Itvisma works by delivering a healthy copy of the SMN1 gene directly into the fluid surrounding the spinal cord (cerebrospinal fluid). This helps motor nerve cells make the SMN protein they need for normal muscle movement and strength. By directly targeting the root genetic cause of SMA, Itvisma may improve motor function and reduce the need for continuous long-term treatments.
What makes Itvisma different is that it’s given as a one-time fixed-dose injection into the cerebrospinal fluid and doesn’t need to be adjusted based on your weight. This approval is especially important because it offers a new targeted treatment option to older children, teens, and adults with SMA – groups that had fewer choices earlier. The first FDA-approved SMA gene therapy, named Zolgensma and approved in 2019, is delivered intravenously (via an IV) based on the patient’s body weight and was approved only for infants younger than 2 years.
Why Was It Approved?
The FDA approved Itvisma based on results of a study in children and teens with SMA type 2 who could sit but had never walked and had not received any previous treatment. In the study, those who received Itvisma showed more improvement in muscle control and movement than those who received a sham procedure (a procedure that mimics drug delivery, but without the active ingredient).
Another study looked at how safe and effective Itvisma was in 27 children with SMA in the same age group who had stopped other SMA treatments (nusinersen or risdiplam). After 52 weeks, Itvisma was found to be safe and well tolerated. Motor abilities were maintained, showing that movement skills did not decline as they normally do in SMA. On average, motor function scores showed a slight improvement of 1.05 points, showing that Itvisma can help preserve and even slightly improve movement in children who have previously received other therapies.
The most common side effects were fever, stomach symptoms, and upper respiratory tract infections, and these were seen in both the treatment and sham groups. Serious side effects included rare occurrences of increased liver enzymes, disrupted sensation, and vomiting in the Itvisma-treated group.
What Do I Need to Know?
Itvisma is given as a one-time injection into the fluid around your spinal cord. The dose is the same for everyone, no matter your weight, which makes it easier to use across different age groups.
Your doctor will review your medical history and monitor you closely after treatment to watch for any problems. Before starting your treatment, let your health care provider know if you have any liver or heart problems and about other details of your medical history. Be sure to tell your doctor about all the vaccinations and medicines, including over-the-counter products, herbal remedies, and vitamin supplements, that you’ve taken.
Contact your health care provider right away if you have a fever, flu-like symptoms, coughing or trouble breathing, dark urine, or yellowing of your skin or eyes. These could be signs of serious side effects.
This treatment is expected to be available in the U.S. in December 2025.
