The FDA has approved onasemnogene abeparvovec-brve (Itvisma, Novartis), an adeno-associated virus vector-based gene therapy for treatment of spinal muscular atrophy (SMA) in patients aged 2 years and older with confirmed mutation in the survival motor neuron 1 (SMN1) gene.

The active ingredient in Itvisma is identical to Zolgensma (onasemnogene abeparvovec-xioi, Novartis), which the FDA approved in 2019 for children younger than 2 years but formulated at a different concentration.

While Zolgensma is administered intravenously based on patient weight, Itvisma is a concentrated formulation administered via a single intrathecal injection independent of patient weight, the FDA explained in a statement announcing approval. 

“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, MD, PhD, professor of neurology and pediatrics and director of the Division of Neuromuscular Medicine at Stanford University School of Medicine in California, said in a statement from Novartis.

“This new route of administration for a single dose of gene replacement therapy can mean so much more than what is measured by numbers on a functional motor scale — it could mean greater independence and freedom in activities of daily life,” added Kenneth Hobby, president of Cure SMA. 

“The SMA disease landscape has dramatically changed over the last 6 years, when the first gene therapy was approved. This is another welcome advancement, and it represents real progress in expanding access for many older patients and addressing the unmet needs that remain in our community,” Hobby said. 

SMA is a rare and often fatal genetic disease that causes progressive muscle weakness. It affects about 1 in 10,000 babies and is caused by a mutation in the SMN1 gene, which encodes the SMN protein — critical for the maintenance and function of motor neurons.

The approval of Itvisma was based on data from the phase 3 STEER study and the open-label phase 3b STRENGTH study, which showed statistically significant improvements in motor function and stabilization of motor abilities with treatment. 

These data were presented at the 2025 Muscular Dystrophy Association Clinical and Scientific Conference. 

Most of the side effects observed with Itvisma are consistent with identified risks associated with Zolgensma. 

“Information from the hepatotoxicity boxed warning in the Zolgensma label is retained in the Itvisma label with appropriate modifications. This approach is supported by clinical data showing hepatotoxicity in Itvisma clinical studies,” the FDA said. 

Itvisma received orphan drug designation, and had fast track, breakthrough therapy, and priority review designations.