A Study of Olezarsen (Formerly Known as AKCEA-APOCIII-LRx) in Participants With Familial Chylomicronemia Syndrome (FCS)

Inclusion Criteria: • Satisfactory completion of treatment with olezarsen in the index study (ISIS 678354-CS3, last dose as scheduled at Week 49) with an acceptable safety profile, per Investigator judgement. Exclusion Criteria: • Have any new condition or worsening of existing condition which in the opinion of the Investigator would make the participant unsuitable for enrollment, or could interfere with the patient participating in or completing the study, including need for treatment with medications disallowed in the index study (ISIS 678354-CS3).