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Page last updated: 18 March 2022


In response to our request, Biogen shared this community update to announce that they are moving ahead with an early-stage investigation into a new treatment for SMA that could potentially treat further unmet needs:

The compound, BIIB115, acquired from Ionis Pharmaceuticals, is currently in the pre-clinical stage of development and builds on knowledge of nusinersen¹′², which was designated an "orphan medicine" for rare disease in April 2012³.

Nusinersen and BIIB115 are both "antisense oligonucleotides" (ASOs), small snippets of synthetic genetic material, or "molecular patches", that target the underlying pathology of SMA¹′².

It is too early to draw comparisons given the early stages of investigation. However, clinical trials are being planned to help understand the ASO’s dosing as well as its safety, tolerability and efficacy profiles. The clinical trial process is a rigorous one with multiple important phases. Initial clinical trials of experimental treatments focus on understanding their safety profile. Establishing the efficacy of BIIB115 will come in later stage studies.

Initial plans for BIIB115 clinical trials are in development. Biogen will be seeking feedback on their designs from our community. This communication is the first in a series to ensure that Biogen develops a clinical programme for BIIB115 that has been informed by the community.


  1. SPINRAZA (nusinersen). Summary of Product Characteristics February 2022.
  2. Biogen Press Release January 2022. Biogen Exercises Option with Ionis to Develop and Commercialize Investigational ASO for SMA.
  3. EMA nusinersen EPAR Summary for the public January 2018.