This study is looking at plozasiran, a medication for adults with severe hypertriglyceridemia (SHTG). Hypertriglyceridemia means having very high levels of triglycerides, a type of fat, in the blood. Phase 3 means it's a late stage of testing to check if the medication is safe and works well. Participants will get plozasiran injections every 3 months or a placebo (a dummy treatment) for a year. After 12 months, they might continue with the real medication in another part of the study.

To join, you must have high triglyceride levels (≥500 mg/dL) shown in tests taken twice, no more than 17 days apart, and be on certain medications unless you can't take them. If you've taken certain similar drugs recently, you can't join.

• Study lasts for 12 months with an option for more if eligible.
• Involves regular injections every 3 months.
• Participants may receive a placebo, meaning no active treatment.