Dive Brief:
- Biogen on Wednesday unveiled updated data showing its spinal muscular atrophy drug salanersen slowed neurodegeneration and improved motor function in an early-stage study.
- The trial enrolled patients who had already been treated with the Novartis’ gene therapy Zolgensma, and found a reduction of 75% in neurofilament light chain levels, a measure used to evaluate neurodegeneration. Half of those patients also achieved a motor function milestone according to World Health Organization standards.
- As part of the update, Biogen also revealed the design for a late-stage study that includes three separate trials of salanersen in newborns, infants already treated with Zolgensma, and teens and older adults who have either not been treated or previously took another SMA drug, Roche’s Evrysdi.
Dive Insight:
Biogen picked up salanersen from its longtime partner Ionis Pharmaceuticals in 2022, looking to it as a follow-up for its successful SMA drug Spinraza. Facing market competition from Zolgensma and Evrysdi, the two companies touted the antisense oligonucleotide drug as an opportunity to treat a slice of the SMA patient population who do not respond to other treatments.
Salanersen uses the same mechanism as Spinraza, but is crafted to be more potent, according to Biogen. It corrects the splicing of a gene to increase production of survival motor neuron proteins, levels of which are low in people who have SMA.
At a medical meeting last June, Biogen presented early data from the Phase 1 study showing its drug was well-tolerated and “led to substantial slowing of neurodegeneration” in eight trial participants with the rare genetic disease. Four of the children treated also demonstrated improvement in motor function, hitting milestones “they previously could not achieve on their own or required assistance to do, such as walking, crawling, standing, or sitting.”
The latest data, drawn from a group of 24 children aged six months to 12 years, continued to show those benefits. Trial participants received two doses salanersen — either at 40 mg or 80 mg — and were followed for at least a year thereafter. All study volunteers saw improvement from baseline on at least one endpoint.
Side effects of salanersen included upper respiratory tract infection, vomiting and fever.
Biogen has already started screening participants for its late-stage salanersen program. “Together with the SMA community, we have designed these studies to confidently answer the most relevant questions for the field and establish salanersen’s role in the future treatment landscape,” Stephanie Fradette, Biogen's head of neuromuscular development, said in a statement.
Investors are keeping an eye on salanersen and a possible approval of a higher dose of Spinraza in the U.S., among Biogen’s other experimental prospects in immunology and kidney diseases, as recent product launches for the big biotech have disappointed. In a note to clients in February, RBC Capital Markets’ Brian Abrahams wrote that “salanersen may have long-term promise.”
Salanersen's "more convenient" dosing — given once a year versus thrice annually for Spinraza — and the improved motor function it can offer patients post-Zolgensma are "key advantages that could sustain [Biogen's] SMA franchise into the 2030s," wrote Andrew Tsai, an analyst at Jefferies, in a note to clients Wednesday.
