First Drug to Treat Spinal Muscular Atrophy Approved by Food and Drug Administration
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First Drug to Treat Spinal Muscular Atrophy Approved by Food and Drug Administration

The disease, which affects muscle strength and movement, is rare and often fatal

December 27, 2016

The Food and Drug Administration (FDA) has approved the first drug ever for treating spinal muscular atrophy (SMA), a rare and often deadly genetic disease that affects muscle strength and movement.

The drug, Spinraza, is injected into the fluid that surrounds the spinal cord.

"There has been a long-standing need for a treatment for spinal muscular atrophy, the most common genetic cause of death in infants, and a disease that can affect people at any stage of life," said Billy Dunn, M.D., director of the Division of Neurology Products in the FDA's Center for Drug Evaluation and Research.

"As shown by our suggestion to the sponsor to analyze the results of the study earlier than planned," Dunn continued, "the FDA is committed to assisting with the development and approval of safe and effective drugs for rare diseases and we worked hard to review this application quickly; we could not be more pleased to have the first approved treatment for this debilitating disease."

Spinraza's effectiveness was shown in a clinical trial, which determined the percentage of patients who showed an improvement in motor milestones such as head control, sitting, the ability to kick when lying on the back, rolling, crawling, standing, and walking. One hundred and twenty-one patients participated, each of whom had SMA that had appeared when the patient was an infant. Each participant was diagnosed before reaching six months old and was less than seven months old when they received their first dose of the new drug. The patients were randomized to either get an injection of Spinraza or to go through a mock procedure without an injection, receiving a skin prick instead. Twice the number of participants got an injection when compared with the number of those who got a skin prick.

The FDA asked the sponsor of the trial to carry out an analysis after the trial to review the results as soon as possible. Of the 121 patients who participated, 82 were eligible for this analysis. Forty percent of those patients who had been treated with Spinraza showed improvement in their major milestones, while none of the patients did who had gone through the mock procedure.

Other trials were also conducted to study the effectiveness of the drug. These studies did not involve control groups, so their results were harder to interpret than the results of the controlled study. However, the findings seemed to generally support the effectiveness first shown in the controlled trial.

The most common side effects seen in the patients who took part in the clinical trials were upper respiratory infections, lower respiratory infections, and constipation. Warnings and precautions included with Spiranza are low amounts of blood platelets and toxicity to the kidneys. Toxicity in the nervous system was seen in animal studies.