By Josh Nathan-Kazis

The Food and Drug Administration has approved a version of the Novartis gene therapy Zolgensma, used to treat infants with spinal muscular atrophy, that will allow older patients to take the treatment.

The go-ahead, which came late Monday, will allow Novartis to keep building on what has been a rare commercial success in the troubled field of gene therapy. At an investor event last week, Novartis CEO Vas Narasimhan said that the new version had "the opportunity to be a multibillion-dollar medicine."

Zolgensma sales were $1.2 billion last year. The consensus call among analysts tracked by FactSet is that sales of the new version of the drug will hit $510 million in 2027.

Zolgensma, which the FDA approved in 2019, is only available for children under the age of 2. The new version, which Novartis will sell under the brand name Itvisma, is approved for spinal muscular atrophy patients aged 2 and older.

"Today's approval shows the power of gene therapies and offers treatment to patients across the SMA disease spectrum," Vinay Prasad, the FDA's chief medical and scientific officer and head of the FDA's Center for Biologics Evaluation and Research, said in a statement.

Spinal muscular atrophy is caused by a gene mutation that affects motor neurons, the cells that control muscle movement. Patients experience progressive muscle weakness and atrophy, and some forms of the condition are fatal. Both the newly approved Itvisma and Zolgensma deliver a working copy of the mutated gene, which makes proteins to protect and maintain motor neurons.

The two Novartis drugs contain the same active ingredient, but at different concentrations. Itvisma is injected into the spinal fluid, while Zolgensma is delivered intravenously.

Novartis's American depositary receipt was up 2.5% on Tuesday, bringing its gain this year to 33%.

Novartis said Tuesday that Itvisma's list price would be $2.59 million, compared with $2.5 million for Zolgensma. Unlike competing drugs from Biogen and Roche, which come with six-figure annual price tags, Itvisma and Zolgensma are one-time treatments.

Novartis told Barron's in a statement that the U.S. price of Itvisma is "35% -- 46% less than the 10-year cost" of existing treatments.

Despite enormous waves of enthusiasm over the past decade, the extraordinary promise of gene therapies has thus far largely failed to translate into commercial success. While some programs have been derailed by patient deaths, others have simply failed to find demand. This February, Pfizer pulled a hemophilia gene therapy off the market less than a year after its launch, citing low uptake.

Zolgensma remains virtually the only gene therapy to have proven a true commercial success. The launch of Zolgensma, along with a competing medicine from Biogen called Spinraza, has changed how doctors approach spinal muscular atrophy.

Before the drugs, there was little to be done for children born with the condition. Now, doctors screen newborns for spinal muscular atrophy, and Zolgensma has shown efficacy at preventing progression of the disease over the long term.

The initial approval of Zolgensma had limited its use to the youngest patients. Use of gene therapies becomes more challenging as patients age and grow, because treating them often requires higher doses of the inactivated viruses used to deliver the replacement genes. That can cause safety issues, but the technique that Novartis has chosen of delivering Itvisma right into the spinal fluid eliminates the need for bigger doses.

The new approval of Itvisma is based on a Phase 3 trial called STEER, which tested the treatment in patients aged 2 to 17 and found a statistically significant improvement on a measure of motor function. Novartis didn't test the treatment in adults, but the FDA said that the company had "provided adequate justification to support expanding the indication" to include adult patients.

Write to Josh Nathan-Kazis at josh.nathan-kazis@barrons.com

This content was created by Barron's, which is operated by Dow Jones & Co. Barron's is published independently from Dow Jones Newswires and The Wall Street Journal.

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November 25, 2025 12:28 ET (17:28 GMT)

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