The Food and Drug Administration on Friday approved Spinraza (nusinersen), the first treatment for children and adults with spinal muscular atrophy (SMA), a rare and often fatal genetic disease affecting muscle strength and movement.
Spinraza is an injection administered into the fluid surrounding the spinal cord.
The agency approved the drug after granting it fast-track status. It was developed by Ionis Pharmaceuticals Inc. of Carlsbad, CA, and Biogen Inc. of Cambridge, MA. Biogen will market it.
“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,” according to 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, 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,” Dunn added. “We could not be more pleased to have the first approved treatment for this debilitating disease.”
Cure SMA, and organization dedicated to the treatment and cure of spinal muscular atrophy, says SMA affects roughly one in 10,000 babies, and about one in every 50 Americans is a genetic carrier. The group funds groundbreaking research and provides support for families.
The FDA noted the disorder, which affects the motor nerve cells in the spinal cord, can impact people of any age. SMA is a hereditary disease that causes weakness and muscle wasting because of the loss of lower motor neurons controlling movement. There is wide variability in age of onset, symptoms and rate of progression. Spinraza is approved for use across the range of spinal muscular atrophy patients, the FDA said.
The efficacy of Spinraza was demonstrated in a clinical trial in 121 patients with infantile-onset SMA who were diagnosed before 6 months of age and who were less than 7 months old at the time of their first dose.
Patients were randomized to receive an injection of Spinraza, into the fluid surrounding the spinal cord, or undergo a mock procedure without drug injection (a skin prick). Twice the number of patients received Spinraza compared to those who underwent the mock procedure. The trial assessed the percentage of patients with improvement in motor milestones, such as head control, sitting, ability to kick in supine position, rolling, crawling, standing and walking.
The FDA asked the sponsor to conduct an interim analysis as a way to evaluate the study results as early as possible; 82 of 121 patients were eligible for that analysis. Forty percent of patients treated with Spinraza achieved improvement in motor milestones as defined in the study, whereas none of the control patients did.
Additional open-label uncontrolled clinical studies were conducted in symptomatic patients who ranged in age from 30 days to 15 years at the time of the first dose, and in pre-symptomatic patients who ranged in age from 8 days to 42 days at the time of first dose.
The studies lacked control groups and therefore were more difficult to interpret than the controlled study, but the findings appeared generally supportive of the clinical efficacy demonstrated in the controlled clinical trial in infantile-onset patients, according to the FDA.
The most common side effects found in participants in the clinical trials on Spinraza were upper respiratory infection, lower respiratory infection and constipation. Warnings and precautions include low blood platelet count and toxicity to the kidneys (renal toxicity). Toxicity in the nervous system (neurotoxicity) was observed in animal studies.
With the FDA approval, Ionis will receive a $60 million milestone payment. It’s also in line for royalties on Spinraza sales. Its shares rose $3.69, or 7 percent, to $57.10 in after-market trading following the announcement of the drug’s approval.
Biogen rose $9.47, or 3.3 percent, to $297.