Biogen, Ionis' experimental spinal muscular atrophy drug nusinersen meets main goal of Phase III study

Biogen and Ionis Pharmaceuticals announced Monday that the investigational spinal muscular atrophy (SMA) treatment nusinersen met the primary endpoint of the ENDEAR Phase III study. In the interim analysis, infants in the nusinersen arm exhibited a statistically significant improvement in the achievement of motor milestones compared to those who did not receive the drug. 

Specifically, the ENDEAR trial was a 13-month study, which investigated nusinersen in 122 patients with infantile-onset SMA. The primary endpoint of the study was the proportion of motor milestone responders based on the motor component of the Hammersmith Infant Neurological Examination. The companies noted that based on the study results, the ENDEAR study will be halted, with all patients offered an opportunity to transition into the SHINE study in which all patients will receive open-label nusinersen. 

Based on the results, Biogen has exercised an option to develop and commercialise the therapy globally, with Ionis, which shares climbed as much as nearly 39 percent on the news, due a payment of $75 million associated with the decision. Biogen also plans to initiate regulatory filings for the treatment in the coming months.  

Under the agreement, Biogen will hold responsibility for all activities and costs associated with the development, regulatory approval and commercialisation of nusinersen, while Ionis will complete the late-stage studies and assist Biogen with regulatory submissions. Biogen will pay Ionis tiered royalties up to a mid-teens percentage on potential sales of the therapy, in addition to as much as $150 million in milestone payments linked to regulatory approvals. 

Commenting on the news, RBC Capital Markets analyst Michael Yee described the data as an "upside surprise as investors did not have high confidence the drug would work." Yee estimated that nusinersen could amass more than $1 billion in revenue.

Nusinersen was awarded orphan drug status as well as fast track designation in the US , while the drug has also been granted orphan drug status in Europe.

For related analysis, see  ViewPoints: Biogen, Ionis looking to nusi-nurse themselves back to health. See also ViewPoints: Early results for AveXis' SMA gene therapy suggest the threat is real for Ionis, Biogen’s nusinersen.


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