2026.

Risdiplam, marketed under the brand name Evrysdi®, is an oral disease-modifying therapy approved by the US Food and Drug Administration (FDA) to treat patients with SMA aged 2 months and above. It works by modifying SMN2 pre-messenger RNA (mRNA) splicing and including exon 7 in the SMN2 mRNA, thereby increasing the levels of functional SMN protein in the body. 


Risdiplam in patients with spinal muscular atrophy previously treated with nusinersen (RISE). ClinicalTrials.gov. August 31, 2022. Accessed September 2, 2022.