This clinical research study is enrolling adults who have high triglycerides (fats in the blood). The study drug, olezarsen, is an investigational drug designed to reduce triglyceride blood levels. If you meet the requirements to participate in this study, you will be randomly assigned to receive either olezarsen or placebo (an inactive substance that contains no drug). During the treatment period, participants will be asked to complete visits every 4 weeks to include a total of 21 visits over approximately 16 months. If eligible, study medication and study visits will be provided free of charge. Compensation is available.