FDA Approves New High-Dose Nusinersen for SMA

The U.S. Food and Drug Administration (FDA) has approved a new, higher-dose regimen of nusinersen (Spinraza), a well-established treatment for spinal muscular atrophy (SMA). This updated option is designed to better meet the ongoing needs of patients and families living with this genetic condition, which affects muscle strength and movement.

Nusinersen, developed by Biogen, has been used for more than a decade at a lower dose, helping many children and adults with SMA. The newly approved high-dose regimen delivers more medication during both the initial “loading” phase and long-term maintenance treatment. For patients new to nusinersen, treatment begins with two higher doses given two weeks apart, followed by maintenance doses every four months. Patients already receiving the lower dose can transition to the new regimen after a single higher-dose adjustment.

“Optimizing the dose of nusinersen builds on a therapy that we already know can change lives,” said Richard Finkel, M.D., director, Center for Experimental Neurotherapeutics at St. Jude Children’s Research Hospital. “The high-dose regimen demonstrated meaningful clinical benefit while maintaining a well-characterized safety profile. I believe high-dose Spinraza will play an important role in the future of SMA care.”

The approval is based on results from the DEVOTE clinical trial, which evaluated the safety and effectiveness of the higher-dose approach. In one key group of infants who had not previously received treatment, those given the higher dose showed significant improvements in motor function compared with untreated patients. This suggests that increasing the dose may offer additional benefits, particularly when treatment is started early.

Importantly, the safety profile of the higher-dose regimen was generally consistent with what doctors already know about nusinersen. However, some side effects were reported more frequently in infants, including infections like pneumonia, as well as issues related to nutrition. As with the lower-dose version, there are also potential risks such as bleeding complications and kidney problems, so regular monitoring with blood and urine tests is required.

“Over the past decade, Biogen has continued to listen, learn and innovate to help advance care for people living with SMA,” said Priya Singhal, M.D., M.P.H., executive vice president and head of development at Biogen. “With more than 10 years of clinical data on nusinersen, the development of the high-dose regimen reflects both the strength of that foundation and our unwavering commitment to the SMA community to optimize treatment options.”

For patients and caregivers, this approval represents an important new option. While it doesn’t replace existing treatments, it provides more flexibility and may help health care providers better tailor care based on individual needs.