Kenneth Hobby, the president of Cure SMA, a patient advocacy group that invested $500,000 in early academic research that led to the development of Spinraza, said more important than the list price of the drug is whether patients who need it will get it.
“Are our families going to get access to the drug in the end?” he said.
About 1 in 10,000 babies are born with spinal muscular atrophy — or about 400 a year in the United States — and it is among the leading genetic causes of death in infants. People with the disease have a genetic flaw that makes them produce too little of a protein that supports motor neurons, leading muscles to atrophy. Spinraza addresses the underlying genetic cause of the disease and enables a backup gene to produce more of the necessary protein.
Blake Farrell, 6, has the disease. As an infant, Blake reached developmental milestones, learning to roll over, sit up and crawl at all the right times. “She was doing everything on target,” Kacey Farrell, Blake’s mother, said recently from the family’s home in Cincinnati.
But as she approached her first birthday, Blake started regressing. She struggled to sit on her own and stopped crawling. At 14 months, tests revealed that Blake had a moderate form of spinal muscular atrophy. As she got older, the muscle loss caused her bones to weaken, and she suffered fractures. She could no longer sit up in the bathtub, and had trouble swallowing food.
In May of 2015, when she was 4, Blake was accepted into a clinical trial for Spinraza, also known as nusinersen. A third of the patients in the study were given a placebo, so the Farrells were not sure if she was getting the real thing. But after receiving her first few doses, which were injected into her spinal fluid, Blake started to improve. She joined her two sisters in the bathtub, sitting up on her own. One day, she even scooted across the floor.
“I was just in shock,” Ms. Farrell said. “These were all things we hadn’t seen her do since she was 8 months old.”
In an analysis of 82 infants in the clinical trial that led to the approval, 40 percent of babies on the drug reached milestones such as sitting, crawling and walking. None of the babies that received a placebo did. The F.D.A. approved the drug months ahead of time and, because the drug treats a rare pediatric disease, granted Biogen a special voucher that it can use to gain priority review of a future drug that would not otherwise qualify for the program.
The F.D.A. said the most common side effects were respiratory infections and constipation, and there is a warning about possible low blood platelet counts and toxicity to the kidneys.
Even though trial investigators did not know which patient was receiving Spinraza, “anecdotally, it just seemed quickly obvious to us that some patients were following a very different trajectory than what we were used to seeing,” said Dr. John Brandsema of the Children’s Hospital of Philadelphia, one of the investigators.
He said that while the patients who improved were the most remarkable, the drug also appears to stop the progression of the disease in other patients.
“It’s hard not to use very exaggerated terms when you are talking about this, because it really is a pretty major step forward,” Dr. Brandsema said.
For now, Blake receives Spinraza free because she is enrolled in an extension study of the drug. But her father, Nick Farrell, a lawyer, said cost is a concern.
“That is a whole lot of money,” he said, adding that among parents of children with the disease, access is already a major topic. “The conversation has already started about, O.K., what’s the next step here?”