Intrathecal Gene Therapy Approved for Adults, Older Children with Spinal Muscular Atrophy
The Food and Drug Administration has approved Itvisma (onasemnogene abeparvovec-brve; Novartis, Basel, Switzerland) for the treatment of people aged 2 years and older with spinal muscular atrophy (SMA) and a confirmed survival motor neuron 1 (SMN1) gene mutation. The adeno-associated virus (AAV) vector-based gene therapy onasmnogene abeparvovec was initially approved in 2019 under the brand name Zolgensma (onasemnogene abeparvovac-xioi; Avexis, Bannockburn, IL) for the treatment of children with SMA aged 2 years and younger. The new approval expands treatment to older children and adults. Itvisma is a 1-time, fixed-dose intrathecal formulation that replaces the missing or nonfunctional SMN1 gene—an approach intended to stabilize or improve motor function and potentially reduce reliance on chronic SMA therapies.
The FDA’s decision to approve Itvisma is based on data from the phase 3 STEER (NCT05089656) clinical study. STEER, a registrational trial, was a randomized, double-blind, sham-controlled study evaluating the efficacy and safety of intrathecal Itvisma treatment in treatment-naïve individuals. Outcomes were assessed using validated motor function scales and followed through 52 weeks. Individuals treated with Itvisma showed an improvement of 2.39 points on the Hammersmith Functional Motor Scale (HFMSE) vs 0.51 points for the sham treatment group (P=.0074).
The approval was also supported by data from STRENGTH (NCT05386680), a phase 3b, open-label study, which evaluated Itvisma treatment in a real-world population of individuals who had already received and discontinued treatment with the FDA-approved therapies Spinraza (nusinersen; Biogen, Cambridge, MA) or Evrysdi (risdiplam; Genentech, South San Francisco, CA). Across both studies, individuals received a single intrathecal administration and were monitored for motor performance, durability of effect, and adverse events.
The prescribing information for Zolgensma, which has an identical active ingredient to Itvisma, includes a Boxed Warning for serious liver injury and acute liver failure. In a statement released by the FDA about the approval of Itvisma, the agency noted that warnings and precautions are warranted due to a potentially increased risk of hepatotoxicity and cardiotoxicity in adults with preexisting medical conditions.
Source: Meglio M. FDA approves new intrathecal administration route for spinal muscular atrophy gene therapy. NeurologyLive. Published November 24, 2025. Accessed November 25, 2025. https://www.neurologylive.com/view/fda-approves-new-intrathecal-administration-route-spinal-muscular-atrophy-gene-therapy
Novartis. Novartis receives FDA approval for Itvisma, the only gene replacement therapy for children two years and older, teens, and adults with spinal muscular atrophy (SMA). Novartis. Published November 24, 2025. Accessed November 25, 2025. https://www.novartis.com/news/media-releases/novartis-receives-fda-approval-itvisma-only-gene-replacement-therapy-children-two-years-and-older-teens-and-adults-spinal-muscular-atrophy-sma
U.S. Food & Drug Administration. FDA approves gene therapy for treatment of spinal muscular atrophy. FDA News Release. Published November 24, 2025. Accessed November 25, 2025. https://www.fda.gov/news-events/press-announcements/fda-approves-gene-therapy-treatment-spinal-muscular-atrophy