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RecruitingNCT07727538Updated Nov 2, 2026

A Study of Olezarsen for the Treatment of Familial Chylomicronemia Syndrome (FCS) in Pediatric Participants

A Phase 3 interventional study of Olezarsen in Familial Chylomicronemia Syndrome, sponsored by Ionis Pharmaceuticals, Inc.. Recruiting at 6 sites in United States. Open to participants aged 2 Years to 17 Years. Per ClinicalTrials.gov, last updated 2026-11-02.

Sponsored by Ionis Pharmaceuticals, Inc. · Phase 3, Interventional, and Treatment

From the registry’s dates

  • Started Jul 2026; still recruiting 3 months later.
Updated Nov 2, 20262 sites addedGo to Updates ↓
Phase
Phase 3
Study type
Interventional
Enrollment
12
Allocation
Not applicable
Ages
2 Years to 17 Years
Sex
All
01

Study summary

The primary purpose of the study is to evaluate the efficacy of olezarsen administered by subcutaneous injection to pediatric participants with FCS.

Read the detailed description

This is a Phase 3 multi-center open-label study to evaluate safety, pharmacokinetics (PK), efficacy, and pharmacodynamics (PD) of olezarsen in pediatric participants (aged 2 to less than (\<)18 years) with FCS. This study consists of three to four periods with the following approximate timeframes: 1-month screening period, 1-year treatment period, an optional 1-year long-term extension treatment period, and a 3-month post-treatment follow-up period.

02

Conditions studied

  • Familial Chylomicronemia Syndrome
03

In context

Lead sponsor

Ionis Pharmaceuticals, Inc. is the lead sponsor of 118 studies on the registry; 10 are open to participants now.

Of its 49 completed or terminated interventional studies of FDA-regulated products, 22 (45%) have results posted.

Browse Ionis Pharmaceuticals, Inc. studies →

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
2 Years to 17 Years
Sexes eligible
All
Accepts healthy volunteers
No

Eligibility criteria

Key Inclusion Criteria:

  1. Parental or legally authorized representative consent must be obtained, and the participants must provide age-appropriate or cognition-appropriate assent, as determined by the Investigator. The parent or legal guardian must be able to understand and comply with the study visit schedule and all other study procedures.
  2. Must be able to comply with all study procedures.
  3. Age 12 to less than 18 years at the time of /assent (Cohort 1); age 2 to less than 12 years at time of informed consent/assent (Cohort 2).
  4. Willing to fast for at least 10 hours before visits requiring fasted blood sampling.
  5. A diagnosis of Familial Chylomicronemia Syndrome (type 1 Hyperlipoproteinemia) by documentation of confirmed homozygote, compound heterozygote or double heterozygote for loss-of-function mutations in type 1-causing genes.
  6. Fasting TGs ≥880 mg/dL at screening. If fasting TG is \< 880 mg/dL, up to two additional tests may be performed during the screening period with any single test used to qualify.

Key Exclusion Criteria:

  1. Diabetes mellitus with any of the following:

    1. Newly diagnosed within 12 weeks prior to screening or during the screening period.
    2. (HbA1c) ≥9.5% at screening.
    3. Change in basal insulin regimen >20% within 3 months prior to screening or during the screening period.
    4. Type 1 diabetes.
  2. History of bleeding, diathesis, or coagulopathy.
  3. Major surgery within 3 months of screening.
  4. Plasma apheresis within 4 weeks prior to screening or planned during the study.
  5. Treatment with another drug, biological agent, or device within one month of screening, or 5 half-lives of investigational agent, whichever is longer.
  6. Active pancreatitis within 4 weeks prior to screening or during the screening period.
  7. diagnosed or treated within 5 years prior to screening or during the screening period.

Note: Other protocol-specified inclusion/exclusion criteria may apply.

Terms in these criteria, in plain language(4)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

HbA1c

A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

Cancer (malignancy)

Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.

Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.

05

Study design

Phase
Phase 3
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
12 participants (estimated)

Study arms

  • Experimental
    Cohort 1

    Participants aged 12 to \<18 years will receive multiple doses of olezarsen, at a dose level that depends on body weight, once every month by subcutaneous injection for up to 1 year. All participants may continue to the optional 1-year long-term extension period with the last dose received being after 2 years of treatment.

