What Is It, and Why Does It Matter?
The FDA has approved Isembyld (apitegromab) for adults and children ages 2 years and older with spinal muscular atrophy (SMA). To take this drug, patients must already be receiving another SMA treatment called an SMN2-targeted therapy. SMA is a rare genetic disease that causes muscles to weaken and waste away over time.
Older SMA treatments work by helping protect nerve cells. But Isembyld is the first treatment that acts directly on the muscles. It blocks proteins that stop muscle growth, which helps improve muscle movement and strength.
Why Was It Approved?
The approval of Isembyld was based on a clinical trial with 188 people ages 2 to 21 years old. All patients in the study were already taking standard SMN2-targeted treatments. Researchers compared people who received Isembyld to those who received a placebo (an inactive treatment) over one year.
The main group studied included children ages 2 to 12 years. After one year, children taking Isembyld showed an average improvement in their physical movement scores. In contrast, children who received the placebo saw their physical movement scores decline. About 34% of patients taking Isembyld had a meaningful improvement in movement, compared to only 14% of patients receiving the placebo.
What Do I Need to Know?
Isembyld is given by a healthcare provider as an intravenous (IV) infusion into a vein. The infusion takes about one to two hours to complete. Patients receive this treatment once every four weeks.
Treatment with Isembyld may increase the risk of bone fractures, including severe broken bones. These fractures can even happen without a fall or injury. Patients with a history of low bone density or prior fractures should discuss these risks with their healthcare provider.
The most common side effects observed during clinical trials included upper respiratory tract infections, vomiting, coughing, viral infections, headaches, stomach flu, a sore throat, and allergic reactions.
Tell your healthcare provider about all your health conditions before starting Isembyld. It is not known if Isembyld is safe during pregnancy or while breastfeeding, so discuss any pregnancy plans with your healthcare provider. Also, give your healthcare provider a full list of all medicines, supplements, and vitamins you take.