Insights > News > FDA Approves Gene Therapy for Treatment of Spinal Muscular Atrophy — Itvisma (onasemnogene abeparvovec‑brve)

FDA Approves Gene Therapy for Treatment of Spinal Muscular Atrophy — Itvisma (onasemnogene abeparvovec‑brve)

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Semi‑realistic 1536×1024 header: left two‑thirds show a soft‑focus DNA double helix, stylized AAV vector schematic, spinal cord silhouette, and motor‑neuron line art connecting to muscle fibers in clinical blues, teal, and muted gold; right third contains a semi‑transparent dark navy backer with large, high‑contrast white headline text reading “FDA Approves Gene Therapy for Treatment of Spinal Muscular Atrophy”; clean sans‑serif typography, subtle data‑visual elements, and safe margins for cropping.

Background and mechanism

Spinal muscular atrophy (SMA) is an autosomal‑recessive neurodegenerative disorder caused by loss‑of‑function mutations in the SMN1 gene, resulting in reduced survival motor neuron (SMN) protein, progressive motor neuron loss, and muscle atrophy. Gene‑replacement therapy using adeno‑associated virus (AAV) vectors delivers a functional copy of SMN1 to motor neurons, restoring SMN protein expression and addressing the genetic root cause of SMA.1

The FDA approval: scope and rationale

On 24 November 2025, the U.S. Food and Drug Administration approved Itvisma (onasemnogene abeparvovec‑brve) for adult and pediatric patients 2 years of age and older with a confirmed SMN1 mutation. Itvisma is an AAV‑based gene therapy formulated for intrathecal administration, enabling direct delivery to the cerebrospinal fluid and motor neurons without weight‑based dosing. The approval was supported by a pivotal Phase 3 trial and bridging evidence leveraging safety and efficacy data from the intravenous formulation Zolgensma (same active ingredient).1

Key clinical evidence and durability

Long‑term follow‑up of early onasemnogene abeparvovec trials demonstrates durable clinical benefit and a favorable safety profile in infants treated with the therapeutic dose, with sustained survival and preserved motor milestones up to multiple years post‑dosing.5 Recent larger studies and real‑world analyses indicate functional improvements across a broader age and weight range, supporting intrathecal delivery for older children and adults.6

Safety considerations

The FDA emphasized hepatotoxicity and cardiotoxicity as adverse events of special interest; the Itvisma label retains warnings informed by Zolgensma data and observed hepatotoxicity in Itvisma studies. Clinicians should monitor liver function and cardiac markers per label guidance and consider comorbidities that may increase risk in adult patients.1

Practical implications for care and access

  • Administration: single intrathecal injection independent of patient weight, enabling treatment of older and heavier patients who were previously ineligible for intravenous dosing.
  • Regulatory designations: Itvisma received Fast Track, Breakthrough Therapy, Priority Review, and Orphan Drug designations, reflecting the unmet need in SMA populations beyond infancy.
  • Epidemiology: SMA incidence is estimated at ~1 in 6,000–10,000 live births, with prevalence estimates varying by region; improved survival and newborn screening are shifting the demographic toward more adults living with SMA.

Comparative snapshot7

ProductRouteIndication (summary)Typical age
Itvisma (onasemnogene abeparvovec‑brve)IntrathecalSMA with SMN1 mutation; ≥2 years≥2 years
Zolgensma (onasemnogene abeparvovec‑xioi)IntravenousSMA due to bi‑allelic SMN1 mutations; <2 years<2 years

The FDA approval of Itvisma represents a significant expansion of gene‑replacement therapy for SMA, enabling targeted intrathecal delivery to older children and adults and reinforcing the therapeutic durability observed with onasemnogene abeparvovec formulations. Ongoing surveillance and careful risk mitigation for hepatotoxicity and cardiotoxicity remain essential as real‑world use broadens.

References (7)

  1. U.S. Food and Drug Administration. FDA Approves Gene Therapy for Treatment of Spinal Muscular Atrophy. FDA News Release. 24 Nov 2025. https://www.fda.gov/news-events/press-announcements/fda-approves-gene-therapy-treatment-spinal-muscular-atrophy 
  2. SMA Foundation. SMA Overview (SMA Overview PDF). https://www.smafoundation.org/wp-content/uploads/2012/03/SMA-Overview.pdf 
  3. Cure SMA. Check Out Cure SMA’s 2024 Annual State of SMA Report. 2025. https://www.curesma.org/2024-state-of-sma-report/ 
  4. SpinalMuscularAtrophy.net. . Is Spinal Muscular Atrophy (SMA) Common? Statistics. https://spinalmuscularatrophy.net/statistics 
  5. Mendell JR, Al‑Zaidy S, Lehman KJ, et al. Five‑Year Extension Results of the Phase 1 START Trial of Onasemnogene Abeparvovec in Spinal Muscular Atrophy. JAMA Neurol. 2021. https://jamanetwork.com/journals/jamaneurology/fullarticle/2780250 
  6. The Lancet Regional Health — Europe. Efficacy and safety of onasemnogene abeparvovec in children with spinal muscular atrophy. https://www.thelancet.com/journals/lanepe/article/PIIS2666-7762(23)00236-3/fulltext 
  7. U.S. Food and Drug Administration. Summary Basis for Regulatory Action — ZOLGENSMA (May 24, 2019). https://www.fda.gov/media/127961/download

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