FDA Approves Drug to Treat Rare Form of ALS

Biogen Inc.’s drug for a rare form of amyotrophic lateral sclerosis was approved by U.S. regulators, marking the first clearance of a treatment targeting a specific genetic cause of the incurable paralysis disease.

The Food and Drug Administration granted clearance for the drug, called Qalsody, through an accelerated approval pathway, meaning Biogen must conduct more research to establish its benefits for it to remain on the market. The approval was disclosed on the agency’s website Tuesday.

ALS, sometimes called Lou Gehrig’s disease, destroys nerve cells that control voluntary muscle movement, including breathing. Around 31,000 people in the U.S. are living with the disease, according to Centers for Disease Control and Prevention estimates. Roughly 5,000 new patients are diagnosed with ALS each year. The FDA estimated there are fewer than 500 patients in the U.S. with the form of ALS that the Biogen drug treats.

Qalsody’s clearance has been a challenging journey for Biogen and partner Ionis Pharmaceuticals Inc. After a late-stage trial failed to show that the drug slowed the disease, the companies didn’t conduct a second, larger trial to confirm whether the drug worked. A second trial would “not appear to be feasible” given the rarity of the disease, FDA staff said in a report in March.

Instead, Biogen applied for clearance through the accelerated approval pathway on the basis that the drug reduces levels of a blood protein associated with brain injury. In an advisory committee meeting in March, Qalsody, formerly known as tofersen, got partial support from an independent panel of advisers. They said the company hadn’t proven the drug worked but they agreed that reducing proteins was a promising sign that the drug would help patients.

“Today also marks a pivotal moment in ALS research,” said Christopher Viehbacher, Biogen’s chief executive officer, in an emailed statement after the approval. “We believe this important scientific advancement will further accelerate innovative drug development for ALS.”

Shares of Biogen fell 3.5% at 2:03 p.m. in New York, while Ionis climbed as much as 0.5%.