Study of ARO-APOC3 (Plozasiran) in Adults With Familial Chylomicronemia Syndrome (FCS)

The purpose of AROAPOC3-3001 is to evaluate the efficacy and safety of ARO-APOC3 (plozasiran) in adult participants with familial chylomicronemia syndrome (FCS). Participants who have met all eligibility criteria will be randomized to receive 4 doses of plozasiran or matching placebo administered subcutaneously. Participants who complete the randomized period will continue in a 2-year open-label extension period where all participants will receive plozasiran.

Inclusion Criteria: * Fasting triglycerides (TG) ≥ 10 mmol/L (≥ 880 mg/dL) at screening refractory to standard lipid lowering therapy * Diagnosis of FCS * Willing to follow dietary counseling as per investigator judgement based on local standard of care * Participants of childbearing potential (males \& females) must use highly-effective contraception during the study and for at least 24 weeks following the last dose of study medication. Males must not donate sperm during the study and for at least 24 weeks following the last dose of study medication * Women of childbearing potential must have a negative pregnancy test at Screening and cannot be breastfeeding * Women of childbearing potential on hormonal contraceptives must be stable on the medication for ≥ 2 menstrual cycles prior to Day 1 Exclusion Criteria: * Current use or use within the last 365 Days from Day 1 of any hepatocyte-targeted siRNA or antisense oligonucleotide molecule * Diabetes mellitus newly diagnosed within 12 weeks of Screening or where HbA1c ≥ 9.0% at Screening * Active pancreatitis within 12 weeks before Day 1 * History of acute coronary syndrome event within 24 weeks of Day 1 * History of major surgery within 12 weeks of Day 1 * Uncontrolled hypertension * On treatment with human immunodeficiency virus (HIV) antiretroviral therapy * Seropositive for hepatitis B virus (HBV) or hepatitis C virus (HCV) * New York Heart Association (NYHA) Clas II, III, or IV heart failure Note: Additional Inclusion/Exclusion criteria may apply per protocol