Amanda Sifford was running out of time. Her lung function had plummeted from 86% to 48% in just five months, and the genetic form of ALS that had killed 14 of her family members was stealing her ability to breathe. Then she became one of the first patients to receive tofersen, Biogen's drug marketed as Qalsody, after its conditional FDA approval in May 2023.

Three years later, her lung function climbed back to 63%. A study following 46 patients found nearly 20 percent improved in breathing, strength and function — a remarkable outcome for a disease that almost always causes continual decline. While about 75% didn't stabilize or improve, their decline was slower than expected. Patients with fast-progressing ALS who received tofersen early lived about three years longer than those who started later.

The drug targets only about 2% of ALS patients whose disease is caused by a SOD1 gene mutation. "It tells us that ALS is treatable," said Dr. Timothy Miller, the trial's principal investigator at WashU Medicine. Patients like Rickey Malloy, who started treatment weeks after diagnosis, have seen their symptoms stabilize or improve, allowing them to undergo unrelated surgeries and participate in physical therapy trials.