The Food and Drug Administration (FDA) has approved Evrysdi™ (risdiplam; Genentech) for the treatment of spinal muscular atrophy (SMA) in patients 2 months of age and older.

Risdiplam is a survival motor neuron-2 (SMN2) splicing modifier designed to treat patients with SMA caused by mutations in chromosome 5q that lead to SMN protein deficiency. In clinical trials, treatment with risdiplam led to an increase in SMN protein with a greater than 2-fold median change from baseline within 4 weeks of initiation; the increase was sustained throughout the treatment period across all SMA types.

The approval was based on data from 2 multicenter phase 2/3 clinical studies (FIREFISH and SUNFISH) that evaluated the efficacy and safety of risdiplam in patients with SMA. The open-label FIREFISH study included 21 patients with infantile-onset SMA (average age of 6.7 months); the double-blind, placebo-controlled SUNFISH study included 180 patients with later-onset SMA (ages 2 to 25 years).

Results from the FIREFISH study showed that 41% (n=7/17) of patients treated with risdiplam achieved the ability to sit independently for at least 5 seconds after 12 months of treatment (as measured by Item 22 of the Bayley Scales of Infant and Toddler Development – Third Edition [BSID-III] gross motor scale). Additionally, 90% (n=19/21) of patients were alive without permanent ventilation after 12 months of treatment, and 81% (n=17/21) of patients were alive without permanent ventilation after 23 or months of treatment.

In SUNFISH, risdiplam was associated with a statistically significant improvement over placebo in motor function as measured by the change from baseline in total Motor Function Measure 32 (MFM32) score at month 12 (primary end point; 1.36 vs -0.19, respectively; 1.55 point mean difference [95% CI, 0.30-2.81]; P =.0156).

As for safety, the most common adverse reactions (≥10%) observed with treatment included fever, diarrhea, and rash. Additional side effects reported in patients with infantile-onset SMA (≥10%) were upper respiratory tract infection, pneumonia, constipation, and vomiting.

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“Evrysdi is the first drug for this disease that can be taken orally, providing an important treatment option for patients with SMA, following the approval of the first treatment for this devastating disease less than 4 years ago,” said Billy Dunn, MD, director of the Office of Neuroscience in the FDA’s Center for Drug Evaluation and Research.

Evrysdi is supplied in an amber glass bottle with two 6mL and two 12mL reusable oral syringes; each bottle contains 60mg of risdiplam and must be constituted by a pharmacist prior to dispensing. Following constitution, the volume of solution is 80mL, providing 60mg/80mL (0.75mg/mL) risdiplam.

The product is expected to be available within 2 weeks.

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1. FDA approves oral treatment for spinal muscular atrophy. Accessed August 10, 2020. 

2. FDA approves Genentech’s Evrysdi (risdiplam) for treatment of spinal muscular atrophy (SMA) in adults and children 2 months and older. Accessed August 10, 2020.

3. Evrysdi [package insert]. South San Francisco, CA: Genentech; 2020.