Three innovative SMA treatments have emerged in recent years: risdiplam, nusinersen (Spinraza), and onasemnogene abeparvovec-xioi (Zolgensma). While initial studies showed these medications had promise in helping children with SMA, long-term data was lacking as to whether these drugs would continue to help over time.
Now, new research data shows that risdiplam can lead to ongoing improvements for infants with SMA. These findings indicate that risdiplam may be a good long-term option for babies who have recently been diagnosed with the condition. Similarly, long-term studies have shown that the other newer treatments continue to help people with SMA as they age.
This past April, Evrysdi maker Genentech announced research findings that infants had better survival rates and experienced motor skill improvements after taking the drug for three years. The data came from the FIREFISH study, during which the medication was given to infants with SMA type 1 between the ages of 1 and 7 months.
The new data shows that risdiplam helps babies live longer. Without treatment, many infants with type 1 SMA do not live beyond the age of 2. However, after three years of treatment with risdiplam, the survival rate of the infants in the study was 91 percent.
Risdiplam also reduces symptoms of SMA and allows children to move around and use their muscles more effectively. Typically, infants with SMA lose the ability to perform certain functions, or they never gain most motor skills in the first place. After a couple of years of risdiplam treatment, however, children with SMA improved or maintained their ability to:
Dr. Levi Garraway, the chief medical officer and head of global product development at Genentech, praised the new data. “These long-term results in babies treated with Evrysdi are very encouraging, with the vast majority improving or maintaining motor function after three years,” he said in the press release. “Support for the compelling efficacy of Evrysdi continues to grow for a broad range of people, including infants with one of the most severe forms of SMA.”
The U.S. Food and Drug Administration (FDA) approved Evrysdi in August 2020 for treating SMA in babies 2 months of age or older. Last May, the FDA approved the drug for use in babies younger than 2 months as well.
Risdiplam helps correct the problems that occur in SMA caused by mutations in the survival motor neuron 1 (SMN1) gene, which makes most of the body’s SMN protein. Without enough SMN protein, nerve cells die, leading to SMN symptoms like muscle weakness, swallowing difficulties, and breathing difficulties. Risdiplam is a “splicing modifier” — it makes changes to the SMN2 gene so that it can make more SMN protein. This helps stabilize or reverse SMA symptoms.
Recent data has also shown that other medications for SMA lead to ongoing benefits. People with this condition currently have two other options.
Spinraza was the first SMA treatment approved by the FDA. In the SHINE clinical trial, researchers have studied the long-term effects of this medication among 292 infants, children, and teens. Data from May 2020 shows that after six and a half years of using nusinersen, children across all age groups either had stable (not worsening) motor function, or their motor skills improved. Additionally, the SHINE study has found that nusinersen is safe to use long term.
An announcement from drug manufacturer Biogen, published in June 2021, provided further information about nusinersen. Researchers followed a group of 13 infants with SMA who’d started using the drug before symptoms appeared. They found that 92 percent still had the ability to swallow nearly four years later. Researchers also reported that nusinersen helped children and teens walk for longer distances without getting as tired. This data shows that nusinersen can delay health problems often caused by SMA.
Long-term research also supports that onasemnogene abeparvovec-xioi, a type of gene therapy for SMA, is safe and effective. A study published in May 2021 — which followed a group of 13 infants who’d received a one-time infusion of the drug for up to 6.2 years — found that the drug was safe. Although some study participants experienced serious adverse events (side effects), none were fatal.
In the onasemnogene abeparvovec-xioi study, the infants also maintained their breathing function, and none needed permanent ventilation. Furthermore, the study participants didn’t experience declines in their motor function, showing that this drug helped maintain their health.
Researchers will continue to study the long-term effects of SMA medications like risdiplam, nusinersen, and onasemnogene abeparvovec-xioi. So far, these medications appear to help infants with SMA maintain their current health levels. Additionally, the two long-term SMA medications are safe to keep taking.
These results highlight the importance of staying on SMA medications. People who use these drugs have better outcomes than do people who remain untreated. Talk to your health care team or reach out to programs that offer financial assistance if you or your child are having a hard time continuing with your current treatment plan.
On mySMAteam, the social network for people with SMA and their loved ones, more than 1,500 members come together to ask questions, give advice, and share their stories with others who understand life with SMA.
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