The risks related to Biogen's drug, tofersen, "are acceptable to the patient population" and would not "preclude approval", staff reviewers said in briefing documents published on the agency's website. The agency has asked advisers to weigh in on approving the use of the drug based on available data, which shows it reduces a key protein related to the disease, and not disease symptoms. In October 2021, tofersen failed to meet the main goal of a late-stage study, but the company said trends of reduced disease progression were observed.A panel of outside advisers to the FDA is set to meet on Wednesday to discuss Biogen's marketing application for the drug to be used as a treatment for ALS associated with mutation in a gene known as superoxide dismutase 1 (SOD1), an ultra-rare form of the fatal neurological disease.  (Reporting by Raghav Mahobe and Bhanvi Satija in Bengaluru; Editing by Krishna Chandra Eluri and Shinjini Ganguli)