BIIB132 is an investigational anti-sense oligonucleotide developed to target ataxin-3 (ATXN3) pre-messenger ribonucleic acid (pre-mRNA). Preclinical studies have shown that lowering of ATXN3 protein is associated with decreased progression of SCA3-like disease. This trial consists of a blinded 12 week study period with a 26 week follow up period to evaluate the safety and tolerability of intrathecal BIIB132 and to assess the effect on treatment response biomarkers in symptomatic SCA3 participants.
The primary objective of this study is to evaluate the safety and tolerability of multiple ascending doses of BIIB132 administered via intrathecal (IT) injection to participants with spinocerebellar ataxia type 3 (SCA3). The secondary objective of this study is to characterize the multiple-dose pharmacokinetics (PK) of BIIB132 administered via IT injection to participants with SCA3.