Medicine Oral Treatment OK’d for Rare Neurological DiseaseBlau Medical News
WASHINGTON — The oral drug risdiplam (Evrysdi) won approval to treat spinal muscular atrophy (SMA) in adults and children 2 months of age and older, the FDA announced Friday.
A liquid medicine, risdiplam is administered daily at home by mouth or feeding tube. “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 four years ago,” said Billy Dunn, MD, director of the Office of Neuroscience in the FDA’s Center for Drug Evaluation and Research, in a statement.
Nusinersen (Spinraza), approved in 2016, was the first drug OK’d for SMA. In 2019, the agency also gave the green light to onasemnogene abeparvovec-xioi (Zolgensma), a gene therapy dubbed “the most expensive drug in the world.”
SMA is caused by reduced levels of survival motor neuron (SMN) protein due to deletions or mutations of the SMN1 gene. A nearly identical gene, SMN2, produces low levels of functional SMN protein. Risdiplam is an investigational SMN2 pre-mRNA splicing modifier designed to increase and sustain SMN protein levels centrally and peripherally.
The drug’s approval was based on two clinical studies: the open-label FIREFISH study in symptomatic infants aged 2 to 7 months, and the placebo-controlled SUNFISH trial in children and adults aged 2 to 25 years with later-onset SMA.
In FIREFISH, 41% (7/17) of infants were able to sit independently for more than 5 seconds after 12 months of risdiplam treatment,”a meaningful difference from the natural progression of the disease because almost all untreated infants with infantile-onset SMA cannot sit independently,” the FDA noted. After 23 or more months of treatment, 81% of infants were alive without permanent ventilation.
In the SUNFISH study of later-onset SMA patients, those treated with risdiplam had an average increase of 1.36 points in their motor function score at 1 year measured by a change on the Motor Function Measure-32 (MFM-32) scale, compared with a 0.19-point decrease in patients who received placebo.
The most common side effects of risdiplam included fever, diarrhea, rash, ulcers of the mouth area, joint pain, and urinary tract infections. Patients with infantile-onset SMA had similar side effects as people with later-onset SMA, but also had upper respiratory tract infection, pneumonia, constipation, and vomiting. Patients should avoid taking risdiplam with drugs that are multidrug and toxin extrusion substrates because it may increase plasma concentrations of those agents, the FDA warned.
FIREFISH and SUNFISH remain ongoing and other trials are underway as well with risdiplam. The drug “is being studied in more than 450 people as part of a large and robust clinical trial program in SMA,” according to a statement by drugmaker Genentech, a Roche unit. “The program includes infants aged 2 months to adults aged 60 with varying symptoms and motor function, such as people with scoliosis or joint contractures, and those previously treated for SMA with another medication.”
Genentech will market the drug and received the FDA approval, but risdiplam is a product of a collaboration between PTC Therapeutics, the SMA Foundation, and Roche, PTC said. The drug will be available within 2 weeks for direct delivery to patients’ homes through Accredo Health Group, an Express Scripts specialty pharmacy.