Biogen clinical data a ‘major catalyst’ for spinal muscular atrophy drug

Biogen Inc. said Monday that it plans to seek US regulatory approval by the end of the year for an experimental drug to treat spinal muscular atrophy in infants.

Encouraging new clinical data has prompted Cambridge-based Biogen to exercise an option to develop and commercialize the drug candidate, called Nusinersen. The compound originated in the labs of Biogen’s partner, Ionis Pharmaceuticals Inc.

An interim analysis of the data, which analysts said was unexpected and ahead of schedule, showed that Nusinersen met its primary goal of significantly improving motor functions in infants who took it in the late-stage trial compared with those who didn’t. Biogen and Ionis also said the experimental drug showed an acceptable safety profile in the patients.

“We’re all thrilled by the outcome,” Biogen chief executive George Scangos, who plans to retire by early next year, told stock analysts in a conference call. “Because when you see the kids and you see their parents, I think there’s nothing more emotional I’ve worked on in my career... We certainly appreciate the urgency of this.”

Shares of Biogen climbed more than 5 percent in late morning trading, while shares of Ionis, based in Carlsbad, Calif., were up nearly 39 percent. Biogen will pay $75 million to Ionis to exercise its option to take over the Nusinersen program,

In a note to investors Monday morning, Mark Schoenebaum, biopharma analyst for research firm Evercore ISI in New York, called Nusinersen a “major catalyst” for Biogen and estimated peak sales of $1.7 billion globally by 2025.

Spinal muscular atrophy, known as SMA, is a rare disease that causes loss of muscle control in infants and children. The leading genetic cause of death in infants, it affects about 12,500 people in the United States and 35,000 to 50,000 worldwide, according to Cure SMA, a 30-year-old patient advocacy group that has worked closely with the drug makers.

Biogen and Ionis have been under pressure from the families of children suffering from SMA to move forward more quickly with the program. The drug program is part of Biogen’s push into new treatments for neurodegenerative diseases, including Alzheimer’s, that are key to the company’s plan to expand beyond its multiple sclerosis drug franchise.

Alfred Sandrock, executive vice president and chief medical officer at Biogen, would not specify how soon the company will apply to the Food and Drug Administration for approval of Nusinersen. But he said company officials worked through the weekend on the application and have also been in touch with European and Asian regulators about the interim data.

“They are very interested in this program, and are encouraging us to file [applications] as rapidly as possible there as well,” Sandrock said in an interview.

Cure SMA president Kenneth Hobby said Biogen and Ionis have had to strike a balance between moving as quickly as they can to treat a disease for which there are no current treatments and making sure they had the clinical data to support their regulatory applications. He said his group has been working to “make sure the patient perspective is factored in” to the data.

In their conference call, Biogen and Ionis executives said they were ending the Nusinersen trial, which enrolled 122 patients around the world, but making the drug available to more infants through an expanded access program at the clinical trial sites even before they file their application with the FDA. Biogen will also move forward with a half a dozen other clinical trials that are testing the drug at different doses in infants, children, and adults with SMA.

Scangos called the interim analysis of Nusinersen “extraordinarily positive.” But Biogen and Ionis officials declined to answer specific questions about their late-stage study, saying their findings will be published and discussed at an upcoming medical meeting.

Company officials also declined to project what they might charge for Nusinersen if it wins FDA approval.