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Zodasiran for Adolescents With Homozygous Familial Hypercholesterolemia: A Phase 3 Study of Efficacy and Safety

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on Homozygous Familial Hypercholesterolemia, a rare inherited condition that causes extremely high levels of cholesterol from birth, especially a type called LDL‑C (low‑density lipoprotein cholesterol, often called “bad” cholesterol). The investigational medicine, zodasiran, is given as a small amount of liquid (200 mg) injected under the skin (subcutaneous injection) to try to lower these cholesterol levels.

The purpose of the study is to see whether treatment with zodasiran can reduce LDL‑C in teenage participants aged 12 to under 18 years. Over about a year, participants receive regular injections and have blood drawn at scheduled visits to check changes in LDL‑C as well as other blood substances such as Apolipoprotein B (a protein that carries cholesterol), non‑HDL‑C (all cholesterol that is not the “good” HDL), Triglycerides (a type of fat in the blood), Angiopoietin‑like Protein 3 (a protein that can affect cholesterol levels), and HDL‑C (high‑density lipoprotein cholesterol, often called “good” cholesterol). The trial is open‑label, meaning both doctors and participants know the medication being used, and there is no comparison group.

The research process

The trial runs in 9 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment and consent

    You provide written informed consent to join the study after receiving information about its purpose and procedures.

    Your participation is recorded and you become an enrolled participant in the trial.

  2. Step 2

    Screening assessments

    You undergo medical history review, physical examination, and laboratory tests to confirm that you have homozygous familial hypercholesterolemia (HoFH) and meet the study criteria.

    All results are evaluated before any study medication is given.

  3. Step 3

    Baseline visit

    You provide a fasting blood sample that is used to measure baseline levels of LDL‑C (the “bad” cholesterol) and other lipids.

    Additional baseline measurements, such as apolipoprotein B, non‑HDL‑C, triglycerides, ANGPTL3, total cholesterol, and HDL‑C, are recorded.

  4. Step 4

    First dose administration

    A study nurse gives you a subcutaneous injection (injection under the skin) of zodasiran at a dose of 200 mg in a solution for injection.

    The injection site and technique are explained to you.

  5. Step 5

    Ongoing treatment period

    You receive additional subcutaneous injections of zodasiran 200 mg at each scheduled study visit throughout the 12‑month treatment period.

    Each injection is administered by study staff according to the study schedule.

  6. Step 6

    Regular clinic visits for monitoring

    You attend clinic visits at predetermined intervals (for example, monthly) where safety checks are performed.

    At each visit a fasting blood sample is taken to assess changes in LDL‑C and other lipid measurements.

    You are asked about any symptoms or side effects you may have experienced since the previous visit.

  7. Step 7

    Mid‑study assessment

    Around month 6, a comprehensive evaluation is conducted to review your cholesterol levels, other lipid values, and overall safety.

    The results help determine how the medication is affecting your condition.

  8. Step 8

    Final month‑12 visit

    You provide a fasting blood sample that is used to calculate the primary outcome: the percent change in LDL‑C from baseline to month 12.

    Secondary outcomes, such as changes in apolipoprotein B, non‑HDL‑C, triglycerides, ANGPTL3, total cholesterol, HDL‑C, and the occurrence of any adverse events, are also measured.

  9. Step 9

    End‑of‑study procedures

    Study staff review all collected data and discuss any remaining health considerations with you.

    The study medication is discontinued, and you receive guidance on follow‑up care as appropriate.

Who can join the trial?

7 criteria

  • Adolescents aged 12 to less than 18 years, who are not pregnant, not breastfeeding, and do not plan to become pregnant during the study.
  • Weight of at least 35 kilograms at the time of screening.
  • Diagnosis of Homozygous Familial Hypercholesterolemia (HoFH) confirmed by a genetic test from a medical record or by a clinical diagnosis.
  • Screening LDL‑C (the “bad” cholesterol) level of 116 mg/dL (3 mmol/L) or higher.
  • Screening hemoglobin A1c (a blood test that shows average blood sugar over the past few months) of 9.5% or lower.
  • Screening total bilirubin (a substance that indicates liver function) less than twice the normal upper limit, unless you have Gilbert’s syndrome (a mild, harmless liver condition).
  • Screening levels of alanine aminotransferase (ALT) or aspartate aminotransferase (AST) (liver enzymes) less than three times the normal upper limit.

Who cannot join the trial?

5 criteria

  • Use of a hepatocyte‑targeted siRNA (a liver‑directed medicine that tells cells to stop making a certain protein) within the past 365 days, except for inclisiran; the study drug and inclisiran must be given at least 4 weeks apart.
  • Use of an antisense oligonucleotide (a short DNA/RNA piece that blocks production of a specific protein) within the past 3 months.
  • Use of evinacumab (a medication that blocks a protein involved in cholesterol regulation) within the past 3 months.
  • Use of systemic corticosteroids (steroid medicines taken by mouth, injection, or inhalation that affect the whole body) unless they are being used as a stable replacement for a pituitary or adrenal gland disorder.
  • Other study‑specific criteria may also prevent participation, as described in the trial protocol.
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Investigated drugs

Zodasiran is an experimental medicine being tested in this study. It is given as a liquid that is injected under the skin (subcutaneous injection). Zodasiran uses a special technology to lower the amount of a protein that causes very high “bad” cholesterol (LDL‑C). By reducing that protein, the drug aims to lower LDL‑C levels in teenagers who have homozygous familial hypercholesterolemia. The trial is looking at how much it can lower LDL‑C and whether it is safe for young people.

What is already known about the treatment

ZODASIRAN - Zodasiran is given as a subcutaneous injection of a 200 mg solution for injection, meaning it is administered under the skin using a small needle. It is an investigational RNA‑targeting therapy that is currently in Phase 3 clinical trials and not yet approved for general medical use. The drug is being studied for people, especially adolescents, with homozygous familial hypercholesterolemia, a condition that causes very high LDL cholesterol levels. Zodasiran works by binding to the messenger RNA that produces a protein involved in cholesterol production, reducing its creation and thereby lowering LDL‑C levels, and it belongs to the class of small interfering RNA (siRNA) medicines.

Investigated diseases

Homozygous Familial Hypercholesterolemia (HoFH) - It is a genetic condition where the body cannot remove low‑density lipoprotein (LDL) cholesterol efficiently. People are born with very high LDL levels that stay high throughout life. The excess cholesterol can build up in blood vessels and around the heart. Over time, this may lead to early signs of artery narrowing. The condition is present from birth and the cholesterol levels tend to remain elevated without intervention.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-523662-24-00Protocol codeAROANG3-3003Estimated enrolment12 patientsSponsorArrowhead Pharmaceuticals Inc.

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