The Medicines and Healthcare products Regulatory Agency (MHRA) has granted marketing authorisation to Biogen for a higher-dose regimen of Spinraza (nusinersen) to treat 5q spinal muscular atrophy (SMA).
The updated regimen includes a more rapid loading phase for ‘treatment-naïve’ patients, with two 50mg doses given 14 days apart, followed by 28mg maintenance doses every four months. Patients transitioning from the existing 12mg regimen will receive a single 50mg dose before moving to the same maintenance schedule.
SMA is a rare genetic neuromuscular condition affecting around 1,600 people in the UK, with around 70 children born with the condition each year. The most common form, 5q SMA, which accounts for an estimated 95% of cases, is caused by changes in a gene responsible for producing survival motor neuron (SMN) protein. This leads to progressive muscle weakness and loss of movement.
Biogen General Manager and Managing Director for the UK and Ireland, Kylie Bromley, said the approval marked “an important milestone for the SMA community”. She added that the firm would continue to work in collaboration with clinicians and patient organisations to improve care, as it had done since Biogen had secured approval for its first SMA treatment in the UK.
The decision is supported by data from the phase 2/3 DEVOTE study and its long-term extension, which evaluated the higher-dose regimen in both treatment-naïve patients and those previously treated with the 12mg dose.
Across the study, adverse events were consistent with the known safety profile of nusinersen, said the company, with no new safety concerns identified in longer-term follow-up. The most commonly reported events included pneumonia, COVID-19, aspiration pneumonia and malnutrition.
Commenting on the approval, Giles Lomax, Chief Executive of Spinal Muscular Atrophy UK, said it ensures continued access to treatment options that can adapt to patients’ changing needs. Mariacristina Scoto, consultant in neuromuscular translational research at Great Ormond Street Hospital for Children, added that the new regimen provides clinicians with additional flexibility when treating patients.
The higher-dose regimen is already approved in the US, EU, Switzerland and Japan, with Biogen continuing to work with regulators to expand access globally.