    Drug: Olezarsen

  • Experimental
    Cohort 2

    Participants aged 2 to \<12 years will receive multiple doses of olezarsen, at a dose level based on information obtained from Cohort 1, once every month by subcutaneous injection for up to 1 year. All participants may continue to the optional 1-year long-term extension period with the last dose received being after 2 years of treatment.

    Drug: Olezarsen

Interventions

  • DrugOlezarsen

    Olezarsen will be administered by subcutaneous injection.

    Also known as: ISIS 678354

06

What researchers measure

Primary outcomes

  1. Percent Change from Baseline in Fasting Triglycerides (TG)

    Time frame: At 6 Months

Secondary outcomes

  1. Number of Participants with Treatment-emergent Adverse Events (TEAEs) and Serious TEAEs Including Independently Adjudicated Events of Pancreatitis, and Withdrawals due to Adverse Events (AEs)

    Time frame: Up to 24 Months

  2. Change From Baseline in Vital Sign Parameter - Heart Rate (Beats per Minute)

    Time frame: Baseline up to 24 Months

  3. Change From Baseline in Vital Sign Parameter - Blood Pressure (Systolic and Diastolic, mmHg)

    Time frame: Baseline up to 24 Months

  4. Change From Baseline in Vital Sign Parameter - Oxygen Saturation (%)

    Time frame: Baseline up to 24 Months

  5. Change From Baseline in Vital Sign Parameter - Respiratory Rate (Breaths per Minute)

    Time frame: Baseline up to 24 Months

  6. Change From Baseline in Vital Sign Parameter - Body Temperature (°C)

    Time frame: Baseline up to 24 Months

  7. Change From Baseline in Body Weight (kg)

    Time frame: Baseline up to 24 Months

  8. Change From Baseline in Height (cm)

    Time frame: Baseline up to 24 Months

  9. Change From Baseline in Pubertal Development Parameter - Sexual Maturity Rating (Tanner Stage)

    Time frame: Baseline up to 24 Months

  10. Change From Baseline in Pubertal Development Parameter - Menarche (Age to the Nearest Month and Year)

    Time frame: Baseline up to 24 Months

  11. Change From Baseline in Clinical Laboratory Parameter - Amylase

    Time frame: Baseline up to 24 Months

  12. Change From Baseline in Clinical Laboratory Parameter - Lipase

    Time frame: Baseline up to 24 Months

  13. Change From Baseline in Clinical Laboratory Parameter - Alanine Aminotransferase (ALA)

    Time frame: Baseline up to 24 Months

  14. Change From Baseline in Clinical Laboratory Parameter - Aspartate Aminotransferase (AST)

    Time frame: Baseline up to 24 Months

  15. Change From Baseline in Clinical Laboratory Parameter - Platelets

    Time frame: Baseline up to 24 Months

  16. Change From Baseline in Electrocardiogram (ECG) Parameter - Heart Rate

    Time frame: Baseline up to 24 Months

  17. Change From Baseline in ECG Parameters Including PR Interval, QRS Duration, QT Interval, and QT Corrected Interval Fridericia's (QTcF)

    Time frame: Baseline up to 24 Months

  18. Peak, Trough (Pre-Dose), and Post-treatment Plasma Concentration of Olezarsen

    Time frame: Up to 24 Months

  19. Change From Baseline in Pediatric Quality of Life Inventory (PedsQL) Generic Core Scales

    Time frame: Baseline up to 24 Months

  20. Change from Baseline in PedsQL Pediatric Pain Questionnaire (PPQ)

    Time frame: Baseline up to 24 Months

  21. Change from Baseline in PedsQL Gastrointestinal Symptoms Module

    Time frame: Baseline up to 24 Months

  22. Percent Change from Baseline in Fasting TG

    Time frame: Baseline, 3 Months, 12 Months, 18 Months, 24 Months

  23. Proportion of Participants who Achieve Fasting TG <880 milligrams per deciliter (mg/dL)

    Time frame: 3 Months, 6 Months, 12 Months, 18 Months, 24 Months

  24. Proportion of Participants who Achieve Fasting TG <500 mg/dL

    Time frame: 3 Months, 6 Months, 12 Months, 18 Months, 24 Months

  25. Proportion of Participants who Achieve ≥40 Percent (%) Reduction in Fasting TG from Baseline

    Time frame: 3 Months, 6 Months, 12 Months, 18 Months, 24 Months

  26. Percent Change from Baseline in Apolipoprotein C-III (apoC-III), Very Low-density Lipoprotein Cholesterol (VLDL-C), Non High-density Lipoprotein Cholesterol (non-HDL-C)

