A Study of ALN-PCSSC in Participants With Homozygous Familial Hypercholesterolemia (HoFH)

- Males and females, ≥12 years of age with a diagnosis of homozygous familial hypercholesterolemia by genetic confirmation or a clinical diagnosis based on a history of an untreated low-density lipoprotein cholesterol (LDL-C) concentration >500 mg/deciliter (dL) [13 millimoles/liter (mmol/L)] together with either xanthoma before 10 years of age or evidence of heterozygous familial hypercholesterolemia in both parents.

- Stable on a low-fat diet.

- Stable on pre-existing, lipid-lowering therapies (such as statins, cholesterolabsorption inhibitors, bile-acid sequestrants, or combinations thereof) for at least 4 weeks with no planned medication or dose change for the duration of study participation.

- Fasting central lab LDL-C concentration >130 mg/dL (3.4 mmol/L) and triglyceride concentration <400 mg/dL (4.5 mmol/L).

- Body weight of 40 kilograms (kg) or greater at screening.

- LDL or plasma apheresis within 8 weeks prior to the screening visit, and no plan to receive it during the study because of the attendant difficulty in maintaining stable concentrations of LDL-C while receiving apheresis.

- Use of mipomersen or lomitapide therapy within 5 months of screening.

- Previous treatment with monoclonal antibodies directed towards PCSK9 within 8 weeks of screening. The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.