Onasemnogene abeparvovec intrathecal

Pharmaceutical company: Novartis Pharmaceuticals

OAV101-IT targets the genetic cause of SMA by delivering a functional copy of the SMN1 (survival motor neuron) gene into nerve cells. This leads to the production of the SMN protein, which is missing in SMA. This protein is essential for the health of nerve cells which help to control muscles.

OAV101-IT has the same active ingredient as Zolgensma (onasemnogene abeparvovec), an approved treatment for some babies and young children with SMA. However, OAV101-IT is administered differently.

While Zolgensma is given as a one-time infusion into the bloodstream, OAV101-IT is given as a one-time injection into the fluid surrounding the spinal cord (an intrathecal injection, also known as a lumbar puncture).

This approach is designed to deliver the treatment directly to the central nervous system, where the motor neurons affected by SMA are located. The intrathecal route may allow the treatment to be used in a broader range of people with SMA, including older and heavier individuals.

The treatment is not currently available in the UK.

The Medicines and Healthcare products Regulatory Agency (MHRA) is reviewing OAV101-IT and will decide whether it can be prescribed by doctors in the UK.

At the same time, the National Institute for Health and Care Excellence (NICE) is assessing the treatment for use on the NHS in England. However, OAV101-IT would only be available if it is approved by the MHRA. Wales and Northern Ireland also normally follow NICE guidance.

We are working in partnership with the charities SMA UK and Treat SMA to make sure the community’s voice is heard during the MHRA and NICE assessments.

People who hadn’t received SMA treatment

OAV101-IT was tested in the phase 3 STEER trial. 126 participants, aged between 2 and 17 years of age, who hadn’t received any treatment for SMA and were able to sit but never walk independently took part in the trial.

Participants were randomly assigned to receive OAV101-IT (75 participants) or a sham procedure (51 participants). This means some participants underwent a procedure that looked like the treatment being tested but did not receive the active treatment.

At the end of the 52-week trial period, participants who received OAV101-IT showed greater improvement in the Hammersmith Functional Motor Scale – Expanded (HFMSE) than those who received the sham procedure. The HFMSE is a test that measures muscle function and helps monitor the progression of SMA. These results suggest that OAV101-IT may help improve motor function and support greater independence in everyday activities.

The treatment was also found to have an acceptable safety profile. The number and type of side effects reported were similar in the OAV101-IT and sham procedure groups.

People who had previously received SMA treatment

OAV101-IT has also been tested in the phase 3 STRENGTH trial. The trial included 27 people with SMA aged between 2 and 17 years of age who had previously received nusinersen or risdiplam treatment but were not currently receiving either drug. All participants received OAV101-IT.

After 52 weeks, participants’ HFMSE scores remained stable. As SMA is a progressive condition, these results suggest that OAV101-IT may help maintain motor function in this group. The treatment showed a similar safety profile to that seen in the STEER trial. These findings are based on studies in children and young people with SMA.

Last updated: 07/07/2026