The FDA accepted the tofersen NDA in July under the accelerated pathway and granted priority review. The antisense oligonucleotide being evaluated for the potential treatment of superoxide dismutase 1 amyotrophic lateral sclerosis (SOD1 ALS).
In its review of the NDA, the FDA requested further information from Biogen which has been supplied. The FDA considered this information as a Major Amendment to the application that requires additional time for review: and consequently the Prescription Drug User Fee Act (PDUFA) goal date has been pushed back three months from January 23 to April 25.
“We are committed to providing any details the agency needs to complete the review of tofersen,” said Priya Singhal, M.D., M.P.H., Head of Global Safety and Regulatory Sciences and Interim Head of R&D at Biogen. “As the review continues, Biogen will maintain the early access program for tofersen.”
Last month, Biogen published open-label-extension 12 month data to the Phase 3 Valor trial for tofersen: showing a slowed decline in clinical function, respiratory function, strength, and quality of life with early initiation of tofersen.
Amyotrophic lateral sclerosis (ALS) is a rare, progressive and fatal neurodegenerative disease that results in the loss of motor neurons in the brain and the spinal cord that are responsible for controlling voluntary muscle movement. People with ALS experience muscle weakness and atrophy, causing them to lose independence as they steadily lose the ability to move, speak, eat, and eventually breathe. Average life expectancy for people with ALS is three to five years from time of symptom onset.
Mutations in the SOD1 gene are responsible for around 2% of the estimated 168,000 people who have ALS globally, leading to the production of a toxic form of the SOD1 protein.
Known as gene silencing, tofersen binds and degrades SOD1 mRNA to reduce synthesis of SOD1 protein production.
After the launch of its Alzheimer’s drug Aduhelm (aducanumab), tofersen represents one of Biogen’s most advanced drugs in its pipeline.