    Time frame: Baseline, 3 Months, 6 Months, 12 Months, 18 Months, 24 Months

  27. Percent Change from Baseline in High-density Lipoprotein Cholesterol (HDL-C) Low-density Lipoprotein Cholesterol (LDL-C), Apolipoprotein B (apoB), Apolipoprotein B-48 (ApoB-48)

    Time frame: Baseline, 3 Months, 6 Months, 12 Months, 18 Months, 24 Months

  28. Event Rate of Adjudicated Acute Pancreatitis

    Time frame: 3 Months, 6 Months, 12 Months, 18 Months, 24 Months

  29. Percentage of Participants with Abdominal Pain Prior to First Dose vs. TEAEs

    Time frame: 3 Months, 6 Months, 12 Months, 18 Months, 24 Months

  30. Change From Baseline in Liver Size as Assessed by Magnetic Resonance Imaging (MRI)

    Time frame: Baseline, 12 Months, 24 Months

  31. Change From Baseline in Liver Fat Content as Assessed by MRI

    Time frame: Baseline, 12 Months, 24 Months

  32. Incidence of Anti-Drug Antibodies (ADA) to Olezarsen

    Time frame: Pre-dose on Days 1, 1 Month, 3 Months, 6 Months, 9 Months, 12 Months, 18 Months and 24 Months; and post-dose on Days 1 and 6 Months

  33. Titer of ADA to Olezarsen

    Time frame: Pre-dose on Days 1, 1 Month, 3 Months, 6 Months, 9 Months, 12 Months, 18 Months and 24 Months; and post-dose on Days 1 and 6 Months

  34. Incidence of Participants with Negative, Treatment-Unaffected, or Treatment-Emergent ADA to Olezarsen

    Time frame: Pre-dose on Days 1, 1 Month, 3 Months, 6 Months, 9 Months, 12 Months, 18 Months and 24 Months; and post-dose on Days 1 and 6 Months

  35. Onset of Treatment-Emergent ADA to Olezarsen

    Time frame: Pre-dose on Days 1, 1 Month, 3 Months, 6 Months, 9 Months, 12 Months, 18 Months and 24 Months; and post-dose on Days 1 and 6 Months

  36. Time to Onset of Treatment-Emergent ADA to Olezarsen

    Time frame: Pre-dose on Days 1, 1 Month, 3 Months, 6 Months, 9 Months, 12 Months, 18 Months and 24 Months; and post-dose on Days 1 and 6 Months

07

Study locations

6 of 6 sites recruiting
08

References and documents

Individual participant data

Plan to share: Yes — Ionis may share anonymized individual participant data, aggregated clinical data, and other types of data that support the results in this study. Data requests from qualified researchers will be considered once all three of the following criteria are met: (1) 12 months from marketing approval of the study drug in both the United States and European Union; (2) 18 months from conclusion of the study; and (3) 6 months from publication of study article. Access would be via a secure environment and is contingent upon approval of a research proposal and entry into an appropriate data use agreement. Requests to access data can be submitted via the website https://vivli.org/ourmember/ionis/.

Data sharing details ↗ · vivli.org

No publications or documents are linked to this record.

09

Updates

2 registry updates since Sep 25, 2026
Sites
2 sites added
Show 2 added (2 United States)
  • Mary Bridge Children's · Tacoma, United States
  • Children's Mercy Hospital · Kansas City, United States
across 2 updates, Oct 8, 2026 – Nov 2, 2026
Show all 2 updates
  1. Nov 2, 2026
    1 site added
    Show site
    • Children's Mercy Hospital · Kansas City, United States
  2. Oct 8, 2026
    1 site added
    Show site
    • Mary Bridge Children's · Tacoma, United States
    + 1 other change: verification date

From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗

10

Registry details

Key details

Study ID
NCT07727538
Lead sponsor
Ionis Pharmaceuticals, Inc.
Responsible party
Sponsor
First posted
Jul 27, 2026
Start date
Jul 31, 2026
Primary completion
Aug 2030 (estimated)
Completion
Aug 2031 (estimated)
Last update
Nov 2, 2026

Study contacts

Ionis Pharmaceuticals, Inc.
Contact
IonisOlezarsenPediatric@clinicaltrialmedia.com
(844) 200-6410

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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