Biogen Presents Additional Salanersen Data Showing New Motor Milestones Achieved in Children with SMA Previously Treated with Gene Therapy

Core Insights - Biogen Inc. presented additional results from the Phase 1b study of salanersen, an investigational antisense oligonucleotide for spinal muscular atrophy (SMA), showing it was well-tolerated and led to functional improvements in children with suboptimal clinical status despite prior gene therapy [1][2][4] Phase 1b Study Results - The study involved 24 participants aged 0.5-12 years, all of whom received at least 2 doses of salanersen (40 mg or 80 mg) [3] - Participants with elevated neurofilament light chain (NfL) levels showed a 75% reduction in NfL at six months, sustained throughout the follow-up [4] - All participants experienced improvement on one or more endpoints, with 12 achieving new WHO motor milestones [4] Phase 3 Clinical Development Program - Biogen introduced the Phase 3 clinical program for salanersen, which includes three global studies: STELLAR-1, STELLAR-2, and SOLAR [5][10] - STELLAR-1 will evaluate salanersen in young, treatment-naïve infants with SMA, while STELLAR-2 will assess its effects when initiated after prior gene therapy [7] - SOLAR will focus on teens and adults with SMA, either treatment-naïve or previously treated with risdiplam [7] Salanersen Overview - Salanersen (BIIB115) is designed to correct splicing of SMN2 pre-mRNA to increase SMN protein production, with a new backbone chemistry allowing for high potency and efficacy with once-yearly dosing [9][10] - The drug is being developed in collaboration with Ionis Pharmaceuticals, which holds the global rights for its development and commercialization [10]