The FDA has approved Itvisma (onasemnogene abeparvovec-brve), a novel gene therapy for spinal muscular atrophy (SMA) in adults and children aged two years and up with a verified mutation in the SMN1 gene. The treatment employs an adeno-associated virus (AAV) vector, a harmless virus engineered to convey a healthy gene into the body. Gene therapy works by replacing a defective gene with the proper form, allowing the body to produce the crucial protein it lacks. 

Vinay Prasad, M.D., M.P.H., the FDA's Chief Medical and Scientific Officer, announced the approval, saying, "Today's approval demonstrates the power of gene therapies and provides treatment to patients across the SMA disease spectrum, including patients of various ages, SMA symptoms, and motor functional levels." This intriguing field of science continues to improve the lives of patients, and the FDA is committed to accelerating the development of products to meet unmet medical needs." 

SMA is a rare genetic condition that children inherit when both parents pass on a defective gene. It causes damage to motor neurones, which are the nerve cells that control movement. When these neurones die, muscles gradually weaken, shrink, and stop working. In its most severe forms, SMA can induce paralysis and was once the largest genetic cause of newborn mortality in the United States. SMA affects around 4-10 in 10,000 live births. 

Risdiplam demonstrated high efficacy in a Phase 3 clinical trial comprising children aged two years and older with verified SMN1 mutations. The manufacturer also supplied scientific data demonstrating how the therapy works within the body, as well as safety and efficacy evidence from Zolgensma, an older product that employs the same active component but is administered via a vein and only to children under the age of two. 

Unlike Zolgensma, Itvisma is administered as a single intrathecal injection, which means it is injected directly into the spinal fluid surrounding the spinal cord. This method allows the medication to reach the motor neurones more directly, with a lower dose and no adjustment for body weight. Itvisma stimulates the body's production of the SMN protein, which is essential for motor neurone survival, by delivering the proper gene to the right location. This therapy addresses the underlying cause of SMA and helps prevent further progression. 

The FDA cautioned that adults, particularly those with pre-existing long-term medical issues, may be at an increased risk of liver or heart-related complications. The safety warnings, including those for liver harm, remain the same as on the Zolgensma label. 

Vijay Kumar, M.D., Acting Director of the Office of Therapeutic Products, stated, "There is still significant unmet demand in SMA, particularly for children of varied ages and motor function levels, primarily those 2 years and beyond. This approval demonstrates our ongoing commitment to supporting and facilitating treatments for patients with rare diseases."

The approval marks an important moment for gene therapy regulation. It reflects growing confidence in targeted genetic treatments and a willingness to extend innovative options to older age groups. It also signals a future in which rare-disease therapies may follow faster evaluation pathways as scientific understanding deepens.