Spinal Muscular Atrophy

Spinal muscular atrophy, or SMA, is an inherited disease that makes muscles weaken and get smaller (atrophy) over time. It usually affects young children and adolescents. Arm, leg, and respiratory muscles are the first to show this atrophy.

Normal voluntary muscle movement takes place when the brain uses motor neurons to send signals to muscles to tell them to move. These motor neurons need certain proteins to survive and be healthy so they can send these signals. SMA is a condition where less proteins are available to motor neurons, so the neurons can no longer function. When the neurons cannot function, the brain can no longer send the signals to move muscles. Because the muscles do not move, they atrophy and stop working.

A person is considered to have later-onset SMA if they were diagnosed with SMA before the age of 2 (Type 2), or after the age of 3 (Type 3). SAPPHIRE is enrolling patients with later-onset SMA.

At this time, there are approved treatments available to help treat SMA, but there are no approved treatments that specifically focus on treating muscle atrophy (a condition in which muscles are smaller and weaker than those of their peers) in SMA.

SAPPHIRE is studying an investigational study drug called apitegromab developed for diseases of muscle atrophy, such as SMA. Apitegromab is designed to target muscle atrophy, muscle strength, and motor function.