Following the news that Biogen is planning a Phase IV trial to test Spinraza (nusinersen) in patients with spinal muscular atrophy (SMA) who have already been treated with Novartis’ gene therapy Zolgensma (onasemnogene abeparvovec);

Philippa Salter, Neurology Analyst at GlobalData, a leading data and analytics company, offers her view:

“Biogen can maintain its dominance in the SMA market by demonstrating that Spinraza can benefit patients who have received Novartis’ gene therapy Zolgensma. Before Zolgensma was approved in 2019, Spinraza was the only treatment option for SMA and, as such, experienced rapid uptake and reached blockbuster status, with $2.1bn global revenue in 2019.

“Zolgensma’s supposed ‘one-time’ treatment challenged Spinraza’s dominance by giving a better quality of life compared with Spinraza’s intrathecal route of administration, which requires a lumbar puncture every time the drug needs to be administered. This reduced the number of patients who would need to take Spinraza and had a negative impact on its sales.

“However, since Zolgensma’s approval, it has become apparent that the gene therapy may not be the ‘one-time’ treatment everybody hoped – as highlighted by some key opinion leaders interviewed by GlobalData, who also flagged a lack of long-term data. If Biogen’s Phase IV trial can demonstrate that Spinraza can provide benefit by improving motor function and reducing need for respiratory support, it will strengthen Spinraza’s position and reduce the impact from the launch of Zolgensma.

“Even if there are positive results from this Phase IV trial, Spinraza is still expected to face competition in the future from other products entering the market, particularly from Roche and PTC Therapeutics risdiplam, which is currently waiting for a decision from the FDA expected later this year. Risdiplam has a similar mechanism of action to Spinraza but a much more favorable oral route of administration, which should give it an advantage.”