Interim Data from the STRONG Trial Indicate that Zolgensma Treatment Improves Motor Function in Older SMA Type 2 Patients

10 October 2019

Interim data from the STRONG trial of AveXis’ gene therapy drug, Zolgensma (AVXS-101), show an increase in motor function scores among older SMA Type 2 patients following a one-time intrathecal (IT) administration of the treatment.

Based on several successful clinical trials, administration of Zolgensma into the blood was recently approved by the FDA in the US for treatment of SMA Type 1 (click here for more information).

One of several ongoing studies (click here for more information), the STRONG trial is investigating the potential of IT injections of Zolgensma directly into spinal cord fluid, which may improve delivery of the gene therapy to the most affected cell type in SMA – the lower motor neurons.

Presented at the Annual Congress of the World Muscle Society this month, preliminary data from the Phase 1/2 STRONG trial in patients with SMA Type 2 indicate that:

  • Patients aged between 2 and 5 years, achieved a mean increase of 5.9 points from baseline in motor function scores as assessed by the Hammersmith Functional Motor Scale-Expanded (HFMSE). This is nearly double the value deemed to be clinically meaningful. This is an improvement on the increase of 4.2 points initially presented in May 2019 at the American Academy of Neurology Annual Meeting.
  • Untreated SMA Type 2 patients historically experience declining motor function scores over time, will never walk without support and often need a wheelchair.
  • Data from patients in the younger cohort (aged between 6 and 24 months at the time of treatment) indicate that 18 motor milestones were achieved among the 16 treated patients, and that two gained the ability to stand independently, and one of whom was able to walk unaided.


Phase 1/2 STRONG is a dose-comparison, multi-centre trial, designed to evaluate the efficacy, safety and tolerability of a one-time IT administration of AVXS-101 in patients with SMA Type 2, who have three copies of the SMN2 gene and who are able to sit but cannot stand or walk at the time of study entry.

As of the data cut-off date, 31 patients were enrolled and divided into two groups based on their age at the time of treatment and given one of three doses.

All patients in the STRONG study experienced at least one adverse event upon treatment, 13 (43%) of which were considered by the investigator to be directly related to treatment.

Seven serious adverse events were reported in four patients (13%), including influenza, pneumonia, elevated liver enzymes (which indicate liver damage), and respiratory failure. Elevated liver enzymes (in one patient) were considered probably related to the treatment. None of the serious adverse events resulted in discontinuation from the study and no deaths were reported.

For more information:

The press release

About AVXS-101