Comparing Spinraza and Evrysdi: Things to Consider

If you are taking Spinraza® (nusinersen) for spinal muscular atrophy (SMA), then you may be curious about Evrysdi® (risdiplam). Both therapies are available in the United States, but there are a few things to consider when comparing them.

Spinraza was approved in 2016 to treat SMA in children and adults. It is delivered through spinal injections. Evrysdi was approved in 2020 to treat SMA in adults and children 2 months and older. It is a liquid drug that can be swallowed or given in a feeding tube.^1-3

Both drugs are approved for all types of SMA.

How do Spinraza and Evrysdi work?

Spinraza and Evrysdi use different methods to increase the level of survival motor neuron (SMN) protein in the body. SMN is produced by the motor neurons and protects against muscle wasting. People with SMA usually have a missing or mutated SMN1 gene, and their backup SMN2 gene only makes 10 to 15 percent of the SMN they need.⁴

Spinraza works by acting on the SMN2 backup gene to make more SMN. It prevents the backup gene from skipping an important step in making the protein by providing a new set of instructions. Evrysdi is a small-molecule drug that also interacts with the SMN2 backup gene. It strengthens the backup gene’s ability to make more SMN protein by binding to it and correcting the skipped step.^5-7

Spinraza is given on a dosing schedule that includes 4 initial doses over several months, then once every 4 months. Evrysdi is taken by mouth every day.^6,7

How do Spinraza and Evrysdi compare?

Recent studies suggest that Evrysdi may work better than Spinraza for certain types of SMA. But it is complicated because the 2 therapies have not been studied in direct comparison. What we know comes from indirect comparisons. This means we may not yet have the whole picture.^8,9

In type 1 SMA, which emerges shortly after birth and is the most common form, Evrysdi may work better. Researchers compared data from different studies that had similar participants. Those taking Evrysdi had better survival and motor function compared to Spinraza.⁸

But comparing the therapies in types 2 and 3 SMA proved harder. The participants in the studies varied too much for the indirect comparison to offer reliable findings.⁸

Limitations

Both Spinraza and Evrysdi have been shown to be very effective. They have both had a large impact on improving the quality of life of those living with SMA.⁹

To really know which drug is more effective, we need to have a study that directly compares them. These are called head-to-head clinical trials. Participants would need to include people with SMA who are:

• Not yet showing symptoms
• Adolescents
• Adults

Including people from all these groups would ensure the strength and reliability of findings across different ages and disease severity. Until that information is available, interpret the indirect comparisons with caution.

Talking to your doctor

If you are considering switching your SMA drug therapy, let your doctor know if you:

• Are pregnant
• Plan to become pregnant
• Are breastfeeding
• Have kidney disease

Make a list of questions to ask your doctor. Here are a few ideas:

• Will the new medicine interact with any of the other drugs I take?
• Would any of my health conditions prevent me from taking the new medicine?
• What is the dosing schedule?
• What common side effects should I know about?
• Are there any serious or long-term side effects I should know about?