FDA clears first oral drug to treat spinal muscular atrophy

FDA approved risdiplam (Evrysdi, Genentech) to treat patients 2 months of age and older with spinal muscular atrophy (SMA), a rare and often fatal genetic disease.

This is the second drug and the first oral drug approved to treat SMA, FDA said in a press release. It received fast track designation and priority review.

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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.

SMA, a hereditary disease, causes weakness and muscle wasting because patients lose lower motor neurons (nerve cells) that control movement. Evrysdi contains a survival of motor neuron 2-directed RNA splicing modifier.

The efficacy of Evrysdi to treat patients with infantile-onset and later-onset SMA was evaluated in 2 clinical studies. The infantile-onset SMA study involving 21 patients tested the ability to sit without support for at least five seconds and survival without permanent ventilation.

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After 12 months of treatment, 4% of patients were able to sit independently for more than five seconds, “a meaningful difference from the natural progression of the disease because almost all untreated infants with infantile-onset SMA cannot sit independently,” FDA said.

After 23 or more months of treatment, 81% of patients were alive without permanent ventilation — a noticeable improvement from typical disease progression without treatment.

Patients with later-onset SMA aged 2 to 25 years were evaluated in a second randomized, placebo-controlled study. Patients on Evrysdi saw an average 1.36 increase in their MFM32 (a test of motor function) total score at the 1-year mark, compared to a 0.19 decrease in patients on placebo.

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