This is a multi-center, open-label extension (OLE) study of up to 60 participants with FCS rolling-over from Study ISIS 678354-CS3 (NCT04568434). Participants will receive olezarsen during a 157-week treatment period, followed by a 13-week post-treatment follow-up period. The length of participation in this study is approximately 201 weeks, which includes an up to 31-day qualification period, a 157-week treatment period, and a 13-week post-treatment evaluation period.
Treatment has been extended to obtain additional safety assessments and efficacy data and to provide patients with continued access to ISIS 678354 until the drug may be available commercially.