FDA Investigates Cancer Risk Linked to Novartis Gene Therapy Zolgensma

The Food and Drug Administration said on Friday, November 6, that it is investigating a serious risk of cancer linked to Zolgensma, the Novartis gene therapy given to young children with spinal muscular atrophy. The agency said it had received reports of malignancies in patients treated with the one-time therapy, including confirmed cases in which the treatment itself appears to have set off the tumor.

What the FDA found

The reported tumors formed in the central and peripheral nervous systems, in the spinal and paraspinal regions, and in the kidney, the FDA said. Three cases involved tumors tied to GLI1, a gene that can drive cancer when it is switched on abnormally. In two of those cases, analysis of tumor tissue found DNA from the therapy's viral carrier inserted into the patient's own genome, in or just ahead of the GLI1 gene, a process called insertional oncogenesis. The agency said the mechanism behind the third GLI1 case is still under investigation.

Zolgensma uses a modified adeno-associated virus to carry a working copy of the SMN1 gene into a child's cells. Spinal muscular atrophy is caused by a faulty SMN1 gene and destroys the nerve cells that control movement, often in infancy. The FDA approved Zolgensma on May 24, 2019, for children under 2 years old. Novartis says more than 6,000 children have received the treatment.

A second therapy carries the same risk

The FDA said the tumor risk also applies to Itvisma, a second Novartis product built on the same viral carrier and gene construct. Itvisma is injected into the spinal fluid and was approved on November 24, 2025, for patients aged 2 and older, including adults. No cases of tumor formation have been reported after Itvisma treatment so far, the agency said.

Novartis disclosed the two linked cases on Friday. The company said it had received nine reports of tumors in patients previously treated with Zolgensma since the therapy was first approved in 2019. It said it notified health authorities in a timely and appropriate manner in both new cases, and that a possible tumor risk is already described in the therapy's prescribing information.

What happens next

The FDA said the overall benefits of Zolgensma and Itvisma continue to outweigh their potential risks for their approved uses. The agency is investigating the risk and evaluating whether regulatory action is appropriate. It is also reviewing whether the current prescribing information and the long-term follow-up studies Novartis is running are enough to investigate and reduce the risk. The current label describes the risk of tumor formation from viral DNA integration as theoretical. Patients who receive either product should be monitored for tumor formation, the FDA said.

Patient advocates want the company to say more in public. SMA Europe, an umbrella group for spinal muscular atrophy organizations across Europe, urged Novartis to provide information on what is known, what is uncertain, and what the cases could mean for children who have already received the treatment.