FDA approves $2.59 million gene therapy for SMA

The FDA has approved Itvisma (onasemnogene abeparvovec-brve) to treat children two years and older, teens, and adults living with spinal muscular atrophy (SMA). It is indicated for patients with a confirmed mutation in the survival motor neuron 1 (SMN1) gene.

Developed by Novartis, Itvisma is a one-time fixed-dose gene therapy that replaces the SMN1 gene and does not need to be adjusted for age or body weight. SMA is caused by mutations in the SMN1 gene, leading to the degeneration of motor neurons, muscle weakness, and atrophy. Approximately 9,000 people in the United States live with SMA.

Itvisma will be available in December and is priced at a wholesale acquisition cost (WAC) of $2.59 million, which the company said reflects its value as the one-time therapy for a broad population. Itvisma, a spokesperson said, is priced at 35% to 46% less than the 10-year cost of the available chronic disease modifying therapies.

Novartis is in discussions with government and private payers and “we are confident in patients receiving timely access across both commercial and public plans,” the spokesperson said.

Novartis offers resources to help eligible patients access their treatment. Novartis Patient Support is a comprehensive program that provides personalized support to assist patients in navigating their insurance coverage and identifying financial assistance options, while also offering educational resources to help them get started on treatment and guide them along the way.

Itvisma is administered intrathecally, meaning it is injected into the space surrounding the spinal cord. This is different from Novartis’ other SMA gene therapy. Zolgensma (onasemnogene abeparvovec-xioi) is administered intravenously and is also a one-time SMN1 gene replacement therapy that was approved by the FDA in 2019. Zolgensma is only indicated for children who are less than two years of age.

“The FDA’s approval of intrathecal onasemnogene abeparvovec is a game-changing advance, expanding the use of transformational gene replacement therapy for SMA across age groups,” John W. Day, M.D., Ph.D., professor of Neurology and Pediatrics, director of the Division of Neuromuscular Medicine at Stanford University School of Medicine, and co-director of Stanford’s Neuro IGNITE Center, said in a news release. “This achievement is not only a significant step forward for SMA—it also signals new possibilities for the broader field of neurological disorders and genetic medicine.”

The approval of Itvisma is based on data from the registrational phase 3 STEER study and supported by the open-label phase 3b STRENGTH study. In these trials, Itvisma showed statistically significant improvements in motor function and stabilization of motor abilities.

The STEER study enrolled 126 treatment-naïve patients who either received Itvisma or a sham. At the end of the 52-week study period, Itvisma resulted in a statistically significant 2.39-point improvement on the Hammersmith Functional Motor Scale Expanded (HFMSE), a specific assessment of motor ability and disease progression for patients with SMA.

The STRENGTH study evaluated 27 patients who had discontinued Spinraza (nusinersen) and Evrysdi (risdiplam), two approved disease-modifying drugs available to treat SMA patients. All patients received Itvisma, which demonstrated a stabilized functioning based on HFMSE and a favorable safety profile.

Adverse events that were consistent across both studies. The most common adverse events in the STEER study were upper respiratory tract infection and pyrexia, and the most common adverse events in the STRENGTH study were common cold, pyrexia, and vomiting.

These data were presented in May 2025 at the 2025 Muscular Dystrophy Association (MDA) Clinical and Scientific Conference.