FDA awards Biogen's ALS drug Qalsody an accelerated approval, following its experts' feedback this time

The FDA has approved another Biogen drug for a neurological disorder. And, unlike the controversial go-ahead for Aduhelm, the agency’s neuroscience division didn’t go against its external advisers’ advice this time.

Tuesday, the FDA granted an accelerated approval to Biogen and Ionis’ tofersen to treat patients with amyotrophic lateral sclerosis (ALS) associated with a mutation in the SOD1 gene. The drug will be sold under the brand name Qalsody.

The move follows the recommendation from an FDA advisory committee in March. At that time, nine experts agreed that Qalsody’s ability to reduce plasma neurofilament light (NfL), a biomarker of nerve injury and neurodegeneration, provides enough basis for a conditional approval. However, thanks to a phase 3 trial flop, the panel voted against full approval.

SOD1-ALS is a small subset of ALS, affecting fewer than 500 patients in the U.S. and about 2% of all 168,000 ALS patients worldwide, according to Biogen’s estimates. Given the limited market size, SVB Securities analysts have put Qalsody’s peak sales potential at about $300 million.

Qalsody is an antisense drug that targets SOD1 mRNA to reduce the production of the SOD1 protein. In a phase 3 trial, the drug showed it can reduce plasma NfL concentration compared with placebo. Both the FDA and its advisers believe the findings are reasonably likely to predict a clinical benefit.

The FDA approval marks a “consensus that neurofilament can be used as a surrogate marker reasonably likely to predict clinical benefit in SOD1-ALS,” Biogen CEO Chris Viehbacher said in a statement. “We believe this important scientific advancement will further accelerate innovative drug development for ALS.”

Still, the drug failed to significantly improve the function of SOD1-ALS patients who had already shown ALS-related weakness. The phase 3 VALOR trial therefore missed its primary endpoint.

Qalsody’s nod comes seven months after the FDA’s approval for Amylyx’s Relyvrio. That drug showed it could preserve physical function and slow the progression of ALS in a randomized phase 2 trial. Relyvrio’s broader reach in ALS has invited blockbuster sales projections.

An accelerated approval means that Biogen is on the hook to provide confirmatory evidence to prove Qalsody’s clinical efficacy. While Qalsody is available under the FDA’s accelerated approval pathway, a phase 3 trial dubbed ATLAS is testing the drug in pre-symptomatic people carrying the SOD1 mutation. The study will compare the proportions of patients who develop ALS symptoms between Qalsody and placebo.

Qalsody’s small market potential means it’s not likely to help Biogen’s business much after the Aduhelm debacle. Instead, the company’s current focus is on an upcoming FDA decision for a potential full approval for a second Alzheimer’s disease drug, the Eisai-partnered Leqembi. A full approval could open the door to wider coverage on Medicare.

In addition, Biogen has the Sage Therapeutics-partnered depression candidate zuranolone in its pipeline. The FDA is set to decide on the GABA modulator in postpartum depression and major depressive disorder by Aug. 5. If approved, that drug could bring blockbuster-level sales.

Biogen exercised an option to acquire Qalsody rights by paying Ionis $35 million in 2018. Biogen is solely responsible for the development and commercialization of Qalsody after the deal.