Tofersen

Tofersen is available to eligible individuals through Health Canada’s Special Access Program (SAP).

In March 2024, Health Canada accepted a New Drug Submission (NDS) for tofersen.

Health Canada’s acceptance triggered a thorough regulatory review of the therapy, which will determine whether tofersen will be approved for use in Canada.

A regulatory decision on the New Drug Submission is expected in early 2025.

ALS Canada is in conversation with Health Canada and Biogen about the need for Canadians to have equitable, timely, and affordable access to this therapy and to advocate to ensure there are no gaps in access for people currently receiving tofersen through the Special Access Program (SAP). We will continue to keep our community updated as we learn more.

Tofersen is an investigational therapy for the treatment of ALS in adults with a pathogenic variant in the SOD1 gene.

The SOD1 gene encodes the information to make a protein called superoxide dismutase 1. This protein helps cells to function properly by clearing toxic byproducts called reactive oxygen species (ROS), also known as free radicals. These byproducts are created naturally in the cell after normal cellular processes and must be broken down regularly to prevent oxidative cell damage.

Many variants in this gene can lead to a defective version of this protein, which becomes toxic and disrupts normal cell biology, contributing to ALS. Variants in the SOD1 gene are believed to cause ten to thirty percent of familial ALS cases and approximately one to four percent of individuals with no obvious family history.

Tofersen is an antisense oligonucleotide (ASO) that targets SOD1 mRNA, leading to reduced production of the SOD1 protein and decreased toxic levels in cells.

In clinical trials, tofersen reduced SOD1 levels in the cerebrospinal fluid (CSF) of people living with SOD1-ALS and levels of NfL, a biomarker indicative of nerve cell damage.

Biogen’s ongoing ATLAS Phase 3 clinical trial aims to further evaluate the efficacy of the therapy and determine whether early treatment with tofersen can delay the onset of ALS symptoms and/or significantly slow decline in function after symptoms appear. Individuals with SOD1-ALS participating in the ATLAS study will be monitored regularly for biological changes that indicate the underlying disease processes have started. This is the first clinical trial to ever test a treatment in individuals who have not yet been diagnosed with ALS.