Zolgensma (onasemnogene abeparvovec) and tumour reports

Clinicians and teams caring for children and adults treated with Zolgensma (onasemnogene abeparvovec, intravenous) or Itvisma (the same gene therapy given intrathecally). That includes neuromuscular, neurology, spine, anaesthesia, radiology and oncology teams.

The story spread quickly in early November 2026. This page brings together the official sources, a short summary and what is still unknown, so you can point colleagues, and through them patients, to one place. Always read the original sources. They take precedence over anything we write here.

What happened

• Zolgensma is a one-time gene therapy for spinal muscular atrophy (SMA), approved in the US in May 2019. An AAV9 viral vector delivers a working copy of the SMN1 gene. The vector DNA mostly stays separate from the chromosomes; a rare insertion into the genome next to a cancer gene could switch that gene on. Until now this was listed only as a theoretical risk.
• 4 November 2026: the UK National MDT told families that Novartis had reported nine tumours worldwide; three had been tested, two were linked to Zolgensma and one appeared unrelated.
• 5 November: Novartis confirmed nine tumour reports among more than 6,000 treated patients since 2019. Two showed vector DNA integrated into the patient's DNA; both patients were treated and remain under monitoring. Novartis says it notified health authorities about each case.
• 6 November: the FDA said it is investigating a serious risk of malignancy. In two cases the vector's promoter region had inserted upstream of or within GLI1, a known oncogene; a third GLI1-associated tumour is still being investigated.

What is known

• Where the tumours were: the central and peripheral nervous systems, the spinal and paraspinal regions, and the kidney (FDA).
• How often: nine reports in more than 6,000 treated patients; at least two confirmed as caused by the vector.
• Itvisma: the FDA applies the same concern to Itvisma (same vector and construct; approved 24 November 2025 for patients aged 2 and over). No tumour has been reported after Itvisma so far.
• Regulators' view: the FDA still judges that the benefits outweigh the risks for approved uses, and it is deciding whether regulatory action is needed.

What is not yet known

• The tumour type (histology) of the confirmed cases. None has been published.
• How long after treatment the tumours appeared, the patients' ages, and how many tumours are malignant.
• Whether the two earlier published cases (below) are among the nine reports.
• What the EMA, MHRA and Swissmedic will advise.

Advice so far

The advice is not yet uniform:

• FDA: "Patients and clinical trial participants receiving treatment with these products should be monitored for tumor formation."
• UK National MDT: routine care and follow-up stay the same; no additional scans, tests or monitoring are needed at this time.

Follow the advice of your national authority and treatment centre.

Why it matters to spine teams

• Several reported tumours were spinal or paraspinal, and many treated children come to spine teams for scoliosis care.
• An unexpected mass on preoperative imaging in a treated child may now carry this possibility.
• Report any tumour in a treated patient to the manufacturer and your regulator (see below).

Read with caution. These are single cases or animal work. Neither published case was shown to be caused by the gene therapy, and it is not known whether either is among the nine reports.

• Spinal cord tumour, 2023. Retson et al., Molecular Therapy 2023.
  • A low-grade epithelioid intramedullary tumour at the conus (T12), 14 months after treatment. It was resected.
  • The authors found no evidence that vector integration drove it, but very little tumour DNA was available, so the test was limited.
• Pilocytic astrocytoma, 2025. Holzwarth et al., Molecular Therapy 2025 (Bonn).
  • A grade 1 pilocytic astrocytoma diagnosed at age 2, about 8 months after treatment.
  • The vector was present, but integration sites were few and not consistent, so the authors concluded the tumour arose independently of treatment.
  • Several authors are Novartis employees.
• Mouse study, 2026. Chen et al., Nature Communications 2026.
  • In SMA mice, a Zolgensma-like vector was associated with liver cancer and cardiac thrombosis over long follow-up.
  • The authors note that AAV-related tumours seem specific to mice, but call for careful long-term monitoring of treated patients.

If a tumour or other suspected adverse reaction occurs in a treated patient, tell the manufacturer and your national authority:

• Manufacturer: Novartis Gene Therapies (US: 1-833-828-3947), or your local Novartis office.
• United States: FDA MedWatch.
• United Kingdom: MHRA Yellow Card.
• Germany: nebenwirkungen.bund.de (Paul-Ehrlich-Institut and BfArM).
• Switzerland: Swissmedic ElViS.
• Other EU countries: EMA: reporting suspected side effects, which links to every national authority.

• Purpose: Safety in Focus briefings gather the official sources on a safety story that matters to spine teams while it is spreading.
• Sources: regulators and manufacturers come first, then national clinical bodies and patient organisations, then published papers. We link to news reports only for background.
• Summary: drafted with AI assistance and read by an editor before publication.
• Updates: each briefing is re-checked every week. New regulator statements are added with their date.
• Status: this briefing is information, not medical advice.