Upon joining the study, you will be assigned to one of two parts based on your age. Age Cohort 1 includes participants aged 12 to less than 18 years. Age Cohort 2 includes participants aged 6 to less than 12 years.

You will first enter either Part A or Part B of the study. Part A focuses on measuring how the medication moves through your body. Part B compares the effectiveness of the medication against a placebo, which is an inactive substance that looks like the medication but contains no active ingredient.

If you are assigned to Part A, you will receive enlicitide, also known as MK-0616. This medication is provided as a film-coated tablet that you will take by mouth.

The study will measure the maximum concentration of the medication in your blood and the total amount of medication in your blood over 24 hours.

Part A lasts until Day 14, at which point you will have completed Visit 5. After completing this visit, you may be eligible to continue into the open-label extension period.

If you are assigned to Part B, you will be randomly assigned to receive either enlicitide (MK-0616) or a placebo. The placebo looks identical to the active medication but contains no active ingredient.

The medication or placebo is provided as a film-coated tablet that you will take by mouth.

Throughout Part B, you will continue taking your current cholesterol-lowering medications at the same doses you were taking before joining the study. These may include statins or other medications used to lower cholesterol levels.

Part B lasts for 24 weeks. During this time, the study will measure changes in your LDL cholesterol, which is often called bad cholesterol, and other cholesterol-related markers in your blood.

Throughout the 24-week period of Part B, regular visits will occur to monitor your health and measure various cholesterol levels in your blood.

The study will track changes in LDL cholesterol, apolipoprotein B (a protein that carries cholesterol in your blood), non-HDL cholesterol (all cholesterol except the good kind), and lipoprotein (a), which is another type of cholesterol particle.

An ultrasound measurement of the thickness of the inner layers of your carotid artery (a major blood vessel in your neck) may also be performed to assess changes over time.

At Week 24, you will complete Visit 7, marking the end of Part B.

After completing Part A (at Day 14) or Part B (at Week 24), you may be eligible to enter the open-label extension period. During this phase, all participants will know they are receiving the active medication enlicitide.

To be eligible for this extension, you must have received at least one dose of the study medication during Part A or Part B and completed the required final visit for that part.

The open-label extension allows continued treatment and monitoring of the medication’s safety and effects over a longer period of time.

The specific duration and dosing schedule for the open-label extension period will be determined based on the study protocol.

Throughout all parts of the study, including Part A, Part B, and the open-label extension, your safety will be monitored continuously.

Any adverse events, which are unwanted or harmful effects that occur during the study, will be recorded and evaluated.

If you experience side effects that are concerning, the study team may decide to stop your treatment with the study medication.