Biogen has paid $75m to take control of Ionis’ nusinersen for spinal muscular atrophy (SMA) after the drug met its objectives in a phase III trial.
The big biotech has said it will now press ahead with regulatory filings for nusinersen in SMA – a rare genetic disease that causes muscle weakness and progressive loss of movement – “in the coming months”, with analysts suggesting it could develop into a $1bn-plus product.
SMA is caused by deterioration in the nerve cells connecting the brain and spinal cord to the body’s muscles, and Ionis was testing nusinersen in an infantile-onset form of the disease to see if it could improve motor function.
The 13-month ENDEAR study revealed that patients taking nusinersen were significantly more likely to achieve an increase in motor function, measured using the Hammersmith Infant Neurological Examination scale, compared to those on placebo.
The trial has now been halted and all placebo patients have been offered the option to swap over to treatment with the active drug (also known as ISIS-SMNRx), which is an antisense compound designed to correct the expression of a gene – called SMN1 – that is impaired in SMA.
A second phase III trial called CHERISH is also ongoing and is due to generate results next year, according to Ionis (formerly known as Isis).
Earlier this year Ionis reported phase II results from an open-label study, which suggested that nusinersen could improve event-free survival and increase muscle function in babies with type 1 (early-onset) SMA.
Some babies were able to sit unaided – something that rarely happens in this form of SMA – and at a recent follow-up assessment there were examples of some of the treated infants crawling, standing and even walking, according to Ionis’ chief business officer Sarah Boyce.
The encouraging data prompted Biogen to exercise an option to develop and commercialise nusinersen globally, taking on responsibility for future costs associated with the programme. Alongside the $75m option payment, Biogen will also pay Ionis up to $150m in regulatory milestones plus tiered royalties up to a mid-teens percentage on potential sales.
Biogen is already running two phase II clinical trials of nusinersen, NURTURE and EMBRACE. NURTURE will examine the efficacy of the drug in pre-symptomatic SMA infants, while EMBRACE is testing the drug in patients who do not meet the entry criteria for ENDEAR and CHERISH.
Approximately one out of every 40 individuals in the US is a carrier of the gene responsible for SMA, and the disease affects around 1 in 10,000 live births. It is the leading cause of genetic infant death and there is currently no approved treatment.
“We see a large opportunity for nusinersen to potentially provide value to patients with SMA and to create a considerable commercial opportunity for about 30,000 to 35,000 patients with SMA in the EU, US and Japan,” said Boyce.
Other companies working on therapies for SMA include Roche/Trophos, Astellas/Cytokinetics and Pfizer/Repligen.