The choice of whether to choose an approved or experimental treatment, and which treatment to choose, is personal. Each individual or family must make that choice based on their own needs, goals, and values.

Treating SMA

Due to a mutation in the survival motor neuron gene 1 (SMN1), individuals with spinal muscular atrophy (SMA) don’t produce survival motor neuron (SMN) protein at high enough levels. Without this protein, the motor neuron cells shrink and eventually die. This causes debilitating and potentially fatal muscle weakness.

One way of treating SMA is to increase the amount of survival motor neuron protein in the body. These ways of treating SMA are often called “SMN-based” or “SMN-enhancing” approaches.

All individuals with SMA have at least one, and often multiple, copies of a second gene, called survival motor neuron gene 2 (SMN2), or the “SMA back-up gene.” SMN2 also produces SMN protein, but only a small percentage of the protein produced by SMN2can be used by the body.

Many SMN-enhancing treatments target this SMN2 gene, causing it to make more useable SMN protein. Other SMN-enhancing approaches work to replace or repair the mutatedSMN1gene directly.

Learn more about FDA approved treatments and other drug programs

Combination Therapies

Increasing the amount of SMN protein in the body is not the only way to treat SMA. The loss of SMN protein also impacts other systems, pathways, and processes, and other treatments target these systems. These approaches are often called “non-SMN” approaches. Many of these non-SMN approaches target the muscles or nerves.

Many researchers believe that it will take a combination of SMN-based and non-SMN treatments to provide the most benefit for those with SMA. This could mean that individuals with SMA will take two drugs together. Or, they may take one type of drug at one stage of the disease, and then another drug at a different stage.

There is less consensus about whether combining two similar treatments—for example, two SMN-enhancing approaches or two non-SMN approaches that target the same system—will provide any additional benefit.

Timing is Key

Regardless of what type of treatment is chosen, it is important that individuals with SMA begin therapy as soon after diagnosis as possible. This is especially important for SMN-enhancing therapies. When SMN levels are low, motor neuron cells shrink and eventually die. In infants with SMA Type 1, 90% of motor neurons have been lost by 6 months of age. And once these neurons are lost, they cannot be regenerated.

Beginning therapy as early as possible is the only way to prevent this motor neuron loss. For babies identified through newborn screening, treatment should begin even before the infant shows symptoms of SMA. In clinical trials of SMN-based therapies, individuals who began treatment earlier had better results than those who began treatment later.

Choosing a Treatment

Currently, there are multiple FDA-approved treatments for SMA. All are SMN-enhancing treatments. In addition to these these approved treatments, several other treatments are being tested in clinical trials. You can see a list of treatments below, including those that are approved by the U.S. Food and Drug Administration (FDA).

Generally, you cannot be on an approved therapy and participate in a clinical trial, though there are some exceptions. For example, certain muscle drugs may be tested in individuals who are also on an approved SMN-enhancing therapy. However, outside of these limited exceptions, the decision to enter a clinical trial means that you or your child must forgo taking an approved therapy.

Available Treatments

The chart below covers therapies that are FDA-approved or are being tested in clinical trials. For information on therapies in earlier stages of development, please see our research section.

Name Stage Marketed/Developed By Type of Therapy Who Can Take it
Spinraza FDA-approved Biogen SMN-enhancing All ages and types.
Zolgensma FDA-approved Novartis Gene Therapies SMN-enhancing Patients with SMA up to 2 years of age.
Evrysdi FDA-approved Genentech/Roche SMN-enhancing Adults and children 2 months of age and older.
Reldesemtiv Phase 2 trial completed Cytokinetics/Astellas Non-SMN (muscle drug) Trials have tested the drug on patients with SMA types 2, 3 and 4 who are age 12 or older.
LMI070 Phase 2 trial ongoing Novartis SMN-enhancing Infants with SMA type 1.
AVXS-101 (IT) Phase 1 trial ongoing Novartis Gene Therapies SMN-enhancing Currently being tested on children 6 months to 5 years of age with 3 copies of SMN2.
SRK-015 Phase 2 trial ongoing Scholar Rock Non-SMN (muscle drug) Individuals between 2 and 21 who have SMA type 2 or 3.